• KSCE Journal of Civil and Environmental Engineering Research
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• v.32 no.3D
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• pp.283-289
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• 2012

Because railways themselves are not enough to provide door-to-door service, they need to be complemented by a transportation system access the stations and a convenient transfer system to access other railway lines. User friendly service policies include a faster, interconnected, and intermodal transportation system. It becomes more important to use deep subterranean space from an economical standpoint in order to promote railway construction projects. In this research, the authors dealt with construction plan for strengthening capacity of deep subterranean railways. Since deep subterranean railways are situated deeper underground than other railways, they are more difficult to access and transfer to, in addition to psychological pressure. Moreover, deep subterranean railways with high speed add access difficulties as the distance between stations increases. Therefore, the authors discuss not only systemization for uniting deep subterranean railways and other transportation facilities but also reinforcement strategies. The purpose of these strategies is so that deep subterranean railways provide mobility while established railways provide accessibility to overcome this problem.

• Journal of the Korean Institute of Rural Architecture
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• v.19 no.1
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• pp.35-42
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• 2017

This study aims to investigate the change in building density and residential environment after the reconstruction of decrepit public rental housing complexes formed in accordance with the Land Readjustment Project during the 1970s-80s. The results of this study can be summarized as follows: First, in terms of change in residential environment after the reconstruction, floor plans that were limited to two to four types and to small apartments measuring $42.9m^2$(13py)-$56.1m^2$ (17py) became varied, presenting 5-6 types of floor plans and various sizes of apartments. In particular, the reconstructed apartments were mainly built in a size smaller than 85($m^2$) and in the 3LDK floor plan and staircase-style unit architectural structure in order to reflect the lifestyle of residents. Second, in terms of change in building density after the reconstruction, the building coverage ratio did not change a lot, but the floor area ratio showed great change depending on the complex, ranging from a minimum of 2.9 times (Singdong Complex) to a maximum of 5.4 times (Eoyangdong Complex). Such change is attributable to the reconstruction policy that aims to improve the residential environment for original residents, secure economic feasibility and efficiency, and reflect the lifestyle of residents while incorporating dividends assigned to the existing housing project members as well as the maximum floor area ratio allowed by the regulation. Additionally, in terms of change in the number of floors and building density after the reconstruction, the former 5-story apartments were changed to apartments with 16-28 stories. Accordingly, the number of households in each complex has also increased by 20%. Third, according to the characteristics of parking facilities in terms of the size and density of parking spaces, former apartment complexes had only aboveground parking lots, not underground parking area. The newly constructed apartment complexes have underground parking space, and the parking-housing ratio is 1.1-1.3 cars.

• Journal of Korean Tunnelling and Underground Space Association
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• v.20 no.2
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• pp.317-329
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• 2018

The study on the existing multi-utility tunnel has examined the general aspects related to the installation of multi-utility tunnel rather than the optimal design and feasibility analysis of accommodation facility in multi-utility tunnel. In the basic planning stage related to the introduction of multi-utility tunnel, it is difficult to determine accommodation facility due to lack of relevant indicators and data. In this paper, VE/LCC analysis method is suggested for the optimal alternative decision of accommodation facilities in multi-utility tunnel. The analysis of the items of individual accommodation facility and the value index for LCC costs were applied to the kind alternatives, and the priorities of each kind were analyzed. In addition, the domestic multi-utility tunnel and analysis result are compared. The result of this study will be helpful to shorten the time and convenience of the user in the process of determining accommodation facility including the first designers when introducing multi-utility tunnel.

• Journal of Korean Tunnelling and Underground Space Association
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• v.19 no.3
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• pp.489-501
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• 2017

The collapse accidents during a open ground excavation in urban areas not only lead to human injuries and material damages in the construction site, but also lead to road sinks and damages to the adjacent facilities due to settlement of ground around the construction site. Therefore, during a open ground excavation in the urban areas, it is necessary to thoroughly prepare for prevention of collapse accidents, and consider whole construction stage such as planning, design and construction. In this study, the priorities to be managed mainly were obtained in order to prevent collapse accidents during a open ground excavation. After analyzing results from past accidents cases for open ground excavations, priorities were evaluated regarding collapse-inducing elements using the Delphi technique which is a decision-making method by consensus among experts. As a result, insufficient groundwater treatment, bad geotechnical investigation and instability on construction, etc. were obtained as priorities for prevention of collapse accidents.

• Journal of Korean Tunnelling and Underground Space Association
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• v.14 no.1
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• pp.79-91
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• 2012

A curved fiber reinforced polymer (FRP) panel is produced with a certain width depending on allowances of manufacturing processes and facilities. An targeted arch-shaped structure could be built by sequential connection of series of the FRP panels. The connection manner between the FRP panels could be given by chemical treatment, mechanical treatment and hybrid method. Among those, the connection between the panels by chemical treatment is commonly adopted. Therefore, For an optimized design of the connected part between FRP pannels, a number of direct shear tests have been undertaken in terms of a number of parameters: surface treatment conditions, bonding materials, etc.. As results, surface grinding condition by sand paper or surface treatment by sand blasting appear properly acceptable methods, and epoxy and acryl resins are shown to be effective bonding materials for the purpose in this study.

• Journal of Korean Tunnelling and Underground Space Association
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• v.10 no.3
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• pp.257-267
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• 2008

Tunnels acting as drains involve groundwater-related problems such as deterioration of drainage systems or leakage through the linings. Generally initial and minor leakage problems can not be recognized by naked eyes. When the leakage over the linings is noticed, damages to structures and facilities have already occurred and could be considerable. Therefore it is vital to recognize initial leakage as early as possible and provide appropriate measures. Detection of leakage under operation requires installing piezometer. However, that may cause destruction of water proofing sheet which is generally not allowed. In this study electric resistivity method, one of the geophysical surveys, was adopted to detect possible leakage through tunnel linings. Physical lining models were made in the laboratory. The electric response was monitored for varying hydraulic conditions. It is shown that the method is very useful to detect initial leakage and monitor the malfunction of drainage system. Furthermore the method can also be used to check the quality of any repairing works of linings.

• Proceedings of the Korean Society for Rock Mechanics Conference
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• 2000.09a
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• pp.171-181
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• 2000

Many Studies of tunnel and tunnelling safety have been developed continuously based on the increasing social interests in underground space since 1990's in Korea. Because the growth of population in metropolitan has been accelerated at a faster pace than the development of the cities, underground facilities have been created as a great extent in view of less land space available. In this study, a lot of types of tunnel failure were surveyed and the detail causes were studied after many cases of tunnel failure were collected. There were suggested brief countermeasure of tunnel failure through case study. An expert system was developed to predict the safety of tunnel and choose proper tunnel reinforcement system using fuzzy quantification theory and fuzzy inference rule based on tunnel information database. The comparison result between the predicted reinforcement system level and measured ones was very similar. In-situ data were obtained in three tunnel sites including subway tunnel under Han river. This system will be very helpful to make the most of in-situ data and suggest proper applicability of tunnel reinforcement system developing more resonable tunnel support method from dependance of some experienced experts for the absent of guide.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2013.05a
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• pp.500-502
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• 2013

The metallic underground pipes like as metropolitan water supply pipes and gas pipes have a screening effects for power induction phenomenon. Generally, urban area has more metallic underground facilities than rural areas because of its buildings or population density. So we can expect high screening effects for the power induction in urban areas, and we call it the city screening factor. We had carried out the measuring test in urban and rural area respectively 30 sites to prove the actual effects of city screening factor and we derived the numerical value of city screening effects. But we faced with a difficult question that how we can classify the real urban areas or rural areas correctly. In this paper, we introduce the classification method using density of building in test area to apply the city screening factor reasonably.

• Fire Science and Engineering
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• v.32 no.4
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• pp.122-130
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• 2018

Recent urbanization, population densification, and the impact of global climate change are causing disasters to become larger and more complex. Meanwhile, in Korea, there is an emphasis on preventing, restoring, and recovering from disasters. However, disaster medical care, which is absolutely necessary to maintain life in a disaster, is being ignored. Therefore, in this study, we selected Seoul as the study area where flood damage is frequent and underground housing is densely populated. Assuming underground housing in the immersion history area as the emergency patient site, transfer distance and transfer time were analyzed. This study considered both accessibility to emergency medical facilities and disaster sites and accessibility from emergency services to disaster sites. Therefore, it seems to be meaningful as basic data for the improvement of emergency medical services.

• Corrosion Science and Technology
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• v.11 no.3
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• pp.77-81
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• 2012

Cathodic protection(CP) is widely used as a means of protecting corrosion for not only marine structures like ship hulls and offshore drilling facilities, but also underground structures like buried pipelines and oil storage tanks. The principle of CP is that the anodic dissolution of metal can be protected by supplying electrons to the cathode metal. When unprotected structures are nearby to CP systems, interference problems between unprotected and protected structures may be happened. The stray current interference can accelerate the corrosion of nearby structures. So far many efforts have been made to reduce the interference in the electric railway systems adjacent to the underground metal structures like buried pipelines and gas/oil tanks. During recent few decades the protection technologies against stray current induced corrosion have been significantly improved and a number of techniques have been developed. However, there is very limited information an marine environments. Some complex harbor structures are protected by two cathodic protection systems, i.e. sacrificial anode cathodic protection(SACP) and impressed current cathodic protection(ICCP). In this case, when the protection current from sacrificial anodes returns to the cathode through electrolyte, it passes through nearby other low resistance metal structures. In many cases the stray current of ICCP systems influences the function of SACP. In this study, the risk of stray current from the SACP system to adjacent reinforced concrete structures has been verified through laboratory experiments. Concrete and steel pile structures modeled a part of bridge have been investigated in terms of CP potential and current between the two. The variation of stray current according to the magnitude of ICCP/SACP has been studied to mitigate it and to suggest the proper protection criteria.