• Fire Science and Engineering
• /
• v.17 no.3
• /
• pp.61-73
• /
• 2003

Most of the accidents occurred from the chemical plants are related to the catastrophic gas release events when the large amount of toxic materials is leaked from its storage tank or transmitting pipe lines. In this case, the greatest concerns are how the spreading behaviors of leakages are depended on the ambient conditions such as air stability and other environmental factors. Hence, we have focused on the risk assessments and consequential analysis for chlorine as an illustrative example. As appeared in the result, Fire & Explosion Index depicted it a bit dangerous with presenting the comprehensive degrees of hazard 90.7. And as a result of Phast6.0/ALOHA, the trends of each scenario appeared considerably identical although there are some differences in the resulting effects according to the input data for the Gas Model. The consequence analysis is performed numerically based on the dense gas mode. In the future, using more correct input data, material properties, and topographical configuration, the method of this research will be useful for the guideline of the risk assessment when the release of toxicants breaks out.

• Korean Chemical Engineering Research
• /
• v.43 no.1
• /
• pp.47-52
• /
• 2005

The wide use of metal dusts have been found in industrial field and many dust explosion accidents occur by fire spread of dust layer. In this study, we developed a new experimental device to examine fire and explosion characteristics of the dust layer. Aspects of the burning zone over metals(Mg, Zr, Ta, Ti, etc) and PMMA(Polymethyl methacrylate) dust layers have been investigated experimentally to clarify behaviors (Spread rate and quenching distance) and effects of $N_2$ surrounding gas on the fire spread over metal dust layers. From the experimental result, it was found that the spread rate of metal dusts is larger than PMMA, the dependability of spread rate over the thickness of dust layer is small, and the minimum oxygen concentration of spread flame over Mg dust layer is 3.6-3.7 vol%. Since high correlation between the spread rate and the reciprocal of quenching distance was seen, relative risk prediction in those inflammable parameters can be predicted.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.11 no.2
• /
• pp.155-163
• /
• 2007

High Strength Concrete (HSC) has weakness that in a fire, it is spalled and brittles. The phenomenon of spalling is made by water vapor's (resulting from evaporation in the material at over $100{^{\circ}C}$)' being confined in watertight concrete. As the concrete strength increases, the degree of damage caused by the spalling becomes more serious because of the permeability. It is reported that the polypropylene(PP) fiber has an important role in protecting concrete from spalling and the optimum dosage of PP fiber is 0.2%. This study was conducted on the nonreinforced concrete specimens. The high-temperature behavior of high-strength reinforced concrete columns with various concrete strength and various dosage of PP fibers was investigated in this study. The results show that the ratio of unstressed residual strength of columns increases as the concrete strength increases and the ratio of unstressed residual strength of columns increases as the dosage of PP fiber increases from 0% to 0.2%, however, the effect of fiber dosage on residual strength of column barely changes above 0.2%.

• Journal of Korean Tunnelling and Underground Space Association
• /
• v.11 no.4
• /
• pp.411-417
• /
• 2009

The thermo-flow field in road tunnel is influenced by some facts such as piston effect of vehicle's move, operation of ventilation facilities, natural wind and buoyancy effect of fire plume. Among those, piston effect is one of primary causes for formation of air flow in road tunnel and has an effect on initial direction of smoke flow in tunnel fire. In this study to analyze the unsteady flow in the tunnel caused by the run of vehicle, the experimental study of vehicle-induced unsteady flow on a reduced-scale model tunnel is presented. While the three types of vehicle shape such as basic type of rectangular shape, diamond-head type and stair-tail type are changed, the pressure and air velocity variations with time are measured. The rising ratio of pressure and velocity are in order of "basic type of rectangular shape > stair-tail type > diamond-head type". The experimental results would be good data for development of a numerical method on the vehicle-induced unsteady tunnel flow.

• Journal of the Earthquake Engineering Society of Korea
• /
• v.9 no.3 s.43
• /
• pp.77-85
• /
• 2005

After the collapse of the World Trade Center in september 11, 2001 and due to the frequent fire-caused damages of buildings during earthquake attacks, social concerns have been increased for the fire proof of the structural members of buildings. Recently, researches have been conducted to improve the fire resistance for building members not by the traditional ways but by utilizing the fire-resisting characteristics of reinforced concrete and structural characteristics of H-steel. In this paper, laboratory tests were conducted in room temperature to investigate the structural performance of the composite beams, which were developed to improve the fire resistance, comprising with concrete incasement between upper and lower flanges of H steel. From the experimental results, the displacement ductility factors of $6\~8$ were obtained. The difference of flexural behavior ol H steel-partial concrete incased composite beams with various composite details seems to be minor. The amount of longitudinal rebars is the most influential factor for the flexural strength of the composite beams. Therefore, if this type of composite beams are selected for designing a building located in moderate seismic lone, identical beam size could be used in several stories of the building.

• Journal of ILASS-Korea
• /
• v.20 no.2
• /
• pp.107-113
• /
• 2015

To date, the demand for Combined Cycle Power Plant (CCPP) has been continuously increased to overcome the problem of air pollution and lack of energy. In particular, the underground CCPP is exposed to substantial fire and explosion risks induced by gas leakage. The present study conducted numerical simulations to examine the fire behavior and gas leakage characteristics for a restricted region including gas turbine and other components used in a typical CCPP system. The commercial code of FLUENT V.14 was used for simulation. From the results, it was found that flammable limit distribution of leakage gas affects fire behavior. Especially, the flame is propagated in an instant in restricted region with LNG gas. In addition, consequence analysis factors such as critical temperature and radiation heat flux are introduced. These results would be useful in making the safety guidelines for the underground CCPP.

• Proceedings of the KIEE Conference
• /
• 2009.07a
• /
• pp.2158_2159
• /
• 2009

본 논문에서는 DC전원설비 접속부에서의 접촉불량에 의한 발열 특성에 대하여 실험, 분석하였으며 사용된 DC 전원설비는 상용 교류전원을 직류전원으로 변환하는 AC/DC 컨버터의 출력전원을 이용하는 LED 가로등 조명설비의 전원 접속부을 대상으로 하였다. 외부의 기계적 진동에 의해 동전선 접속부에 아크와 열이 발생하며 이때 발생한 발열 온도와 열 분포를 측정하였으며 적열부가 형성된 후 25분이 경과하였을 때 최고 $842.68^{\circ}C$까지 온도가 상승하였으며 접속부의 접촉전압은 1.5~1.6V, 통전전류는 6.6~6.9A로 약간의 변화만 나타남을 볼 수 있었다. 또한 DC전원에서 동전선 접속부에서의 산화물 생성과 증식 거동에 대하여 분석하였으며 AC전원에서와 유사하게 산화물이 형성되어 성장함을 볼 수 있었다. 이러한 실험과 분석 결과는 향후, DC 전원설비에서의 전기화재 예방을 위한 자료로 활용 가능할 것으로 기대된다.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2008.11a
• /
• pp.875-878
• /
• 2008

This paper summarizes on the state-of-the-art research on the reinforced concrete (RC) walls for evaluating and predicting the performance of RC walls analytically and experimentally. A brief discussion of the research trends is presented to propose the further research direction of RC walls. In the paper, 102 papers published on the ACI, Engineering Structure, KCI journal, and AIK journal are collected and reviewed.

• Proceedings of the Computational Structural Engineering Institute Conference
• /
• 2006.04a
• /
• pp.928-931
• /
• 2006

Due to their light weight, high stiffness-to-weight and strength-to-weight ratios, and potentially high resistance to environmental degradation, resulting in lower life-cycle costs, polymer composites, are increasingly being considered for use in civil infrastructure applications. Recently, an FRP deck has been installed on a state highway, located in New York State. In this study, a thermal stress analysis was conducted using finite element method to study failure mechanisms of the superstructure. This analysis evaluated small and large temperature gradient effects on the FRP deck considering lightweight of FRP deck and ply orientations at the interface between steel girders and FRP deck Finite element model was verified using the load tests of the bridge deck. Finally, the analytical results shows the possible failure mechanism of FRP deck under various temperature changes and its corresponding index is suddenly varied depending on the rapid change of temperature on the deck plate.

• Proceedings of the KSR Conference
• /
• 2007.05a
• /
• pp.1319-1324
• /
• 2007

Many researches have been performed to analyze the smoke movement in tunnel fires by using field model. Recently, FDS(Fire Dynamics Simulator) v.4, which is one of the field model and developed from NIST(National Institute of Standards and Technology), is widely used. In tunnel fires, FDS can show detail results in local point, but it has difficulties in boundary condition and taking long computing time as the number of grid increases. So, there is a need to use alternative method for tunnel fire simulation. A zone model is different kind of CFD method and solves ordinary differential equation based on conservation and auxiliary equations. It shows good macroscopic view in less computing time compared to field model. In this study, therefore, to confirm the applicability of CFAST in tunnel fire analysis, numerical simulations using CFAST are conducted to analyze smoke movement in longitudinal ventilation reduced-scale tunnel fires. Then the results are compared with experimental results. The differences of temperature and critical velocity between numerical results and experimental data are over $30^{\circ}C$ and 0.9m/s, respectively. These values are out of error range. It shows that CFAST 6.0 is hard to be used for tunnel fire simulation.