• 한국안전학회지
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• 제26권6호
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• pp.26-30
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• 2011

Experimental investigations were performed to examine the effects of different electrostatic discharge ignition energies on LPG/air mixture explosions in an explosion chamber. The chamber consisted of 500 mm in length, with a $100{\times}100mm^2$ cross section. Three different ignition energies were used: 0.30 mJ, 46 mJ and 98 mJ. Flame propagations were recorded by a high speed video camera. The results of flame speed and pressure obtained from the different ignition energies were discussed. It was found that as the energy increased, different flame initiations occurred. This caused the time interval in both the flame and pressure developments. It was also found that the flame speed and the pressure were less sensitive to both 0.30 mJ and 46 mJ, except for the ignition energy of 98 mJ.

• Journal of the Korean Wood Science and Technology
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• 제41권2호
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• pp.111-122
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• 2013

The steam explosion-chemical pretreatment is a more effective wood pretreatment technique than the conventional physical pretreatment by accelerating reactions during the pretreatment process. In this paper, two-stage pretreatment processes of hardwood were investigated for its enzymatic hydrolysis and the succinic acid yield from the pretreated solid. The first stage pretreatment was performed under conditions of low severity to optimize the amount of solid recovery. In the second stage pretreatment washed solid material from the first stage pretreatment step was impregnated again with chemical (alkaline or chlorine-based chemicals) to remove a portion of the lignin, and to make the cellulose more accessible to enzymatic attack. The effects of pretreatment were assessed by enzymatic hydrolysis and fermentation, after the two stage pretreatments. Maximum succinic acid yield (16.1 g $L^{-1}$ and 77.5%) was obtained when the two stage pretreatments were performed at steam explosion -3% KOH.

• Structural Engineering and Mechanics
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• 제87권3호
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• pp.273-282
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• 2023

Concrete construction, one of the oldest building practices, is commonly used in all parts of the world. Concrete is the primary building material for both residential and commercial constructions. The challenge of protecting the buildings, hence nation, against the attack of terrorism has raised the importance to explore the understanding of building materials against the explosion. In this research, a security check-post (reinforced concrete frame filled with plain cement concrete) has been chosen to study the behavior of structural elements under blast loading. Eight nitroglycerines-based dynamite blasts with varying amounts of explosive charge, up to 17 kg weight has been carried out at various scale distances. Pressure and acceleration time history records are measured using blast measuring instruments. Security check post after being exposed by explosive loading are photographed to view cracking/failure patterns on the structural elements. It is noted that with the increase of quantity of explosive, the dimensions of spalling and crack patterns increase on the front panels. Simple empirical analyses are conducted using ConWep and other design manuals such as UFC 3-340-02 (2008) and AASTP-1 (2010) for the purpose of comparison of blast parameters with the experimental records. The results of experimental workings are also compared with earlier researchers to check the compatibility of developed equations. It is believed that the current study presents the simple and preliminary procedure for calculating the air blast and ground shock parameters on the structures exposed to blast explosion.

• 한국해양공학회지
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• 제26권3호
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• pp.46-54
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• 2012

More than 70% of the accidents that occur on offshore installations stem from hydrocarbon explosions and fires, which, because they involve blast effects and heat, are extremely hazardous and have serious consequences in terms of human health, structural safety, and the surrounding environment. Blast barriers are integral structures in a typical offshore topside module to protect personnel and safety critical equipment by preventing the escalation of events caused by hydrocarbon explosions. Many researchers have shown the adequacy of the simple design tool commonly used by the offshore industry for the analysis and design of blast walls. However, limited information is available for corrugated blast wall design with explosion impact response characteristics. Therefore, this paper presents a parametric study on the explosion impact response characteristics of an offshore installation's stainless steel corrugated blast wall. This paperalso investigates and recommends design parameters for the structural design of a corrugated blast wall based on a nonlinear structural analysis of experiential results.

• 한국가스학회지
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• 제20권3호
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• pp.30-37
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• 2016

내압 방폭전기기계 기구는 인화성 가스가 존재하는 위험장소에서 사용되어도 인화성 가스의 점화원이 되지 않는 구조로 이루어져야 한다. 또한 전기 스파크를 발생시키는 부품이 점화원이 되어 기계 기구 내부에서 폭발 시 최대 압력에 견디고 내부 화염이 외부로 전파되어 가스나 증기 폭발을 일으키지 않도록 설계되어야 한다. 본 연구에서는 화염 틈새를 통해 외부로 분사되는 연소 생성물의 분사가 외부 가스나 증기를 점화시킬 정도의 온도나 에너지를 가질 수 없도록 하는 MESG(Maximum Experimental Safe Gap)의 중요한 물리적인 메커니즘에 대해 규명하였다. IEC 60079-20-1:2010 기준에 의해 프로판- 아세틸렌-공기로 이루어진 3성분계 혼합가스의 MESG를 실험하여 MESG 값을 측정하고 가스 폭발시의 최대 폭발압력을 측정하였다. 결과로는 아세틸렌 가스 보다는 폭발력이 낮은 프로판 가스의 조성이 MESG 값과 폭발압력에 더욱 큰 변수로 작용함을 알 수 있었다.

• 한국가스학회지
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• 제16권5호
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• pp.58-65
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• 2012

현재 가연성 가스의 누출시 누출된 가스의 확산과 VCE에 의한 과압을 예측하기 위해 여러 모델들이 이용되고 있다. 그러나 이 모델들은 누출설비의 지형과 장애물 그리고 건물들의 영향에 대해서는 충분히 고려하지 않은 단순한 접근방법을 이용하고 있다. 이에 본 연구는 누출된 물질의 연소형태, 설비의 Geometry, 난류, 장애물, 바람의 영향 등 여러 변수를 고려하여 보다 정확하게 분석할 수 있는 CFD(Computational Fluid Dynamics) Model을 검토함으로서 누출된 가스의 확산과정과 분포형태 그리고 폭발시 화염과 과압의 결과를 2D와 3D의 가상공간에서 제시하였다. 이러한 CFD 분석결과는 폭발에 대한 리스크 분석과 리스크 기반의 설계에 있어 유용하게 활용될 것으로 판단된다.

• 한국지열·수열에너지학회논문집
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• 제14권3호
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• pp.21-28
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• 2018

This paper presents two-step simulations to calculate the influence of blast-induced pressures on explosion-protection valves installed at the boundary between a protection facility and a tunnel entering the facility. The first step is to calculate the respective overpressure on the entrance and exit of the tunnel when an explosion occurs near the tunnel entrance and exit to approach the protection facility. Secondly, the blast pressures on the explosion-protection valves mounted to walls located near the tunnel inside approaching the protection facility are analyzed with a 0.1 ms time variation using the results obtained from the first-step calculations. The following conclusions could be derived as a results: (1) The analysis of the entrance tunnel scenario, P1, leads to the maximum overpressure of 47 kPa, approximately a half of the ambient pressure, at the inner entrance due to the effect of blast barrier. For the scenario, P2, the case not blocked by the barrier, the maximum overpressure is 628 kPa, which is relatively high, namely, 5.2 times the ambient pressure. (2) It is observed that the pressure for the entrance tunnel is effectively mitigated because the initial blast pressures are partially offset from each other according to the geometry of the entrance and a portion of the pressures is discharged to the outside.

• Geomechanics and Engineering
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• 제2권1호
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• pp.1-18
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• 2010

The analysis of structure response and design of buried structures subjected to dynamic destructive loads have been receiving increasing interest due to recent severe damage caused by strong earthquakes and terrorist attacks. For a comprehensive design of buried structures subjected to blast loads to be conducted, the whole system behaviour including simulation of the explosion, propagation of shock waves through the soil medium, the interaction of the soil with the buried structure and the structure response needs to be simulated in a single model. Such a model will enable more realistic simulation of the fundamental physical behaviour. This paper presents a complete model simulating the whole system using the finite element package ABAQUS/Explicit. The Arbitrary Lagrange Euler Coupling formulation is used to model the explosive charge and the soil region near the explosion to eliminate the distortion of the mesh under high deformation, while the conventional finite element method is used to model the rest of the system. The elasto-plastic Drucker-Prager Cap model is used to model the soil behaviour. The explosion process is simulated using the Jones-Wilkens-Lee equation of state. The Concrete Damage Plasticity model is used to simulate the behaviour of concrete with the reinforcement considered as an elasto-plastic material. The contact interface between soil and structure is simulated using the general Mohr-Coulomb friction concept, which allows for sliding, separation and rebound between the buried structure surface and the surrounding soil. The behaviour of the whole system is evaluated using a numerical example which shows that the proposed model is capable of producing a realistic simulation of the physical system behaviour in a smooth numerical process.

• 한국안전학회지
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• 제35권6호
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• pp.25-31
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• 2020

Boiling Liquid Expanding Vapor Explosion(BLEVE) can cause not only economic damage to the plant but also serious casualties. LPG accidents account for 89.6 percent of all accidents caused by gas leaks in Korea over the past nine years, while casualties from accidents also account for 73 percent of all accidents, according to statistics from the Korea Gas Safety Corporation. In addition, a potential explosion and a fire accident from one LPG storage tank may affect the nearby storage tanks, causing secondary and tertiary damage (domino effect). The safety distance standards for LPG used by LPG workplaces, charging stations, and homes in Korea have become stricter following the explosion of LPG charging stations in Bucheon. The safety distance regulation is divided into regulations based on the distance damage and the risk including frequency. This study suggests two approaches to optimizing the safety distance based on the just consequence and risk including frequencies. Using the Phast 7.2 Risk Assessment software by DNV GL, the explosion overpressure and heat radiation were derived according to the distance caused by BLEVE in the worst-case scenario, and accident and damage probability were derived by considering the probit function and domino effect. In addition, the safety distance between LPG tanks or LPG charging stations was derived to minimize damage effects by utilizing these measures.

• 한국가스학회지
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• 제3권1호
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• pp.21-26
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• 1999

화학공장에서 발생하는 사고는 공장 자체의 손실을 가져 올 뿐만 아니라 주위 지역에도 영향을 미친다. 그리고 사고로 인한 피해는 대형화할 가능성이 크다. 이에 따라 화학 공장의 안전 관리의 중요성이 부각되고 있다. 사고의 정량 평가는 사고의 규모를 미리 예측하는 것으로 이를 통해 공정 장치의 layout, 주위와의 최소 안전거리 예측, 대피 시설의 설치 등과 같은 대책을 세울 수 있다 본 연구에서는 화학공장의 3대 사고형태 중 화재와 폭발의 피해 예측을 용이하게 하기 위한 프로그램을 작성하였다. 화재의 경우에는 Pool Fire와 Fireball로 인한 피해를 예측할 수 있도록 하였고, 폭발의 경우에는 UVCE와 BLEVE로 인한 손실을 예측 할 수 있도록 하였다. 화재는 화염에서 나오는 복사열을 피해 정도를 예측하는 기준으로 사용하였고, 폭발은 과압을 기준으로 하였다. 특히, BLEVE의 경우에는 파편의 예상 비산 거리도 추정할 수 있도록 하였다. 각각의 결과를 이용해 Probit 분석을 할 수 있도록 하였다. 그리고 이를 기존에 발생했던 부천의 LPG 폭발 사고에의 분석에 사용해본 결과 노출 허용 거리가 800m이었다. 그리고 Probit 분석 결과 1도 화상, 2도 화상, 화재 사망은 각각 450m, 280m, 260m 이상일 경우 직접적인 피해가 없을 것으로 예측되었다. 사고 분석 결과는 이를 한국산업안전공단에서 Dupont의 SAFER 프로그램을 사용하여 얻어낸 예측치와 $3\%$이내의 같은 결과를 얻었다.