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Using Robotic Technology to Inspect Underground Spaces Using Robotic Technology to Inspect Underground Spaces ▲ Senior Research Fellow Lee Seong-won and Research Specialist Shim Seung-bo, Department of Geotechnical Engineering Research Complex and Diverse Underground Spaces The underground space of the city is a familiar place. It has huge shopping malls, serves as a passageway for transportation, and becomes a workplace as well. With the full utilization of underground spaces, the range of human activity has been expanded greatly, but is also naturally accompanied by risks. There are various risk factors such as collapse or flooding that accompany the underground space. The Department of Geotechnical Engineering Research at KICT is researching geotechnical engineering technologies that are essential to civil engineering construction, such as for tunnels and underground spaces, structural foundations, slopes, soft ground, and earthquakes. “Based on our current progress in research and development, the Department of Geotechnical Engineering Research is working with a focus on four major research subjects. To be specific, when constructing earthworks and foundation structures, they are classified under “development of technologies for automation of quality control,” “development of technologies for advanced management of three-dimensional infrastructure,” “development of technologies for securing safety of earthquake response facilities,” and “development of technologies for utilizing large underground spaces.” Members of the department are dedicated to the research based on expertise in their respective field. With our cutting-edge research achievements, we are leading the development of technologies for South Korea’s underground spaces.” With industrialization progressing in earnest, Korea's underground spaces are also becoming more and more complex. As the highways were built, tunnels through mountains were also constructed in various places, and recently the world's fifth longest undersea tunnel was opened in Boryeong. Research Specialist Sim Seung-bo explains that the underground space in Korea can be largely classified into railway tunnels, road tunnels, undersea tunnels, and utility-pipe conduit tunnels based on characteristics such as shape, size, and use. “The longest high-speed rail tunnel in South Korea is the Yulhyeon Tunnel, which is 50.25 km long and connects Suseo Station in Seoul to Jije Station in Pyeongtaek. The recently completed Boryeong Undersea Tunnel is one of the undersea tunnels, stretching to a length of 6.93 km. Finally, the most important tunnel is the utility-pipe conduit tunnel. This tunnel contains systems accommodating electricity, communication, heating, water, and conduit pipes necessary for living in the city. This tunnel is called a “lifeline” because it acts like the blood vessels that distribute energy to the body. Such tunnels are classified as national security facilities and are kept inaccessible to the general public.” Utility-pipe Conduit Accidents Leading to Large-scale Disasters A fire that broke out in the communication tunnel under the KT Ahyeon branch building on November 24, 2018 was an accident that clearly demonstrated the importance of the utility-pipe conduit tunnel. As a result of the accident, approximately 79 m of the communications tunnel on the first basement floor was burned out, and the Internet, mobile phone, and the wireless communications services provided by KT in the western area north of the Hangang River in Seoul became unavailable. “Unlike other tunnels, the utility-pipe conduit tunnel takes up space even for the internal accommodation facilities, so the space for people to move is very narrow. That was why it took so much time to extinguish the fire, which soon led to a large-scale accident. Based on the total amount of damage at that time alone, KRW 8 billion in property damage and KRW 30 billion in compensations were incurred. On the day of the accident, text messages were sent out to inform people, but no one could know why their phones were not working because the KT network was cut off.” It was called a digital disaster situation, where financial transactions and payment systems were cut off as the high-speed internet was unavailable at the time, and an elderly person in his 70s who could not report to 119 for help ended up dying due to the severance of communications. As a result, the scale and impact of direct and indirect damages in our daily life and society from an accident in the utility-pipe conduit tunnel raised the awareness that it could potentially lead to a bigger and more serious disaster than previously anticipated. Accordingly, thorough inspection and management of underground spaces including utility-pipe conduits have become much more important. “In Korea, infrastructure built during the period of economic development and growth are gradually approaching the end of their life expectancy, resulting in more frequent accidents. Such accidents can inevitably increase with aging, which has prompted us to take a closer look at practical ways to protect the safety of our citizens from such risks.” Robotic Technology Enabling Autonomous Travel and Inspection Periodic inspection is the most important means to safely manage underground space facilities. In particular, management through regular precision inspection is required. The conventional inspection method is known to have been carried out in a human-centered manner. Precision inspection is an inspection method where the inspector visually checks the damage point, then measures and records the size of the specific point using a crack gauge or crack detection microscope. In this case, it is said that it is not easy to diagnose the condition objectively because it inevitably involves the subjective judgment of the inspector. In addition, there are disadvantages in that costs are continuously required to improve safety through maintenance by increasing the frequency of inspection. The research team has developed technology for an automated inspection robot that travels inside the tunnel in the place of workers to inspect damage points on concrete structures. “The development of technology for automated inspection robots is divided into three phases: The phase of developing the core technology for each constituent technology, the phase of integration between constituent technologies, and the phase of on-site testing. In Phase 1, damage detection technology using deep learning as well as damage measurement technology using stereo vision are developed. In Phase 2, an inspection scenario according to the measurement result is implemented by linking the uncrewed moving object and the robot arm. Finally, automated inspection robotic technology is completed through on-site testing so that precision inspections can be performed in a tunnel environment.” The biggest advantage of automated inspection robotic technology is that it can be used flexibly in maintaining underground spaces based on the convergence of multiple core technologies. The robot is applied with technology for an uncrewed traveling object that can autonomously travel inside the tunnel, technology for the robot arm that can avoid complex internal accommodation facilities, and technology for the artificial intelligence sensor that can detect and measure damage points. This inspection technology was developed to also enable remote control through a wireless network, enabling convenient application by administrators. "The utility-pipe conduit is an underground lifeline; it is a tunnel that jointly accommodates communications lines, utility lines, and heating and gas pipes. In the past, tunnels and pipelines were laid in a complex urban underground system according to their respective uses, such as communications, utilities, and gas pipelines. To facilitate joint accommodation, it is essential to cut the costs of operating and maintaining utility-pipe conduits. It is expected that operation and maintenance costs can be reduced through the use of automated inspection robotic technology and that various accommodation facilities can be safely and efficiently managed within the utility-pipe conduit tunnel.” Provision of Safe and Sustainable Infrastructure The research team plans to continue its research to provide safe and sustainable infrastructure to society. The team will continue to advance this research in various forms and ultimately contribute its best efforts to the perfection of uncrewed and automated technologies for the maintenance of underground facilities. “In our future society, the aging of our population will be accelerated thanks to the extension of average life expectancy, while the economically active population will decrease accordingly. Under such circumstances, the maintenance of infrastructure relying on the workforce is expected to become more difficult. In response to these issues, we plan to develop the necessary technologies for automation and uncrewed maintenance and to further develop the technologies needed to enable automated damage repair.” Department of Geotechnical Engineering Research Date2022-03-28 Hit 949
Cloud-based Integrated Indoor Air Quality Control System for Public Use Facilities Cloud-based Integrated Indoor Air Quality Control System for Public Use Facilities ▲ Research Fellow Song Su-won, Indoor Air Quality Organization Preface Recently, the importance of natural ventilation has gained attention due to public anxiety about the spread of COVID-19 in public use facilities. Interest in ventilation systems installed with high efficiency filter has also increased due to the connection between air pollution, such as particulate matter and other pollutants, and various respiratory and skin diseases. In addition to outdoor air pollution, the period for natural ventilation is becoming shorter and shorter as a result of heat waves and extreme heat due to climate change. Moreover, due to the inadequate operation and maintenance of ventilation systems, there are growing concerns with indoor air quality in public use facilities. Ventilation systems help improve indoor air quality and reduce pollutants. However, if these systems are not managed properly, they can actually harm people’s health. System characteristics and usage patterns can also widely vary, particularly in the case of public use facilities such as elderly care facilities, daycare centers, and underground complex facilities. Therefore, it is important to set standardized control criteria for indoor air quality by facility type and to establish measures for the efficient operation and management of ventilation systems based on indoor air quality monitoring data.In an effort to promote the comprehensive management and improvement of the indoor air quality of public use facilities, this article introduces and discusses the configuration and related services of the Cloud-based Integrated Indoor Air Quality Control System for Public Use Facilities, developed by the Indoor Air Quality Organization of the Korea Institute of Civil Engineering and Building Technology (KICT). Measures to Control Indoor Air Quality in Public Use Facilities In South Korea, air quality standards for public use facilities are generally being recommended by type of facility with "Standards for Maintaining Indoor Air Quality" and "Recommended Standards for Indoor Air Quality" in accordance with the Enforcement Regulations of the Indoor Air Quality Control in Public Use Facilities, Etc. (hereinafter "Enforcement Regulations on Indoor Air Quality Control") by the Ordinance of the Ministry of Environment. However, some local governments have established their own ordinances to measure and control indoor air quality on a regular basis. Table 1 shows standardized pollutant limits for the maintenance of indoor air quality for public use facilities. These standards set limits for a total of 10 substances including particulate matter (PM-10), carbon dioxide, formaldehyde, total floating bacteria, carbon monoxide, ultra fine particulate matter (PM-2.5), nitrogen dioxide, radon, total volatile organic compounds, and mold. The control standards for each pollutant are continuously being strengthened. The indoor air quality in public use facilities varies greatly depending on the type of facility and how well the air quality is controlled. Therefore, in order to systematically and comprehensively control and improve indoor air quality at public use facilities, it is necessary to develop efficient ventilation controls and data-based, integrated control technologies that reflect the characteristics and usage patterns of different facility types. In other words, it is necessary to develop technologies that collect and store information on indoor air pollutants measured in real time through IoT sensors installed indoors and outdoors. It is also necessary to develop technologies that can effectively control and improve various aspects of indoor air quality using sensor-based environmental control algorithms, as well as to develop systems for the active control of heating, cooling, and ventilation and for rapid response to safety accidents. Furthermore, in order to develop efficient technology, it is necessary to implement a cloud-based integrated system to control indoor air quality, and related services requires customization per type and region of public use facility (users, building managers, local governments, etc.). Cloud-based Integrated Indoor Air Quality Control System In order to provide active, cloud-based, indoor air quality management and services, the Indoor Air Quality Organization constructed its own cloud server—including a communications server, DB server, processing server, and communication network security equipment—at the KICT. The organization is using this cloud server to conduct empirical research on public use facilities such as elderly care facilities, daycare centers, and underground complexes. As shown in Figure 1, the cloud server of the Integrated Indoor Air Quality Control System is largely divided into: a data communications, processing, and connection server; a data storage DB server; and a Web/WAS integrated virtualization server. The data communications/processing/connection server collects information on the facility, indoor and outdoor air quality, and the operation of the facility’s control equipment, all of which is transmitted through the cloud network by various indoor air quality (IAQ) and outdoor air quality (OAQ) sensors, ventilation systems (or air purifiers, etc.), and mobile devices. This collected information is transmitted to the data storage DB (Database) server. The integrated Web/WAS virtualization server uses the Integrated Indoor Air Quality Control System to provide IAQ/OAQ monitoring, control, data analysis, and information sharing services for public use facilities. Integrated Indoor Air Quality Control System Service As shown in Figure 2, the Integrated Indoor Air Quality Control System consists of an IAQ integrated management and service module, a system control module, an external system interworking module, and a data collection module. The modules are configured in such a way so as to allow data to flow freely throughout the system. The IAQ integrated management and service module integrates and manages facility data collected from each module, data on the status and operation of indoor air quality control devices, such as the ventilation system, air purifiers, air conditioners, etc., and data on indoor and outdoor air quality. This integration of data makes it possible to provide customized services for each type of facility. In addition, since the IAQ integrated control and service module includes the IAQ integrated management, mobile, and connection (additional) services, it is possible to provide various services according to customer type. government) management services and individual facility (type) management services. For regional (local government) integrated control systems, as shown in Figure 4, the location of the relevant facility and surrounding outdoor air quality sensors are displayed on the map. When a system user clicks on a facility indicated on the map screen, the system displays item-specific indices for real-time measurement of indoor air quality as well as a weighted integrated indoor air quality evaluation index. Also, when the user clicks the relevant shortcut, the system displays an integrated monitoring screen that shows the overall status of indoor and outdoor air quality of the facility. After the user logs in and moves to the control screen of the ventilation system, the indoor air quality improvement devices (ventilation system, air purifier, etc.) can be controlled using manual, automated, or integrated operation methods, allowing for the selective control of various devices according to the real-time status of the facility’s indoor and outdoor air quality. The system can also predict and inform the user of the lifespan of built-in ventilation filters. Mobile services not only enable users of individual facilities to monitor indoor air quality, but they also allow users to register their indoor air quality improvement devices (IAQ sensors, ventilation systems, air purifiers, etc.) for control and maintenance. In other words, when a user, such as the building manager of a facility, logs into the system, he or she can view information on the status of the facility and its indoor air quality sensors and can even register the facility’s air improvement devices. Each registered IAQ sensor and indoor air quality improvement device (ventilation system, air purifier, air conditioner, etc.) across all connected facilities automatically transmits data to the cloud server through the network (using API, etc.) so that the facility user can monitor, in real time, the indoor air quality and maintain the facilities and equipment (such as ventilation systems or air purifiers) for the relevant location. As shown in Figure 6, connection (additional) services primarily include an IAQ improvement and management solution, a linked service, and an IAQ improvement solution. The IAQ improvement and management solution includes IAQ monitoring (sensor), IAQ improvement and management, fire services (prompt response to safety accidents), and standard operating procedures (SOP) for each facility type. Through the linked service, additional services can be linked to the system, such as a 3D/AR/VR system, occupancy detection and prediction system, and an AI-based indoor air quality prediction system. The IAQ improvement solution provides empirical data on and recommends IAQ improvement and management solutions for each type of facility. Conclusion In order to substantially improve and control the indoor air quality at public use facilities, it is necessary to implement an active integrated control system service that utilizes sensing data and that can perform efficient ventilation facility control, etc. that is well-suited to the characteristics and usage patterns of different types of facilities. This article introduced the configuration and related services of one such system—the Cloud-based Integrated Indoor Air Quality Control System for Public Use Facilities, developed by the KICT’s Indoor Air Quality Organization. Following the development of its Cloud-based Integrated Indoor Air Quality Control System for Public use Facilities, the Indoor Air Quality Organization continues to conduct empirical research to improve the overall indoor air quality at public use facilities, including daycare centers and underground complex facilities. Through its continuous cooperation with local governments, such as the Seoul, Incheon, Goyang, and Siheung governments, it is anticipated that the organization will be able to provide customized services for public use facilities and regional users (users, building managers, local governments, etc.). Date2021-12-28 Hit 1064
Development of Technology to Turn Food Waste Into Fuel Development of Technology to Turn Food Waste Into Fuel ▲ Research Specialist Ahn Kwang-ho and Senior Research Fellow Kim I-tae, Department of Environmental Research Preface Food waste has typically been recycled in the form of compost and animal feed, using methods such as: the fermentation extinction method, in which woody biochips and food wastes are mixed together in the presence of air; anaerobic digestion, in which microorganisms decompose food waste in the absence of air; and drying and carbonization, in which the food waste is dried and carbonized. As the fermentation extinction and anaerobic digestion methods make use of microorganisms, they require longer residence time and effective management of microorganisms. The drying and carbonization method requires partial energy as compared to the fermentation extinction and anaerobic digestion methods and requires shorter amount time for treatment, which ultimately makes it a useful method for recycling large amounts of food waste in a shorter amount of time compared to the fermentation extinction and anaerobic digestion methods. Renewable-energy Portfolio Standard (RPS) Possibility of Replacing Wood Pellets Using Food Waste Wood pellets are a type of material that is mainly used as a Bio Solid Refuse Fuel (Bio-SRF). Wood pellets are a solid refuse fuel used for coal-mixed firing, which is highly dependent on imports under the RPS system. As of 2019, compared to Korea’s domestic production of about 240,000 tons of wood pellets, a significantly higher volume of around 2.56 million tons were imported, which highlights the possibility of using biomass that utilizes food waste as a possible alternative to using wood pellets (Figure 1). Also, even though Bio-SRF is not as widely used as wood pellets for power generation, its use is consistently increasing (Figure 2). If biomass (produced using food waste) could be used to replace solid refuse fuels for coal mixed firing which are highly dependent on imports, it would save Korea approximately USD 280 million per year based on costs as of 2017. Biochar Biochar, a combination of the words biomass and charcoal, retains intermediate properties that are somewhere between organic matter and charcoal. These properties are the result of thermal decomposition that happens at a certain temperature in anoxic conditions (without the presence of oxygen). Although woody materials have been conventionally used to make biochar, in more recent years, organic resources such as food waste have been increasingly used as raw materials to manufacture biochar. Biochar is porous, so it has the advantage of promoting air circulation when it is injected into the soil. Additionally, since it does not promote decomposition or the transformation of microorganisms, it does not emit the carbon found in the soil into the atmosphere. As such, it is currently being considered for various uses. Current Status of Technology Development (Establishment of an Eco-friendly Pilot Plant) This study sought to explore an efficient treatment method for food waste as well as the potential use of food waste as fuel by lowering the salt concentration of the food waste in order to resolve the issue of high concentration of salt, which is a major obstacle to converting food waste into fuel. Researchers used a desalting process and a carbonization process (300–500 ℃ as temperature of the carbonization furnace) to produce a biochar that satisfies the quality standards (Table 2) for Solid Refuse Fuel products. Figure 3 shows the biochar production facility (working capacity of 100 kg) built within the Gimpo City Resource Center which has been used by the researchers. In order to make the biochar, researchers fed dry food samples through the fuel input hopper and carbonized the material at a temperature of 300 to 500 °C. The resulting gas was burned off through an emission gas combustion unit, and the resulting biochar was stored in the outlet. Salt was then removed from the biochar using a desalting system with Dissolved Air Flotation (DAF) technologies. The final biochar product was then dried and converted into fuel. Under temperature conditions of 300–500 ℃ and a residence time of 10–30 minutes, the high calorific value of the materials increased from an average of 5,475 kcal/kg before desalting to an average of 5,568 kcal/kg after desalting, and the chlorine ion concentration decreased from an average of 2.42% before desalting to an average of 0.97% after desalting. Based on these results, researchers concluded that, under certain temperature conditions, it was possible to use food waste to obtain biochar that could meet the quality standards for Bio Solid Refuse Fuel (Bio-SRF). Legislative Preparations Despite the feasibility of converting food waste into fuel using the above technology, it is difficult to turn food waste into fuel due to current legislation on renewable fuel materials (Table 3). In order for this technology for converting food waste to reach its full potential, it must be supported by appropriate legislation. Legislation should be promoted to allow food waste to be included as a Solid Refuse Fuel product if it meets certain criteria. Conclusion In March of last year, the Korea Institute of Civil Engineering and Building Technology (KICT) began working toward effectively treating and converting food waste into fuel by entering into business agreements with the Gimpo City Resource Center and the Korea Midland Power (KOMIPO). In the near future, it is considered that large amounts of food waste may be treated and utilized as compost and livestock feed, as well as be used as fuel through biomass gasification. Many researchers hope that technology and legislation can continue to advance so that food waste can be put to better use as a source of renewable fuel. Department of Environmental Research Date2021-12-28 Hit 1009
Analysis of Floods in North Korea Using Multiple Satellite Data on Precipitation (Flood Cases in August 2020) Analysis of Floods in North Korea Using Multiple Satellite Data on Precipitation (Flood Cases in August 2020) ▲ Research Fellow Kim Joo-hun, Department of Hydro Science and Engineering Research / Senior Researcher Choi Yun-seok, Department of Hydro Science and Engineering Research Estimation of Precipitation Using Satellite Data In the field of water resources and atmospheric science, remote sensing technology is widely recognized as a very useful tool that helps scientists observe global precipitation. Precipitation estimates obtained using satellite data target a broader spatial range than estimates obtained through ground observatories and weather radars and have the additional advantage of producing consistent and uniform precipitation information (Hong et al., 2016). Satellite precipitation estimates first became possible in April 1960 with the launch of the TIROS-1 (Television Infra-Red Observation Satellite), a cutting-edge satellite that provided scientists with meteorological images for the first time ever. In 1979, the field of meteorology took another step forward when meteorologist Phillip Arkin developed a method for estimating precipitation using infrared (IR) data. Another development came in 1987, when the Defense Meteorological Satellite Program (DMSP) launched a satellite equipped with an SSM/I (Special Sensor Microwave/Imager) and a multi-channel passive microwave radiometer, allowing for active research on precipitation estimates. In the 1990s, the importance of global precipitation estimates gained increased recognition, prompting the US NASA's Mission to Planet Earth Program to begin measuring precipitation from outer space. In 1997, NASA and the Japanese Aerospace eXploration Agency (JAXA) ramped up their efforts to produce satellite precipitation data and jointly launched the Tropical Rainfall Measuring Mission (TRMM) to estimate rainfall in tropical and subtropical regions (35°N–35°S). Following these series of developments, the scientific community began acquiring vast amounts of hydrological knowledge related to rainfall. Since the launch of the TRMM, satellite precipitation data has continued to be obtained through: Multi-satellite Precipitation Analysis (TMPA); NOAA CPC Morphing (CMORPH) at the NOAA’s Climate Prediction Center in the United States; and Global Satellite Mapping of Precipitation (GSMaP) by JAXA (Joo-hun Kim et al., 2015). The 2014 GPM Core satellite was designed to replace the TRMM satellite. The GMP Core satellite produces IMERG satellite precipitation data with a higher spatio-temporal resolution than previous satellites, boasting a temporal resolution of 30 minutes and a spatial resolution of 0.1 deg. for the spatial range of 60N–60S. Satellite precipitation data, such as that produced by the GPM Core satellite, promotes the scientific knowledge of global precipitation and accelerates the development of global eco-hydrological models. The data obtained from satellites is utilized for hydrological research in various ways and is used to analyze regional precipitation and/or flooding patterns (Hong et al., 2019). There are many regions worldwide—such as regions in East Asia, Southeast Asia, and Africa—where hydrological measurements have not yet been fully obtained and precipitation evaluation studies are actively being conducted using satellite precipitation data. Satellite precipitation data, such as IMERG and GSMaP, calculate precipitation estimates for most of the Earth' surface by combining information from the GPM satellite group pictured in Figure 1. This data is compiled to produce precipitation data on a global scale, as seen in Figure 2. NASA satellites produce IMERG date with 30-minute temporal resolution and 0.1deg. of spatial resolution, and JAXA satellites generate GSMaP satellite precipitation data with a 1-hour temporal resolution and 0.1 deg. of spatial resolution. Analysis of Floods in North Korea Using Precipitation Data From Multiple Satellites Hydrometeorological data for North Korea is produced at 6-hour intervals by compiling data from 27 observation stations in North Korea, reports from North Korean media, and the World Meteorological Organization (WMO). However, when researchers analyzed the precipitation data from the 27 North Korean observatories, from 03:00 on July 28, 2020 to 09:00 on August 7, 2020 through the Meteorological Data Open Portal site of the Korea Meteorological Administration, they found that the data from the aforementioned time period was 42.8% incomplete. These results led them to conclude that obtaining precipitation data from North Korea was disadvantageous because it is difficult to secure a full dataset for a specific time period, and the reliability of the data cannot be verified. On June 6, 2020, a North Korean defector made an appearance on the MBC Program “Unification Observatory” and commented that “weather forecasters [in North Korea] deceive even the North Korean Supreme Leader.” A spokesperson from the Korea Meteorological Administration responded, saying, “In weather forecasting, loyalty alone isn't enough to deliver correct information.” Currently, North Korea's weather prediction and observation technologies are evaluated as being at the same level as South Korea's in the 1990s. In order to overcome some of these gaps in data availability and accuracy, researchers analyzed the rainfall in North Korea using satellite data on the damage caused by heavy rains in North Korea in August 2020. They also used satellite precipitation data and the rainfall-runoff model to estimate the approximate amount of flooding and to determine other characteristics of rainfall and flooding in North Korea. In order to analyze the accuracy of the precipitation data obtained via satellite, researchers compared the satellite data with the total precipitation data obtained from three observation stations—Cheongyang-ri, Odeok Elementary School, and Sang-ri Elementary School—and GSMaP satellite precipitation data for the Han River system in Yeoncheon-gun, which is adjacent to North Korea. The correlation coefficient was determined to be about 0.996, meaning that the satellite precipitation data showed a high level of accuracy when compared to the data obtained through other means. Since the satellite data slightly underestimated the amount of precipitation, compared to measurements obtained on the ground, researchers calculated the precipitation distribution for North Korea by applying a correction factor of 1.69 to the satellite data, as shown in Figure 4. The GRM model employed by the KICT (Korea Institute of Civil Engineering and Building Technology) was used as an analysis tool for flood volume evaluation. Since the flow of floodwaters in North Korea cannot be actually observed by South Korean scientists, it was difficult for researchers to verify the results of their floodwater simulations. Therefore, the default parameters of the GRM model were applied to the floodwater/runoff simulation without any separate application of other corrective measures. Given these limitations, the researchers of the floodwater simulation study presented their results on simulated flow as “estimates,” as opposed to actual values. Furthermore, when conducting the runoff/floodwater simulation, the impact of dams and watersheds were not considered, and it was assumed that all flows were natural runoffs. The simulation area (Figure 4) included the entire region of North Korea, as well as some parts of China and Russia, which belong to the Amnok River and Duman River basins. Some areas of South Korea were also included in the simulation area as part of the Imjin River and the Bukhan River basins. In terms of the precipitation data utilized for the runoff simulation, calibrated satellite precipitation was applied for the period of 00:00 on August 1, 2020, to 00:00 on August 16, 2020 at a time interval of 1 hour. Figure 5 is a hydrograph comparing the simulated flow using the aforementioned calibrated satellite precipitation data and the observed flow at Hantan Bridge. The watershed area of Hantan Bridge is about 1,014 km2, and about 50% of the watershed is located in North Korea. There is also an additional reservoir with a watershed area of about 50 km2 in the upstream North Korean region. In Figure 5, the simulated flow at Hantan Bridge reflects the observed upward and downward trends of the hydrograph. However, the peak flooding that occurred around 15:00 on August 5 was estimated by the simulation to be higher (6,048㎥/s) than the flooding actually observed (4,785㎥/s). The differences between the simulation results and onsite observations were attributed to a variety of factors, namely, the fact that: the runoff model was not calibrated; the default model values were applied; and the impact of the many dams distributed throughout North Korea and watershed changes were not considered. The accuracy of the simulation flood estimates for North Korea could be improved if these issues were rectified. Despite these limitations, satellite precipitation data can be used as a substitute for ground observation data in areas where there is no ground observation data available, or in areas with a limited spatial and temporal range for ground observation. Satellite precipitation data also has the advantage of providing unified information on spatial expansion. In the future, the results from this study can be used to conduct further research on and improve the accuracy of precipitation data for the entire Korean Peninsula. Department of Hydro Science and Engineering Research Date2021-09-28 Hit 1425
Development of Smart Modular Multi-story Hanoks Development of Smart Modular Multi-story Hanoks ▲ Senior Research Fellow Lim Seok-ho, Department of Building Research The Concept of Smart Modular Hanoks A smart, modular, multi-story hanok is a multi-story hanok (Korean traditional house) comprised of cube-shaped modules that are pre-assembled, transported to a building site, and then assembled together like Legos, allowing for the excellent and quick completion of the building process. In other words, this type of hanok combines the off-site, modern modular construction method with the features of a traditional Korean house. This type of construction method improves the living environment of traditional Korean hanoks and improves their overall economic efficiency. In 2021, the Korea Institute of Civil Engineering and Building Technology (KICT) utilized integrated steel and wood technologies as well as structural glue-laminated timber (GLT) to advance its design and construction technologies and to create a smart, modular, multi-story hanok with a prefab percentage of 80% or more. Traditional Korean hanoks are very expensive, due to the use of onsite construction technologies, and typically have poor thermal and sound insulation. The KICT's module technology—used in 2017 to complete a demonstration project for a 6-story, multi-unit dwelling—solves these problems, improving housing performance, economic efficiency, and constructability. While researching this new construction process, developers created a bonding technology designed especially for lifting and stacking—enabling single-story hanok modules to be constructed into multi-story buildings—and developed a smart technology that improves the structural safety of the hanok balconies. The balcony is one of the major design elements of the multi-story hanok and features an upper handrail (gaeja-nangan) that projects outward. Using these technologies, developers were able to lay the groundwork for further technological and economic improvements, while also reducing costs by more than 30% (an effect of reducing the construction period by more than half). Traditional hanoks built onsite typically cost KRW 12 million per 3.3 m2. In order to verify the reusability, recyclability, and portability of their modular hanoks, developers dismantled and immediately reassembled the modular components. They then performed a series of assessments to demonstrate the constructability and technical feasibility of the smart, multi-story hanoks. The modular hanok construction technology was developed as part of the Hanok R&D Group and the Modular Multi-unit Dwelling Demonstration R&D Group, funded through the KICT's SME support project, implemented for two years, beginning from 2019. Key Technologies of Smart, Modular, Multi-Story Hanoks a. Development of Wooden, Modular Houses Using GLT GLT, with its verified structural integrity, is a critical element of building multi-story, modular hanoks. GLT is used in the modular hanok construction process for the development of converged and integrated joints, which are also equipped with horizontal and vertical connections and rings for lifting. In order to improve the overall performance of smart modular homes, it is necessary to create passive structures and dramatically reduce energy consumption, which can be achieved by using new materials for the external wall body (façade). Since South Korea has a relative lack of natural wood resources, GLT must be utilized by overlapping smaller pieces of wood, as opposed to large planks, the latter of which would create an overwhelming demand for wood. As seen in Figure 2, interconnected wooden modules for multi-story hanoks are constructed using steel hardware and applied with an exterior finishing material that preserves the traditional hanok appearance after the building has been completed. During the R&D process, the structural safety of these fabricated wooden modules was verified using a lift test (Figure 3). b. Standardization of Modular Hanok Technologies In order to secure the economic feasibility of multi-story, modular hanoks, it was imperative for developers to standardize and normalize all associated modular construction processes. As seen in Figure 4, developers sought to realize economy of scale and normalize modular development through the mass production of the MC design and by maintaining the preferred dimensions of key housing materials and parts. c. Technologies for the Assembly and Construction of Modular Hanoks The assembly and construction processes for modular hanoks, as shown in Table 1, were applied to the demonstration project completed in Yangpyeong, Gyeonggi-do, Korea. The completed demonstration project consists of three standard modules, each measuring 3 m×6 m, and an additional half-module (3.5 modules total) that spans two stories (92.56 m2 in total floor area). It took about three days to assemble the modules, and following construction, developers conducted a series of habitability performance tests, such as tests for airtightness and sound insulation. A BIPV system was attached to the surface of the outer wall of the “smart hanok,” and the solar energy produced as a result was used to light the interior of the eco-friendly hanok. In order to fully realize the developers’ vision of a “smart hanok,” a high-insulation, large-exterior, finish-integrated panel was applied to the structure and the joints were minimized to improve airtightness, sound insulation, and heat insulation performance. After the structure was completed, the developers conducted a series of verification and performance assessments, the results of which showed that the developers had achieved their goal of dramatically improving the habitability performance of traditional hanoks. Conclusion The scenic views of Korean houses—most commonly seen when traveling by train or looking down from a nearby mountain—are mostly comprised of hanoks that were erected during the Saemaeul Movement and have become one of the unique and representative features of South Korea. Now that Korea has risen to become one of the world’s top 10 economic powers, it is time to restore the dignity and identity of Korean houses to a level befitting national prestige. When people travel to other global regions, such as Switzerland in Europe, they often find themselves admiring and envying how the houses perfectly harmonize with the natural environment. It is clear that the governments of these countries had excellent insight and invested a considerable amount of money, over a long period of time, in systematic landscape management and housing maintenance at the national level. Even though Korea is known for its hanoks, which perfectly harmonize with Korea's natural environment and topography, the nation is now filled with apartments, which do not reflect Korea’s national identity, as well as low-end row houses and poor-quality single dwellings. It is high time for Korea to undergo a national housing transition and reorganization that revives and preserves the country’s original land and beauty. This study on modular hanoks was originally begun with these goals in mind. Hanoks, a type of traditional housing in Korea, have been overlooked and neglected in modern times due to their high costs, prolonged construction periods, and overall poor living environments. However, attempts should now be made to improve and popularize the traditional hanok by incorporating modern architectural technologies. As researchers and developers, we dream of creating a traditional hanok that anybody can enjoy. Although similar attempts have been made sporadically in the past, these attempts have undeniably failed due to excessive stubbornness on the part of those unwilling to modernize traditions and a lack of the general economic feasibility of hanoks. The development of modular “K-hanoks”—which combine bold modern construction methods and technologies with hanok apartment buildings, public buildings, and cultural and tourism auxiliary facilities—is leading the way for the reimagination of traditional hanok buildings. Department of Building Research Date2021-09-28 Hit 1800
Development of Smart Monitoring System for Concrete Structures Using FRP Nerve Sensors Development of Smart Monitoring System for Concrete Structures Using FRP Nerve Sensors ▲ Senior Research Fellow Park Young-hwan, Department of Infrastructure Safety Research Foreword As of December 31, 2019, out of the total of 35,902 highway bridges in Korea, 81.7% were concrete bridges, while all 2,682 of the highway tunnels were concrete structures. Most of today's social overhead capital (SOC) infrastructures are concrete structures. Concrete structures deteriorate due to a range of factors, and their structural safety degrades due to excessive loads. But up to now, the safety management and maintenance of concrete structures has mainly depended on visual inspection by manpower, and thus remains at a subjective and qualitative level. Accordingly, there are problems in terms of reliability, real-time status identification, and response to safety assessment results. To solve this problem, in this study, we developed embedded distributed fiber optic sensors for concrete structures (Nerve Sensors in Concrete Structures), which have excellent durability and reliability and address the problems of existing point-type sensors, and installed them in concrete structures, enabling them to measure the strain of concrete structures in many locations in a manner similar to the human body's nerves. Through their application, we developed a technology that enables the smart safety management of concrete structures. Development of Nerve Sensor The nerve sensors in concrete structures developed in this study are based on optical fibers with excellent durability and reliability. As optical fiber is vulnerable to damage, it is difficult to embed it in a concrete structure. For this reason, we devised a method to protect the optical fiber by embedding it in a circular FRP (Fiber Reinforced Polymer) rod, and developed a manufacturing technology to produce it efficiently. To this end, the use of pultrusion and braidtrusion were reviewed, and manufacturing technology that employs pultrusion was adopted in consideration of quality control. For nerve sensors to properly grasp the behavior of concrete members, integrity with the concrete must be secured. To accomplish this, the study was conducted on the surface shape of nerve sensor and surface treatment technology. To connect the nerve sensors to the measuring instrument after embedding them in the concrete structure, the optical fiber must be removed from the FRP rod. Since the FRP rod is made of thermosetting resin, it is not easy to abstract the optical fiber. Therefore, it is necessary to develop technology for this. In this study, heat abstraction, mechanical abstraction, and chemical abstraction were studied and reviewed, and an optimal technology for easy optical fiber abstraction was developed. To measure the strain of the structure at many locations with nerve sensors, optical fiber-based distributed measurement technology is needed. The distributed measurement technology developed thus far is not suitable for monitoring concrete structures in terms of the measurement interval, measurement accuracy, measurement time, etc. In this study, a distributed measuring instrument that solves these problems was developed in collaboration with specialist organizations, and its performance was verified through a number of experiments. However, the developed distributed measuring instrument has a problem in that dynamic measurement is not easy. To solve this problem, a semi-distributed dynamic measuring instrument was also studied, and the applicability was confirmed through various verifications of the developed prototype (Figure 2). Development of Nerve Sensor Utilization Technology Since the purpose of developing the nerve sensor is to directly measure the strain occurring in the concrete member, it is essential to ensure the reliability of the measurement in order to secure an integrated behavior between the concrete and the nerve sensor. In other words, between the surface of the FRP rod constituting the nerve sensor and the concrete surrounding it, it is necessary to secure an adhesive force that is greater than the required performance to ensure the reliability of the measurement. In this study, various surface treatments were examined for this purpose, and suitable surface treatment methods were derived through adhesion experiments. By comparing the value measured by the nerve sensor after installing the developed nerve sensor in the concrete member with the value measured by the existing verified sensor (electrical resistance strain sensor, FBG-based fiber optic sensor), it was confirmed that the nerve sensor has sufficient accuracy for structure monitoring. The values were obtained during the loading test. The method of installing the nerve sensors in new structures and in existing structures is different. In a new structure, the nerve sensor is installed along the rebar, so it can be placed relatively easily. But in an existing structure, a groove must be created on the concrete surface and the nerve sensor embedded using adhesive (Figure 3). Since the nerve sensor uses optical fiber, it has the advantage of remotely acquiring data using an existing optical (photonic) network. In other words, it is possible to connect the nerve sensors embedded in multiple structures to the optical network, and measure each nerve sensor using the optical instrument at the base station or the integrated control office. In this way, the safety of multiple structures can be efficiently managed (Figure 4). Development of Smart Monitoring Technology Based on Digital Twin Digital twin technology was used to detect, evaluate, and predict damage to structures using data collected from nerve sensors installed in structures. A digital twin is a computer model (digital model) of an existing structure. By reflecting the sensor data in the digital twin, it is possible to understand or predict the current condition of the real structure by computer-simulating situations that may occur in the real structure. As a result, the conditions and safety of the structure can be efficiently managed (Figure 5). To assess the performance of a structure after it has been built using a digital twin, a finite element analysis program is needed. The existing programs in this area that are commercially available cannot implement nerve sensors. They also have high prices and license issues. For this reason, we developed our own analysis engine in this study. When a digital twin is built using acceleration data, changes in the overall behavior of the structure can be detected, but localized damage is difficult to detect. However, if a digital twin is built using the strain data of the nerve sensors, it has the advantage not only of detecting the overall behavior change but also of detecting important local damage in terms of maintenance. In this study, a strain-based model updating technology was developed to reflect the characteristics of the nerve sensors, and an integrated digital twin system was developed to assess the damage and performance of the structure by linking it with its own analysis engine (Figure 6). The applicability of the developed technology was verified by comparing the results of the integrated digital twin system that does not require a load test with the results of the existing method to assess the performance of a structure through an in-situ load test for an actual bridge to which the nerve sensors are applied. Conclusion In this study, a measuring instrument related to a fiber optic-based nerve sensor was developed to scientifically and efficiently manage the condition of concrete structures, and its performance was verified through various experiments. To assess the safety and damage of structures, a digital twin technique using nerve sensor data was developed, and its potential was verified through its application to the field. The technology developed in this study can be applied to both new and existing concrete structures, and is expected to contribute to the smart monitoring of concrete structures in the future. Date2021-06-29 Hit 887
VR/AR-based Smart Construction Simulation Technology VR/AR-based Smart Construction Simulation Technology ▲ Senior Researcher Seo Myung-bae, Department of Future Technology and Convergence Research Construction Meets Virtual Reality Technology In 2018, the Korean Ministry of Land, Infrastructure and Transport (MOLIT) announced the "Smart Construction Technology Roadmap” that can increase productivity by applying the latest ICT technology covered by the Fourth Industrial Revolution to the construction field. This was a move to enhance the competitiveness and safety of construction sites. In recent years, Korean construction sites have faced a number of issues that include an aging workforce, shortened working hours, and a sharp decrease in the number of skilled workers. As such, there was an urgent need to come up with response strategies to tackle these issues. Ultimately, this roadmap encompasses the government's will to dominate the future market while investing in innovative growth in construction by applying cutting-edge ICT to the construction field. Smart construction technology is technology that incorporates 3D modeling technologies, such as BIM (Building Information Modeling), drones, robots, IoT, big data, AI, VR/AR, and mobile, into construction (Figure 1). In the last 20 years, the development and application of high-performance materials in the construction field have been increasing. Recently, carbon fiber has been introduced as a replacement material for rebar or rebar mesh. The thickness of carbon fiber is about one-tenth that of human hair, but it has a tensile strength ten times stronger than iron. The biggest advantage of carbon fiber as a construction material is that it is noncorrosive. From 10,000 to 50,000 carbon fiber filaments are gathered to form a bundle with a diameter of 2 to 5 mm; with this bundle, a textile grid reinforcement having a grid shape with an interval of 2 to 4 cm can be made. A textile grid can be used as a reinforcement for concrete or mortar, and when mortar is used as a binder, it is called TRM (Textile Reinforced Mortar) (Figure 1). Since the coating thickness required to secure durability is not necessary for the TRM design and construction due to the non-corrosive nature of the textile grid, it has the advantage of being able to construct very thin structures. In the construction field, the use of BIM (Building Information Modeling), a three-dimensional information model, is becoming compulsory. Based on this, the demand for a new market combining VR/AR/MR technologies and advanced sensor devices is increasing. In 2016, GS E&C presented the optimal construction method using BIM-based on-site equipment simulation, beating leading construction companies around the world and winning the contract to build a vehicle depot in Singapore worth KRW 1.7 trillion. Since virtual construction simulation technology can be used for the review of the design, constructability and maintenance by multiple stakeholders including the client, the contractor, the designer, and the civil petitioner, there is high potential for innovation in the existing construction process. It can also be used as digital twin-based technology by linking to smart cities. In addition, virtual reality technology can be developed into user experience and experience-based technology rather than simply being visually utilized. Based on this, it is highly probable that it can be utilized for legal review, safety review, design certification, and virtual construction. The ultimate purpose of virtual construction technology is to enable an improved level of productivity and quality in the construction industry based on process innovation, and to support the base technology of the construction industry through various simulations and decision-making. How VR/AR-based Smart Construction Simulation Technology is Being Utilized at Home and Abroad, and its Current Status In practice, VR (Virtual Reality) technology is highly likely to be utilized in the design stage, while AR (Augmented Reality) and MR (Mixed Reality) technologies are highly applicable in the construction and maintenance stage. For example, the US-based AECOM and the US-based Marquette University utilize VR technology for decision-making in the design stage, such as building design, urban design, and road design, while the Finland-based VTT and the US-based Bently mainly use AR technology in the construction and maintenance field. In addition, it was found that VR-based disaster/disaster simulation, which is centered on Japan, and AR and MR, which is centered on private companies, are being used in the education and collaboration fields (Figure 2). Why Is the Application of VR Technology Slow in the Construction Field, and How Can this be Resolved? In Korea, there are various examples of VR technology being applied to the construction field. But there are not many cases in which it is actively applied to work, such as to support the client's decision making, to win a project contract, or by large construction companies in cyber model houses for publicity and sales. Recently, as BIM has been actively used, the number of cases of simple design review using VR tools compatible with BIM modeling authoring tools are increasing. But still, these are just at the prototype level. The research team conducted various virtual construction simulation experiments using a three-sided large virtual demonstration mockup laboratory, which was built at the KICT (Korea Institute of Civil Engineering and Building Technology) in 2016. We learned that the additional work required to carry out various simulations when BIM drawings, which are 3D drawings actually used in construction, are projected to the VR environment, is quite time-consuming. Ultimately, the market is not being vitalized despite the fact that VR technology brings great effects when it is applied to construction. This is because it takes a lot of manpower and time to produce good quality VR content, and thus economic efficiency is not secured. Therefore, this research team developed, based on BIM, a 3D model in the construction field, the best practice simulation that maintains the same quality when converted into a VR simulation while reducing the cost by shortening the time required to create the simulation compared to the conventional model. It has the best effect when the VR technology is utilized in the construction field rather than simply in the design review, interference check, and construction review. As a result, we conclude that it is possible to develop a new market if the effect of the VR technology is verified through field application, and related research was conducted to solve this issue (Figure 3). Improving the Productivity of VR Content Production, the First Step in Vitalizing Virtual Construction In creating VR content using the BIM model, if you simply want to create it with flat-based VR technology on a monitor rather than at a high level of quality, you still can do it with a simple tool. However, as users' expectations are rising with the advancement of technology, a lot of manpower and time is required to implement a realistic simulation with high immersion using VR HMD (Head Mounted Display) worn on the head. In fact, based on a 200 mega-scale plant facility, it was found that it took about 3 months to analyze the raw data, lighten the data, and optimize the object in order to produce content that meets the requirement of 120 FPS (Frames Per Second). 120 FPS is the minimum requirement for a realistic simulation that does not produce dizziness for the viewer. In this study, to reduce the time and cost of implementing high-quality BIM data in a VR environment, we have developed an attribute lightweighting algorithm that reduces the physical data volume and automatically removes unnecessary BIM attributes to reduce the time required to convert existing BIM data to VR (BIM to VR). We also developed an auto material technology that can reduce manual work by extracting BIM model attributes and automatically mapping the most used textures (materials) in the construction field to create high-quality content based on a blank 3D model with nothing on it. The related core technology was transferred to a private company and was used to produce actual VR contents for Hyundai E&C. In addition, to verify this technology, a test was conducted based on 10 files of 200 mega-size. In the case of material mapping, the time taken was reduced by 50% compared to the conventional technology, and it was certified for its performance by the TTA (Telecommunications Technology Association) in March 2020. Virtual Construction Simulation Platform, Best Practice Development, and Field Application To vitalize virtual construction, it is very important to produce optimal contents that allow the various stakeholders including the client, designer, and construction company to actually feel the effect and verify the effect through field application. Therefore, at the beginning of the study, the optimal simulation contents were seriously considered for various stakeholders, and the simulation was developed in consideration of the public nature, urgency, and ripple effects due to the special nature of KICT as a public institution. Since VR technology has strength in preliminary review based on 3D model, fire and noise simulation contents were developed. For fire simulation, the ignition source location and size of the fire can be adjusted at will, and the 3D model attribute information is linked to simulate the speed at which the flames spread. This technology can be used for future user experience-based firefighting design. In addition, by developing a noise simulation with visual effects, contents were developed that can support a response to complaints in the future (Figure 5). AR and MR technologies can be used for facility maintenance and performance assessment in the field. In this study, the technology for AR-based railway facility performance assessment, AR-based tunnel facility maintenance, MR-based fire OJT (On-The-Job-Training), landscape review, and equipment remote control was developed. By actually applying these in the field, their potential was verified (Figure 6, 7). Although BIM drawings are required for these simulations, a simulation platform was developed using FBX, a 3D neutral file format, considering that there are various authoring tools for creating BIM. FBX file was imported, the data weight reduction and auto material were run, each simulation is made as an add-in type plug-in, and then only base attributes (fire and noise level, location of the user, etc.) are set and mounted on the drawing. It was created in the form of a platform to enable simulation in various environments (Figure 8, 9). To verify the core simulation technology developed in this project, the effectiveness of the technology was verified by applying it to the city of Goyang, Seoul Metro, and the Daegok-Sosa Zone 4 complex tunnel site. In addition, as part of the effort to advance into overseas markets, we signed an MOU with Tanal Group, a company owned by the Prince of Saudi Arabia, in February 2020 to apply BIM to VR core technology in the Saudi new city development project (Neon City). Discussions are also ongoing for the establishment of a local research institute, joint research, and core technology transfer. Conclusion Through this study, a productivity improvement technology for VR simulation content production to revitalize the virtual construction market, the development and field application of seven best practice cases, and technology transfer of core technologies to private companies were carried out. AR/VR/MR convergence technology in the construction field is a non-contact core technology that can respond to COVID-19 and is expected to grow explosively in the future. It is expected that it will be necessary to conduct additional studies from various angles, such as securing technological competitiveness and preoccupying the future construction market, developing additional success stories, researching applicable fields, discovering business models, and providing institutional support to revitalize the related industries. In addition, it is considered that smart construction virtualization simulation research can be used as a base technology for pioneering new markets in the future because it will allow the temporal and spatial constraints of the conventional construction industry to be overcome, and economic efficiency, diversity, and practicality to be secured. Department of Future&Smart Construction Research Date2021-06-29 Hit 1671
Technology for Fire Safety in Underground Spaces to Support the Commercialization of Fuel Cell Electric Vehicles Technology for Fire Safety in Underground Spaces to Support the Commercialization of Fuel Cell Electric Vehicles ▲ Research Fellow Yoo Yong-ho, Department of Fire Safety Research Foreword The two keywords that best summarize the trend of today's global automotive market are "electric" and "self-driving." These paradigms, which can be observed in the automotive industry of the EU, the US, and also Korea, sum up a strategy pursued by developed nations seeking to lead the future car industry to induce investment and create jobs in related manufacturing and service industries, which would function as a national growth engine. As the key nations of the world, with the exception of the US, are in support of the Paris Agreement, the shift toward electric vehicles is in line with their efforts to reduce vehicle-emitted carbon dioxide in order to meet their individual energy efficiency improvement and pollutant emission reduction targets. Also notable are the large-scale underground developments taking place around the world in response to a continuing increase in the demand for mobility, and to environmental changes in metropolitan areas. The idea is to keep above-ground environments pleasant and to make use of deep-underground spaces as a sustainable development option. Today, in Korea, traffic inefficiency in Seoul its surrounding area is a serious issue causing economic losses that amount to KRW 12.5 trillion each year (OECD Territorial Reviews for Seoul, 2002). Statistics from the Korea Transport DataBase of the Korea Transport Institute indicate that this cost will increase at a rate of 5.88% each year to reach a staggering KRW 16 trillion by 2031. As such, underground developments in Korea are expected to be accelerated. This report outlines the present and future of environment-friendly vehicles. In particular, safety technology for underground developments taking place in support of the hydrogen economy and the increased use of hydrogen vehicles are examined. Korea's Fuel Cell Electric Vehicle Industry A commitment to reducing carbon dioxide emission requires a switch from fossil fuel-run combustion engine vehicles to electric vehicles. Through systemic reforms, the key nations are aiming for the elimination of internal combustion engine vehicles by 2030, or by 2040 at the latest. As can be seen in Table 1, the different types of electric vehicles include battery electric vehicles, plug-in hybrid electric vehicles, hybrid electric vehicles, and fuel cell electric vehicles. A fuel cell electric vehicle, powered by electricity generated using hydrogen, uses fuel cells in place of a battery or combines fuel cells with a battery or a supercapacitor to supply electricity to its onboard motor. By sucking in air from the atmosphere, it induces a chemical reaction between oxygen and hydrogen in its fuel cells to generate electrical energy and run its motor. Unlike other electric vehicles, a fuel cell electric vehicle uses fuel cells for power generation and a secondary battery for power storage. As the secondary battery is for storing just a small quantity of energy, it characteristically has a small capacity. Some notable facts about the Korean hydrogen vehicle industry are that it was responsible for the world’s first mass production of hydrogen vehicles in 2013, and produces hydrogen vehicles capable of the longest driving range in the world. In addition, 99% of the core parts used in Korean-made hydrogen vehicles are produced domestically. Korea's developed petrochemical industry and extensive experience in the running of industrial plants mean that the Korean hydrogen vehicle industry has access to the hydrogen pipelines and high-purity hydrogen production technology required for hydrogen supply (approximately 1.64 million tons a year as of January 2019), that it is capable of creating sufficient demand for hydrogen and achieving economic efficiency of hydrogen, and that through facility expansion and process conversion, it will be capable of supplying by-product hydrogen on a large scale. In its "Roadmap to a Hydrogen Economy" announced January 2019, the Korean government expressed its vision of an industrial ecosystem that would foster a hydrogen economy largely constituted of hydrogen vehicles and fuel cells. As can be seen in Figure 1, plans are in place to increase the number of fuel cell electric vehicles in use from 889 in 2018 to 81,000 (65,000 in Korea alone) by 2022, and to 6.2 million (2.9 million in Korea alone) by 2040. Plans are being formed to supply buses, taxis, and commercial trucks that run on hydrogen. Use of Underground Space in Various Countries Countries around the world, recognizing the importance of underground development for the future benefit of the environment, are engaged in the building of underground infrastructure, underground future cities, and underground expressways. In Europe and the US, roads are being built deep under downtown areas as a starting point for the conservation of above-ground green areas, to solve the problem of traffic congestion, and to promote sustainable development and green growth. Prime examples include The “Big Dig" of Boston (US); the Shinjuku Central Loop Line of Tokyo (Japan); and the A86 Underground Ring Expressway of Paris (France). In Korea, a proposal was developed in 2009 to construct underground expressways that would meet the rapidly increasing demand for expressways in the Seoul area and reduce traffic congestion in the existing road network by increasing road capacities. Table 2 shows the wide range of large-scale underground road construction projects currently being planned and under review in Korea. Dangers of Fire and Explosions in an Underground Space Underground developments are particularly vulnerable to fire. In the last five years, a total of 130 cases of accidents involving fire in a tunnel, roughly 26 a year, were reported in Korea (National Fire Data System). A notable one occurred in Dalseong Tunnel 2, in which a fire started by an overheated brake lining of a vehicle carrying a missile spread to the wooden encasement containing the missile and caused an explosion, resulting in damages to the tunnel ceiling that included longitudinal and net-shaped cracks 0.3 mm to 1 mm wide, scaling, and spalling, as well as surface scaling in paved surfaces. Underground developments are particularly vulnerable to fire. In the last five years, a total of 130 cases of accidents involving fire in a tunnel, roughly 26 a year, were reported in Korea (National Fire Data System). A notable one occurred in Dalseong Tunnel 2, in which a fire started by an overheated brake lining of a vehicle carrying a missile spread to the wooden encasement containing the missile and caused an explosion, resulting in damages to the tunnel ceiling that included longitudinal and net-shaped cracks 0.3 mm to 1 mm wide, scaling, and spalling, as well as surface scaling in paved surfaces. Safety Technology for Response to Leakages, Fires, and Explosions Involving a Fuel Cell Electric Vehicle in a Semi-enclosed Underground Space As a nation anticipating the mass commercialization of fuel cell electric vehicles, we should identify and develop countermeasures to address the risks associated with the operation of fuel cell electric vehicles, and with accidents involving a fuel cell electric vehicle, including the characteristics of a fire occurring in a typical underground space. Hydrogen is a gas with no color, scent, taste, or toxicity. Hydrogen is also the lightest the element. At one-fourteenth the weight of oxygen, when released into the atmosphere hydrogen characteristically disperses at a high speed of 20m/s. Due to its low minimum ignition energy level of 0.02 MJ, static electricity can ignite hydrogen to cause a fire. With a flammability limit of 4% to 75%, hydrogen can cause a fire or explosion in a wide range of conditions. Today's typical fuel cell electric vehicle comes with 2 or 3 pressurized 700 bar hydrogen tanks fitted under the rear seats or the trunk. Each of these tanks supplies hydrogen to a fuel cell stack. Each hydrogen tank is equipped with a thermally activated pressure relief device, an essential safety device, which on detecting abnormal temperature or pressure, automatically opens the valve to release pressurized hydrogen from the tank to adjust the pressure inside the tank. For such a system, a technology that addresses the risk of gas leakage or a jet fire/explosion caused by a malfunction of the safety device or damage to a hydrogen tank in a car accident is needed. In recognition of the research trend in this technology in key nations around the world, the National Fire Agency of Korea commissioned research and development related to response to fires caused directly or indirectly by a fuel cell electric vehicle in a semi-enclosed underground space. The Korea Institute of Civil Engineering and Building Technology (KICT) is currently spearheading said research and development endeavors, in which fire safety technology for an improved field response to fires and explosions caused by a fuel cell electric vehicle in an underground space such as a tunnel or an underground parking lot is being researched and developed as shown in Figure 3. The KICT is concurrently carrying out research in the formation of standard operating procedures for the optimal control of different types of fire and in the risks of leakage and fire posed by different types of hydrogen charging stations to provide the future hydrogen industry with valuable and essential safety technology. Conclusion Hydrogen is a green energy source that can be the solution to humanity's energy and environmental issues, and we must prepare to make a switch to a hydrogen-based society. Such a change would align with the paradigm shift of phasing out fossil fuel use and nuclear power generation, while achieving greenhouse gas reduction targets. Of all the technologies required for a hydrogen society, safety technology is paramount. In consideration of this, safety reviews based on qualitative and quantitative risk assessments and analyses should be prioritized. Department of Fire Safety Research Date2021-03-30 Hit 914
Self-driving Technology and the Role of the KICT Self-driving Technology and the Role of the KICT ▲ Research Specialist Kim Ji-soo, Department of Future Technology and Convergence Research Experts agree that the advent of the self-driving vehicle will revolutionize the concept of mobility in our everyday lives. Tesla recently revealed its FSD (Full Self-Driving) beta program, which naturally piqued the interest of the masses in self-driving vehicles. The term "self-driving" conjures up a number of images, perhaps of a driver watching a movie instead of the road, or passengers engaged in face-to-face conversation in a car without a driver's seat. A video released on the internet depicting a driver activating the auto pilot function and going to sleep caused quite a stir. In this sense, a self-driving vehicle can be called a "driverless vehicle." However, a driverless vehicle is just one type of self-driving vehicle, as not all self-driving vehicles can do without a driver. This report provides a definition of self-driving and the self-driving vehicle, outlines the current level of self-driving technology, and examines how the Korea Institute of Civil Engineering and Building Technology (KICT) can contribute to the self-driving field. Definition of a Self-driving Vehicle In English-speaking parts of the world, self-driving is also referred to as "autonomous driving" or "automated driving." But these terms lack a concrete definition or classification. In the automotive industry, "automated driving" most closely resembles "self-driving" in meaning, and the US Department of Transportation and most of its transportation and automotive-related subsidiaries are using it. "Autonomous driving," which encompasses a wider range of meanings including "the means to travel without spatial restrictions," is generally used to represent the concept of self-driving. The definition of "self-driving" that is observed globally was announced by the US Society of Automotive Engineers (SAE) in January 2014 and is in compliance with the SAE's official standard J3016, "Taxonomy and Definitions for Terms Related to Driving Automation Systems for On-Road Motor Vehicles," revised in June 2018 and in effect to this day. SAE J3016 defines driving through a 6-level structure that defines the roles of the driver—i.e., the person seated in the driver's seat—and the automated driving system (ADS), as well as the instances of driver-ADS interaction at each level. In the field of self-driving, a vehicle controlled and driven by an ADS as defined in SAE J3016 is commonly referred to as a self-driving vehicle The Levels of Self-driving In the structure of driving defined in SAE J3016, at levels 0 to 2 the driver is in control, and at levels 3 to 5 the ADS is in control. The role of the ADS when the driver is in control is as follows. At level 0, the ADS provides driver alerts and safety support—e.g., blind spot alerts, collision alerts, etc.—at crucial moments. At level 1, the ADS assists with either steering or acceleration/braking—e.g., lane departure prevention and adaptive cruise control (either forward/backward or sideways). At level 2, the ADS assists with both steering and acceleration/braking (forward/backward and sideways), with the driver remaining vigilant and in control of the vehicle while receiving such ADS support. Advanced driving assistance systems (ADAS) featured in vehicles available on the market today provide such level 2 driver assistance functions. At level 3, the driver can only assume direct control of the vehicle by taking over the ADS. At level 4 and above, the person seated in the driver's seat is not a driver, with the difference between level 4 and level 5 being whether the operational design domain (ODD) of an ADS is limited or unlimited. It is commonly thought that a linear progression through these levels of self-driving must take place—that is, that one level must be perfected before the next can be applicable; however, this is not necessarily the case. Let us hypothesize a self-driving shuttle operating on the grounds of the KICT along a route between the entrance of the main building and the entrance of the Innovation Center, with set stops along the way. This shuttle, as long as no traffic control takes place on the roads within the KICT, will be able to perform level-4 self-driving—i.e., driverless driving—at a speed of 20 km to 30 km per hour without causing accidents. Indeed, with very limiting ODD conditions in place, the technology available today is sufficient for level-4 self-driving. However, because ODD limits are removed at level 5—i.e., all limits, including road and weather conditions, are removed—the vehicle in question must be able to self-drive to any destination, at least in a single country. As such, level 5 cannot be attempted until level 4 is perfected. Self-driving Technology: The Present Globally, the development of self-driving technology is taking place in two directions. First, automakers and parts suppliers are working to create an ADAS that can achieve self-driving; second, IT-driven companies such as Waymo (Google), Uber, and Cruise are working to enable full self-driving—i.e., level 4 and over—to create future mobility services. With the former, level-3 self-driving is pursued by improving level-2 ADASs, or ODD expansion at level 2 is sought. That is, automakers are seeking to maintain their existing market share by continuously improving and expanding the commercial technology they already have. One exception is Tesla, which competes with traditional automakers by taking an IT- and electronics-oriented approach rather than an automotive-oriented one. In the field of ADASs, traditional automakers and Tesla share the ultimate goal of realizing level 4 self-driving or higher, but as far as the release of technology is concerned, the two are diametrically opposed. While traditional automakers remain conservative, in that they do not venture to commercialize technology that has not yet been guaranteed as safe, Tesla, as with its FSD beta, takes the risk of releasing incomplete technology. Automakers, Tesla included, have developed ADASs, e.g. HDA-2 of Hyundai/Kia, FSD of Tesla, Super Cruise of GM/Cadillac, Co-pilot 360 of Ford/Lincoln, and Driving Assistant of BMW, but none of those are yet capable of level-3 self-driving. With the latter, the dominant trend is not the development of self-driving technology for impending commercialization, but the creation of a complete self-driving technology to be applied to the creation of different kinds of mobility services. Some prime examples of such mobility services include the robo-taxis developed by Waymo and Uber and the self-driving trucks of TuSimple, services that are still in their infancy, as well as the self-driving-car-sharing platform developed by the GM-owned Cruise, which began as an aftermarket self-driving platform. As such, a comparison with the former may give the impression that these companies have not much to show in the way of breakthroughs, but the fact of the matter is that because their goal is not the progressive development of self-driving technology but to cut straight to level 4, they actually have obtained a vast pool of data through testing that is so large in scale that it dwarfs that of the former. In actuality, these companies have already achieved level-3 self-driving, but their biggest limitation is their still-very-limited ODD. Most of their testing is carried out in perennially arid regions like California and Arizona. Indeed, ODD expansion is such a massive barrier that even Waymo, which has made the greatest progress, began testing in rainy Florida only in the fall of 2019. Self-driving Technology: The Limit Self-driving can be defined as the execution of part or the entirety of driving, which used to be performed by a human driver, by a vehicle or, to be exact, a computer built into a vehicle. The act of driving takes place through the stages of perception, judgment, and control. At the stage of perception, the functions of the human eyes and ears are performed by sensors, and the functions of the human brain are performed by a cognitive algorithm that connects sensors to a self-driving program. At the stage of judgment, a self-driving program takes over the functions of the human brain. At the stage of control, the functions of the human arms and legs are performed by a self-driving module (actuator). Technology involved in judgment and control is primarily developed by automakers and electronics suppliers. Because a solution to every single scenario that could occur during driving is required and self-driving must resemble human-driving as closely as possible, the functions of judgment and control can be fulfilled without perception. As such, the perception stage presents the biggest challenge in achieving the technological integrity of self-driving, or in expanding an ODD. The situation that poses the greatest danger to a human driver is when they are not able to perceive their surroundings accurately. The occurrence of an accident can depend on the speed of reaction (judgment or control), which is the product of driving experience or individual constitution; however, if heavy rainfall severely impairs the driver's vision or lanes cannot be discerned because of snow on the road, even a driver with competent judgment and control will experience difficulty. Self-driving must overcome such diverse driving difficulties through technology, but the sensors commonly used in self-driving are all fundamentally limited in function. Moreover, any unprecedented driving situation will not be recognized, which can lead to a critical safety issue, as has been demonstrated by accidents involving Tesla vehicles. In particular, overcoming limits in ODD expansion related to weather conditions or non-standardized situations, e.g. roadworks in progress, is a huge task for industry players pursuing self-driving through ADAS or IT. Perceptive technology based on sensing technology and artificial intelligence is improving at an accelerated rate, but the fundamental limits on the function of sensors cannot be completely eliminated. Efforts to Overcome Limitations and the Role of the KICT The information provided in this report thus far pertains to the "standalone" automated vehicle (AV), which drives based on information fed by sensors and a precision map. To overcome the limits of the AV, research into connected automated vehicles (CAV), which combine the AV with the concept of the connected vehicle (CV) , a separate area of development, is taking place around the world. In 2015, the KICT formed plans for the creation of an HD map, the most basic information required in self-driving, and succeeded in creating one for the first time in Korea. It is also developing a range of technologies for communicating road safety information, such as road surface temperature and the presence of potholes, to vehicles through infrastructure. Another project underway is the development and testing of a local dynamic map (LDM), a dynamic information platform that detects, generates, and supplies real-time environmental information to automated vehicles. Because not every AV is a CAV, ways to overcome the limits of an AV that does not use communication must be researched. An AV is activated by a human to be self-driven—this process takes place on the road. As such, the difficulties experienced by the human and vehicle must be resolved on the road. From this standpoint, the Smart Mobility Research Center is working on finding the causes of sensor perception reduction and addressing them through road infrastructure improvement. "Self-driving sensor data collection equipment" for understanding how a sensor perceives a road environment has been created and is being used to research sensor perception with the goal of developing road infrastructure that will remove reductions in sensor perception by 2022. In this endeavor, only a limited range of road infrastructures will be developed; however, as sensor data research will take place on a greater scale in the future, allowing the setting of the road infrastructure standards required for self-driving, the KICT is expected to play a core function in the self-driving field. Department of Future&Smart Construction Research Date2021-03-30 Hit 1005
Technology to Reduce Scattering Dust in City Roadworks Technology to Reduce Scattering Dust in City Roadworks ▲ Senior Researcher Baek Cheol-min, Department of Infrastructure Safety Research ▲ Senior Researcher Yang Seong-rin, Department of Infrastructure Safety Research ▲ Postdoctoral Researcher Lee Jong-won, Department of Infrastructure Safety Research ▲ Student Researcher Han Su-hyeon, Department of Infrastructure Safety Research Background Dust is an airborne particulate matter. Dust released directly into the atmosphere is called "scattering dust." Main sources of scattering dust include construction sites and plants where cement, coal, earth/sand, or aggregates are handled. As with general dust, scattering dust can be divided based on particle size (diameter) into total suspended particles (TSP) under 50 μm, fine dust under 10 μm, ultrafine dust under 2.5 μm, and extremely fine dust under 1 μm. Environmental issues related to scattering dust include the dust dome effect, impaired visibility, respiratory disorders such as pneumoconiosis, and deterioration of facilities. Exposure to fine dust (PM10) harms the human body. A 10 μg/m³ increase in fine dust concentration increases the likelihood of death by stroke by 10%, and worsens asthmatic symptoms by 29%. Since 1987, the World Health Organization has been providing guidelines related to fine dust. In 2013, the International Agency for Research on Cancer, a subsidiary of the World Health Organization, classified fine dust as a "Group 1" carcinogen. The Ministry of Environment of Korea attributes 30% to 50% of fine dust production to foreign countries, i.e. China. With regard to domestic production of fine dust, in the Seoul area, it attributes 29% to diesel vehicles. Nationwide, it attributes 41% to business operations such as manufacturing plants. A notable finding is that in cities such as Seoul, the concentration of roadside fine dust is 4 to 11 μg/㎥ higher than the concentration of fine dust measured in the atmosphere. This has been found to be caused by vehicle emissions and roads. The National Institute of Environmental Research defined fine dust as an atmospheric pollutant in 2015, and has since been setting limits on fine dust emission in its regular reports on national air pollutants emission. Figure 1 is an overview of scattering dust production in 2017, the National Institute of Environmental Research's latest finding, and it can be seen that over 60% of scattering dust is attributed to construction and roads. As such, there is an increasing need for research on the means and technologies for monitoring and reducing scattering dust created by construction and roads. Development of Technology to Reduce Scattering Dust in Roadworks Since 2013, the Korean government has been executing progressively strengthened control of scattering dust through policies and manuals on scattering dust (Figure 2). In 2019, the cold months of December to March were designated as a "high-concentration fine dust" period, and intensive control of fine and scattering dust has been implemented. Reduction of scattering dust requires a technology that can continuously reduce the precursors of scattering dust, NOx, SOx, and fine dust (PM10, PM2.5). Roadworks are primarily taking place in cities such as Seoul where a concentration of population, traffic, and industry is present. As most such roadworks involve the maintenance of existing roads rather than the construction of new ones, scattering dust is generated at a high rate during production and installation processes. Scattering dust from roadworks makes up a large proportion of the scattering dust generated by paved roads. The research and development of technology to reduce scattering dust in all stages of road pavement have been set as a component of the "Development and Verification of Technology for Reducing Road-generated Fine Dust," a national research and development project of the Korea Agency for Infrastructure Technology Advancement to be executed over five years from 2019 to 2023, and are being carried out by 14 organizations including the KICT. This research group is developing technology to reduce the generation of scattering dust throughout all stages of road pavement, as shown in Figure 3, with the goal of reducing scattering dust generation in production phases by more than 30% (reduction of precursors such as NOx included) and at installation and operation phases by more than 10%. So far, in-plant facilities (combustion chambers, dust collection systems, etc.), eco-friendly scattering dust suppressants, sidewalk-driven scattering dust removal vehicles, and equipment to measure volumes of scattering dust generated by road pavement have been developed. Detailed plans for the practical application of developed technologies are being formed through field trials, systemization, and cooperation with related agencies (see Figure 4). Some notable achievements of the research group include the following. POSCO Engineering & Construction developed an eco-friendly scattering dust suppressant with improved mechanical and environmental function achieved through a newly developed technique of mixing silicate hybrid polymers with palm oil. This product, compared to the world's best-rated product, is 80% more economical and reduces loss of scattering dust by 2.54 times. A sidewalk-driven scattering dust removal vehicle developed by DaeilTec, which has a compact size and features water blasting and remote control, is currently being field-trialed in partnership with the Seoul Metropolitan Government. The Korea Expressway Corporation Research Institute developed a tester for measuring volumes of scattering dust generated by road pavement. This equipment measures scattering dust directly generated by the abrasion of tires and pavement materials, and plays a crucial role in the development of technology for reducing tire wear (see Figure 5). With regard to the production phases involved in road pavement, laws on reducing scattering dust production by road pavement material production facilities will be enacted with the aim of establishing national standards and systems for reducing scattering dust and its precursors (NOx), to be implemented in the domestic market. In terms of the installation phases, elementary technology, products, and guidelines for reducing scattering dust production in road pavement works will be developed. For the operation phases, products and their operating methods for reducing scattering dust production by sidewalks and road surfaces will be developed. The research group's goal is to develop technology for reducing scattering dust production in all stages of road pavement works, from production to installation to operation, and to develop a system that can measure volumes of scattering dust production. Conclusion The Seoul Metropolitan Government recently designated six self-governing districts (Seocho-gu, Eunpyeong-gu, Jung-gu, Geumcheon-gu, Dongjak-gu, Yeongdeungpo-gu) as "focused fine dust control zones," and is providing their residents with a wide range of effective means for reducing fine dust, as well as for protection from fine dust. The fine dust generated by roads in cities has become a serious environmental issue that directly affects the health of pedestrians and drivers. By identifying and developing means to reduce scattering dust production throughout all stages of road pavement (production, installation, operation), this research is expected to improve the roadside atmosphere and minimize the risks to which pedestrians are exposed. Date2021-03-30 Hit 703

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