• 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.20 no.2
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• pp.92-96
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• 2010

In this study, experiments were conducted to evaluate the effectiveness of ventilation equipment in underground fires. Two type of Ventilators were used in experiments. Experiments were carried out using ethanol square pool fire. Maximum heat release rate was about 460kW. Visibility and temperature distribution were evaluated according to mechanical ventilation. In blower type ventilation, visibility was increased and temperature was lowered.

• Proceedings of the Korea Institute of Fire Science and Engineering Conference
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• 2010.10a
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• pp.171-174
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• 2010

도로터널에서의 미분무수 소화시스템의 적용 가능성을 검토하기 위해 실물 화재 실험을 수행하였다. 적용된 화원은 실물 승용차 화재와 유류화재를 모사한 화원면적 $1.4m^2$의 heptane pool 화재이며, 기존 도로터널에 설치된 저압 물분무 시스템과 고압 미분부수 소화시스템과의 냉각효과 비교실험을 수행하였다. 도로터널 내의 환기조건을 구현하기 위해 실물모형 터널의 한 편에 터널 유속(0.9~3.8 m/sec 범위) 발생장치를 설치하였으며, 화원에서 하류 방향으로 터널 내 온도분포를 측정하였다. 실험 결과 1/5의 유량을 사용하는 고압 미분무수 소화시스템은 저압 물분무 시스템과 동등한 수준의 냉각효과를 보였다.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.26 no.5
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• pp.703-709
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• 2002

In order to investigate the smoke movement in three dimensional room fires, the center fire, wall fire and corner fire plume in different sized fires were studied experimentally by rectangular pool fire using methanol as a fuel. As the fire size became larger for the center fires placed at the center of the floor, the air flow rate entrained through the opening, average hot layer temperature, flame angle deflected backwards and mean flame height was observed to increase. On the other hand, as the fire size became smaller, the neutral plane height in the door and time reached steady-state was observed to decrease. The average hot layer temperature, mean flame height and doorway neutral plane height obtained from comer fire were higher than those produced by wall fires and center fires. The simple model for describing the effect of walls on the mean flame height was presented. It was shown that the model provides a good description of the present measurements, when used with the assumption by Hansell(1993), that the increase of the average flame height is equal to the ratio of the open to the total perimeters of the trays. Also the two models for predicting the effects of walls on the mean flame height were presented. These models overestimated the measured values of the mean flame height above fuel trays close to a wall and in a corner by approximately 19-26%, respectively.

• Journal of the Korean Society of Safety
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• v.34 no.1
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• pp.27-33
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• 2019

Combustion characteristics of gasoline/ethanol fuel were investigated both numerically and experimentally for vehicle fire safety. The numerical simulation was performed on the well-stirred reactor (WSR) to simulate the homogeneous gasoline engine and to clarify the effect of ethanol addition in the gasoline fuel. The simulating cases with three independent variables, i.e. ethanol mole fraction, equivalence ratio and residence time, were designed to predict and optimized systematically based on the response surface method (RSM). The results of stoichiometric gasoline surrogate show that the auto-ignition temperature increases but NOx yields decrease with increasing ethanol mole fraction. This implies that the bioethanol added gasoline is an eco-friendly fuel on engine running condition. However, unburned hydrocarbon is increased dramatically with increasing ethanol content, which results from the incomplete combustion and hence need to adjust combustion itself rather than an after-treatment system. For more tangible understanding of gasoline/ethanol fuel on pollutant emissions, experimental measurements of combustion products were performed in gasoline/ethanol pool fires in the cup burner. The results show that soot yield by gravimetric sampling was decreased dramatically as ethanol was added, but NOx emission was almost comparable regardless of ethanol mole fraction. For soot morphology by TEM sampling, the incipient soot such as a liquid like PAHs was observed clearly on the soot of higher ethanol containing gasoline, and the soot might be matured under the undiluted gasoline fuel.

• Journal of the Korean Society of Safety
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• v.27 no.3
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• pp.71-76
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• 2012

The coflow velocity effect on the minimum extinguishing concentration(MEC) was investigated experimentally in heptane cup-burner flames. Various inert gases($N_2$, Ar, $CO_2$, He) were added into the oxidizer to find the critical concentration and the effectiveness of the agents on flame extinction. The experimental results showed that the MECs were increased with increasing coflow velocity for most inert gases except helium, but the higher coflow velocity induced the lower burning rates of heptane. This indicated that the increase of coflow velocity resulted in the decrease of fuel velocity evaporated from fuel surface, and hence the stain rate on the reaction zone was also decreased. In the case of helium as a additive, the extinguishing concentration was independent of the coflow velocity because the heat conductivity was ten times larger than the other inert gases and flow effect by a strain rate might be compensated for heat loss to the surroundings.

• Fire Science and Engineering
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• v.27 no.2
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• pp.62-69
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• 2013

In this study, a full scale experiment was carried out to analyze the heat and smoke movement. The experiment was conducted a kindergarten that is scheduled to reconstruction. The kindergarten is a two-story building and the area of each floor is 252 $m^2$. 36 l heptane was used as a fuel and heptane was burned in a 0.8 m square steel pool. Maximum heat release rate was 1.7 MW at natural condition. Smoke movement and temperature variation were measured during the experiment. In the first floor corridor, smoke was moved downward about 1.4 m at 1 minute after a fire. Corridor was filled with smoke at 4 minutes after a fire. In the second floor, temperature was maintained at $70^{\circ}C$ or less. But, second floor rooms were filled with smoke.

• Journal of the Korean Institute of Gas
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• v.23 no.6
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• pp.39-60
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• 2019

Korea Gas Safety Corporation is developing consequence analysis system for combustible materials release events to enhance risk assessment technology and its efficiency. Unlike general consequence analysis programs, the final consequence area was implemented through ETA analysis based on API-581 standard, and a convenient user interface was constructed based on HTML5-based responsive web technology. In addition, a phase equilibrium module using third-order state equations (such as Peng-Robinson, SRK, and RK) and fugecity was implemented to analyze the mixture quality. Also. using the consequence analysis algorithm introduced in CCPS books and TNO Yellow Book, we developed material leak analysis module, fireball, pool fire, jet fire, flash fire, and vapor cloud explosion consequence assessment module. In addition, the conditions for calculating the safety distance were prepared with using the control values in the EIGA standard, PAC, and Bevi Reference Book.

• Proceedings of the KSR Conference
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• 2007.05a
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• pp.1307-1312
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• 2007

This experiments are performed to investigate the effect of ventilation velocity on a high pressure water mist fire suppression in subway train. The experiment is conducted in half scale modeled train of a steel-welled enclosure (8.0m*2.4m*2.1m). The ventilation velocity is controlled by the ventilation duct through an inverter in the range of 0 to 2 m/s. The coverage-radius and an injection angle of an high pressure water mist system are measured. The mist nozzle with 7-injection holes is operated with pressure 80 bar. The heptane pool fires are used. The fire extinguishment times and the temperatures are measured for the ventilation velocities. In conclusion, because the momentum of injected water mist is more dominant than that of ventilation air, the characteristics of water mist, the fire extinguishment times and the temperatures are affected very little by ventilation velocity.

• Journal of the Korean Society of Safety
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• v.27 no.6
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• pp.59-63
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• 2012

The use of dry chemical powder has been increased as it can be stored for a long period and sustain in stable condition compared to gas or liquid phase extinguishing agents. A new type of dry chemical powder using Zeolite was produced in the research. Chemical powder was adsorbed into Zeolite 13X, a porous material appearing negative catalytic effect, to create extinguishing powder obtaining core shell structure and measured physical properties and run a small scale fire extinguishment. SEM, XRD, TA analysis was also executed, and extinguishing characteristics were measured by fire extinguishing experiment on oil pool fire. The experiment showed that the average particle size of Zeolite 13X was equivalent, indicating about $3{\pm}1{\mu}m$ and thermal analysis result illustrated that Zeolite 13X showed exothermic reaction peaks at $900^{\circ}C$ due to solid-state transformation. Extinguishing characteristics on oil fire of $NaHCO_3$/Zeolite 13X and $NH_4H_2PO_4$/Zeolite were improved, influenced by adsorbed extinguishing powders on Zeolite 13X and Zeolite 13X that contains high phase transition temperature.