• Journal of Korea Water Resources Association
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• v.53 no.4
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• pp.303-312
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• 2020

An underground deep tunnel system is a facility in form of a reverse siphon for an under flood defense structure. In this study, the 'Shinwol rainwater storage and drainage system', which is under construction for the first time in South Korea, in order to confirm the effects of undular bore and pressurized air on the hydraulic stability of the facility in various flood scenarios a hydraulic model experiment was performed. As a result of this study, it was analyzed that the undular bore generated downstream pushed the pressurized air collected in the facility while moving upstream, and the pressure inside the pipe increased at this time. It was analyzed that the pressure during the passage of the undular bore was greater than the sum of the static pressure and dynamic pressure at the time and overflow occurred when the cross-sectional size of the pressurized air was more than 40% of the cross sectional area of the tunnel. It is determined that this is correlated with the volume of pressurized air collected in the facility, and it is determined that it is necessary to study the relationship between velocity of undular bore and the volume of pressurized air in the future.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.44 no.4
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• pp.587-593
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• 2024

Recently, countries such as Japan and France are actively using three-dimensional development of land to secure available land. In Korea, too, the lack of available land within cities is a major problem, and in particular, the problem of decline due to disconnection due to division due to the railroad is emerging. As a solution to this, interest in three-dimensional development is increasing day by day, but the application or legal effectiveness of the concept is still lacking. Therefore, in this study, assuming that the Gyeongbu Line railway in Busan is underground, we attempted to apply the type of multi-dimensional development appropriate for each region to the land that would be created, and to predict how much it would contribute to urban competitiveness by arranging the necessary facilities for each part. To this end, we have developed an urban competitiveness index that can evaluate the layout of facilities by region, and since the range of the region is different from the existing evaluation indicator, it is judged that the three-dimensional development of the railway facility site can have a positive impact on the competitiveness of the city as a result of the prediction through a subjective survey.

• Tunnel and Underground Space
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• v.16 no.1 s.60
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• pp.11-25
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• 2006

The world's largest nucleon decay experiment facility is constructed at a depth of approximately 1,000 meters, in the Kamio Mine, Japan. The excavated cavern is consisted of a cylinder of 42.4 m high and a semi elliptical dome of 15.2 m high, with a bottom diameter of 40 m. The total excavation volume is approximately $69,000\;m^3$. Because of the character as a large cavern excavation in deep underground, there is many unknown factors in rock mechanics. Based on the results of rock test and numerical analysis, the monitoring of rock mass behavior accompanying progress of construction was performed by various instruments installed in the rock mass surrounding the cavern. The monitoring data was used in the study of measures for cavern stability.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.62 no.7
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• pp.905-912
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• 2013

Power system fault analysis is commonly based on well-known symmetrical component method, which describes power system elements by positive, negative and zero sequence impedance. In case of balanced fault, such as three phase short circuit, transmission line can be represented by positive sequence impedance only. The majority of fault in transmission lines, however, is unbalanced fault, such as line-to-ground faults, so that both positive and zero sequence impedance is required for fault analysis. When unbalanced fault occurs, zero sequence current flows through earth and skywires in overhead transmission systems and through cable sheaths and earth in cable transmission systems. Since zero sequence current distribution between cable sheath and earth is dependent on both sheath bondings and grounding configurations, care must be taken to calculate zero sequence impedance of underground cable transmission lines. In this paper, conventional and EMTP-based sequence impedance calculation methods were described and applied to 345kV cable transmission systems (4 circuit, OF 2000mm2). Calculation results showed that detailed circuit analysis is desirable to avoid possible errors of sequence impedance calculation resulted from various configuration of cable sheath bonding and grounding in underground cable transmission systems.

• Journal of the Korean Institute of Gas
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• v.13 no.2
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• pp.49-56
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• 2009

This thesis suggests ways for ensuring the safety of domestic autogas (liquefied petroleum gas) vehicles by conducting comparison and analysis on the status of market diffusion and safety management scheme in foreign countries as well as in Korea. According to the result of the survey on the status of domestic autogas safety management, the national scheme to secure the safety of autogas vehicles seems neither well-organized nor sufficiently-controlled. Actually, the gas leakage check-ups conducted for 5,000 autogas cars revealed that about 4 percent of them had leakage problems. As a result, it was acknowledged that the autogas safety regulations being operated in advanced countries need to be selectively introduced for the domestic autogas industry. Consequently, in line with the recent permission to use autogas as a fuel for subcompact cars etc., this thesis is recommending some methods to enhance the safety management scheme for autogas cars such as the amendment of facility regulations including the ventilation of underground parking lots, mandatory attachment of labels claiming autogas cars and indicating periodical inspections etc.

• Journal of Korean Tunnelling and Underground Space Association
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• v.9 no.3
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• pp.287-298
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• 2007

Recently, as the construction of new railway and the relocation of existing line increase, tunnel structures get longer. The railway fire accidents in long tunnel bring large damages of human life and disaster. The interest on safety in long tunnel has been growing and the safety standard for long tunnels is tightening. For that reason, at the planning stage of a long tunnel, the optimum design of safety facility for minimizing the risks and satisfying the safety standard is required. For the reasonable design of a long railway tunnel considering high safety, qualitative estimation for tunnel safely is required. In this study, QRA (Quantitative Risk Analysis) technique is applied to design of a long railway tunnel for assuring the safety function and estimating the risk of safety. The case study for safety design was carried out to verify the QRA technique for two railway tunnels.

• Journal of Korean Tunnelling and Underground Space Association
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• v.9 no.4
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• pp.343-349
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• 2007

The reduced scale fire test provides basic data but it is not enough to analysis real fire problem directly because there is no exact analogy theory between a real fire and the reduced scale model. Therefore we have developed the large scale calorimeter in order to the real scale fire test. This advanced large scale calorimeter used for physical properties such as a heat release rate, based upon consumption of $O_2$ method. Using this large scale calorimeter, we cameo out the real scale vehicle fire test in order to evaluation for heat release rate. We obtained the calculated result for HRR $2.3{\sim}3.4\;MW$ and this result is very similar to the PIARC candidate HRR. It is approve that this facility has the reliability and it is capable of applying to the advance fire research in the future.

• Journal of Korean Tunnelling and Underground Space Association
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• v.14 no.1
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• pp.37-53
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• 2012

There is considerable uncertainty in ground properties used in tunnel designs. In this study, a back analysis was performed to find optimal ground properties based on the artificial neural network facility of MATLAB program of using tunnel monitoring data. Total 81 data were constructed by changing elastic modulus and coefficient of lateral pressure which have great influence on tunnel convergence. A sensitivity analysis was conducted to establish an optimal training model by varying the number of hidden layers, the number of nodes, learning rate, and momentum. Meanwhile, the optimal training model was selected by comparing MSE (Mean Squared Error) and coefficient of determination ($R^2$) and was used to find the correct elastic moduli of layers and the coefficient of lateral pressure. In future, it is expected that the suggested method of this study can be applied to determine the optimum tunnel support pattern under given ground conditions.

• Journal of Korea Multimedia Society
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• v.14 no.8
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• pp.1041-1049
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• 2011

According to the development of society and infrastructure, effective underground facility management is growing more important them ever. In the process various monitoring systems are studied and developed for water works pipe-network. Especially, RTD-1000 system with the based on Pc. Reflector-monitoring device is constructed and steered by several local governments. But, this system have to be improved result from based on PC system structure at the point of resource management, heat, power consumption and size. In this paper, RTD-2000 is proposed are a substitution of improved RTD-1000 with many respect and portable one. This system is designed and implemented with ARM-9 development kit based on WinCE and LCD eliminate TDR(Time Domain Reflector-Meter). Various surveillance programs based on windows are mounted on RTD-1000 are replaced with dedicated embedded application softwares. Simulation and evaluation for performance comparison are performed for the prove of effectiveness of RTD-2000.

• Tunnel and Underground Space
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• v.23 no.3
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• pp.192-202
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• 2013

The domestic demand of natural gas has increased continuously due to the sudden rise of oil price and regulations on greenhouse gas to global warming. In order to improve the supply security of natural gas market in Korea, the agreement on supply of pipeline natural gas (PNG) in Russia was signed between Gazprom and Korea Gas Corporation in 2008. If the supply plan of Russian natural gas is realized, underground storage facilities would be required in order to balance supply and demand of natural gas because the gas demand is concentrated in the winter. This study investigated the safety of the storage facility in quantitative way considering several design parameters such as gas pressure, depth of the storage cavern, rock condition and in-situ horizontal stress ratio. Two dimensional stress analyses were conducted using axi- symmetry condition to examine the behavior of cavern depending upon suggested design parameters. Results showed that the factor of safety, defined as the ratio of 'shear strength'/'shear stress', was largely affected by the depth, rock class and gas pressure but was insensitive to the coefficient of lateral pressure(Ko).