• 한국신재생에너지학회:학술대회논문집
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• 2009.06a
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• pp.315-318
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• 2009

Hydrogen is the ideal candidate as an alternative energy carrier, so many hydrogen storage methods are investigated. The hydrogen storage method using metal hydride is good candidate as energy sources for portable devices because hydrogen-storage as metal hydride shows large volumetric storage density. In this study, we investigated the variations of hydrogen charging/discharging performance of metal hydride tanks at different temperature conditions. We charged metal hydride tanks with hydrogen in low temperature because of the exothermic reactions of hydrogen absorption while we discharged in high temperature to provide sufficient heat because of the endothermic reactions of desorption. In addition, we investigated the difference of hydrogen charging/discharging performance between two tanks having different sizes.

• 한국신재생에너지학회:학술대회논문집
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• 2007.06a
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• pp.5-8
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• 2007

In this paper, numerical investigation has been carried out to study performance of methane autothermal reformer and dynamic behavior for light-off under various operating conditions. In order to simulate the given problems, numerical methods are incorporated using finite-volume method. In addition, porous medium approach is accepted because the catalytic phenomena occur in porous media. Also, start-up issue is significant in autothermal reformer although the reaction is marginally exothermic. Thus, in this study transient behavior has been also investigated to find out optimal operating conditions for start-up.

• Journal of Powder Materials
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• v.10 no.5
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• pp.310-317
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• 2003

Two-component ceramic (alumina-zirconia) composites were fabricated by a soft-solution process in which polyethylene glycol (PEG) was used as a polymeric carrier. Metal salts and PEG were dissolved in ethyl alcohol without any precipitation in 1:1 volume ratio of alumina and zirconia. In the non-aqueous system, the flammable solvent made explosive, exothermic reaction during drying process. The reaction resulted in formation of volume expanded, porous precursor powders by a vigorous decomposition of organic components in the precursor sol. The PEG content affected the grain size of sintered composites as well as the morphology of precursor powders. The difference of microstructure in sintered composite was attribute to the solubility and homogeneity of metal cations in precursor sol. At the optimum amount of the PEG polymer, the metal ions were dispersed effectively in solution and a homogeneous polymeric network was formed. It made less agglomerated particles in the precursor sol and affected on uniform grain size in sintered composite.

• Proceedings of the KIEE Conference
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• 2007.11c
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• pp.138-140
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• 2007

$TiO_2-V_2O_5$ sol was fabricated using sol-gel method and $TiO_2-V_2O_5$ thin films were fabricated using dip-coating method. $V_2O_5$ sol was added 0.01mo1e, 0.03mo1e, 0.05mo1e into $TiO_2$ sol. Viscosity of sol increased fast from about 1,000 minutes and sol began gelation from about 10,000 minutes. As a results of crystalline properties, $V_2O_5$ peaks were not found despite of $V_2O_5$ addition. Endothermic reaction occurred due to evaporation of solvent and dissociation of OH at $80^{\circ}C$. Exothermic reaction occurred due to combustion and oxidation of solvent at $230^{\circ}C$, occurred to combustion and oxidation of alkyl group at $350^{\circ}C$. Thickness of thin films increased $0.1{\sim}0.25{\mu}m$ every a dipping.

• Journal of the Korean Society of Safety
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• v.13 no.4
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• pp.180-185
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• 1998

The evaluation of thermal and pressure hazard of chemicals on the manufacturing, transporting and storaging is important in the chemical industry for safety. In this study, the thermal decomposition characteristics of intermediate of Saccharin were investigated by using Accelerating Rate Calorimeter(ARC) and Differential Scanning Calorimeter(DSC). Experimental results showed that decomposition temperatures in p-TSA were about 280~$318^{\circ}C$ by DSC and $201^{\circ}C$ by ARC. In case of o-TSA were about $336^{\circ}C$~$360.8^{\circ}C$ by DSC and $299^{\circ}C$ by ARC. The decomposition temperature acquired by ARC was about $70^{\circ}C$ lower than that by DSC. The exothermic runaway reaction in case of p-TSA occured in 598 minute and o-TSA in 5 minute. For the safety in the chemical industry, we should consider the ARC data as well as DSC data in the handling and design of process.

• 한국연소학회:학술대회논문집
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• 2000.05a
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• pp.85-92
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• 2000

End-gas temperatures were measured using CARS technique in a conventional DOHC spark-ignition engine fueled with PRF80. The measured pressure data were analyzed using band pass filter method. The measured CARS temperatures were compared with adiabatic core temperatures calculated from measured pressure. Significant heating by pre-flame reaction in the end gas was observed in the late part of compression stroke under both knocking and non-knocking condition. CARS temperatures measured at 10 crank angle degree before knock occurrence was higher than adiabatic core temperatures. These results indicate that there exist some exothermic reactions in low pressure and temperature region. CARS temperatures began to be higher than the adiabatic core temperature when the end-gas temperatures reached 700 K. The temperature elevation due to the pre-flame reaction correlated better with CARS temperature than with cylinder pressure.

• 한국연소학회:학술대회논문집
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• 1999.10a
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• pp.47-54
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• 1999

A method is developed to include the effect of volume expansion in the description of the flame dynamics using G-equation. Line volume-source is used to represent the effect of the exothermic process of combustion with source strength assigned by the density difference between the burned and the unburned region. The present model provides good agreement with the experimental results by using realistic volume expansion ratio which was not reached in the previous researches. Including volume expansion, the flow predicts the same behavior of measured velocity field qualitatively. The flame propagation in varying flow field due to volume expansion provides a promising way to represent the wrinkled turbulent premixed flames in a numerically efficient manner.

• 한국연소학회:학술대회논문집
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• 2005.10a
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• pp.20-27
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• 2005

I consider the structure of steady wave system which is admitted by the continuum equations for materials that undergo phase transformations with exothermic chemical reaction. In particular, the dynamic phase front structures between liquid and gas phases, and solid and liquid phases are computationally investigated. Based on the one-dimensional continuum shock structure analysis, the present approach can estimate the nano-width of waves that are present in combustion. For illustration purpose, n-heptane is used in the evaporation and condensation analysis and HMX is used in the melting and freezing analysis of energetic materials of interest. On-going effort includes extension of this idea to include broad range of liquid and solid fuels, such as rocket propellants.

• Bulletin of the Korean Mathematical Society
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• v.20 no.2
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• pp.99-103
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• 1983

Internal heat generation is one of the insidious conditions affecting the quality of an industrial product after it is cast, coated, molded, forged or laminated. Frequently, the product is pressed into service before the exothermic chemical reactions in the generic material has been completed. The heat liberated from this continuing chemical reaction or the residual deformation from the rheological activities in the materials must be adequately removed or prevented, or the product may be discolored, warped, weakened or even "ignited" spontaneously. Numerous instances of premature structural failures, product-recalls, and/or system-malfunctions have been recorded in recent history. The Coulee Dam was poured with pre-chilled concrete just to negate this freakish encore. It is well-known that concrete (a non-isotropic conducting medium), for instance, takes 28 days to develop its full strength. During this period of curing it is conceivable that the processes of internal heat generation, heat conduction and heat dissipation take place simultaneously inside the medium.he medium.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.07b
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• pp.545-548
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• 2002

$(Ba_{0.6-x}Sr_{0.4}Ca_x)TiO_3$(BSCT) (x=0.10, 0.15, 0.20) powders were prepared by the sol-gel method and BSCT thick films were fabricated by the screen-printing method. The structural properties as a faction of the composition ratio were studied. As a result of the differential thermal analysis (DTA), exothermic perk was observed at around $860^{\circ}C$ dne to the formation of the polycrystalline perovskite phase. The BSCT thick films sintered at $1350^{\circ}C$ for 2h showed the average grain size of $2{\sim}7{\mu}m$. The average thickness of BSCT thick films, obtained by 3 times of screen-printing, was approximately $85{\mu}m$.