• Journal of the Korean Institute of Gas
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• v.14 no.3
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• pp.8-13
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• 2010

Hydrogen is expected to become a new, clean source of energy for the next generation. Therefore, many studies have investigated the characteristics of the hydrogen flame. However, because the hydrogen flame has high temperature, the flame does not emit visible light, and the flame propagates at a high velocity, investigating its characteristics is difficult. In the present study, in order to simultaneously examine the flame temperature and flame propagation velocity of hydrogen/air mixtures, ultra fine thermocouples with diameters of 12.7, 25.4, and 50.8 ${\mu}m$ are utilized. The results show that it is possible to detect the arrival time of the flame. Due to the temperature compensation with the time constants of thermocouples, it is also possible to estimate the flame temperature.

• Fire Science and Engineering
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• v.19 no.3 s.59
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• pp.44-51
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• 2005

The flame propagation velocity and the flame arrival time of methyl alcohol, which is widely used as a material of paint industry and organic synthesis, d mixing solvent, and an analytical reagent, were examined at different temperatures and concentrations. It was found that the smaller the vessel size, the easier and faster the combustion. The maximum combustion velocity was 200 cm/sec in the small vessel at $30^{\circ}C$. The flame arrival time was determined to be longer with larger vessels. and shorter with higher concentrations.

• Proceedings of the Korea Institute of Fire Science and Engineering Conference
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• 2012.04a
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• pp.19-22
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• 2012

본 연구에서는 폭발사고가 반복되고 있는 마그네슘합금(Mg-Al alloy) 분진의 예방대책을 위한 안전자료로 활용하기 위하여 폭발특성평가 실험과 화염전파속도를 추정하였다. 화염전파속도는 폭발과압 강도에 영향을 주지만 분진폭발에서는 화염의 확산에 따른 피해예측에도 중요한 자료로 활용될 수 있다. 밀폐공간의 분진폭발에서 화염전파속도를 계산하기 위하여 분진의 연소시간과 화염면의 도달시간을 고려하여 폭발압력으로부터 추정하는 방법을 제시하고 마그네슘합금의 성분비율에 따라 폭발에 따른 화염전파속도를 계산하였다. 그 결과, Mg-Al(60:40 wt%), Mg-Al(50:50 wt%), Mg-Al(40:60 wt%)의 최대화염전파속도는 각각 15.5, 18, 15.2 m/s로 추정되었으며 성분비율에 따라 최대화염속도는 변화하는 경향을 나타냈다.

• Journal of Energy Engineering
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• v.3 no.1
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• pp.62-69
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• 1994

화염중에 존재하는 이온 및 전자의 전기적 성질을 이용하여 연소실내의 화염전파속도를 파악하기 위해 실린더 헤드에 이온 프로브를 삽입하여 천연가스 및 가솔린의 화염전파속도를 측정하였다. 본 연구에 이용된 이온전류장치 설계에 의한 방법은 광학적 측정 장비에 비해 간단하며 쉽게 측정할 수 있고 가격도 저렴하고 응답성도 우수하였다. 이온 프로브의 제작과 신호처리에 관한 기초적인 지식을 얻었으며 천연가스 및 가솔린의 연소시 연소압력의 상승지점과 이온발생지점이 일관성있게 나타났다. 기관회전수의 증가에 따라서 연소실내의 화염전파속도가 증가했으며 같은 연소조건이라고 할 수 있는 동일 기관회전수, 당량비의 조건에서 점화시간에 대한 화염전파속도를 비교해 보면 메탄의 경우가 이론치보다 6 ms∼9 ms 정도 늦었다. 또한, 메탄가스 및 가솔린에 대해 이온 전류강도 및 화염 도달시간을 측정하였으며 연소실 벽면에서는 열전달에 의한 냉각효과로인해 화염 전파속도 및 이온농도가 감소했다.

• Journal of the Korean Institute of Gas
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• v.16 no.4
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• pp.32-37
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• 2012

The aim of this study is to evaluate the characteristics of explosion and flame velocity that can be utilized to factories where Mg-Al alloy metal powders are handled in the form of raw materials, products or by-product for similar dust explosion prevention and mitigation. Because the strength of the blast pressure is the result due to flame propagation, flame velocity in dust explosion can be utilized as a valuable information for damage prediction. An experimental investigation was carried out on the influences of content ratio of Mg-Al alloy (mean particle size distribution of 151 to 161 ${\mu}m$). And a model of flame propagation velocity based on the time to peak pressure and flame arrival time in dust explosion pressure, assuming the constant burning velocity, leads to a representation of flame velocity during dust explosion. As the results, the maximum flame velocity of Mg-Al(60:40 wt%), Mg-Al(50:50 wt%) and Mg-Al(40:60 wt%) was estimated 15.5, 18 and 15.2 m/s respectively, and also tend to change with content ratio of Mg-Al.

• 한국방재학회:학술대회논문집
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• 2011.02a
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• pp.154-154
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• 2011

최근 세계 각지에서 발생하는 대규모 터널 화재사고는 많은 사상자를 동반하고 이에 따른 경제적, 사회적 손실 또한 방대하게 진행되는 실정이다. 터널 구조물의 화재 특성상 외부에 쉽게 노출되지 않기 때문에 화재 발생 시 화재에 노출된 표층이 박리되거나 비산해서 단면결손이 생기는 폭렬 현상(explosive spalling)이 발생하게 된다. 이러한 폭렬 현상은 붕괴와 같은 대형 참사로 이어질 가능성이 크다. 따라서 본 연구에서는 터널 내 화재 발생 시 콘크리트 구조물의 폭렬에 의한 붕괴를 예방하기 위하여 이액형 상온경화 실리콘 고무와 인체에 무해한 친환경 첨가제인 펄라이트를 일정한 혼합비(5wt%, 10wt%, 15wt%, 20wt%)로 혼합하여 고성능 난연 복합체를 제조하고, 열적 특성과 난연 특성을 연구를 진행하였다. 열적 특성에 관한 시험으로 TGA를 측정하였으며, 난연 특성에 관한 시험으로는 화염 시험, 내화로 시험, 탄화로 시험을 진행하였다. 우선 TGA 시험은 $20^{\circ}C/min$ 승온 속도로 $800^{\circ}C$까지 실험을 하였고, 화염 시험은 제작한 시편과 gas torch($1200^{\circ}C$)의 화염 거리를 약 10cm로 하여 약 1시간 동안 시험을 하였다. 내화로 시험은 내화로 장치를 이용하여 RABT curve(5분만에 $1200^{\circ}C$도달 후 한 시간 동안 유지 후 냉각, 총 시험 시간 180분) 조건을 만족하는 환경에서 제작한 시편을 콘크리트에 부착하여 콘크리트의 내부온도를 측정하였다. 탄화로 시험은 탄화로 장치를 이용하여 $2^{\circ}C/min$ 승온속도로 $900^{\circ}C$까지 실험을 하여 외부 형태 변화를 관찰하였다. 각각의 시험 결과 TGA 열분해 결과 순수한 실리콘 고무보다 난연제인 펄라이트를 첨가했을 때 더 높은 온도에서 초기 분해 거동을 보였으며, 최종 잔류량은 80%를 보였고, 5 wt%의 펄라이트가 혼합된 시편의 최종 잔류량이 높은 것으로 보아 열분해에 가장 강한 조성임을 알 수 있었다. 화염 시험 결과 펄라이트가 혼합된 모든 시편에서 $300^{\circ}C$가 넘지 않은 결과를 보였다. 이는 제조된 복합체가 화염에 직접적으로 장시간 노출이 되어도 안전하다는 것을 알 수 있다. 내화로 및 탄화로 시험 결과 펄라이트가 15wt%와 20wt%가 첨가된 시편들보다 5wt%와 10wt% 첨가된 시편들이 고온에서 안정하다는 것을 보였다.

• Korean Chemical Engineering Research
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• v.54 no.3
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• pp.367-373
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• 2016

Many of plastic powders handled in industry are combustible and have the hazard of dust fire and explosion accidents. However poor information about the safe handling has been presented in the production works. The aim of this research is investigated experimentally on explosive characteristics of various plastic powders used in industry and to provide additional data with safety informations. The explosibility parameters investigated using standard dust explosibility test equipment of Siwek 20-L explosion chamber. As the results, the dust explosion index ($K_{st}$) of ABS ($209.8{\mu}m$), PE ($81.8{\mu}m$), PBT ($21.3{\mu}m$), MBS ($26.7{\mu}m$) and PMMA ($14.3{\mu}m$) are 62.4, 59.4, 70.3, 303 and 203.6[$bar{\cdot}m/s$], respectively. And flame propagation velocity during plastic dust explosions for prediction of explosive damage was estimated using a flame propagation model based on the time to peak pressure and flame arrival time in dust explosion pressure assuming the constant burning velocity.

• Fire Science and Engineering
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• v.28 no.3
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• pp.43-48
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• 2014

The purpose of this study is to analyze the flame propagation speed, radiation range, diffusion pattern and combustion completion time of a fire by filling a divided space with single combustible substance. It was found that the flame propagation speed was the fastest (0.2 s) for kerosene and the lowest (82.1 s) for alcohol. In the case of paint thinner, it took 19.0 s for the flame to reach its peak at the fastest speed after ignition while in the case of alcohol, it took 138.6 s for the flame to reach its peak at the lowest speed. In the case of the combustion of 200 ml of flammable liquids, the combustion completion time was 79.9 s for paint thinner, which is the shortest, 135 s for gasoline, 170 s for kerosene, 231.4 s for diesel and 337.0 s for alcohol. In addition, when flammable liquids are combusted, the lower part of the flame is governed by laminar flow pattern and the upper part of the flame showed turbulence pattern. In the case of a test performed for bean oil, it could be seen that if the fire source was removed, the flame was automatically extinguished without further combustion and that white smoke was generated due to incomplete combustion.

• Fire Science and Engineering
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• v.29 no.3
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• pp.31-36
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• 2015

This study analyzed the flame characteristics when igniting 200 ml of flammable liquids containing equal parts gasoline and another flammable liquid. These mixtures were used to fill a divided space in a simulation. The length of one side of the divided space was 2,000 mm, and the length of the combustion device was 1,000 mm. The mixture with alcohol had the highest flame propagation speed (0.7 s), while the mixture with light oil showed the lowest (1.2 s). The gasoline and acetone mixture reached peak flame in 25.5 s, at the highest speed, while the mixture with light oil reached peak flame in 163.7 s at the lowest speed. The gasoline and light oil showed the longest continuous combustion time (332.7 s), while the gasoline and paint thinner showed the shortest (121.5 s). A fire inspector who is examining the scene of a fire needs to analyze both the statements of the first eyewitness and the flame characteristics collectively.

• Journal of the Korean Institute of Gas
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• v.16 no.3
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• pp.65-70
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• 2012

Experimental investigations were carried out to examine the explosion characteristics by different sizes in the wall surface shape of a water gel barrier in an explosion chamber, 1,600 mm in length with a square cross-section of $100{\times}100\;mm^2$. The sizes in the wall surface shape were varied by using water gel barriers with a cross-section of $100{\times}200\;mm^2$ and its were varied in the bottom of the chamber away 300, 700 and 1,100 mm, respectively from the closed end of the chamber. The flame propagation images were photographed with a high speed camera and the pressure was recorded using a pressure transducer and a data acquisition system. It was found that as the size of the wall surface shape increased, the flame propagation process and the time taken to reach the maximum pressure were found to be faster. As a result, both the flame speed and the explosion overpressure increased as the size of the wall surface shape increased.