• Explosives and Blasting
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• v.30 no.2
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• pp.43-51
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• 2012

The Demolition blasting has been applied for buildings and structures so far. In this study, however, a confined vessel blasting filled with water has been focused. A small amount of explosives were placed in a sealed vessel with water, perfect elastic body, supposed as a relay agent in it, and the blasting aspect was observed. Blasting pressure was standardized by Abel's equation of state. In result, if there was a relay agent in it, the pressure vessel was torn apart with smaller power than its tensile strength. If there was not, it needed 7.1~8.5 times as much power as the previous one, and the blasting pressure had not also affected the demolition and it had gone or vanished until it reached a certain point, In terms of pressure vessel made by steel, the elastic-plastic failure was took a place, and the first yield point happened along the welded area as a form of heating plastic failure we thought.

• Journal of the Korean earth science society
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• v.41 no.5
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• pp.478-489
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• 2020

This study presents an analysis of infrasonic signals from two accidental explosions in Gwangyang city, Jeonnam Province, Korea, on December 24, 2019, recorded at 12 infrasound stations located 151-435 km away. Infrasound propagation refracted at an altitude of ~40 km owing to higher stratospheric wind in the NNW direction, resulting in favorable detection at stations in that direction. However, tropospheric phases were observed at stations located in the NE and E directions from the explosion site because of the strong west wind jet formed at ~10 km. The transmission losses on the propagation path were calculated using the effective sound velocity structure and parabolic equation modeling. Based on the losses, the observed signal amplitudes were corrected, and overpressures were estimated at the reference distance. From the overpressures, the source energy was evaluated through the overpressure-explosive charge relationship. The two explosions were found to have energies equivalent to 14 and 65 kg TNT, respectively. At the first explosion, a flying fragment forced by an explosive shock wave was observed in the air. The energy causing the flying fragment was estimated to be equivalent to 49 kg or less of TNT, obtained from the relationship between the fragment motion and overpressure. Our infrasound propagation modeling is available to constrain the source energy for remote explosions. To enhance the confidence in energy estimations, further studies are required to reflect the uncertainty of the atmospheric structure models on the estimations and to verify the relationships by various ground truth explosions.

• Proceedings of the Safety Management and Science Conference
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• 2010.11a
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• pp.277-281
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• 2010

본 연구에서는 사료분진의 폭발 특성을 연구하여 분진에 의한 폭발사고 위험을 감소시키고 방지대책에 필요한 기초자료를 제공하기 위해 Hartman1)식 분진폭발장치를 사용하여 다양한 사료를 실험하였다. 실험결과로 사료농도가 폭발확률에 미치는 영향은 농도가 높을수록, 사료분진의 입경이 작을수록 폭발확률이 커지고 분진농도가 증가할수록 폭발압력이 증가하였으나 일정농도를 넘어서면 오히려 폭발압력이 감소하는 경향을 보였으며 불활성물질을 첨가할 경우에는 10%이상 첨가할 경우에 폭발억제 효과를 보였다.

• Explosives and Blasting
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• v.24 no.2
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• pp.23-31
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• 2006

Optimum additive which gets Possible detonation sensitivity and minimum stability has been selected among several additives. It is able to mitigate a chemical reaction without destroying a structure of emulsion. Kinecker has been developed by mixing both matrix and selected additive through a perfect formulation. The detonation pressure is reduced by 40.66%(47.27% by Nitro Dyne's program), and hole pressure by 33.25% and even VOD by 52.88% against currently used emulsion explosives.

• Journal of Korean Tunnelling and Underground Space Association
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• v.23 no.6
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• pp.605-612
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• 2021

Amid growing global damage due to abnormal weather caused by global warming, the introduction of eco-friendly cars is accelerating to reduce greenhouse gas emissions from internal combustion engines. Accordingly, many studies are being conducted in each country to prepare for the explosion of hydrogen fuel in semi-closed spaces such as tunnels and underground parking lots to ensure the safety of hydrogen-electric vehicles. As a result of predicting the explosion pressure of the hydrogen tank using the equivalent TNT model, it was found to be about 1.12 times and 2.30 times higher at a height of 1.5 meters, respectively, based on the case of 52 liters of hydrogen capacity. A review of the impact on the human body and buildings by converting the predicted maximum explosive pressure into the amount of impact predicted that all predicted values would result in lung damage or severe partial destruction. The predicted degree of damage was applied only by converting the amount of impact caused by the explosion, and considering the additional damage caused by the explosion, it is believed that the actual damage will increase further and safety and disaster prevention measures should be taken.

• Journal of the Korean Institute of Gas
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• v.15 no.5
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• pp.13-18
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• 2011

Experimental studies were carried out to investigate the characteristics of explosion mitigations by varying concentrations of agar gel barriers in an explosion chamber, 1400 mm in length, with a square cross-section of $100{\times}100mm^2$. Another extension chamber, $100{\times}100{\times}300mm^3$, was made to hold a gel barrier. Four different gel concentrations were used in the measurements: 2, 3, 4, 5 %(by weight of gel). Displacement of the gel barrier was measured using a high speed camera, and pressure development was measured using pressure transducers and a data acquisition system. It was found that as the concentrations of the gel barriers increased, the gel rupture time and the time taken to reach the maximum pressure increased. It was also found that the increment of gel concentrations increased the reduction percentage in the maximum pressure between before and after gel barrier.

• Fire Science and Engineering
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• v.17 no.4
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• pp.111-116
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• 2003

LPG explosion characteristics in non-uniform concentration was investigated with a 270 liter explosion vessel of which the scale is 100 cm${\times}$60 cm${\times}$45 cm. Vented explosion and closed explosion system were used. Experimental parameter were position of ignition source, nozzle diameter and flow rate of gas. Non uniform concentration was controlled by the nozzle diameter and flow rate. Explosion pressure were measured with strain type pressure sensor and the flame behavior was pictured with the video camera. Based on this experimental result, it was found that the flow rate of gas and the duration of gas injection are important factor for mixing the gas in the vessel. And as the increase the non-uniformity of gas concentration, explosion pressure and pressure rise rate Is decrease but the flame resident time in the vessel is increase. Therefore gas explosion to fire transition possibility will increase in non-uniform concentration gas explosion.

• Journal of the Korean Institute of Gas
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• v.24 no.3
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• pp.20-26
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• 2020

In this study, experimental study was conducted to examine the influence of explosion pressure and flame propagation velocity of methane-air mixtures due to the obstacles placed in the explosion space. We used the quantified parameter named barrier ratio in order to generalize the effect of explosion pressure and flame propagation velocity in the closed explosion space with obstacles. From experimental observations, the explosion pressure and flame propagation velocity regardless of the number of obstacles increased with barrier ratio. In the same methane concentration of 10% methane, the flame propagation velocity without obstacle (barrier ratio = 0) was 3.46 m/s but 24.24 m/s (increase about 7 times) with 3 obstacle and barrier ratio of 0.98. In the same barrier ratio, explosion pressure and flame propagation velocity increased sharply with increasing of the number of obstacles.

• Fire Science and Engineering
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• v.12 no.4
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• pp.13-19
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• 1998

We investigated the weight loss according to temperature using Thermal Gravimetric Analysis(TGA) in order to find the thermal hazard of carbon black(Hi-Black 10, Hi-Black 50L) dusts, and the properties of dust explosion in variation of the surface functional groups and specific surface area of their dust with the same particle size. Using Hartman's dust explosion apparatus which estimate dust explosion by electric ignition after making dust disperse by compressed air, dust explosion experiments have been conducted by varying concentration and size of carbon black dust. The explosion pressure of both carbon black increased as the specific surface area increased. The results indicated that Hi-Block 50L of which specific surface area was larger three to four times than that of Hi-Black 10 was much easier of dust explosion.

• Korean Chemical Engineering Research
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• v.58 no.3
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• pp.356-361
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• 2020

Propylene is widely used in petrochemical manufacturing at over 200 ℃. However, since propylene is a flammable gas with fire and explosion risks, inert nitrogen is injected to prevent them. In this study, experiments were conducted using propylene-nitrogen-oxygen upon pressure changes at 200 ℃. At 21% oxygen, as pressure increased from 0.10 MPa to 0.25 MPa, lower explosion limit (LEL) decreased from 2.2% to 1.9% while upper explosion limit (UEL) increased from 14.8% to 17.6%. In addition, minimum oxygen concentration (MOC) decreased from 10.3% to 10.0%, indicating higher risks with the expanded explosive range as pressure increased. With increase of pressure from 0.10 MPa to 0.25 MPa, explosion pressure increased from 1.84 MPa to 6.04 MPa, and the rate of rise of maximum explosion pressure increased drastically from 90 MPa/s to 298 MPa/s. It is hoped that these results can be used as basic data to prevent accidents in factories using propylene.