• 한국대기환경학회지
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• 제12권4호
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• pp.479-485
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• 1996

Volatile organic compounds are air pollutants exhausting from industrial process, evaporation of solvent, and so on. Most of VOCs are the combustible gas of low calorific value as it is diluted by air. The systems burning such a hazardous gas need to increase enthalpy in order to increase flame stability. In this study an incinerator with reciprocating flow in the honeycomb ceramic has been used for the experiment of VOCs control. By the reciprocating flow system, the enthalpy of combustion gas is effectively regenerated into the enthalpy increases of the combustible gas through the honeycomb ceramic, which provides a heat storage. The position of the reaction zone is strongly dependent on the parameters of mixture velocity and time frequency. Flame front is changed to the point where burning velocity is coincided with burning velocity in the honeycomb ceramic. In this system it is important that flame front should be located symmetrically at the center of honeycomb ceramic for the purpose of increasing the reaction rate at one point. Peak temperature becomes higher with decreasing time frequency, at which the flow direction is regularly reversed.

• 대한기계학회논문집B
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• 제39권1호
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• pp.11-19
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• 2015

본 논문에서는 다물질(가연성 기체 혼합물과 금속관) 수치 해석 기법을 활용하여 밀리미터 크기의 얇은 두께의 금속관 내에서의 데토네이션을 모델링하였다. 데토네이션의 해석을 위하여 수소와 에틸렌 혼합물의 실험과 이론적 값을 기반으로 최적화된 1단계 아레니우스 형태의 화학 반응식, 이상기체 상태 방정식을 활용하여 모델링하였다. 또한 금속관의 재료인 구리와 철은 Mie-Gruneisen 상태 방정식과 Johnson-Cook 강성 모델을 활용하여 큰 압력에 의한 관의 소성 변형을 모델링하였다. 다물질 수치 해석을 위한 경계면의 추적 및 경계면 값의 결정은 각각 hybrid particle level-set 기법과 ghost fluid method(GFM)을 통하여 획득하였다. 수치적 해석 결과는 실험값과의 비교를 통하여 검증 하였으며, 관두께(두꺼운 관과 얇은 관)에 따른 내부 유동장의 변화를 확인하였다. 얇은 관의 경우, 데토네이션에 의해 발생하는 높은 내부 압력에 의하여 관의 소성 변형이 일어나고, 이에 따라 발생하는 팽창파에 의해 내부 기체 혼합물의 압력 및 밀도의 감소현상을 확인하였다.

• 대한화학회지
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• 제54권3호
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• pp.295-299
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• 2010

액화석유가스-공기 불꽃에 대한 2가지 열적 금지제(즉, 돌가루, 탄산칼슘)의 억제효과를 연구하였다. 이를 위해 이들 금지제를 가하기 전과 후 가연성 혼합물의 가연성 한도를 측정하여 조사하였다. 그 결과, 탄산칼슘이 돌가루에 비해 억제 효과가 우수하였다.

• 한국전기전자재료학회논문지
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• 제21권9호
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• pp.812-817
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• 2008

A catalytic combustible sensor for LPG/LNG detection was fabricated on $Al_2O_3$ substrate using planar technology. The catalysts of Pd and Pt were added to ${\alpha}$- and ${\gamma}-Al_2O_3$ powders. The mixture of Pt, Pd and $Al_2O_3$ were homogenized by using a three roll mixer. TCR characteristics of Pt heater were optimized with the heat treatment temperature. Sensing properties were investigated as a function of the microstructure of $Al_2O_3$, the gas concentration and the variation of input voltage. ${\alpha}-Al_2O_3$ sintered at 500 $^{\circ}C$ is more suitable as LPG/LNG sensor due to good grain shape and size distribution of about 300 nm than that of ${\gamma}-Al_2O_3$ which is in irregular shape and with a particle size of 5-30 ${\mu}m$. The sensor has shown maximum output voltage of 14 mV for 1000 ppm $C_4H_{10}$ and 3.8 mV for 1000 ppm $CH_4$ at 5.0 V input voltage.

• 한국자동차공학회논문집
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• 제12권3호
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• pp.19-26
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• 2004

A prior fundamental study was executed using a constant volume chamber to improve the burning properties of lean pre-mixture by the injection of active radicals generated in the sub-chamber. In consequence, RI method shows remarkable progress in the aspects of burning velocity and combustible lean limit compared with SI method. In this study, the necessary additional works have been performed to be based on the former results. We changed parameters as the initial temperature and the initial pressure of mixture. And the effects of residual gas at issue in a real engine were investigated. As a result, the effects of initial temperature were significant, but on the other hand, those of initial pressure were slight. The correlation of passage hole number between overall passage hole area was grasped. And the more detailed analysis is required on residual gas.

• 한국화재소방학회:학술대회논문집
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• 한국화재소방학회 1997년도 International Symposium on Fire Science and Technology
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• pp.185-192
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• 1997

The combustion of cellulose insulation treated with Borax, Boric acid and Aluminum Sulfate as combustion retardants is examined by candle type combustion tester. The cellulose fibers in cellulose insulation are classified by diameter as less than 0.2mm, 0.2mm-0.5mm, 0.5mm-2mm and more than 2mm. The burning behavior of cellulose insulation are studied by LOI (Limit Oxygen Index: Beginning point of smoldering), L- point (Lower point of combustion transition from smoldering- flaming to flaming combustion), LOI, L-point and H-point rise with the increasing particle size of cellulose fibers because thermal decomposition rate of cellulose fiber decreases. The phenomena of combustion transition from smoldering to flaming combustion are determined by the generating rate of combustible gas and the formation rate of combustible gas mixture within the zone of cellulose fiber heated.

• 한국화재소방학회논문지
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• 제18권2호
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• pp.20-26
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• 2004

본 논문은 가스폭발로부터 화채로의 전이현상 및 전이 방지 연구를 위해 가로 세로 높이가 각각 $100 cm {\times} 60 cm {\times} 45 cm$인 폭발용기를 사용하여 폭발 후 화재로의 전이현상을 고속 비디오로 가시화하고 가시화된 영상을 분석하여 그 기구들을 확인하였다. 고체 가연물로는 신문용지를 가로 세로가 $30cm {\times} 20cm$크기로 절단하여 사용하였고 LPG-공기 혼합가스는 10㎸ 전기 스파크를 사용하여 점화시켰다. 실험 변수로는 혼합가스의 농도, 개구부의 크기 및 가연물의 위치 등이었으며, 파열면의 크기는 $10cm {\times} 9cm, 13cm {\times} 10cm, 27cm {\times} 20cm, 40cm {\times} 27cm$로 하였고 가연물의 설치 위치는 4종류로 하였다. 폭발 후 전이 방지 기구의 고찰은 가스 소화약제인 이산화탄소를 이용하여 실험하였다. 실험 결과 가스폭발로부터 화재로의 전이 현상은 혼합가스의 농도와 고온의 화염 및 연소가스에 노출되는 시간에 많은 영향을 받으며 폭발 후 분위기의 냉각이나 불활성화를 통해 화재로의 전이를 방지 할 수 있음을 알 수 있었다.

• 대한전자공학회논문지
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• 제16권1호
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• pp.19-23
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• 1979

$S_nO_2$ and $Z_nO$ based semiconductor combustible gas sensors have been fabricated and measured their charactcnstics. Adding about 0.5 wt % $P_dCf_2$ to the mixture of $S_n0_2$ and $Z_nO$ improved the sensitivity. The devices were fired for one hoar in air in the tewerature range of $400^{\circ}C$ to $1000^{\circ}C$. Their electrical conductivity was changed by t he change of atmosphenc pressure around then.

• 한국안전학회지
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• 제8권4호
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• pp.107-113
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• 1993

Small rectangular explosion chamber of its size 25cmX25cmX32cm with a circular bursting diaphram at the top was used to study the mechanism of gas explosion to fire transition phenomena, the process of ignition of solid combustibles during a gas explosion. To visulize the explosion to fire transition phenomena, transparent acryl window and high speed camera system were used. The test piece of solid combustible in this experiments was a 5cm$\times$5cm square sheet of newspaper which was placed in the explosion chamber filled with a LPG-air mixture. The mixture was ignited by an electric spark at the center of the chamber. Explosion to fire transition phenomena and the behavior of out flow and in flow of gas through the opening yielded by bursting the diaphram was visualized with shlieren system and without shlieren system. Diameter of a bursting dlaphram at the top of the explosion chamber was varied 5cm, 10cm, and 15cm, and the position of test piece were varied with 6 point. Explosion pressure was measured with strain type pressure transducer, and the weight difference of the test piece before and after each experimental run was measured. By comparing the weight difference of solid combustibles before and after the experiment and the behavior of out flow and inflow of gas after explosion, it was found that the possibility of ignition was depends on the LPG-air mixture concentration and the exposure period of test piece to the burnt gas. Test result of this experiments it was found that the main factor of this phenomena are that heat transfer to the test piece, and the pyrolysis reaction of test piece. Based on the results, the mechanism of the explosion to fire transition phenomena were inferred ; gas explosion- heat transfer to solid combustibiles ; pyrolysis reaction of solid combutibles : air inflow ; mixing of the pyroly gas with air ignition.

• 오토저널
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• 제1권1호
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• pp.28-41
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• 1979

Propane-Air premixed combustible gas was ignited by the conventional current break system inside the open combustion chamber under the atmospheric pressure and the room temperature to measure the flame propagating speed and the burning speed, also to elucidate the history of the propagating flame behavior and wall effects to flame shape by using Ion Gap Method and High Speed Schlieren Photography. The results obtained show that the maximum flame propagating speed and maximum burning speed are approximately 292 cm/sec and 36 cm/sec at the mixture ratio 4.6%, respectively. The cellular flame structures can be observable in the rich mixture region, moreover, the cellular structures become finer, with increasing the mixture strength.