• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2008.11a
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• pp.60-63
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• 2008

Phase change in combustion of energetic materials happens inevitably. The product gas generated by combustion is at extreme temperature and pressure state. The interaction between a gas and metal generates high strain rate deformation and complex wave phenomena. In order to perform combustion simulation containing phase changes, we develop an elegant model for phase change and provide a proof of performance via vapor explosion example.

• Proceedings of the Korean Society of Disaster Information Conference
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• 2023.11a
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• pp.119-120
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• 2023

유해화학물질의 제조, 취급사업장의 화학사고에 대한 대응에는 어느 정도 체계적으로 이루어 지고 있으나 유해화학물질의 운송 중 설비결함이나 교통사고에 의한 폭발, 누출사고는 장소 및 시간등이 확정되지 않고 다양한 변수로 인하여 정부기관의 신속한 대응에는 많은 어려움이 따르고 있다. 다양한 변수들을 고려한 화학사고 업무대응 매뉴얼이 부족하고 현장지휘체계의 신속한 구성과 협업에 의한 비상대응체계를 구축하여 운영하는데 현실적으로 많은 어려움이 있어 이에 대해서 효과적으로 대응하는 방안을 수립하기 위해 검토해야 할 사항들에 대해 알아보고자 한다.

• Journal of the Korean Institute of Gas
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• v.12 no.2
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• pp.1-6
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• 2008

For the safety design and operation of many gas process, it is necessary to know certain explosion limit, flash point, autoignition temperature (AIT) and minimum oxygen concentration of handling substances. Also it is necessary to know explosion limit at high temperature and pressure. In this study for the safe handling of hydrogen, explosion limit and AIT of combustion properties for hydrogen were investigated. By using the literatures data, the lower and upper explosion limits of hydrogen recommended 4.0 vol% and 77.0 vol%. Also the AIT of hydrogen with ignition sources recommended $400^{\circ}C$ at the electrically heated crucible furnace (the whole surface heating) and recommended $640^{\circ}C$ at the local hot surface. The new equations for predicting the temperature and the pressure dependence of the explosion limits of hydrogen are proposed. The values calculated by the proposed equations were a good agreement with the literature data.

• Korean Chemical Engineering Research
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• v.55 no.2
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• pp.190-194
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• 2017

The combustion properties for the prevention of the fire and explosion in the work place are flash point, explosion limit, autoignition temperature (AIT) etc.. The using of the corrective combustion properties of the MSDS (Material Safety Data Sheet) of the handling substance for the chemical process safety is very important. For the safe handling of benzyl alcohol which is widely used in the chemical industry, the flash point and the AIT were measured. And, the lower explosion limit (LEL) of benzyl alcohol was calculated by using the lower flash point which obtained in the experiment. The flash points of benzyl alcohol by using the Setaflash and Pensky-Martens closed-cup testers measured $90^{\circ}C$ and $93^{\circ}C$, respectively. The flash points of benzyl alcohol by using the Tag and Cleveland open cup testers are measured $97^{\circ}C$ and $100^{\circ}C$. The experimental AIT of benzyl alcohol by ASTM 659E tester was measured as $408^{\circ}C$. The LEL of benzyl alcohol measured by Setaflash closed-cup apparatus was calculated as 1.17 vol% at $90^{\circ}C$. In this study, it was to possible predict the LEL by using the lower flash point of benzyl alcohol which measured by Setaflash closed-cup tester.

• Journal of the Korea Society for Simulation
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• v.28 no.2
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• pp.1-14
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• 2019

A full scale hydrodynamic simulation that requires an accurate reproduction of shock-induced detonation was conducted for design of an energetic component system. A detailed hydrodynamic analysis SW was developed to validate the reactive flow model for predicting the shock propagation in a train configuration and to quantify the shock sensitivity of the energetic materials. The pyrotechnic device is composed of four main components, namely a donor unit (HNS+HMX), a bulkhead (STS), an acceptor explosive (RDX), and a propellant (BPN) for gas generation. The pressurized gases generated from the burning propellant were purged into a 10 cc release chamber for study of the inherent oscillatory flow induced by the interferences between shock and rarefaction waves. The pressure fluctuations measured from experiment and calculation were investigated to further validate the peculiar peak at specific characteristic frequency (${\omega}_c=8.3kHz$). In this paper, a step-by-step numerical description of detonation of high explosive components, deflagration of propellant component, and deformation of metal component is given in order to facilitate the proper implementation of the outlined formulation into a shock physics code for a full scale hydrodynamic simulation of the energetic component system.

• Fire Science and Engineering
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• v.31 no.3
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• pp.25-30
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• 2017

Because of the vertical combustion characteristics of combustible substances, accurate substance safety information for their safe use, handling and transportation is essential. The flash point, fire point, explosion limits and autoignition temperature (AIT) are important safety parameters which need special attention in chemical plants and laboratories that handle dangerous materials. In this study, tert-butylbenzene which is widely used as an intermediate material in the chemical industry was selected. For the reliability of the flammable properties of tert-butylbenzene, this study was investigated the explosion limits of tert-butylbenzene in the reference data. The flash points, fire points and AITs by the ignition delay time for tert-butylbenzene were experimented. The lower flash points of tert-butylbenzene by using the Setaflash and Pensky-Martens closed-cup testers measured $39^{\circ}C$ and $44^{\circ}C$, respectively. The flash points of tert-butylbenzene by using the Tag and Cleveland open cup testers are measured $51^{\circ}C$ and $54^{\circ}C$. And the fire points of tert-butylbenzene by the Tag and Cleveland open cup testers were $54^{\circ}C$ and $58^{\circ}C$ respectively. The AIT of tert-butylbenzene measured by the ASTM 659E tester was measured as $450^{\circ}C$. The lower explosion limit of $39^{\circ}C$ which measured by the Setaflash flash point tester was calculated to be 0.68 vol%.

• Explosives and Blasting
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• v.41 no.1
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• pp.1-18
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• 2023

Stemming is a process applied to blast holes to prevent gases from escaping during detonation. A stemming material helps confine the explosive energy for longer and increases rock fragmentation. This study developed a stemming material based on a shear-thickening fluid (STF) that reacts to dynamic shock. Two blasting experiments were conducted to Field-verify the performance of the STF-based stemming material. In the first experiment, the pressure inside the blast hole was directly measured based on applying the stemming material. In the second field verification, tunnel blasting was performed, and the blasting results of sand stemming and, that of the STF-based stemming case were compared. The measurement results of the pressure in the blast hole showed that when the STF-based stemming material was applied, the pressure at the top of the blast hole was lower than in the sand stemming case, and the stemming ejection was also lower. The results of the field application verify that the excavation performance of the STF-based stemming case in the tunnel blasting was superior to that of the sand stemming case.

• Korean Chemical Engineering Research
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• v.52 no.6
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• pp.706-712
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• 2014

Explosives are reactive material that contain a great amount of high potential energy. They produce detonation if released suddenly, accompanied by the production of strong light, high heat, great noise and high pressure. Damage at surrounding detonation point is affected by high pressure and blast wave for explosives detonation. Consequently, analysis of pressure and blast wave is very important. This study focuses on the analysis of maximum overpressure and blast wave of explosives for safety assurance. First of all, four cases of the amount of HMX were selected. Secondly, maximum pressure and blast wave were calculated through detonation simulation along with a set of TNT and HMX quantities. The peripheral effect of detonation point was analyzed by calculating overpressure and absolute velocity and considering detonation occurred in the center of geometry by HMX. Also, maximum overpressure and blast wave of HMX were compared to equivalent amount of TNT, which was taken as a base case and verified through theoretical HMX graph. This study contributes to the base case for overpressure and blast wave of complex gunpowder containing HMX.

• Journal of Astronomy and Space Sciences
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• v.22 no.4
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• pp.377-384
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• 2005

Since gamma-ray bursts(GRBs) have been first known to science societites in 1973, many scientists are involved in their studies. Observations of GRB afterglows provide us with much information on the environment in which the observed GRBs are born. Study of GRB afterglows deals with longer timescale emissions in lower energy bands (e.g., months or even up to years) than prompt emissions in gamma-rays. Not all the bursts accompany afterglows in whole ranges of waveleogths. It has been suggested as a reason for that, for instance, that radio and/or X-ray afterglows are not recorded mainly due to lower sensitivity of detectors, and optical afterglows due to extinctions in intergalactic media or self-extinctions within a host galaxy itself. Based on the idea that these facts may also provide information on the GRE environment, we analyze statistical properties of GRB afterglows. We first select samples of the redshift-known GRBs according to the wavelength of afterglow they accompanied. We then compare their distributious as a function of redshift, using statistical methods. As a results, we find that the distribution of the GRBs with X-ray afterglows is consistent with that of the GRBs with optical afterglows. We, therefore, conclude that the lower detection rate of optical afterglows is not due to extinctions in intergalactic media.

• Congress of the korean instutite of fire investigation
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• 2011.04a
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• pp.137-160
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• 2011

본 사고분석을 통해 154 kV 절연부싱에서의 폭발사고에 대한 원인을 규명하였다. 결과적으로, 절연부싱의 사양은 국제표준에 적합하였다. 사고당일 기록된 자료에 의하면 R상과 S상에서 거의 동시에 지락사고가 발생하였으며, 지락지속시간은 약 75 ms로써 사고의 영향을 준 시간은 약 67 ms인 것으로 나타났다. R상은 아크에 의한 탄화 흔적, S상은 아크에 의한 탄화흔적과 외부열에 의한 탄화흔적, T상은 외부열에 의한 탄화흔적, 용융흔적은 R상과 S상의 케이블접속부와 플랜지에서 각각 발생하였다. S상의 절연부싱을 이용하여 탄화패턴 중 아크에 의한 것과 일반 열에 의한 것을 분류하여 연면방전이 발생한 것을 입증하였다. 사고추정 시나리오는 현장조사과정에서 나타난 현상과 목격자 진술, 사고원인 분석자료 등을 토대로 하여 작성되었다. 따라서 사고추정을 통해 분석된 자료는 아크생성단계, 열폭주 단계, 폭발단계, 화재단계로 구성하였다. 사고원인 가능성은 사고의 원인, 형태, 영향을 통해 나타난 연결고리를 검토하여 가능성이 낮은 부분을 배제하는 방식으로 진행되었다. 절연부싱의 사고원인은 표면의 오염물질 부착 가능성이 가장 높았다. 이를 근거로 하여 제조, 시공, 관리적 측면에서의 방지대책을 고려하는 것이 바람직할 것으로 판단된다.