• Journal of Hydrogen and New Energy
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• v.32 no.6
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• pp.551-564
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• 2021

The use of clean energy based on the hydrogen economy is increasing rapidly due to the greenhouse gas reduction policies and the increase in the need for hydrogen. Currently, South Korea government have been considering a plan to construct hydrogen refueling stations at expressway service area for the purpose of supplying hydrogen vehicles. In the case of a hydrogen refueling stations, a quantitative risk assessment (QRA) must be performed because it includs and uses a high pressurized hydrogen storage tank. In this study, QRA was conducted using societal risk and F-N curve by the consequence assessment (CA) of jet fire and explosion according to the population density, capacity of the high pressurized hydrogen storage tank and frequency assessment (FA) data to the general hydrogen refueling stations systems in expressway service area. In the cases of jet with a leak diameter of 7.16 mm, regardless of expressway service area location, the societal risk was over 1E-04 that was acceptable for as Low As reasonably practicable (ALARP) region (workforce), but unacceptable for ALARP region (public). In the cases of gas explosion, all expressway service area satisfy ALARP region. In the case of the population density is over 0.0727, QRA for constructing the hydrogen refueling stations, must be conducted.

• Fire Science and Engineering
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• v.30 no.2
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• pp.114-122
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• 2016

This study is to analyze the explosion and fire risks due to high temperature and short circuit current of Lithium batteries. This study selected the typical types of Li-polymer batteries and Li-ion batteries as the test samples. The result of explosion risk assessment due to the high temperature showed that, while a Li-polymer battery had $170^{\circ}C$ explosion on average, a Li-ion battery had $187^{\circ}C$ explosion. The measurement result of temperature increase due to short circuit current revealed that, in case that protection circuit module (PCM) was normally working, there was little of temperature increase due to over-current limitation. However, in case that PCM was out of order, the temperature of a Li-polymer battery increased up to an average of $115.7^{\circ}C$ and the temperature of a Li-ion battery increased up to an average of $80.5^{\circ}C$, which showed the higher risks of fire and burn.

• Journal of the Korean Society for Geothermal and Hydrothermal Energy
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• v.18 no.3
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• pp.7-18
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• 2022

Secondary batteries used in electric vehicles have a potential risk of ignition and explosion. Various safety measures are being taken to prevent these risks. A numerical study was performed using a computational fluid dynamics code on the cases where pressure relief vents that can reduce the blast overpressures of batteries were installed in the through-compression test room, short-circuit drop test room, combustion test room, and immersion test room in facilities rleated to battery used in electric vehicles. This study was conducted using the weight of TNT equivalent to the energy release from the battery, where the the thermal runaway energy was set to 324,000 kJ for the capacity of the lithium-ion battery was 90 kWh and the state of charge (SOC) of the battery of 100%. The explosion energy of TNT (△H_TNT) generally has a range of 4,437 to 4,765 kJ/kg, and a value of 4,500 kJ/kg was thus used in this study. The dimensionless explosion efficiency coefficient was defined as 15% assuming the most unfavorable condition, and the TNT equivalent mass was calculated to be 11 kg. The internal explosion generated in a test room shows the very complex propagation behavior of blast waves. The shock wave generated after the explosion creates reflected shock waves on all inner surfaces. If the internally reflected shock waves are not effectively released to the outside, the overpressures inside are increased or maintained due to the continuous reflection and superposition from the inside for a long time. Blast simulations for internal explosion targeting four test rooms with pressure relief vents installed were herein conducted. It was found that that the maximum blast overpressure of 34.69 bar occurred on the rear wall of the immersion test room, and the smallest blast overpressure was calculated to be 3.58 bar on the side wall of the short-circuit drop test room.

• Journal of the Korean Institute of Gas
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• v.21 no.4
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• pp.84-91
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• 2017

Recent years have witnessed the increased usage of flammable metals, such as aluminum or magnesium, in wide range of high-tech industries. These metals are indispensable for the improvement of physical properties of materials as well as the design capability of the final product. During the process, unwanted metal dusts could be released to the environment. This can lead to an occupational health and safety issues. Due to their flammable nature, more serious problem of an explosion can happen in extreme cases. The explosion is the combustion of tiny solid particles and vapor mixture, caused by pyrolysis. This complex composition makes engineering analysis more difficult, compared to simple gas explosions or vapor cloud combustions. The study was conducted to assess this light metal dust explosion in an effort to provide the bases for a risk assessment. Dust explosion characteristics of each material was carefully evaluated and an appropriate analysis tool was developed. A comprehensive database was also constructed and utilized for the calibration of the developed response model and the verification for its accuracy. Subsequently, guidelines were provided to prevent dust explosions that could occur in top-notch industrial processes.

• Fire Science and Engineering
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• v.31 no.3
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• pp.97-105
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• 2017

Because asphalt is a solid at normal temperature and is not a hazardous material as stipulated in the Safety Management Act on Hazardous Materials, it is often recognized as having no risk of fire or explosion. On the other hand, it is as dangerous as flammable liquid because it is heated to $170-180^{\circ}C$ and stored in a storage tank. This study analyzed the risk of fire and explosion during the storage and handling of asphalt and the actual conditions of asphalt regulations by fire service organizations. Moreover, this study analyzed the domestic case of explosions in the production process of asphalt concrete (ASCON) and domestic and foreign cases of asphalt storage tank explosions. The analysis suggested that unlike Japan, Korea has no asphalt regulations in fire service organizations. Explosions can occur when ignition is delayed after fuel is sprayed on the dryer drum burner of the aggregates during the production of ASCON. A physical explosion can occur in the storage tank when environmental purification facilities suddenly work strongly to remove air pollutants or bad smells during the heating of asphalt in an asphalt storage tank. In addition, explosions can occur when fires such as welding is performed in the asphalt storage tank.

• Industry Promotion Research
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• v.9 no.2
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• pp.37-44
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• 2024

This study selected the worst-case scenario for fireball and vapor cloud explosion (VCE) of a styrene monomer storage tank installed in a petrochemical production plant and performed damage prediction and accident impact analysis. The range of influence of radiant heat and overpressure due to fireball and vapor VCE during the abnormal polymerization reaction of styrene monomer, the main component of the mixed residue oil storage tank, was quantitatively analyzed by applying the e-CA accident damage prediction program. The damage impact areas of radiant heat and explosion overpressure are analyzed to have a maximum radius of 1,150m and 626m, respectively. People within 1,150m of radiant heat of 4kW/m2 may have their skin swell when exposed to it for 20 seconds. In buildings within 626m, where an explosion overpressure of 21kPa is applied, steel structures may be damaged and separated from the foundation, and people may suffer physical injuries. In the event of a fire, explosion or leak, determine the risk standards such as the degree of risk and acceptability to workers in the work place, nearby residents, or surrounding facilities due to radiant heat or overpressure, identify the hazards and risks of the materials handled, and establish an emergency response system. It is expected that it will be helpful in establishing measures to minimize damage to workplaces through improvement and investment activities.

• Journal of the Korean Society of Safety
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• v.32 no.1
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• pp.134-139
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• 2017

This study has been performed to investigate the risk perceptions of employees in nuclear power plants. A representative sample of 473 employees was surveyed(about 79% response rate). The questionnaire included scales on both risk perceptions of critical five hazards that could be occurring in the nuclear power plants and two psychometric attitudes. Higher risk perceptions between managers and non-managers to five hazards used in this study were entirely obtained from the managers. It was also found that the perceived higher hazards were in the following order: radiation exposure, radioactive release, explosion, fire and radioactive waste. For the controllability, higher risk perceptions to the all factors were obtained from the managers, and higher ones were non-managers in the dread.

• Journal of the Korean GEO-environmental Society
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• v.21 no.5
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• pp.23-33
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• 2020

As the scale of the economy expands, the number of cases of damage in enclosed spaces such as tunnels is increasing due to the accident of transportation vehicles of dangerous substances such as explosive flammable materials that have increased rapidly. In the case of road tunnels in particular, in the aspect of protection against the long-winding trend and the environment in the downtown area, the number of cases of passing through the downtown area increases, and securing the safety of structures against unexpected extreme disasters such as explosions during tunnel passage is very urgent. For this reason, developed countries are already conducting a review of internal bombardment, but there are almost no evaluation and countermeasures for explosion risk in Korea. Therefore, in this study, in order to evaluate the explosion safety of road tunnels, a boiling liquid explosive explosion (BLEVE), which is considered to have the greatest explosion load among vehicles driving on the road, is set as a reference explosion source, and the equivalent TNT explosion load is used for simulation of the explosion. A method of conversion was presented. In addition, by applying the derived explosion load, dynamic behavior simulation was performed by assuming various variables for the tunnel, and the explosion safety of the tunnel was analyzed.

• Korean Chemical Engineering Research
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• v.61 no.1
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• pp.80-88
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• 2023

Ensuring safety in the designing of manufacturing and handling facilities for low-density polyethylene (LDPE) is difficult because there are no standards for the dust explosion characteristics of LDPE. In this study, a dust explosion test was performed on two dust samples collected from a bag filter (LDPE 1) during the LDPE manufacturing process and sedimentary dust (LDPE 2) leaked outside a facility such as a silo, and the LDPE 2 explosion test results were summarized. Particle size analysis showed that the volume-based particle diameter (median) was 95.04 ㎛ and the number density was 0-1 ㎛. The maximum explosion pressure (P_max) was 6.6 bar, and the maximum rate of explosion pressure rise was 366 [bar/s] at 1500 g/m³. Accordingly, the dust explosion index (K_st) was 99.4 bar·m/s, which was confirmed as ST-1 grade. Moreover, the minimum ignition energy and minimum ignition temperature was 10 mJ and 450 ℃, respectively. Currently, manufacturing and handling design is based on the characteristic values of high-density polyethylene (HDPE). However, as the test results show that LDPE 2 dust has a higher risk than HDPE (particle diameter 61.6 ㎛), caution is required when using the HDPE design criteria in the LDPE manufacturing process.

• Korean Chemical Engineering Research
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• v.62 no.1
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• pp.27-35
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• 2024

Fuel gases such as methane and propane are used in explosion hazardous area of domestic plants and can form non-uniform mixtures with the influence of process conditions due to leakage. The fire-explosion risk assessment using literature data measured under uniform mixtures, damage prediction can be obtained the different results from actual explosion accidents by gas leaks. An explosion characteristics such as explosion pressure and flame velocity of non-uniform gas mixtures with concentration change similar to that of facility leak were examined. The experiments were conducted in a closed 0.82 m long stainless steel duct with observation recorded by color high speed camera and piezo pressure sensor. Also we proposed the quantification method of non-uniform mixtures from a regression analysis model on the change of concentration difference with time in explosion duct. For the non-uniform condition of this study, the area of flame surface enlarged with increasing the concentration non-uniform in the flame propagation of methane and was similar to the wrinkled flame structure existing in a turbulent flame. The time to peak pressure of methane decreased as the non-uniform increased and the explosion pressure increased with increasing the non-uniform. The ranges of K_G (Deflagration index) of methane with the concentration non-uniform were 1.30 to 1.58 [MPa·m/s] and the increase rate of K_G was 17.7% in methane with changing from uniform to non-uniform.