• 한국전산유체공학회:학술대회논문집
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• 2005.10a
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• pp.207-212
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• 2005

In designing a ventilation system of a road tunnel, a possibility of using the system as a smoke control system in case of a tunnel fire has to be considered. In the present study, a numerical simulation on ventilation system is performed considering jet fan operations and moving traffic. A fire-mode operation by reversing some fan operations in case of a tunnel fire is also simulated. The results show that ventilation operation can control the pollutants effectively, and fire-mode operation can control smoke and temperature effectively to prevent a disaster.

• Proceedings of the Korea Air Pollution Research Association Conference
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• 2000.11a
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• pp.136-138
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• 2000

The vehicle emissions of primary air pollutants are described by the emission factor (EF), defined as the emitted mass (g) of a compound per distance (km) and vehicle. The EF can be determined by exhaust measurements from single vehicles in dynamometric tests. However, the EF of a large number of vehicles has to be measured to obtain the representative results for actual road traffic emissions. Road traffic emissions can also be determined by exhaust measurements of driving vehicles or in tunnel measurements. (omitted)

• Atmosphere
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• v.25 no.3
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• pp.473-482
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• 2015

In this study, street canyons with a higher downwind building (so called, step-up street canyons) are considered for understanding characteristics of flow and reactive pollutants' dispersion as a basic step to understand the characteristics in wider urban areas. This study used a CFD_NIMR_SNU coupled to a chemistry module just including simple $NO_X-O_3$ photochemical reactions. First, flow characteristics are analyzed in step-up street canyons with four aspect ratios (0.33, 0.47, 0.6, 0.73) defined as ratios of upwind building heights to downwind building height. The CFD_NIMR_SNU reproduced very well the main features (that is, vortices in the street canyons) which appeared in the wind-tunnel experiment. Wind speed within the street canyons became weak as the aspect ratio increased, because volume of flow incoming over the upwind building decreased. For each step-up street canyon, chemistry transport model was integrated up to 3600 s with the time step of 0.5 s. The distribution patterns of $NO_X$ and $O_3$ were largely dependent on the mean flow patterns, however, $NO_X$ and $O_3$ concentrations were partly affected by photochemical reactions. $O_3$ concentration near the upwind lower region of the street canyons was much lower than background concentration, because there was much reduction in $O_3$ concentration due to NO titration there. Total amount of $NO_X$ in the street canyons increased with the aspect ratio, resulting from the decrease of mean wind intensity.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.20 no.1
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• pp.1-10
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• 2008

A transient 3-D numerical simulation was performed to analyze the fire safety in a railway tunnel equipped with a mechanical ventilation system. The behavior of pollutants was studied for the emergency operation mode of ventilation system in case of fire in the center of the rescue station and near the escape route. Various schemes of escape route construction for connection angle($45^{\circ}$, $90^{\circ}$, 135^{\circ}$) and slope($10^{\circ}$) were evaluated for the ventilation efficiency in the fire near the escape route. From the results, it was shown that the mode of the ventilation fan operation which pressurizes the tunnel not under the fire and ventilates the smoke from the tunnel under the fire is most effective for the smoke control in the tunnel in case of the fire occurrence. It was also shown that the blowing of jet fan from the rescue tunnel to the main tunnel should be in the same direction as the flow direction in the main tunnel arising from the traffic and the buoyancy.

• Journal of Korean Society for Atmospheric Environment
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• v.27 no.5
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• pp.614-622
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• 2011

In this study, a new tunnel ventilation method with a high velocity air curtain flow has been investigated for improving the ventilation exhaust efficiency and removing air pollutants in subway tunnels. At upper or lower position right downstream of a main duct connected with a ventilation opening, air curtain flows were suppled into the main duct where the air flow velocity was in the range of 2~6 m/s. Exhaust efficiency was monitored for both cases with and without air curtain flow for different air velocities, locations and injection angles of the air curtain. Particulate matter concentrations (PM10, PM2.5 and PM1.0) were also checked at both the main duct and ventilation opening before and after supplying air curtain flows. Lower air velocity of the main duct flow, higher air velocity of the air curtain led to higher exhaust efficiency and the air curtain condition of 30..inclined injection toward the main flow showed the maximum exhaust efficiency. The exhaust efficiency of about 24% without the air curtain could be improved to about 34% after using the air curtain flow. PM concentration decreased at the main duct and increased at the ventilation opening after using the air curtain flow. Therefore, the suggested method to use air curtain flows in tunnels will be probably one of the promising tools to reduce air pollutants in subway tunnels.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.30 no.4 s.247
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• pp.373-380
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• 2006

Annubar is one of popular tools to measure the exhausted gas flow rate from the stacks. For the accurate monitoring of the amount of discharged pollutants, calibration of annubar is very important. Calibration of annubar has been carried out in a wind tunnel. When the length of annubar is longer than the test section size of wind tunnel, it is very difficult to find out typical value of annubar coefficients. So, a measurement technique to calibrate annubar longer than the size of the test section of wind tunnel must be developed. In the present study, an experiment is performed to measure the annubar coefficients in such a limited size of the wind tunnel. The experimental annubar coefficient by using a partial blocking technique is very close to the annubar coefficient of normal condition.

• Proceedings of the SAREK Conference
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• 2007.11a
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• pp.270-275
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• 2007

Pollutants emitted by Diesel trains seriously affected on the ventilation characteristics in the subway or railway tunnel network systems. Thus, numerical prediction results and analyses are required to engineers who should design ventilation facilities. So here, this paper presents some numerical results about the ventilation characteristics, such as pollutants distributions and a suitability of the ventilation facilities pre-designed in case that diesel trains use the same railway track with normal passenger trains

• Proceedings of the KSR Conference
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• 2006.11b
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• pp.192-195
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• 2006

With increasing concerns of indoor air quality, $CO_2$ concentration in the public transportation, such as train, bus, and subway, draws big interests. The $CO_2$ concentration in the indoor air is regarded as index of ventilation status rather than that of adverse health effect. In this study, we measured the time-series of $CO_2$ concentrations in the KTX cabin during the journey of Gyongbu-line (Seoul-Busan) and Honam-line (Seoul-Mokpo) with the number of passengers on board. At the same time, the concentration of particulate matter (PM), temperature, humidity and gaseous pollutants including HCHO and VOCs were monitored. It is found that the $CO_2$ concentration was correlated linearly with number of passengers and was highly correlated with tunnel regions where the ventilation unit (flap) was closed.

• Journal of odor and indoor environment
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• v.17 no.4
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• pp.303-314
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• 2018

The urban railway system is a convenient public transportation system, as it carries many people without increasing traffic congestion. However, air quality in urban railway environments is worse than ambient air quality due to the internal location of the source of air pollutants and the isolated space. In this paper, characteristics of particulate matter (PM) pollution in urban railway environments are described from the perspective of diurnal variation, chemical composition and source apportionment of PM. PM concentrations in concourse, platform, passenger cabin, and tunnel are summarized through an analysis of 34 journal articles published in Korea and overseas. This information will be helpful in developing effective policies to reduce PM pollution in urban railway environments.

• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.1408_1409
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• 2009

It's described the discharge characteristics and ICP-AES analysis of insulators by surface deterioration in this paper. For the assessment of insulators, there are applied the conductivity of dusts, contact angle measurement of the insulator surfaces and the ingredient analysis in each area. Through the analysis of pollutants attached to insulators inside the tunnel, the cleaning cycle is discussed. As the results, it would be expected to the electrical safety.