• Proceedings of the Korea Air Pollution Research Association Conference
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• 2010.04a
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• pp.631-632
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• 2010

• Proceedings of the Korea Air Pollution Research Association Conference
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• 2009.10a
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• pp.286-288
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• 2009

• Asian Journal of Atmospheric Environment
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• v.10 no.4
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• pp.217-225
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• 2016

The purpose of the study was to initially investigate the concentration patterns of $PM_1$, $PM_{2.5}$ and $PM_{10}$ in the Seoul subway lines, and then to figure out the PM behaviors of internal and external sources inside subway tunnels. The PMs were monitored by a light scattering real-time monitor during winter (Jan. 8-26 in 2015) and summer (July 2-Aug. 7 in 2015) in tunnel air, in passenger cabin air, and in the ambient air. The daily average $PM_{10}$, $PM_{2.5}$, and $PM_1$ concentrations on these object lines were $101.3{\pm}38.4$, $81.5{\pm}30.2$, and $59.7{\pm}19.9{\mu}g/m^3$, respectively. On an average, the PM concentration was about 1.2 times higher in winter than in summer and about 1.5 times higher in underground tunnel sections than in ground sections. In this study, we also calculated extensively the average PM mass ratios for $PM_{2.5}/PM_{10}$, $PM_1/PM_{10}$, and $PM_1/PM_{2.5}$; for example, the range of $PM_{2.5}/PM_{10}$ ratio in tunnel air was 0.82-0.86 in underground tunnel air, while that was 0.48-0.68 in outdoor ground air. The ratio was much higher in tunnel air than in outdoor air and was always higher in summer than in winter in case of outdoor air. It seemed from the results that the in/out air quality as well as a proper amount of subway ventilation must be significant influence factors in terms of fine PM management and control for the tunnel air quality improvement.

• Proceedings of the KSR Conference
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• 2011.10a
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• pp.1309-1314
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• 2011

People spend approximately 80 ~ 90 % of their time in various kinds of indoor spaces. And, in metropolitan area, most people spend more than 1 hour in public transportation everyday. For this reason, people's interest in the indoor air quality is drastically increasing. Among various indoor air pollutants, $CO_2$ is one of the most severe environmental concerns. Ventilation is commonly used to keep low $CO_2$ concentration in the passenger cabin. However, ventilation may worse the indoor air quality problem in case of subway because the tunnel is seriously polluted by particulate matters. In this study, an alternative way to remove $CO_2$ was suggested. The adsorption of $CO_2$ by $CO_2$ adsorbent was studied. Zeolite modified with base was prepared, and $CO_2$ removal performance was tested in $4m^3$ and $24m^3$ environmental chambers. It was found that $CO_2$ adsorbent could effectively remove $CO_2$ in the chambers.

• 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.

• Particle and aerosol research
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• v.11 no.1
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• pp.1-8
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• 2015

In this study, indoor $PM_{10}$ concentration was measured by different type of real-time instruments in public transport vehicles. Light-scattering method is widely used in measuring the size of particulate matters and there is two types of light-scattering methods; one is the nephelometer type which measures the light-scattering degree by aerosol cloud, the other is the spectrometer type which measures light-scattering degree by individual particle. We observed the variation of $PM_{10}$ in KTX, subway and express bus carriages by 1-minute resolution and found that there is similar tendency in pattern among 4 light-scattering devices but difference in absolute concentrations. By comparing gravimetric result in a subway cabin, the spectrometer type device, C, was chosen as a reference device. The conversion factors of nephelometer device A-1, A-2, and B were 1.666, 1.463 and 2.125 respectively.

• 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.

• Fire Science and Engineering
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• v.23 no.1
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• pp.1-6
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• 2009

The aim of this study is to analyse the sensitivity of fire simulation parameters including grid size and solid angle number which affect the performance of subway cabin fire simulation by FDS 4.07 version. The results of sensitivity analysis shows average of $10{\sim}20%$ differences in plume temperature, upper layer temperature, and layer height depending on the change of grid size. The study also shows that simulation with 0.05m grid size produces better resolution than that with coarse one which is 0.1m.