• Journal of the Computational Structural Engineering Institute of Korea
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• v.27 no.4
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• pp.281-288
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• 2014

As a gas explosion is the most fatal accident in shipbuilding and offshore plant industries, all safety critical elements on the topside of offshore platforms should retain their integrity against blast pressure. Even though many efforts have been devoted to develop blast-resistant design methods in the offshore engineering field, there still remain several issues needed to be carefully investigated. From a procedure for calculation of explosion design pressure, impulse of a design pressure model having completely positive side only is determined by the absolute area of each obtained transient pressure response through the CFD analysis. The negative pressure phase in a general gas explosion, however, is often quite considerable unlike gaseous detonation or TNT explosion. The main objective of this study is to thoroughly examine the effect of the negative pressure phase on structural behavior. A blast wall for specific FPSO topside is selected to analyze structural response under the blast pressure. Because the blast wall is considered an essential structure for blast-resistant design. Pressure time history data were obtained by explosion simulations using FLACS, and the nonlinear transient finite element analyses were performed using LS-DYNA.

• Korean Chemical Engineering Research
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• v.57 no.6
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• pp.790-803
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• 2019

The dioctyl terephthalic acid (DOTP) process produces plastic plasticizers by esterification of terephthalic acid with powder in the form of octanol. In this study, the dust explosion characteristics of terephthalic acid directly injected into the manhole in the form of powder in the presence of flammable solvent or vapor in the reactor of this process were investigated. Dust particle size and particle size distribution dust characteristics were investigated, and pyrolysis characteristics of dust were investigated to estimate fire and explosion characteristics and ignition temperature. Also, the minimum ignition energy experiment was performed to evaluate the explosion sensitivity. As a result, the average particle size of terephthalic acid powder was $143.433{\mu}m$. From the thermal analysis carried out under these particle size and particle size distribution conditions, the ignition temperature of the dust was about $253^{\circ}C$. The lower explosive limit (LEL) of the terephthalic acid was determined to be $50g/m^3$. The minimum ignition energy (MIE) for explosion sensitivity is (10 < MIE < 300) mJ, and the estimated minimum ignition energy (Es) based on the ignition probability is 210 mJ. The maximum explosion pressure ($P_{max}$) and the maximum explosion pressure rise rate $({\frac{dP}{dt}})_{max}$ of terephthalic acid dust were 7.1 bar and 511 bar/s, respectively. The dust explosion index (Kst) was 139 mbar/s, corresponding to the dust explosion grade St 1.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2015.10a
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• pp.205-207
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• 2015

LNG/LPG는 폭발가능성이 크기 때문에 매우 위험한 물질이다. LNG/LPG는 gas상태의 연료를 극 초저온에 고 압력 상태로 고농축한 액체 연료이다. 온도나 압력에 따라 물질의 상태가 변하기 때문에 폭발이나 화재가 일어날 수 있다. 하지만 무조건 사고가 일어나는 것은 아니며 현재까지도 화재나 폭발이 일어난 경우가 드물다. LNG/LPG선박은 충돌이나 파손 등 사고위기가 클수록 위험하다. 사고위기가 일어나는 요소로는 복잡한 항로, 많은 선박 수, 해마다 증가하는 LNG/LPG의 수요량 등이 있다. 본 연구에서는 LNG/LPG관련 해양사고 시나리오를 만들기 위해 사고 연계 고리(Accident chain)를 만들어 분석하였다. 해양사고의 연계 고리를 만들기 위해서는 story가 필요하다는 것을 알게 되었고, Risk를 통해 Peril과 Hazard를 분석 할 수 있었다. LNG/LPG의 위험성은 고압에 기인하는 위험, 화재위험, 동상위험, 화학반응의 위험, 질식 위험 등으로 분류 할 수 있었다. 아직까지는 LNG/LPG선박의 화재 및 폭발사고는 거의 일어나지 않았으나 매년 그 수요량이 증가하고 있고, 매우 위험한 물질임을 본 연구를 통해 알 수 있었다.

• Explosives and Blasting
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• v.35 no.3
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• pp.21-30
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• 2017

When explosives explode in water, the effect of post-explosion gas after explosion should be considered, unlike explosion in the air. During explosion in water, the propagation velocity of the explosion pressure is faster than when the explosion occurs in the air. The generated gas is diffused and trapped in the form of bubbles by water before the energy is dissipated. At this time, the bubble expands and contracts, creating a shock wave. In order to investigate this series of phenomena, a cylinder type steel water tank capable of observing the interior was fabricated and explosion experiments were conducted. In this study, a small amount of shell-free pentolite was exploded in water. Experiments were performed to observe the behavior of the generated gas bubble as well as to measure the shock wave generated. We designed the experimental method of underwater explosion and examined the results.

• The Journal of the Korea institute of electronic communication sciences
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• v.12 no.1
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• pp.93-100
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• 2017

Four-stroke cycles in an automobile engine are suction stroke, compression stroke, combustion stroke and exhaustion stroke. A normal operation of engine in compression and power stroke must be processed in optimal fuel-air pressure. In this paper we describe a development of measuring equipment for engine cylinder pressure with observing supply current to self motor(start motor). By comparing the current wave on pressure of the 4 or 6 cylinder in engine, a abnormal cylinder state will be found. The validity of the proposed measuring equipment was shown by experiment for real automobile.

• Journal of the Korean Chemical Society
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• v.60 no.1
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• pp.9-15
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• 2016

The theoretical investigation has been performed to predict detonation velocity, detonation pressure, and thermodynamic stability of HMX/LLM-116 cocrystal. All possible geometries of HMX, LLM-116, and cocrystal have been optimized at the B3LYP/cc-pVTZ level of theory. The binding energy for the trigger bond and cluster has been calculated to predict the thermodynamic stability. The MP2 binding energies were obtained using single point energy calculation at the B3LYP optimized geometries, and the density has been calculated from monte carlo integration. The detonation velocity and detonation pressure have been calculated using Kamlet-Jacobs equation, while enthalpy has been predicted at the CBS-Q level of theory.

• Journal of the Korean Institute of Gas
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• v.11 no.2 s.35
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• pp.65-70
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• 2007

The explosion phenomenon and hazard estimate of LP gas, the study was examined into variation of oxygen concentration and LP gas concentration. As the result of experiment, the lower explosive limit was decreased as the increased at concentration of LP gas and 21% of oxygen concentration. Minimum oxygen concentration was 14.5%. 12.0%, 11.5% at 1.0, 1.5 and 2.0 bar respectively. And maximum explosion pressure was increased for $6.46kg/cm^2,\;9.41kg/cm^2\;and\;13.49kg/cm^2$ according to increased of pressure. The speed of flame propagation was increased as the higher with initial pressure of LP gas.

• Proceedings of the Korean Institute of Industrial Safety Conference
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• 2002.05a
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• pp.149-152
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• 2002

보일러는 가정 및 각종 건물, 산업체에서 난방 및 급탕 그리고 동력원으로써 중요한 역할을 하고 있으며, 또한 증기의 사용 증가에 따라 증가하고 있는 추세이다. 이러한 산업용 보일러나 압력 용기의 경우 내부의 높은 압력과 많은 양의 열을 보유하고 있으므로 주로 기기의 파열이나 폭발과 같은 엄청난 파괴력에 의해, 공장이나 사업장의 직접적 또는 간접적으로 많은 손해를 초래하게 된다.(중략)

• Explosives and Blasting
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• v.28 no.1
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• pp.55-62
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• 2010

Explosive welding was planed in a closed drift of a mine for its reuse. In this study, we analyzed the stabilization of roof and pillar which were expected to be affected by overpressure experienced during the continual explosive welding. Three equations, normal equation, CONWEP and DDESB, were used for the estimation of overpressure. The investigation shows that the continual use of the explosive welding in a drift may result in considerable damage on the drift.

• Proceedings of the Korea Institute of Fire Science and Engineering Conference
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• 2013.04a
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• pp.115-115
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• 2013

최근의 분진폭발은 플라스틱, 의약품, 목재, 곡물 저장고, 고체연료, 화학제품 제조공정 등을 포함하여 성형 및 가공 공정 등에서 화재폭발사고가 발생되고 있다. 폐목재를 재활용하여 PB(Particle board)를 생산하는 국내 제조사업장에서는 화재폭발 사고가 빈번히 발생하고 있어 예방대책이 요구되고 있다. 본 연구에서는 폐목재 제조공정의 사고예방과 목재분진 취급공정에 대한 안전대책 등을 제시하기 위하여 사고원인 물질인 폐목재 부유분진의 폭발특성실험을 실시하고 실험결과를 검토하였다. 또한 폐목재 분진의 화재폭발위험성을 상세히 평가하기 위하여 해당 물질의 자연발화점, 축열저장시험, 및 최소점화에너지 등의 화재폭발위험특성값을 실험적으로 조사하였다. 본 연구에서 사용한 폐목재 시료의 비구형 입자형태를 가지는데 입도분석기의 측정 결과 평균 입경은 $15.96{\mu}m$로 조사되었다. 또한 목재 분진의 함수율은 3.88%이며 중금속함유량은 1.73%이다. 자연발화점 측정결과 $225.5^{\circ}C$로서 비교적 낮게 측정되었고 퇴적분진에 대한 화재의 위험성은 높게 나타났다. 반면에 축열저장시험 결과를 통하여 공정관리 온도 및 보관온도를 $150^{\circ}C$ 이하로 관리하면 축열에 의한 자기분해 위험성은 낮은 것으로 판단되었다. 그러므로 축열에 의한 화재폭발 등의 위험성은 낮은 것으로 사료 된다. 최대폭발압력($P_{max}$)은 8.7 bar이며 폭발하한농도 (LEL)는 $60g/m^3$으로 나타났다. 부유분진의 폭발특성실험 결과 분진폭발지수(Kst)는 폭발등급 St 1 (0$bar{\cdot}m/s$)으로 나타났으며 폭발에 의한 위험성이 약한 분진으로 판정되었다. 최소점화에너지(MIE)는 10mJ < MIE <30mJ의 범위로 측정되었으며, 계산에 의해 추정된 최소점화 에너지(Es) 값은 14 mJ로서 일반적인 발화감도(Normal ignition sensitive)로 분류되었다. 이는 실질적인 점화원만 제거하여도 분진폭발을 예방할 수 있다는 것을 의미한다. 그러나 분진 폭발사고를 예방을 위하여 MIE값이 공정운전온도 $100^{\circ}C$ 초과 시에 급격히 낮아질 수 있으므로 운전 온도 설정에 있어서 주의가 필요하다.