• Journal of the Korean Geotechnical Society
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• v.24 no.11
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• pp.25-34
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• 2008

An application of concrete track is being actively processed for the construction of Korean high speed railway. The concrete track has an advantage in decreasing the maintenance cost, whereas it has much difficulty controlling the long term settlement after settlement occurred. Therefore, the management and control of settlement are very important for the successful construction of concrete track. The purpose of this paper is to verify the allowable settlement between concrete track and ballast track, and piled raft foundation installation effects as settlement reducers for concrete track. Therefore, a series of 3D finite element analyses that take into account the allowable settlement were performed for major parameters such as soil condition, pile installation and loading type. Based on the analysis, it is shown that concrete track causes much smaller settlement than ballast track, and the effect of installation is necessary to effectively reduce the settlement of concrete track.

• Journal of Environmental Health Sciences
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• v.34 no.1
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• pp.34-41
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• 2008

The objective of this study is to provide the research data on the actual concentrations of $PM_{10},\;PM_{2.5},\;PM_1\;and\;CO_2$ in Seoul subway carriages. Mean concentrations of $PM_{10},\;PM_{2.5}\;and\;PM_1,\;and\;CO_2$ in subway carriages were investigated at levels of $215.1{\pm}101.4{\mu}g/m^3,\;86.9{\pm}38.6{\mu}g/m^3,\;27.0{\pm}11.4{\mu}g/m^3,\;and\;1,588{\pm}714ppm$, respectively. The mean concentrations in subway carriages were higher when the train ran on an underground track rather than on an above ground track. The measured concentration of particulate matter varied with the time of day and was highest in the morning, followed by noon and evening while the $CO_2$ concentration was highest in the morning, followed by evening and noon. In relation to correlation among the pollutants: the correlation between $PM_{10}\;and\;PM_{2.5}$ was 0.92, and that between $PM_{2.5}\;and\;PM_1$ was 0.94. The inclusion rate of $PM_{2.5}\;to\;PM_{10}$ was $41{\pm}7%$ and that of $PM_1\;to\;PM_{2.5}\;was\;32{\pm}4%$. In addition, the $CO_2$ concentration had a positive relation with the number of people in a carriage, whereas the concentration of $PM_{10}$ had negative correlation to the number of people. In relation to these two pollutants we calculated using a regression equation (34.06+0.04$CO_2$(ppm)-0.09 PM10$({\mu}g/m^3)$($R^2$=0.30, p<0.01, n=707), that a maximum number of 61 persons would ensure that each pollutant is maintained below the criteria level, applicable to subway stations.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.17 no.1
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• pp.13-20
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• 2007

This study was performed to investigate the concentrations of PM($PM_{10}$, $PM_{2.5}$, $PM_{1}$) and it's affecting factors in the subway from line 1 to line 8 in Seoul metropolitan area, from Sep. 1 to 30, 2005. PM concentrations were measured at the entrances and centers in subway passenger cabins by a light scattering equipment. And the affecting factors to PM were estimated based on the number of passenger, door open and close and running area etc. The geometric means of $PM_{10}$, $PM_{2.5}$ and $PM_{1}$ concentration in Seoul subway passenger cabins were $214{\mu}g/m^3$, $86.6{\mu}g/m^3$ and $27.0{\mu}g/m^3$, respectively. These mean concentrations in subway carriage were higher when it ran on an underground track than on a ground track. And running time(7AM-9AM, 11AM-13PM, 6PM-8PM) significantly influenced to the concentrations of $PM_{10}$, $PM_{2.5}$ and $PM_{1}$. Daily profile of $PM_{10}$ and $PM_{2.5}$, $PM_{1}$ expressed as an 10 minutes average, showed similar variation pattern over day period. In correlation analysis, significant relations among $PM_{10}$, $PM_{2.5}$ and $PM_{1}$ were detected(p〈0.01). In particular, correlation coefficient between $PM_{10}$and $PM_{1}$ was highly significant(r=0.94). Further study is needed to identity the sources of PM in subway cabins and to compare pollutants concentration among subway lines.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.12
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• pp.603-610
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• 2016

Over 12 years have passed since the first commercial operation of a Korean high-speed train. Since then, the transport capacity of the high-speed lines has become almost saturated. Therefore, studies have been carried out to increase the operating speed of the trains in order to increase their transportation capacity. This study was carried out to improve the critical speed of the KTX-Sancheon, Korean high-speed train, in order to increase its operating speed. A dynamic analysis of the KTX-Sancheon train was performed using the contact data obtained from the wheel wear profiles that were measured from a KTX-Sancheon train in commercial operation. The analysis results were verified by comparing them with the measurement acceleration data obtained from KTX-Sancheon. The suspension parameters were optimized to improve the operation speed. The critical speed of KTX-Sancheon was increased by 9.4% after the optimization by the response surface method. The optimized suspension parameters are expected to be used for the new bogie design to increase the operating speed of KTX-Sancheon from 300km/h to 350km/h.

• Journal of Environmental Health Sciences
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• v.31 no.1
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• pp.39-46
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• 2005

This study was performed to investigate the concentration of $PM_{10}$ and $PM_{2.5}$ in inside train and platform of subway 1, 2, 4 and 5 in Seoul, KOREA. $PM_{10}$, $PM_{2.5}$, temperature, humidity and carbon dioxide were monitored using Portable Aerosol Spectrometer at afternoon (between 13:00 and 16:00). The concentrations of $PM_{10}$ and $PM_{2.5}$ in inside train were monitored to be higher than those measured in platform. In addition, $PM_{10}$ concentration in both platform and inside train were found to be greatly higher than range of from 35 ${\mu}g/m^3$ to 81${\mu}g/m^3$ in ambient air reported by Ministry of Environment. This study found that there were many inside train in subway 1, 2, 4 line where exceeded 150 ${\mu}g/m^3$ of Korean PM10 standard. The average percentage that exceeded PM10 standard was 83.3% in line 1, 37.9% in line 2 and 63.1% in line 4, respectively. In particular, most of inside train in subway line 1 were over PM10 limit. PM2.5 concentration ranged from 77.7 ${\mu}g/m^3$ to 158.2 ${\mu}g/m^3$, which were found to be greatly higher than ambient air PM2.5 standard promulgated by United States Environmental Protection Agency (US-EPA) (24 hours arithmatic mean : 65 ${\mu}g/m^3$, year average : 15 ${\mu}g/m^3$). The percentage of $PM_{2.5}$ in $PM_{10}$ was 86.2% in platform, 81.7% in inside train, 80.2% in underground and 90.2% in ground. These results indicated that fine particles ($PM_{2.5}$) accounted for most of $PM_{10}$.

• Proceedings of the KSR Conference
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• 2008.06a
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• pp.1809-1815
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• 2008

This experiment simulated the fire driven flow of an underground station through parallel processing method. Fire analysis program FDS(Fire Dynamics Simulation), using LES(Large Eddy Simulation), has been used and a 6-node parallel cluster, each node with 3.0Ghz_2set installed, has been used for parallel computation. Simulation model was based on the Kwangju-geumnan subway station. Underground station, and the total time for simulation was set at 600s. First, the whole underground passage was divided to 1-Mesh and 8-Mesh in order to compare the parallel computation of a single CPU and Multi-CPU. With matrix numbers($15{\times}10^6$) more than what a single CPU can handle, fire driven flow from the center of the platform and the subway itself was analyzed. As a result, there seemed to be almost no difference between the single CPU's result and the Multi-CPU's ones. $3{\times}10^6$ grid point one employed to test the computing time with 2CPU and 7CPU computation were computable two times and fire times faster than 1CPU respectively. In this study it was confirmed that CPU could be overcome by using parallel computation.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.29 no.2
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• pp.185-194
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• 2019

Objective: This study was conducted to investigate the intensity of the extremely low frequency magnetic fields(ELF-MF) generated inside of the cabins during subway operation. Methods: The ELF-MF intensity were investigated on 30 subway lines in Korea, including in the Greater Seoul Metropolitan Area(Seoul and Gyeonggi-do Province), Incheon, Busan, Daegu, Daejeon, and Gwangju. ELF-MF intensity was measured at 0.9 m from the floor using EMDEX II meters with a resolution of $0.01{\mu}T$. All data were collected every three seconds and analyzed with EMCALC 2013 version 3.0B software. Basic characteristics of subway operation, including alternative current(AC) or direct current(DC), voltage level, and opening year of the line were investigated. Real-time information during measurement, such as the time of departure, moving and arrival of trains, were also recorded. Results: The arithmetic mean(AM) and maximum(Max) intensity of ELF-MF were $0.62{\mu}T$ and $11.51{\mu}T$, respectively. Compared by region, the ELF-MF intensity measured inside cabin were the highest in the Seoul Metropolitan Area($AM=0.80{\mu}T$), followed by Busan($AM=0.30{\mu}T$), Daegu($AM=0.29{\mu}T$), Incheon($AM=0.14{\mu}T$), Gwangju($AM=0.04{\mu}T$) and Daejeon($AM=0.03{\mu}T$). The average ELF-MF level measured in AC trains($AM=1.36{\mu}T$) was also significantly higher than in DC trains($AM=0.28{\mu}T$). In terms of the opening year of the subway, trains opened before 1990($AM=0.85{\mu}T$) was the highest and the lowest was 2000-2009($AM=0.24{\mu}T$). Conclusions: The AC supply has the greatest influence on the generation of the ELF-MF intensity in subway cabins.