• Fire Science and Engineering
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• v.23 no.4
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• pp.13-18
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• 2009

The main objective of the present study is to investigate smoke propagation in railway tunnels with rescue stations. In particular, based on measurement of HRR (heat release rate) for pool fires formed at different locations, the influence of fire source location on smoke behavior is examined. The fuel is n-heptane and pool fires are generated with a square length 4cm. With the use of MVHS (Modified Volumetric Heat Source) model for fire source, extensive numerical simulations are performed by using the commercial code FLUENT (Ver.6.3) Predicted smoke temperatures and smoke propagation are discussed. From numerical predictions, it is found that ventilation systems may be necessary in the railway tunnels because the smoke moves along the tunnel, and consequently it enters the non-accident tunnel. It is also confirmed that the cross-passage and fire protection wall systems contribute to control the smoke.

• Journal of Satellite, Information and Communications
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• v.9 no.4
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• pp.26-31
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• 2014

In this paper, we present performance analysis of video smoke detection based on BPN-Network that is using multi-smoke feature, and Neural Network. Conventional smoke detection method consist of simple or mixed functions using color, temporal, spatial characteristics. However, most of all, they don't consider the early fire conditions. In this paper, we analysis the smoke color and motion characteristics, and revised distinguish the candidate smoke region. Smoke diffusion, transparency and shape features are used for detection stage. Then it apply the BPN-Network (Back-Propagation Neural Network). The simulation results showed 91.31% accuracy and 2.62% of false detection rate.

• Fire Science and Engineering
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• v.22 no.2
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• pp.49-56
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• 2008

Smoke propagation for the Daegu Metro fire is reproduced by a reduced-scale model experiment. The three-story station building was modeled with 1/20-scale, and the tunnel connected to the platform was not completely modeled because of its length. To include the flow resistance the tunnel provides the mesh screens were used in the model. The fire scenario was selected based on the fire growth rate of the metro car seat where the fire initiated. The time when smoke arrived at each compartment in the station building was measured by thermocouples and visualization. Regarding fire ventilation, the air supply that has been accepted as conventional design in a subway metro building intensifies smoke spread. The results show that the whole building was filled with smoke in about 10 minutes in case of no ventilation.

• Fire Science and Engineering
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• v.17 no.3
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• pp.13-19
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• 2003

In this paper, numerical calculations are conducted to predict the characteristics of the heat transfer and smoke propagation in a cydodrome. The gas flow velocity and temperature around the origin of the fire is obtained by using a plume model and the turbulent flow characteristics are considered by standard $textsc{k}$-$\varepsilon$ turbulent model. In this study, the transient thermal behavior can be used for designing fire detection of large rooms.

• Journal of the Korean Society for Railway
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• v.11 no.3
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• pp.294-299
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• 2008

The present study investigates the ventilation effects on smoke spreading with the rescue stations. Experiments for tunnel fires were carried out for n-heptane pool em at different fire locations, and the heat release rates (HRR) were obtained by addition, using the commercial code (FLUENT), the present article presents numerical results for smoke behavior in railway tunnels with rescue station, and it uses the MVHS (Modified Volumetric Heat Source) model for estimation of combustion products resulting from the fire source determined from the HRR measurement. As a result, it is found that smoke propagation is prevented successfully by the fire doors located inside the cross-passages and especially, the smoke behavior in the accident tunnel can be controlled through the ventilation system because of substantial change in smoke flow direction in the cross-passages.

• 유체기계공업학회:학술대회논문집
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• 2006.08a
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• pp.575-578
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• 2006

In designing smoke-control system of rescue station in train tunnel, a purpose is to prevent a disaster by proposing the jet fan operation together with smoke-control curtain in tunnel fire. This study has investigated the relationship of the Heat Release Rate(HRR) and a adequate ventilation velocity to control the fire propagation in tunnel fire, and has improved the effect of the smoke-control curtain on preventing the flow of pollutants. In this study, Computational Fluid Dynamics(CFD) simulations with ST AR-CD(ver 3.24) were carried out on predicting the fire spreading and the flow of pollutants, considering jet fan operations and effect of smoke-control curtain. Our simulation domain is the full scale model of the 'DAEGWALLYEONG' 1st tunnel. The results represent that ventilation operation can control the fire spreading and pollutants effectively to prevent a disaster.

• Proceedings of the KSR Conference
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• 2008.06a
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• pp.2130-2138
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• 2008

The present study investigates the ventilation effects on smoke spreading characteristics in railway tunnels with the rescue stations. Experiments were carried out for n-heptane pool fires with a square length 4 cm at different fire locations, and the heat release rates (HRR) were obtained by the measurement of burning rates. In addition, using the commercial code (FLUENT), the present article presents numerical results for smoke behavior in railway tunnels with rescue station, and it uses the MVHS (Modified Volumetric Heat Source) model for estimation of combustion products resulting from the fire source determined from the HRR measurement. As a result, it is found that smoke propagation is prevented successfully by the fire doors located inside the cross-passages and especially, the smoke behavior in the accident tunnel can be controlled through the ventilation system because of substantial change in smoke flow direction in the cross-passages.

• Tunnel and Underground Space
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• v.12 no.1
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• pp.31-36
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• 2002

This paper concerns smoke propagation in tunnel fires with various size of fire source. Experiments carried out in model tunnel and those results were compared with numerical results. The Froude scaling law was used to scale model tests for comparison with larger scale tests. In order to validate for numerical analysis, temperature distribution of predicted data was compared with measured data. Examining the temperature distribution, we found that smoke layer does not come down under 50% of tunnel heights for a short tunnel heights for a short tunnel firs without ventilation. Front velocity of smoke layer is proportional to the cube root of heat release rate. And it is in good agreement with existing empirical expression and numerical prediction. In a short tunnel fire, horizontal propagation of smoke layer is more important than vertical smoke movement for evacuation plan.

• Tunnel and Underground Space
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• v.15 no.6 s.59
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• pp.452-461
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• 2005

In a bidirectional tunnel, the accident rate is 1.5 times as high as that of one directional tunnel , the risk of a fire is increased. On fire, there is a problem that the jet fan should not be operated until completion of refuge. To be special, as the great damages occur owing to the expansion of smoke in long tunnels, there is a need to minimize fatality by constructing cross passage and smoke removal system. This study aims at verifying the efficiency of smoke exhaust system through fire propagation simulation as well as scale model test. The results show that completion of escape through emergency exit requires 335 seconds, while addition of smoke exhaust system reduce the escape time to 185 seconds. Also, near the fire source temperature decreased by about $60^{\circ}C$. Without the exhaust system, fire propagation speed was in the range of 0.36 and 0.82 m/s, and it dropped to $0.27\~0.58\;m/s$ with the exhaust system on. Taking into account the escape speed of tunnel users, usually $0.7\~1.0\;m/s$, the emergency exit built every 150m is sufficient for the safe egress. The ultimate goal of this study is to provide fundamental information for the smoke exhaust system in bidirectional tunnels.

• Journal of Korean Tunnelling and Underground Space Association
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• v.22 no.4
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• pp.347-365
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• 2020

In order to resolve traffic problems in urban areas and to increase the area of green spaces, tunnels in downtown areas are being increased. Additionally, the application of large port smoke extraction ventilation systems is increasing as a countermeasure to smoke extraction ventilation for tunnels with high potential for traffic congestion. It is known that the smoke extraction performance of the large port smoke extraction system is influenced not only by the amount of the extraction flow rate, but also by various factors such as the shape of the extraction port (damper) and the extraction air velocity through a damper. Therefore, in this study, the design standards and installation status of each country were investigated. When the extraction air flow rate was the same, the smoke extraction performance according to the size of the damper was numerically simulated in terms of smoke propagation distance, compared and evaluated, and the following results were obtained. As the cross-sectional area of the smoke damper increases, the extraction flow rate is concentrated in the damper close to the extraction fan, and the smoke extraction rate of the damper in downstream decreases, thereby increasing the smoke propagation distance on the downstream side. In order to prevent such a phenomenon, it is necessary to reduce the cross-sectional area of the smoke damper and increase the velocity of passing air through the damper so that the pressure loss passing through the damper increases, thereby reducing the non-uniformity of smoke extraction flow rate in the extraction section. In this analysis, it was found that when the interval distance of the extraction damper was 50 m, the air velocity passing through damper was 4.4 m/s or more, and when the interval distance of the extraction dampers was 100 m, the air velocity passing through damper was greater than 4.84 m/s, it was found to be advantageous to ensure smoke extraction performance.