• Journal of Korean Tunnelling and Underground Space Association
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• v.20 no.6
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• pp.1161-1175
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• 2018

An unexpected event could be easily followed by a large secondary accident due to the limitation in sight of drivers in road tunnels. Therefore, a series of automated incident detection systems have been under operation, which, however, appear in very low detection rates due to very low image qualities on CCTVs in tunnels. In order to overcome that limit, deep learning based tunnel incident detection system was developed, which already showed high detection rates in November of 2017. However, since the object detection process could deal with only still images, moving direction and speed of moving vehicles could not be identified. Furthermore it was hard to detect stopping and reverse the status of moving vehicles. Therefore, apart from the object detection, an object tracking method has been introduced and combined with the detection algorithm to track the moving vehicles. Also, stopping-reverse discrimination algorithm was proposed, thereby implementing into the combined incident detection processes. Each performance on detection of stopping, reverse driving and fire incident state were evaluated with showing 100% detection rate. But the detection for 'person' object appears relatively low success rate to 78.5%. Nevertheless, it is believed that the enlarged richness of image big-data could dramatically enhance the detection capacity of the automatic incident detection system.

• Journal of the Korean Society for Railway
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• v.15 no.6
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• pp.579-587
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• 2012

Shin-gumho station in Seoul underground subway have been selected to be experimentally investigated and analyzed for the real air supply & exhaust capacity compared to the original capacity of ordinary and emergency condition. The depth of Shin-gumho station is 43.6m which consists of the island-type platform ($8^{th}$ floor in underground) and a two-story lobby (first & second floor in underground). An emergency staircase connects between the platform and the lobby. Hot-wire anemometer, capture hood, wind vane & velocity meter and data acquisition systems are employed to perform the automatic measurement in this experiment. For ordinary case, air supply and exhaust capacity in the lobby were reduced by 34% and 46% compared to the original capacity, respectively. Air supply and exhaust capacity in the platform were reduced by 66% and 38%, respectively. For emergency case, air supply in the lobby was reduced by 42% and air exhaust in the platform was reduced by 28% compared to the original capacity. Therefore, air pollution in the station is expected to be worse in the ordinary environment and smoke control capability in the platform will be weakened in case of fire emergency.

• Explosives and Blasting
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• v.21 no.2
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• pp.21-30
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• 2003

Currently, the shotcrete used as basic support in the tunnel excavation, has the advantages of maintaining high-level strength in condition of early shooting with thin thickness based on the excavation characteristics of rock mass. Therefore supreme equipment and materials were developed and the great strides have continued. Also, the development of measurement technology and the rocks behaviors of undergound are evaluated in detail and the designs of strength and thickness are made. The reinforcement materials development of new material is carried on. Most of the coal fly ash produced in Korea fire power plant is fly ash and bottom mash. Fly ash has been producing to be applied in many fields such as cement, aggregate, construction, civil, agriculture and fisheries. Also a lot of experiments are actively on the way. Therefore in this experiment, in order to use the fly ash mixed with concrete as a material of shotcrete, the experiment was performed in the best content to reduce the compression strength and the shooting rebound ratio of the excavated surface to use fly ash as a substitute material of concrete. As a result, when 15%.wt substitution was made to the fly ash, about 10% of compression strength and 6% of rebound ratio was reduced.

• Tunnel and Underground Space
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• v.2 no.1
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• pp.95-101
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• 1992

Norwegian technology related to preinvestigations, planning, design and construction of large underground caverns is wellknown worldwide. However, so far this technology is only slightly verified through scientiffic reports and documentation. The "Rock cavern stadium" research program is an interdisciplinary program related to the ongoing building and future use of Gjovik Olympic Subsite which is the largest cavern in the world for public purposes with a span of 61 meters and a height of 25 meters. The estimated budget for this program is about USD 4 million which is made possible through grants from The Royal Norwegian Council for Scientific and Industrial Research as well as through contributions from Norwegian and Swedish companies that are participating. The program is carried out in collaboration with The Foundation for Scientific and Industrial Research at the Norwegian Institute of Technology. The Norwegian Geotechnical Institute and The Eastern Norway Research Center. The research program will continue until the end of 1994 to ensure that input comes from a full period of use in this stadium with different activities like exhibitions, conferences, concerts etc being included as verification through full-scale measurements and observations. The research program has five subtasks. Three of these are related to subjects like Energy consumption. HVAC installations. Fire safety design, Engineering geology and Rock mechanics, Environmental aspects. The fourth subtask is concerned with the collection of basic data, results and experience from these three subtasks to provide a basis for national Norwegian guidelines related to this interdisciplinary subject area. The guidelines will first be presented as a manual for planning and engineering purposes. The realization of this research program is a unique opportunity to enhance the expertise that has been acquired from this cavern stadium. By involving research in this extraordinary project from the excavation and building phase to its subsequent use. this will give the participants know-how and expertise which is very much in demand internationally. The coordination of the international activities between the participants as well as preparation of participations and presentations in international conferences and symposium are included in the fifth task of this national research program.

• Tunnel and Underground Space
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• v.23 no.4
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• pp.319-325
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• 2013

The objective of this study is to assess risks which might occur in connection with the storage of the highly compressed air in underground opening. Risk factors were selected throughout literature survey and analysis for the characteristic of CAES. Large risk factors were categorized in three components; planning and design phase, construction phase, and operation & maintenance phases. Large category was composed of 8 medium risk groups and 24 sub-risks. AHP technique was applied in order to analyze the questionnaires answered by experts and high-risk factors were selected by evaluating the relative importance of risks. AHP analysis showed that the operation & maintenance phases are the highest risk group among three components of large category and the highest risk group of eight medium risk groups is risk associated with the quality and safety. Risk having the highest risk level in 24 sub-risks is evaluated to be a failure of tightness security of inner containment storing compressed air.

• Proceedings of the Korean Geotechical Society Conference
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• 2006.03a
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• pp.1100-1109
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• 2006

In this study, two different technologies which can measure temperature simultaneously at many points are introduced. One is to use a thermal sensor cable that is comprised of addressable thermal sensors connected in parallel within a single cable. The other is to use an optic fiber with Distributed Temperature Sensing (DTS) system. The difference between two technologies can be summarized as follows. A thermal sensor cable has a concept of 'point sensing' that can measure temperature at accurate position of a thermal sensor. So the accuracy and resolution of temperature measurement are up to the ability of the thermal sensor. Whereas optic fiber sensor has a concept of 'distributed sensing' because temperature is measured by ratio of Stokes and anti-Stokes component intensities of Raman backscatter that is generated when laser pulse travels along an optic fiber. It's resolution is determined by measuring distance, measuring time and spatial resolution. The purpose of this study is that application targets of two temperature measurement techniques are checked in technical and economical phases by examining the strength and weakness of them. Considering the functions and characteristics of two techniques, the thermal sensor cable will be suitable to apply to the assessment of groundwater flow, geothermal distribution and grouting efficiency within 300m distance. It is expected that the optic fiber sensor can be widely utilized at various fields (for example: pipe line inspection, tunnel fire detection, power line monitoring etc.) which need an information of temperature distribution over relatively long distance.

• Journal of the Korean Institute of Traditional Landscape Architecture
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• v.32 no.4
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• pp.120-131
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• 2014

Sajikdan(a sort of national shrine in Korea) built at the time of foundation of Joseon was entrenched into Sajik Park going through Japanese colonial era and recently the efforts to restore it is in progress. The details of change in Sajikdan in terms of diachronic analysis are as follows: Firstly, the first period refers to one prior to Japanese colonial era from the first king (also named as "Taejo" in Korean) of the Joseon Dynasty, during which it secured and strengthened the presence as a place for performing important national rites in a nation. It was built on the foot of Inwangsan Mt. at the time of the first king in Joseon Dynasty at first, was destroyed fully by fire during a Japanese Invasion period to Korea(1592-98) and afterward its ancestral ritual facilities were completed under the regime of Youngjo. However, as Japanese intervention coming to the fore, its place was destroyed and then ancestral rites were also abolished in 1908. Secondly, next period falls on 1910 to 1944 when it was transformed and entrenched into a park by the Japanese Empire. While facilities related to a park and an heterogeneous building around the part of boundary were set up, the area of altar, a ritual house and d door of Sajikdan were also designated as historical remains and treasures. Thirdly, this period refers to one from Korea's liberation year from Japanese colony(1945) to the year of 1984 when it had a mixed placeness with the statues, monuments and buildings with heterogeneous nature built. Furthermore, a door of Sajikdan was removed and reconstructed over twice due to opening of Sajik Tunnel. Fourthly, a final period falls on 1985 to the present when efforts are in progress to restore the historicity and symbolism of Sajikdan. A plan for restoration is promoted but now is a difficult time suffering from troubles caused by residents' resistance. Scrutinized historical researches through excavation investigation and residents' understanding are required altogether for restoration of Sajikdan.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.37 no.6
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• pp.1017-1023
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• 2017

Duration induced by freeway crashes has a critical influence on traffic congestion. In general, crash duration composes detection and verification, response, and clearance time. Of these, the crash clearance time determined by a crash clearance team has attracted considerable attention in the freeway congestion management since the interest of the first two time stages faded away with increasing ubiquitous mobile phone users. The objective of this study is to identify the critical factors that affect freeway crash clearance time using a Cox's proportional hazard model. In total, 6,870 crash duration data collected from 30 major Korean freeways in 2013 were used. As a result, it was found that crashes during the night, with trailer or larger size truck, and in tunnel section contribute to increasing clearance time. Crashes associated with fatality, completed damage of crashed vehicle (s), and vehicles' fire or rollover after crash also lead to increasing clearance time. Additionally, an increase in the number of vehicles involved resulted in longer clearance time. On the other hand, crashes in the vicinity of tollgate, by passenger car, during spring, on flat section, and of car-facility type had longer clearance time. On the basis of the results, this paper suggested some strategic plans and mitigation measures to reduce crash clearance time on Korean freeway systems.

• Tunnel and Underground Space
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• v.31 no.1
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• pp.52-65
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• 2021

In this study, authors analyzed the vapor cloud explosion induced by propane leak at the PEMIX Terminal, which is the propane storage facility outside of Mexico City. TNT equivalence mass for the leaked 4750 kg propane was estimated to be 9398 kg. Blast parameters such as peak overpressure, positive phase duration, and impact at 40-400 (m) away from the center of the explosion were calculated by applying TNT Equivalency Method and Multi-Energy Method. The probability of damage due to lung damage, eardrum rupture, head impact, and whole-body displacement impact by applying the probit function obtained using blast parameters was evaluated. The peak overpressure obtained using Multi-Energy Method was found to be greater than the peak overpressure obtained by applying the TNT Equivalency Method at all distances considered, but it was evaluated that there was no significant difference from the points above 200 m. The peak overpressure obtained by Multi-Energy Method was computed to assess the extent of damage to the structure, and it was shown that structures within 100 m of the explosion center would collapse completely, and that the glasses of the structures 400 m away would be almost broken. The probability of death due to lung damage was shown to vary depending on a human body's position located in the propagating direction of shock wave, and if there is a reflecting surface in the immediate surroundings of a human body, the probability of death was estimated to be the greatest. The impact of shock wave on lung damage, eardrum rupture, head impact, and whole-body displacement impact was evaluated and found to affect whole-body impact < lung damage < eardrum rupture

• Journal of the Korean Geotechnical Society
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• v.23 no.4
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• pp.15-24
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• 2007

Two kinds of temperature monitoring technology have been introduced in this study, which can measure coincidently temperatures at many points along a single length of cable. One is to use a thermal sensor cable comprizing of addressable thermal sensors. The other is to use an optic fiber sensor with Distributed Temperature Sensing (DTS) system. The differences between two technologies can be summarized as follows: A thermal sensor cable has a concept of "point sensing" that can measure temperature only at a predefined position. The accuracy and resolution of temperature measurement are up to the capability of the individual thermal sensor. On the other hand, an optic fiber sensor has a concept of "distributed sensing" because temperature is measured practically at all points along the fiber optic cable by analysing the intensity of Raman back-scattering when a laser pulse travels along the fiber. Thus, the temperature resolution depends on the measuring distance, measuring time and spatial resolution. The purpose of this study is to investigate the applicability of two different temperature monitoring techniques in technical and economical sense. To this end, diverse experiments with two techniques were performed and two techniques are applied under the same condition. Considering the results, the thermal sensor cable will be well applicable to the assessment of groundwater flow, geothermal distribution and grouting efficiency within about loom distance, and the optic fiber sensor will be suitable for long distance such as pipe line inspection, tunnel fire detection and power line monitoring etc.