• Journal of the Korean Society of Safety
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• v.20 no.3 s.71
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• pp.42-46
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• 2005

The static electricity by thinner flow and discharge energy is investigated experimentally for the purpose of preventing the electrostatic discharge and damage. Test system for evaluating streaming electrification consists of a teflon pipe, a reservoir tank a pump, flowmeters and an electrometer. When dielectric liquid flows through a pipe from one vessel to another, the potential difference generated in the collecting vessel is due to the accumulation of charges. These charges result from the convection of a part of the electrical double layer existing in the tube at the contact between the liquid and the inner wall. When the fluid velocity increases, the electric current increases proportionally. The charging current and accumulated charges by streaming electrification at the thinner velocity of 40cm/s are measured a range of 5 nA and $0.27{\mu}C$ respectively. This amount of static discharge energy generated by streaming electrification is enough to ignite flammable solvent. Therefore surface electric potential should decrease by using electrostatic shielding and ground.

• Journal of the Korean Society of Safety
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• v.18 no.3
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• pp.54-59
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• 2003

The discharge energy by electrostatic discharge of the charged human body is calculated under the assumption that the stored charge is dissipated completely. However, it is well-known that the charge is slightly remained after electrostatic discharge. Therefore, The Rompe-Weisel model of the discharge analysis, which has somewhat more of a physical justification than the conventional energy equation, is proposed. It is proposed that the electrical conductivity of the arc should be proportional to the energy density transferred to it by Ohmic dissipation. For the electrostatic discharge energy analysis, the Rompe-Weisel model was compared by quasi static analysis. As a consequence, a study on a reliable energy evaluation based on simulation models during electrostatic discharge is carried out in this paper and is adopted to estimate the explosion hazards of flammable gases.

• 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.

• Journal of the Korean Society of Safety
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• v.23 no.5
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• pp.67-72
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• 2008

The lower flash points for the flammable binary systems, 2-propanol+formic acid and 2-propanol+n-butyric acid, were measured by Cleveland open cup tester. The optimization method using van Laar equation and the Raoult's law were used to estimate the lower flash points and were compared with experimentally-derived data. The calculated values based on the optimization method were found to be better than those based on the Raoult's law.

• Proceedings of the Korea Institute of Fire Science and Engineering Conference
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• 1997.11a
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• pp.162-168
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• 1997

A theoretical model for the interaction of the moving heat source and a solid substrate when they are in contact is described. for purposes of the model the substrate is assumed to act as a continuum and the Fourier equation for transient. three-dimensional conduction is solved using Laplace and Fourier transformations. Unlike most previous models, this model shows the explicit relations between the properties of heat source and that of the substrate. Since the size, shape and speed of heat source impact the ignition of substrate, considerable attention is devoted to evaluating these parameters. Results are presented which show the effects of the size, shape and speed of heat source on the substrate.

• Fire Science and Engineering
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• v.26 no.4
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• pp.63-69
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• 2012

Explosion limit is one of the major combustion properties used to determine the fire and explosion hazards of the flammable substances. In this study, the lower explosion limit (LEL) and upper explosion limit (UEL) of organic halogenated hydrocarbons were predicted by using the heat of combustion and chemical stoichiometric coefficients. The calculated explosion limits by the proposed equations agreed with literature data within a few percent. From the given results, using the proposed methodology, it is possible to predict the explosion limits of the other organic halogenated hydrocarbons.

• Fire Science and Engineering
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• v.23 no.6
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• pp.98-110
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• 2009

The burned patterns of fire are changed very diversely according to the direction of wind, conditions of combustibles, shape of buildings and so on in the fire scenes. And careful attentions are required on the determining of ignition point and fire causes. In this study, we examined that the burned pattern of fuel controlled fires and ventilation controled fires that impose a heavy burden on fire investigators, carbonized marks of floor, formed by flammable liquids, and combustion marks of falling firing materials through the fire cases. We suggest a proper fire investigation method.

• Proceedings of the Korea Institute of Fire Science and Engineering Conference
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• 2009.04a
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• pp.276-285
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• 2009

화학물질의 분류 및 표시의 국제표준화시스템(GHS)을 조기에 구축하고 국내에 사용하는 화학물질을 보다 안전하게 제조, 저장 및 운송하기 위하여 위험물안전관리법과 GHS시험 방법으로 다양한 인화성액체 시험을 실시하여 이들의 결과에 대한 연관성을 도출하고, 국내 실정에 적합한 국제표준화 시험방법을 선택가능방식(Building Block Approach)으로 제시하고자 한다. 위험물의 80%를 차지하는 인화성액체의 분류에 필요한 시험은 인화점이 가장 중요한 요소지만, 도료류와 같은 혼합물은 가연성액체량과 GHS-연소지속성에 따라 위험물/비위험물로 분류될 수 있다. 도료류는 두 시험의 분류결과가 대부분 비슷하게 나타나 GHS-연소지속성시험을 선택가능방식을 통해 우리나라에 적합하게 도입하는 것이 바람직 할 것으로 보인다.

• 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 Powder Materials
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• v.26 no.1
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• pp.28-33
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• 2019

The gas sensor is essential to monitoring dangerous gases in our environment. Metal oxide (MO) gas sensors are primarily utilized for flammable, toxic and organic gases and $O_3$ because of their high sensitivity, high response and high stability. Tungsten oxides ($WO_3$) have versatile applications, particularly for gas sensor applications because of the wide bandgap and stability of $WO_3$. Nanosize $WO_3$ are synthesized using the hydrothermal method. As-prepared $WO_3$ nanopowders are in the form of nanorods and nanorulers. The crystal structure is hexagonal tungsten bronze ($MxWO_3$, x =< 0.33), characterized as a tunnel structure that accommodates alkali ions and the phase stabilizer. A gas detection test reveals that $WO_3$ can detect acetone, butanol, ethanol, and gasoline. This is the first study to report this capability of $WO_3$.