• 한국전산유체공학회:학술대회논문집
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• 2011.05a
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• pp.169-172
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• 2011

Recently, railroad long tunnels are increasing and growing longer due to topological feathers like a lot of mountain in Korea. But fire disaster of a long tunnel cause many people to injury and death. For that reason, at the early design stage of a long tunnel, risk assessment and mitigation measure of risk for satisfying tunnel safety are required. According to the railroad facility safety standard (Korean MLTM Announcement No. 2006-395), risk assessment for railroad-tunnel fire should be performed when design stage. Therefore, various methods of risk assessment for tunnel fire have been studied and applied. In the paper, QRA(Quantitative Risk Analysis) for fire risk assessment by using CFD code is presented and the usefulness of CFD is discussed.

• 한국전산유체공학회:학술대회논문집
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• 2011.05a
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• pp.373-378
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• 2011

As the number of deeply-underground subway station(DUSS) increases, the safety measures for DUSS have been requested. In this research, Shingumho station (The line # 5, Depth: 46m) has been selected as case-study for the analysis of smoke-spread speed with the different fire strength. Field test data measured for actual fan in DUSS was applied as a condition of a simulation. The whole station was covered in this analysis and total of 4 million grids were generated for this simulation. The fire driven flow was analyzed case by case to compare the smoke-spread effect according to the fire strength. in order to enhance the efficiency of calculation, parallel processing by MPI was employed and large eddy simulation method in FDS code was adopted.

• 한국전산유체공학회:학술대회논문집
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• 2008.03b
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• pp.415-419
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• 2008

In this study, analysis of water mist behavior is performed using numerical simulation. Water mist is characterized by the droplet flow which is one of the multiphase flows and is discrete fluid droplets in continuous air. It is important to choose the proper diameter of droplet-size and the distance between the fire location and the position of water mist because it depends on the buoyancy from fire. Therefore the behavior of water mist with fire should be simulated by FLUENT, a commercial computational fluid dynamics(CFD) program, with Lagrangian discrete phase model. (DPM)

• Proceedings of the KSME Conference
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• 2001.06a
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• pp.871-876
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• 2001

One-touch fittings are important components that can make a quick and tight connection between pneumatic pipe systems. In this study, the stress analyses with various working pressures on these one-touch fittings are carried out using finite element method. Material properties, to use the stress analyses, are measured by the universal tester and digital Vickers hardness tester. The stress analyses on the circular shell spring forced by various pressures(100, 150, 200, 250kpa) and on the main body due to the fluid-structural interaction are investigated. Results show that the stresses of one-touch fitting are concentrated to supported part of main body and the soundness of a circular shell spring with maximum pressure 250kpa was confirmed.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.08a
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• pp.137-137
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• 2010

현재 반도체의 공정 중 80% 이상이 플라즈마를 사용하는 공정이며 태양전지나 디스플레이의 공정에서 플라즈마를 이용하는 공정이 점차 증가하고 있다. 따라서 공정의 재현성과 안정성의 향상에 대한 요구도 증가하고 있다. 이러한 요구들을 달성하기 위하여 공정에 직접 이용되고 있는 플라즈마의 특성을 파악하는 것은 필수적인 요소이다. 본 연구에서는 전기장 시물레이션을 사용하여 플라즈마 밀도(Plasma density)를 계산하였다. 그리고 실제 반도체 식각 공정에 사용되고 있는 플라즈마 밀도를 량뮤어 프로브로 측정하여 시물레이션 값과 비교하여 최적의 공정조건을 찾아보았다.

• Proceedings of the Korea Institute of Fire Science and Engineering Conference
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• 2012.04a
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• pp.424-427
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• 2012

본 연구에서는 최근 증가하고 있는 대심도역사의 제연팬 용량에 따른 연기확산영향에 대하여 분석하였다. 시뮬레이션모델은 신금호 역사(5호선, 깊이 46m)를 대상으로 하였으며, 제연팬 용량에 따른 연기확산 영향을 분석 하였다. 현장조사 및 실측을 통하여 계측된 실제 역사의 제연팬에 관한 데이터를 화재시뮬레이션 조건으로 적용하였다. 역사전체를 해석 대상으로 하여 총 400만개의 격자를 사용하였으며, 제연팬 용량에 따른 연기확산 영향 비교를 위하여 화재 시나리오를 작성하여 Case별로 화재해석을 수행하였다. 계산 효율을 높이기 위하여 MPI병렬처리기법을 사용하였으며 해석코드는 LES(large eddy simulation) 기법을 주로 사용하는 FDS5 code를 사용하였다.

• Proceedings of the KSR Conference
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• 2008.06a
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• pp.1246-1254
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• 2008

The land transportation is the most common way to transport passengers as well as freight among other mode of transportations and consequently more likely to be constructed for faster and convenient travel In this regard, the demand for tunnel constructions will be increasing and the safety inside the tunnel will be considered major concern more than ever. In this paper, we show probabilistic methodology to calculate the personal risk of each evacuee starting from a different location in a tunnel on fire. Passenger evacuation time and smoke spread time are both assumed to be continuous random variables having specific distributions. The evacuation of passengers at each location and the safety facilities inside the tunnel are also crucial factors to calculate the probability of death.

• Proceedings of the KSR Conference
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• 2009.05a
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• pp.1040-1046
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• 2009

Thanks to the recent development of computing technology, the various forms of high-performance computers are available. Among them, the parallel-clustering CPU machines are realized for the high performance computing. These supercomputers (cluster computers) can be applied to various industries due to the advantages of lower price. Especially in the field of numerical flow simulation, use of supercomputers can produce results quickly, and various engineering problems can be reviewed effectively case by case. In this paper, an application of supercomputers (cluster computers) were examined for railroad industry of fire flow simulation by using parallel computational method. It make sure that the supercomputers are very useful tools for railroad engineering.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.31 no.2 s.257
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• pp.173-180
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• 2007

A series of field tests were performed to develop aerodynamic characteristic evaluation method and countermeasure technology in conventional and high-speed railway. The strength of rolling stock-induced wind which affect the people and substructure in platform and nearby track were investigated. The slipstream of passing trains was measured by hot-wire array system. The speed of trains was 110 - 125km/h for conventional ones and 300km/h for high-speed ones. The streamlined shape trains cause about 50% smaller-scale slipstream compared to the non-streamlined ones.

• Proceedings of the KSME Conference
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• 2008.11b
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• pp.2477-2482
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• 2008

Effect of computational domain size in simulating of periodic obstacle flow has been investigated for the flow past tube banks. Reynolds number, defined by freestream velocity (U) and cylinder diameter (d), was fixed as 200, and center-to-center distance (P) as 1.5d. In-line square array was considered. Drag coefficient, lift coefficient and Strouhal number were calculated depending on domain size. Circular cylinders were implemented on a Cartesian grid system by using an immersed boundary method. Boundary condition is periodic in both streamwise and lateral directions. Previous studies in literature often use a square domain with a side length of P, which contains only one cylinder. However, this study reveals that size is improper. Especially, RMS values of flow-induced forces are most sensitive to the domain size.