• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.11
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• pp.349-356
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• 2020

The heat release rate (HRR) and fire growth rate of fire for the solid combustibles consisting of multi-materials was measured through the ISO 9705 room corner test, and the computational analysis in a closed compartment was performed to simulate a fire using the heat release rate prediction model provided by a Fire Dynamics Simulator (FDS). The method of predicting the heat release rate provided by the FDS was divided into a simple model and a pyrolysis model. Each model was applied and computational analysis was performed under the same conditions. As the solid combustible consisting of multi-materials, a cinema chair composed mostly of PU foam, PP, and steel was selected. The simple model was over-predicted compared to the predicted heat release rate and fire growth rate using the pyrolysis model in a closed compartment.

• Proceedings of the Korea Institute of Fire Science and Engineering Conference
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• 2013.11a
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• pp.178-179
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• 2013

본 연구에서는 현재 사용되고 있는 건축물 내의 화장실 칸막이 재료를 대상으로 ISO 5660-1 콘칼로리미터(Cone calorimeter) 실험을 실시하여 대상 실험 재료들의 연소 특성을 비교 평가 하였다. 모두 5종류의 실험체를 사용하였으며, 화재 발생시 연소 중요 평가항목인 착화시간(Time to ignition), 총 방출열량(Total heat release), 최고 열방출율(Peak heat release rate), 평균 열방출율(Mean heat release rate)을 중점적으로 평가하였다. 실험결과, 착화시간은 일반 합판패널에서 빠르게 일어났으며, 총 방출열량, 최고 열방출율, 평균 열방출율은 고밀도 압축패널에서 높게 나타난 것으로 분석되었다.

• Journal of the Korean Society of Propulsion Engineers
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• v.20 no.6
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• pp.1-10
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• 2016

For the active control of a combustion instability, a change should be made in pressure fluctuation or heat release fluctuation using an acoustic driver or a secondary fuel injection. Also, to determine the location and timing of a secondary fuel injection, one needs to know the distribution of heat release fluctuation under combustion instability. In the present research, the distribution of heat release fluctuation has been experimentally measured by changing hydrocarbon fuel, inlet velocity, equivalence ratio, and acoustic forcing condition. It was confirmed that heat release fluctuation with regards to vortex shedding was significantly affected by the $Damk{\ddot{o}}hler$ number. Under the cases of the $Damk{\ddot{o}}hler$ number above approximately 4 - 5, hot spot region was generated in the leading edge of vortex and cold spot region was in the trailing edge. On the contrary, the cases of the $Damk{\ddot{o}}hler$ number below 3 showed the opposite trend.

• Composites Research
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• v.14 no.5
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• pp.38-45
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• 2001

Kaiser effects of thermo-acoustic emission (AE) from composite laminates under the repetitive thermal cyclic loads have been quantitatively analyzed in consideration of AE source mechanisms. The repetitive thermal load brought about a large reduction. i.e. an exponential decrease in AE total ringdown counts and AE amplitudes. It was thought that generation of thermo-AE during the first thermal cycle was not caused by crack propagation but by secondary microfracturing due to abrasive contact between crack surfaces. For the repetitive thermal cycles, a few number of weak thermo-AE events were generated due to some frictional sliding contact. Such behavior of thermo-AE showed different characteristics according to specimen kinds and the maximum temperature in the thermal load cycles.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2004.10a
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• pp.137-140
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• 2004

Oscillating heat release associated with periodic vortex-flame interaction was investigated experimentally. Turbulent jet flames were stabilized with recirculating hot products in a dump combustor, and large-scale periodic vortices were imposed into the jet flame by acoustic forcing. Forcing frequencies and operating parameters were adjusted to simulate unstable combustor operation in practical combustors. The objectives were to characterize vortex-heat release interaction that leads to unwanted heat release fluctuations and to identify the proper fuel injection pattern that could be used for actively suppressing such fluctuations. Phase-resolved CH* chemiluminescence and schlieren images were used as diagnostic tools. The results were compared at corresponding phases of vortex shedding cycle.

• Fire Science and Engineering
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• v.32 no.6
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• pp.28-33
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• 2018

To measure the full scale fire test and heat release rate of bed mattresses according to the building compartment space, a fire test was performed using the Standard test method to determine the heat release rate of mattresses and mattress sets (KS F ISO 12949: 2011). Both test locations showed similar fire growth until approximately 3 minutes after burner ignition. After 3 minutes, the heat release rate in the test room was higher than the open calorimeter. For bed mattresses (SS), the maximum heat release rate in the open calorimeter was 735 kW and the maximum heat release rate in the test room was 992 kW. For bed mattresses (Q), the heat release rate in the test room increased more rapidly than the open calorimeter. The maximum heat release rate in the open calorimeter was 1,087 kW (346 s) and the maximum heat release rate in the test room was 2,127 kW (287 s). The difference between the maximum heat release rate and the measurement time according to the test location was confirmed.

• Proceedings of the Korean Nuclear Society Conference
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• 1995.05a
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• pp.525-530
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• 1995

최적 열수력 전산 코드인 CATHARE2 Vl.3u 코드를 이용하여 영광 3/4호기 midloop 운전중 잔열제거(RHR) 기능 상실사고를 해석하였다. 본 연구의 주된 목적은 사고시 계통에서 발생하는 열수력 현상의 이해 향상 및 증기발생기 열제거 능력 평가에 있다. 사고 복구 절차 관점에서 노심 비등, 노출 시점 및 계통압력 등이 중요한 인자이다. 본 계산 수행시 사용한 가정은 다음과 같다. 가) 초기 계통 수위는 고온관 중간에 위치하며 그 윗 부분은 질소 가스로 차 있다. 나) 3/4 인치 크기의 방출 밸브가 원자로 용기 상부 및 가압기 상부에 각각 설치되어 있으며, RHR 흡입구에 수위지시계가 설치되어 있다. 다) 증기발생기의 이차측은 U-튜브가 잠기도록 물로 차있다. 라) 두 증기발생기의 대기 방출 밸브(ADV)는 항상 열려 있어 사고시 이차측 압력을 대기압으로 유지하기에 충분하다. 사고는 원자로 정지 2일 후 발생하였다고 가정한다. 이와 같은 조건하에서 사고시 주된 계통 열제거 수단은 증기발생기 U-튜브내의 응축 작용이며 이는 전체 열제거량의 94%로 나타났다. 노심 비등 시점온 사고후∼300초 이후이며, 계통압력은 10,800초 이후에 최고 압력인 0.25MPa에 도달한 후 그 값을 계속 유지하고 있다. RHR 배관에 연결된 수위지 시계를 통해 10,200초 이후부터 냉각수가 방출되었다. 2개의 방출밸브 및 수위지시계를 통하여 방출된 유량에 근거하여 원자로 용기 냉각재 수위가 고온관 바닦까지 낮아지는 시점을 계산하면 사고 약 6.4 시간 이후가 된다.

• Proceedings of the Acoustical Society of Korea Conference
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• 1998.06c
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• pp.469-472
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• 1998

수중에서 발생된 기포들의 상화작용에 의한 방출주파수의 변화를 알아보기 위해 선배열 기포에 대해 이론적으로 연구하였다. 기포들의 결합진동에 의한 방출주파수는 가능한 가장 저주파수의 음파가 발생됨을 설명하였으며, 일부의 기포가 음원역할을 하는 실제적인 선배열 기포의 경우는 방출주파수가 기포의 총 개수보다는 음원기포의 개수와 기포간 거리에 좌우됨을 밝혔다. 이러한 이론결과는 참고문헌[6]의 실험결과에 비교적 잘 일치하였다. 이것은 기포간의 결합진동은 기포들의 초기 발생조건에 따라 이론적으로 다르게 다루어야 함을 의미한다.

• Fire Science and Engineering
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• v.22 no.5
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• pp.72-78
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• 2008

The mass loss rate and heat release rate of EPS sandwich panel cores were analysed using variable external irradiation level. The experimental materials were exposed to incident heat fluxes form 20 to 50 kW/$m^2$. For the measurement of mass loss rate and heat release rate, the size of specimen was $100mm{\times}100mm{\times}50mm$ and the samples were 3 different kinds. The combustion heat were carried out from the Oxygen bomb calorimeter and the mass loss rate and heat release rate were carried out from the Mass loss calorimeter according to ISO 5660-1. As the results of this study, the mass loss rate of Type A, B, and C were 2.7 g/$m^2s$, 2.8 g/$m^2s$, and 2.3 g/$m^2s$ and the heat release rate of Type A, B, and C were 58.23 kW/$m^2$, 47.19 kW/$m^2$, and 50.06 kW/$m^2$ respectively at the heat flux of 50 kW/$m^2$. In conclusion, when the heat release characteristics applied to a classification system of Canada, Type A and C can be classified grade C-3, and Type C can be classified grade C-2 from all data of this study.

• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.1406_1407
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• 2009

Fowler-Nordheim의 전자 방출과 열전자 방출 메카니즘을 이용하여 절연유체 내 전계에 의한 도체의 음극에서 전자 방출현상과 열에 의한 열전자 방출현상을 고려하고 유한요소법(Finite Element Method)을 이용하여 해석하였다. 절연유체 내 공간전하에 대한 해석기법으로 푸아송 방정식, 양이온, 음이온, 전자에 대한 전하연속 방정식, 온도에 대한 열 확산 방정식으로 이루어진 5개의 지배방정식에 Fowler-Nordheim의 전계 방출과 Richardson-Dushman의 열전자 방출을 경계조건으로 부여하였다. 단자 전류는 유한요소법과 잘 부합하는 에너지법으로 계산되었다. 쌍 곡선형 PDE의 공간전하 전파에 대한 지배 방정식은 일반적으로 수치적인 불안정성을 가지므로 인공 확산 항을 고려하여 이를 해결하였다. 제안된 해석법은 세 개의 캐리어를 가진 x-y 좌표축의 2차원 평판 모델에 적용하여 그 유효성을 확인하였다.