• 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.

• International Journal of Precision Engineering and Manufacturing
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• v.9 no.4
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• pp.63-65
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• 2008

The increased interest in reducing the environmental effects caused by releasing organic compounds and aqueous waste has motivated the development of polymeric materials in supercritical fluids. Recently, supercritical fluids have been used in material synthesis and processing because of their special properties, such as high diffusivity, low viscosity, and low surface tension. Supercritical carbon dioxide is the most attractive because it is non-toxic, non-flammable, and has moderate critical temperature and critical pressure values. Supercritical carbon dioxide can also swell most polymers. In this study, we prepared polymer/clay nanocomposites using supercritical fluids. Cloisites 10A, 15A, 25A, and 30B used in this study are montmorillonites modified with a quaternary ammonium salt. The nanocomposites of polymer/clay were characterized by X-ray diffraction, thermogravimetric analysis, and differential scanning calorimetry.

• Transactions of the Korean Society of Mechanical Engineers
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• v.10 no.2
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• pp.232-240
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• 1986

Extinction characteristics of the two interacting premixed flames are analyzed for the effects of flame stretch and preferential diffusion using large activation energy asymptotic analysis by adopting counterflow system as a model problem. Results show that the flammable limit of the thermally interacting premixed flames is extended compared to the single flame, and the extinction mechanism is classified into weak and strong interactions. As the lewis number of the deficient species increases, the region of strong interaction diminishes which can explain the different characteristics of the extinction boundaries of the lean (rich) methane/air and butane/air flames. The influence of the flame stretch to the interaction boundaries is also studied.

• Proceedings of the KIEE Conference
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• 1994.07b
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• pp.1543-1546
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• 1994

Ignitabilility of explosive gas mixture by spark of dry cell in case of short circuit by accident was studied for the purpose of evaluation of intrinsically safe characteristics of dry cell that manufactured in Korea. IEC type spark test apparatus, $21{\pm}2$ Vol% of hydrogen - air mixture, and dry cell that produced in Korea was used for the experiment. The result of this research could be used for design, manufacturing, and using the intrinsically safe electrical apparatus.

• Journal of the Korean Applied Science and Technology
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• v.20 no.2
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• pp.110-117
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• 2003

Pyrophosphoric modified polyesters (TATBs) were synthesized by polycondensation of adipic acid, trimethylolpropane, 1,4-butanediol, and tetramethylene bis(orthophosphate). Two-component PU flame-retardant coatings (TATBCs) were prepared by blending TATBs with HDI-Biuret. Most of the physical properties of the flame-retardant coatings were comparable to those of non-flame-retardant coatings. Coatings containing 10 and 15wt% 1,4-butanediol, TATBC-10C and TATBC-15C were not flammable in the vertical flame-retardancy test.

• Carbon letters
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• v.16 no.1
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• pp.11-18
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• 2015

The process of oxidizing polyacrylonitrile (PAN)-based carbon fibers converts them into an infusible and non-flammable state prior to carbonization. This represents one of the most important stages in determining the mechanical properties of the final carbon fibers, but the most commonly used methods, such as thermal treatment ($200^{\circ}C$ to $300^{\circ}C$), tend to waste a great deal of process time, money, and energy. There is therefore a need to develop more advanced oxidation methods for PAN precursor fibers. In this review, we assess the viability of electron beam, gamma-ray, ultra-violet, and plasma treatments with a view to advancing these areas of research and their industrial application.

• Journal of the Korean Society of Safety
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• v.14 no.1
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• pp.93-100
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• 1999

By using literature data, the empirical equations have been derived which describe the interrelationships of explosion and other related properties of n-alcohols. The properties which have been correlated data are : lower and upper explosive limits, heats of combustion, carbon numbers. Also, the new equation for predicting the temperature dependence of lower explosive limits(LEL) of n-alcohols on the basis of explosive limits, heats of combustion, flame propagation theory and mathematical method is proposed. The values calculated by the proposed equations were a good agreement with literature data within a few percent. From a given explosive properties. by using the proposed equations, it is possible to predict the other properties. It is hoped eventually that this method will permit the estimation of the explosive properties of alcohol with improved accuracy and the broader application for other compounds.

• Journal of the Korean Society of Safety
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• v.7 no.3
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• pp.35-42
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• 1992

Ignition energy effects of concentration of mixed gas In closed cylindrical vessel(1, 832㎤) are studied. The ignition energy ranged from 25 Joule to 110 Joule, and hidrogen and methane gases were used for flammable gas at stoichiometric condition with oxygen gas and nitrogen gas (N2) was for inert gas, which concentration was maximum 60% . The explosion pressure, temperature, concentration of product gases were calculated. It is found that - The explosion pressure and explosion velocity increase with ignition energy. - The gradience of explosion velocity with ignition energy is steeper than explosion pressure. - The results of calculation are similiar with results of experiment. - NOx is not serious product gas for methane and hydrogen gas, but CO is serious at certain concentration for methane in asphyxiation.

• Journal of the Korean Institute of Gas
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• v.11 no.4
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• pp.7-11
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• 2007

There has been a report of fire and explosion accident in regenerated thermal oxidizer (RTO). This paper was to investigate accident causes of RTO in the resin re-treatment process. The experiments carried out physicochemical properties and thermal stability analyses by using flash point tester, flammable range apparatus, autoignition tester, GC/MSD and thermal screening unit. We inferred causes of fire and explosion from the regenerated thermal oxidizer to prevent an accident of its process.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.13 no.10
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• pp.865-870
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• 2000

In this paper, catalytic combustible gas sensor was fabricated and tested under flammable gases such as CH$_4$and $C_4$H$_{10}$by using Pt coil as a heater and/or temperature sensing element. Fine $Al_2$O$_3$powder was used for a bead and Pt, Pd noble metal powder for a catalyst. Resistance variation of Pt wire was traced by the changes of the gas concentrations in a chamber. Output voltage was then monitored to obtain the gas concentration from the resistance variation. In this experiment, MgO was used to protect cracks in the based and TiO$_2$to increase the sensitivity of the sensors. Water glass was also added to enhance the selectivity to the combustible gases.s.