• Journal of computational fluids engineering
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• v.15 no.2
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• pp.47-54
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• 2010

In the present study, a numerical simulation for the diffusion of hydrogen leakage of FCV(Fuel Cell Vehicle) in a tunnel was performed to aid the assessment of risk in case of leakage accident. The temporal and spatial distributions of the hydrogen concentration around FCV are predicted from the present numerical analyses. Flammable region of 4-74% and explosive region of 18-59% hydrogen by volume was identified from the present results. Factors influencing the diffusion of the hydrogen jet were examined to evaluate the effectiveness of tunnel ventilation system for relieving the accumulation of the leaked hydrogen gas. The distribution of the concentration of the leaked hydrogen for various cases can be used as a database in various applications for the hydrogen safety.

• Proceedings of the Korea Institute of Fire Science and Engineering Conference
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• 2007.11a
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• pp.205-210
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• 2007

This study on the prevention of electric fire. Generally the electric fire is caused by break or disconnection of the power line, short circuit and poor contact, arcing fault ect. In these causes, this paper is studied on the detection of poor contact and arcing fault. The arcing fault is caused by poor contact mainly. The arcing fault can occurs a electric fire by interaction of flammable gas and materials and it can be caused of tracking and carbonization. These phenomenons is also caused of electric fire. Therefore this paper is studied on the detection of arcing fault and poor contact.

• Journal of the Korean Society of Safety
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• v.5 no.1
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• pp.41-48
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• 1990

In this study the explosion characteristics of terephtalic acid dust(PTA) was investigated with the Hartmann type apparatus. The minimum ignition energy, minimum explosible concentration, flame propagation velocity, explosion pressure, explosion pressure rise rate and the effect of inert dust(talcum) on explosion characteristics were measured. Flame velocity was 50m/s at 700g/m$^3$ concentration, and the explosion pressure and explosion pressure rise rate were most likely with that of gas explosion. It was found that an inert dust acts as a heat sinker and it disturbs the combustion of flammable dust, as a result, explosion pressure and explosion pressure rise rate were decreased and minimum explosion concentration was increased with increasing the fraction of talcum dust in PTA.

• Progress in Superconductivity and Cryogenics
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• v.7 no.2
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• pp.44-46
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• 2005

A SMES can be a perfect alternative energy storage device to the chemical batteries which are needed by most of the renewable energy supply systems. The chemical battery storage system is so expensive to maintain and causes another environmental problem because they are not recyclable. But, SMES has semi-permanent lifetime and no environmental problems cause it only need coolants which is non flammable, clean and recyclable gas. In order to verify the feasibility of a SMES for the renewable electrical power supply system, electrical characteristics of a test SMES coil with the photovoltaic power system were analyzed in this paper. Simulation results show that we can charge 40 amps of current in test SMES coil using solar power system. The experimental verification will be performed just after development of the peak power tracking system for the solar system.

• Proceedings of the SAREK Conference
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• 2005.11a
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• pp.564-569
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• 2005

Recently, from the viewpoint of global wanning, natural gas CO2 is considered as a main refrigerant for hot water system. The characteristics of CO2 is not toxic, not flammable, high pressure, and high refrigerating capacity. Also it is widely available as a byproduct of industrial processes. This paper describes the performance analysis program of the swash plate type compressor using CO2 refrigerant. Estimates of the refrigerant flow rate, compression work, discharge temperature and volumetric, compressor efficiencies of the CO2 swash plate type compressor are obtained from the various design parameter such as the inclination angle of the swash plate, discharge hole area and suction hole area.

• Journal of the Korean Society of Safety
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• v.23 no.5
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• pp.49-53
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• 2008

Glow discharge has lots of attractive properties, such as lower discharge sustaining voltage, no generation of ozone, and so on. And more, ionizer was developed recently using an atmospheric pressure glow discharge. On the other hand, ionizer needs a compressed or blown air to transport ion for charged objects. This air is very useful in explosive hazardous area to prevent the explosion of flammable gas and/or vapor by ignition sources, e.g. electrical spark. In this paper, we investigated the ionizing characteristic of atmospheric pressure glow discharge by controlled air flow rate from 5 liters to 60 liters a minute, and compared with decay time between the corona discharge and glow discharge as a function of some direction and distance from discharge ion source. We confirmed that an air flow rate needs 25 liters a minute to sustain the most suitable atmospheric pressure glow discharge and to increase an ionizing efficiency.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2019.11a
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• pp.77-78
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• 2019

Organic insulating materials can cause fatal toxic gases when burned, which can lead to human injury. As a combustible material, the risk of fire spreading is great. Therefore, there is a need for a study on the lightweight cured body for the non-combustible inorganic insulation to replace the flammable organic insulation. This study aims to examine the properties of lightweight foamed concrete according to the dilution concentration of animal foaming agent which forms a closed void when foaming as a part of the experiment to examine the utility of the lightweight foamed concrete as an insulating material. Bubbles occupy a large volume of lightweight foam concrete and have a great influence on the properties. Therefore, the stability of the bubble is very important, and as a result of the experiment, it is determined that 3% of the smallest vesicles are prepared at the proper dilution concentration.

• Journal of the Korean Institute of Gas
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• v.15 no.1
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• pp.60-67
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• 2011

The interest about new and renewable energy is increasing to reduce the burden of problems by depletion of fossil fuels and air pollutions. For example, LNG/CNG and LPG are expected to be replaced, especially in transportation use, by HCNG mixture and DME-LPG mixture, respectively. Because these new energies are still flammable gases, it is not inherently safe from the explosion. In this research, the quantitative risk analysis for using alternative mixtures in existing recharging facilities has been studied by using three types of explosion models (TNT equivalency model, PHAST and CFD-based FLACS) to manage the risk effectively. The differences of results by models were compared against, and the practical ways of when and how to use these models were suggested. It was also predicted that conventional gas filling stations would be converted as new energy stations without additional explosion risk.

• Nuclear Engineering and Technology
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• v.48 no.4
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• pp.881-892
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• 2016

Following the Fukushima accident and its extended station blackout, attention was brought to the importance of the spent fuel pools' (SFPs) behavior in case of a prolonged loss of the cooling system. Since then, many analytical works have been performed to estimate the timing of hypothetical fuel uncovery for various SFP types. Experimentally, however, little was done to investigate issues related to the formation of a flammable gas mixture, distribution, and stratification in the SFP building itself and to some extent assess the capability for the code to correctly predict it. This paper presents the main outcomes of the Experiments on Spent Fuel Pool (ESFP) project carried out under the auspices of Swissnuclear (Framework 2012-2013) in the PANDA facility at the Paul Scherrer Institut in Switzerland. It consists of an experimental investigation focused on hydrogen concentration build-up into a SFP building during a predefined scaled scenario for different venting positions. Tests follow a two-phase scenario. Initially steam is released to mimic the boiling of the pool followed by a helium/steam mixture release to simulate the deterioration of the oxidizing spent fuel. Results shows that while the SFP building would mainly be inerted by the presence of a high concentration of steam, the volume located below the level of the pool in adjacent rooms would maintain a high air content. The interface of the two-gas mixture presents the highest risk of flammability. Additionally, it was observed that the gas mixture could become stagnant leading locally to high hydrogen concentration while steam condenses. Overall, the experiments provide relevant information for the potentially hazardous gas distribution formed in the SFP building and hints on accident management and on eventual retrofitting measures to be implemented in the SFP building.

• Korean Journal of Optics and Photonics
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• v.28 no.4
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• pp.166-171
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• 2017

Hydrogen gas is a green energy sources because it features no emission of pollutants during combustion. But hydrogen gas is very dangerous, being flammable and very explosive. Hydrogen gas detection is very important for the safety of a nuclear power plant. Hydrogen gas is generated by oxidation of nuclear fuel cladding during a critical accident, and leads to serious secondary damage in the containment building. This paper discusses the development of a Raman lidar system for remote detection and measurement of hydrogen gas. A small, portable Raman lidar system was designed, and a measurement algorithm was developed to quantitatively measure hydrogen gas concentration. To verify the capability of measuring hydrogen gas with the developed Raman lidar system, experiments were carried out under daytime outdoor conditions by using a gas chamber that can adjust the hydrogen gas density. As results, our Raman lidar system is able to measure a minimum density of 0.67 vol. % hydrogen gas at a distance of 20 m.