• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2008년도 제30회 춘계학술대회논문집
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• pp.187-192
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• 2008

A simplified model for an isolated aluminum particle burning in air is presented. Burning process consists of two stages, ignition and quasi-steady combustion (QSC). In ignition stage, aluminum which is inside of oxide film melts owing to the self heating called heterogeneous surface reaction (HSR) as well as the convective and radiative heat transfer from ambient air until the particle temperature reaches melting point of oxide film. In combustion stage, gas phase reaction occurs, and quasi-steady diffusion flame is assumed. For simplicity, 1-dimesional spherical symmetric condition and flame sheet assumption are also used. Extended conserved scalar formulations and modified Shvab-Zeldovich functions are used that account for the deposition of metal oxide on the surface of the molten aluminum. Using developed model, time variation of particle temperature, masses of molten aluminum and deposited oxide are predicted. Burning rate, flame radius and temperature are also calculated, and compared with some experimental data.

• 한국수소및신에너지학회논문집
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• 제30권6호
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• pp.499-504
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• 2019

Due to the rapid spread and low minimum ignition energy of hydrogen, rupture is highly likely to cause fire, explosion and major accidents. The self-ignition of high-pressure hydrogen is highly likely to ignite immediately when it leaks from an open space, resulting in jet fire. Results of the diffusion and leakage simulation show that jet effect occurs from the leakage source to a certain distance. And at the end of location, the vapor cloud explosion can be occurred due to the formation of hydrogen vapor clouds by built-up. In the result, it is important that depending on the time of ignition, a jet fire or a vapor cloud explosion may occur. Therefore, it is necessary to take into account jet effect by location of leakage source and establish a damage minimizing plan for the possible jet fire or vapor cloud explosion. And it is required to any kind of measurements such as an interlock system to prevent hydrogen leakage or minimize the amount of leakage when detecting leakage of gas.

• 한국화재소방학회논문지
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• 제24권5호
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• pp.39-49
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• 2010

본 연구에서는 담뱃불에 의한 낙엽 착화 특성에 대해 실험과 수치 해석을 이용하여 담뱃불로 인한 산불 발생 위험성에 대해 구명하고자 한다. 실험 방법은 P. densiflora와 Q. variabilis 2종의 낙엽에 대해 수분함유량, 풍속, 바람방향 대비 담뱃불 위치, 낙엽에서의 담뱃불 위치, 담배 굵기, 낙엽의 부서짐 정도, 경사조건 등 총 2,304 조건에 대해 5회 반복실험을 실시하였다. 낙엽의 온도변화는 전산수치해석을 통해 분석하였다. 실험 결과, 전체 2,304 조건의 실험에서 약 8.6%인 197조건에서 발화가 되었고 각 조건별 5회 반복실험에서 모두 발화된 최적조건은 전체의 약 0.6%인 13조건으로 조사되었다. 담뱃불로 인해 100% 발화가 가능한 최적 조건은 수분함유량 15% 미만, 부서진 낙엽상태, 풍속 2.0m/s 이상, 담뱃불이 낙엽에 덮여 있는 조건이 일치할 경우인 것으로 분석되었다. 열전달 수치해석을 이용한 Q. variabilis 낙엽의 온도변화를 분석한 결과, 담뱃불 부근의 낙엽 바닥면에서 약 $307^{\circ}C$(Max. $317^{\circ}C$) 이상 온도가 지속 되는 것으로 나타났다. 따라서 Q. variabilis의 자연발화 및 착화온도가 각각 $307^{\circ}C$, $305^{\circ}C$인 것에 비추어 담뱃불로 인한 발화가 가능한 것으로 분석되었다.

• 한국자동차공학회논문집
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• 제5권1호
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• pp.9-14
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• 1997

The pump-pipe-injector system is that most commonly used type of injection equipment for diesel engines. In this study, a new electromagnetic fuel injection system was designed and carried out the experiment of single cylinder direct injection(DI) diesel engine. This system do not need the cam shaft for fuel injection. The effects of the injection timing on the combustion process and emission were investigated. The results are that 1) atomization was improved, 2) combustion pressure was increased and ignition delay became shorter than before, 3) Low smoke level guarantee with more advanced injection timing without abnormal combustion but NOX concentration was increased as the injection time advanced.

• 한국안전학회지
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• 제19권3호
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• pp.32-39
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• 2004

This papers describes on the experimental consideration for the intrinsically-safe explosion-proof capability of rechargeable battery's body about main item rechargeable battery and cellular phone battery which is selling in domestic that IEC(International Electrotechnical Commission) recommend the measurement of ignition limit by short circuit of rechargeable battery and temperature increase test to use a explosion grade Group IIC type of explosion-proof type apparatus test an object of hydrogen gas. Because of that there are many different results for existence or nonexistence for ignition by different company and different types. It is concluded that the maximum of self temperature increasing by spark circuit of rechargeable battery is $180^{\circ}C$ in case of Nickel-Hydrogen and $110^{\circ}C$ in case of Nickel-Cadmium. The reaction of cellular battery for external temperature have following processes. It is confirmed that the temperature of reaction is rise slantly as the ambient temperature rising, then exterior shape of one is swell up and change when the temperature of ambient reach to about $130\~140^{\circ}C$, and when reach to about $160^{\circ}C$ the battery is blown up. Therefore, it is considered that have to be in considering selection of rechargeable battery using in itself due to different ignition limits of various rechargeable battery when the portable electric containing rechargeable battery are designed, produced and used, the characteristics and the proper safety factors of devices.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2002년도 하계학술대회 논문집 Vol.3 No.2
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• pp.666-669
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• 2002

The differences of the effects of mechanical substance pre-activation in the mills with divers force effect schemes on the self-propagating high temperature synthesis (SHS) of the $SiO_2$ + 37.5% Al system were investigated. The power saturation of activated material state are estimated referring on the variations of dilatometry curve paths. The effects of activation time on the temperature of sample self-ignited in the furnace, combustion temperature and completeness of the quartz reaction with aluminium were determined. The enhancing effects of organic modifiers of quartz particle surfaces on the further SHS synthesis development were shown.

• 한국가스학회지
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• 제13권6호
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• pp.39-43
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• 2009

가솔린 엔진은 전 세계적으로 중소형 및 대형차 등 전반적으로 사용되고 있으며, 장기적으로 차량 부하에 따른 배기가스의 증가가 주변 환경에 대한 위협이 가중되고 있어 여기에 대한 대처가 필요하다. CNG엔진은 기존의 가솔린 SI 엔진에 비하여 유해 배출가스 농도가 적어 다른 연료에 비해여 청정연료로서 유리하며, 많은 관련 연구자들이 여기에 대한 여러 논문을 통하여 잠재적 청정연료로서 확인되었다. 출력과 열효율의 측면에서 약간 가솔린 연료에 비하여 떨어지지만 일산화탄소와 탄화수소 배출량은 유리하며, 질소산화물은 약간 증가하는 현상이 나타났다. 본 논문에서는 기존 가솔린엔진과 CNG엔진의 배출물을 비교 검토하였다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2008년도 춘계학술대회 논문집 전기기기 및 에너지변환시스템부문
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• pp.110-112
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• 2008

A linear generator driven by a hydrogen combustion engine has been developed. Unlike rotary engine-generator systems, the linear counterpart is inherently unable to start by itself unless external force is provided for initial compression/ignition cycle. When the generator is connected to utility power lines through a bidirectional power conversion system, however, the self start-up can be done by driving the generator as a motor. This paper introduces a prototype 1kW linear hydrogen engine-generator system being developed and shows the self start-up is possible with proper motoring mode.

• 산업기술연구
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• 제23권A호
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• pp.29-33
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• 2003

This paper proposed methods of filament preheating to extend a fluorescent lamp life. The ballast for the fluorescent lamp can be classified into two main groups magnetics and electronics. The electronic ballast is lighter and smaller than the magnetic ballast and it can dim up and down. There are two ways to start the fluorescent lamp in the electronic ballast: rapid start and instant start. Also there are two methods of the driving inverter self excited oscillation and force excited oscillation. The rapid starting is different from the instant starting in that the rapid start is preheating the filament before the steady state. If there is a preheating process before the lamp ignition, the life of the fluorescent lamp can be increased. This paper presented the preheating methods for self excited oscillating system and force excited oscillating system.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1996년도 하계학술대회 논문집 B
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• pp.1304-1306
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• 1996

A regenerative signal amplifying gate driver of self-excited electronic ballast is presented. It can be used for high pressure sodium (HPS) lamp without auxiliary external ignitor. Since the HPS lamp requires very high ignition voltage at start up, the resonant frequency of the circuit must be increased to obtain high voltage oscillations in spite of relatively small resonant current. The presented gate driver amplifies the current of gate drive transformer and raises the gate-source voltage Quickly to turn on the MOSFET switches. Hence, the resonant frequency can be increased more than 100kHz. The HPS lamp used in the simulation and experiment has the rating of 400W input power at 220V input ac voltage source. The experiments show that the resonant frequency is above 150kHz at start up.