• Journal of the korean Society of Automotive Engineers
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• v.14 no.5
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• pp.61-68
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• 1992

Knock phenomenon is an abnormal combustion originated from autoignition of unburned gas in the end-gas region during the later stage of combustion process and it accompanys a high pitched metallic noise. Engine Knock is accompanied with a vibration of engine cylinder and when it is severe, it can cause major engine demage. Engine Knock is characterized in terms of knock crank angle, knock pressure, pressure jump and knock intensity. In this study, a 4-cylinder spark ignition engine was used for experiment and eighty consecutive cycles were analyzed statistically. The purpose of this study is to characterize spark ignition engine knock as a function of ignition timing and fuel research octane number. The result of this study can be summerized as follows. Knock occurrence angle approached TDC as ignition timing is advanced. Pressure and knock intensity gradually increased as spark timing is advanced. Mean knock occurence angle gradually approached TDC as fuel research octane number is decreased for identical spark timing. Knock intensity increased linearly as RON is decreased.

• Journal of the Korean Society of Combustion
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• v.2 no.1
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• pp.39-51
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• 1997

A review of probability density function(PDF) methodology and direct numerical simulation for the purpose of modeling turbulent combustion are presented in this study where particular attention is focused on the modeling problem of turbulent molecular mixing term appearing in PDF transport equation. Existing mixing models results were compared to those evaluated by direct numerical simulation in a turbulent premixed medium with finite rate chemistry in which the initial scalar field is composed of pockets of partially burnt gases to simulate autoignition. Two traditional mixing models, the least mean square estimations(LMSE) and Curl#s model are examined to see their prediction capability as well as their modeling approach. Test calculations report that the stochastically based Curl#s approach, though qualitatively demonstrates some unphysical behaviors, predicts scalar evolutions which are found to be in good agreement with statistical data of direct numerical simulation.

• 한국연소학회:학술대회논문집
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• 2000.05a
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• pp.85-92
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• 2000

End-gas temperatures were measured using CARS technique in a conventional DOHC spark-ignition engine fueled with PRF80. The measured pressure data were analyzed using band pass filter method. The measured CARS temperatures were compared with adiabatic core temperatures calculated from measured pressure. Significant heating by pre-flame reaction in the end gas was observed in the late part of compression stroke under both knocking and non-knocking condition. CARS temperatures measured at 10 crank angle degree before knock occurrence was higher than adiabatic core temperatures. These results indicate that there exist some exothermic reactions in low pressure and temperature region. CARS temperatures began to be higher than the adiabatic core temperature when the end-gas temperatures reached 700 K. The temperature elevation due to the pre-flame reaction correlated better with CARS temperature than with cylinder pressure.

• Journal of the Korean Society of Safety
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• v.25 no.4
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• pp.30-35
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• 2010

For the safe handling of acetone, the flash point, the explosion limit at $25^{\circ}C$ and the temperature dependence of the explosion limits were investigated. And the AIT for acetone were experimented. By using the literatures data, the lower and upper explosion limits of acetone recommended 2.5 vol% and 13.0 vol%, respectively. In this study, the lower flash points of acetone recommended $-20^{\circ}C$. This study was determined relationship between the AITs and the ignition delay times by using ASTM E659-78 apparatus for acetone, and the experimental AIT of acetone was $565^{\circ}C$. The new equations for predicting the temperature dependence of the explosion limits of acetone is proposed. The values calculated by the proposed equations were a good agreement with the literature data.

• Proceedings of the Korea Institute of Fire Science and Engineering Conference
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• 2005.11a
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• pp.334-339
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• 2005

• Journal of ILASS-Korea
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• v.13 no.2
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• pp.91-98
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• 2008

In the present study, in order to understand the overall spray combustion characteristics of DME fuel as well as to identify the distinctive differences of DME combustion processes against the conventional hydrocarbon liquid fuels, the sequence of the comparative analysis have been systematically made for DME and n-heptane liquid fuels. To realistically represent the physical processes involved in the spray combustion, this studyemploys the hybrid breakup model, the stochastic droplet tracking model, collision model, high-pressure evaporation model, and transient flamelet model with detailed chemistry. Based on numerical results, the detailed discussions are made in terms of the autoignition, spray combustion processes, flame structure, and turbulence-chemistry interaction in the n-heptane and DME fueled spray combustion processes.

• Journal of the Korean Society of Safety
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• v.26 no.2
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• pp.36-41
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• 2011

For the safe handling of n-hexane, the explosion limit at $25^{\circ}C$, the temperature dependence of the explosion limits and the lower flash point were investigated. And AITs(auto-ignition temperatures) by ignition delay time for n-hexane were experimented. By using the literatures data, the lower and upper explosion limits of n-hexane recommended 1.0 Vol% and 8.0 Vol%, respectively. In this study, the lower flash points of n-hexane recommended $-23^{\circ}C$. This study measured relationship between the AITs and the ignition delay times by using ASTM E659-78 apparatus for n-hexane, and the experimental AIT of n-hexane was $240^{\circ}C$. The new equations for predicting the temperature dependence of the explosion limits of n-hexane is proposed. The values calculated by the proposed equations were a good agreement with the literature data.

• Journal of the Korean Society of Safety
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• v.24 no.2
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• pp.42-47
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• 2009

The flash point and the AIT(auto-ignition temperature) are the most important combustible properties used to determine the potential for the fire and explosion hazards of flammable material. In order to know the accuracy of data in MSDS(Material Safety Data Sheet), the flash point of n-acids were measured by using Pensky-Martens closed cup tester(ASTM D93), Setaflash closed cup tester(ASTM D3278), Tag open cup tester(ASTM D1310) and Cleveland open cup tester(ASTM D92). Also, the AIT of n-acids were measured by using ASTM E659-78 tester. The measured the flash points and the AIT were compared with literatures and MSDS in KOSHA. The measured the flash points and the AIT were different from those in literatures and MSDS. Therefore, This paper shows that it is needed to investigate the MSDS compatibility of n-acids for the fire safety objectives.

• Proceedings of the Korea Institute of Fire Science and Engineering Conference
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• 2011.04a
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• pp.416-420
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• 2011

• Proceedings of the Korea Institute of Fire Science and Engineering Conference
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• 2011.11a
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• pp.357-359
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• 2011