• Solar Energy
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• v.15 no.3
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• pp.29-38
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• 1995

The heat-storage characteristics accompanied by exothermic reaction at the regeneration of $Ca(OH)_2$ in tile heat-storage mode of a chemical heat pump system using a $Ca(OH)_2/CaO$ reversible thermochemical reaction was examined in a lab-scale unit. In this heat-storage mode, the particle bed of CaO could be regenerated by heating the $Ca(OH)_2$ packed bed to the higher temperature at which the equilibrium pressure in the reactor is greater than the water vapor pressure in the condenser. The results are i) the dehydration, thermal decomposition, rate of $Ca(OH)_2$ was higher at the lower part of particle bed than at the upper part, ii) in the reactor, the dehydration was proceeded along radial and axial direction, from inner part to the outer part, which explains heat transfers from the center to wall and from the tenter to lower or upper part of reactor.

• Korean Chemical Engineering Research
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• v.57 no.2
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• pp.219-224
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• 2019

In this study, the adsorption characteristics of cephalomannine on commercial adsorbent Sylopute were investigated using different parameters such as adsorption temperature, time, and initial cephalomannine concentration for the efficient separation of Taxus chinensis-derived cephalomannine by adsorption process. The Temkin isotherm model showed good fit to the equilibrium adsorption data. The adsorption capacity decreased with increasing temperature and the adsorption of cephalomannine onto Sylopute was physical in nature. Adsorption kinetic data fitted well with pseudo-second-order kinetic mode. According to the intraparticle diffusion model, film diffusion and intraparticle diffusion did not play a key role in the entire adsorption process. The process of cephalomannine adsorption onto Sylopute was exothermic and spontaneous. In addition, the isosteric heat of adsorption was constant even with variation in surface loading indicating homogeneous surface coverage.

• Journal of the Korean Institute of Gas
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• v.27 no.3
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• pp.134-140
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• 2023

Activated carbon is a carbonaceous material mainly used as a gaseous or liquid adsorbent. As fire-related accidents occur consistently due to the accumulation of heat of adsorption and oxidation of volatile organic compounds, the explosive characteristics and thermal stability of powdered and granular activated carbon made from coal and coconut shells were evaluated. As a result of the particle size analysis, the powdered activated carbon was in the particle size range (0.4~3) ㎛, and thermal properties such as exothermic onset temperature and decomposition behavior were analyzed using a differential scanning calorimetry and a thermogravimetric analysis. As a result of the evaluation of the explosion hazards for dust, both coal-based and coconut-based powdered activated carbon are classified as St1 class with weak explosion, but this is a relative and does not mean that the explosion hazards is absolutely low. Therefore, it is necessary to establish countermeasures for reducing the damage.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.34 no.4
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• pp.375-381
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• 2010

In this paper, the heat-transfer characteristics of steam reforming in an annular reactor are presented. Heat is supplied by the catalytic combustion of syn-gas. The thermal behaviors of exothermic and endothermic reactions in a directly coupled concentric-tube packed-bed reactor were investigated experimentally. The gas mixture supplied for catalytic combustion consisted of the off-gas emitted from MCFC anode. Methane in steam at a suitable S/C (steam-to-carbon) ratio was used in the reforming reactions. On the basis of the experimental results, a simple simulation was performed to predict the temperature profile required in the reforming side of the reactor to achieve optimum hydrogen yield. The results of this study may be utilized as reference data in future studies for further development of coupled reactors.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.8 no.3
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• pp.435-441
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• 1998

Li-SGICs as a anode of lithium ion battery were synthesized by high-pressure method as a function of the Li-contents. The characteristics of these prepared compounds were determined from the studies with X-ray diffraction method and differential scanning calorimeter (DSC) analysis. From the results of X-ray diffraction, it was found that the lower stage intercalation compounds were formed with increase of Li-contents. The mixed stages in these compounds were also observed. In the case of the $Li_{30;wt%}$-SGIC, the compounds in the stage 1 structure were formed predominantly, but the structure of only pure stage 1, due to the structural defect of synthetic graphite, was not observed. The enthalpy and entropy changes of the compounds could be obtained from the differential scanning calorimetric analysis results. From the results, it was found that exothermic and endothermic reactions of Li-SGICs are related to thermal stability of lithium between artificial graphite layers.

• Transactions of the Korean hydrogen and new energy society
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• v.13 no.1
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• pp.90-99
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• 2002

In order to utilize hydrogen energy in a large-scale in the future, development of effective hydrogen storage method is essentially required as well as that of efficient hydrogen production method. The hydrogen storage method using metal hydrides has been holding the spotlight as a safer and higher-density hydrogen storage method than conventional hydrogen storage methods such as liquid hydrogen or compressed hydrogen storage method. However when metals react with hydrogen to store hydrogen as metal hydrides, they undergo exothermic reactions, while metal hydrides evolve hydrogen by endothermic reaction. Therefore, hydrogen storage tank should have such structure that it can absorb or release reaction heat rapidly and efficiently. In this study, a review on the improvement of the heat release and absorption structure in the hydrogen storage tank was conducted, and as a result, a new type of hydrogen storage tank with the structure of vertical-type wall was designed and manufactured. Experimental results showed that this new type of tank could be used as an efficient hydrogen storage tank because its structure is simpler and manufacture is easier than cup-type hydrogen storage tank with the structure of packed horizontal cup.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.9 no.6
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• pp.604-608
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• 2016

In recent years, research and development has been carried out in order to increase the economical efficiency and stability in terms of efficient use of energy for the heating apparatus. Especially, technology development for high performance and new functional materials is actively being carried out. This paper focuses on the development of exothermic products with excellent energy transfer characteristics. The heating element used for bedding or mattress uses a heating wire. Since the heating wire is thin, the distribution of heat is concentrated only around the heating wire,. In addition, electromagnetic induction is harmful to the human body and energy consumption is high. Therefore, it is aimed to develop a planar heating panel using SiC ceramics which can radiate far-infrared rays and anions to be harmless to the human body, but also has excellent heat conduction to enhance energy efficiency.

• Journal of the Korean Institute of Gas
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• v.24 no.3
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• pp.40-46
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• 2020

Tertbutylperoxymaleate is the one of the organic peroxides used as a raw material of initiator formulations of artificial marble manufacturing. In this study, the thermal decomposition characteristic of TBPM was evaluated using the differential scanning calorimeter in the air and nitrogen circumstance. Regardless of the reaction atmosphere, TBPM showed the exothermic peak due to the drastic decomposition reaction below 130 ℃. The activation energy estimated by dynamic methods had a range of 203~217 kJ/mol and that estimated by model-free analysis method had a range of 118~232 kJ/mol with a thermal conversion. And the ADT₂₄, the temperature that lead to the maximum heating rate within 24 hours, was evaluated as (80~95) ℃ using the estimated activation energy.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.20 no.8
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• pp.71-79
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• 2006

For clearing the cause of firing due to the tacking on the surface of phenolic resin, this paper describes the analysis through a couple of methods ; FT-IR; DTA; photograph analysis, etc. Phenolic resin has been widely employed as a case of low voltage appliances. In the experiment it was confirmed that its surface was carbonized and graphitized by the external fire. In the FT-IR test a graphite specimen thermally treated at $150[^{\circ}C]$ showed the 2 different IR absorption peaks at $1,730[cm^{-1}]\;and\;1,680[cm^{-1}]$. In normal phenolic resin, the exothermic peak appeared at $450[^{\circ}C]$, while in graphite specimen, it appeared at $610[^{\circ}C]$ in DTA test. From the results, the electrical fire causes could be cleared and it is expected to protect the human life and property from the electrical fire by using the important data.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.22 no.1
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• pp.51-56
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• 2012

In the present study, we investigated the effect of mechanical alloying (MA) on the formation of amorphous VCo system through solid state reaction during ball milling. Two types of powder samples, ${\sigma}$-VCo intermetallic compound and $V_{50}Co_{50}$ powder mixture, were applied as a starting materials. With increasing milling time, a structural characteristics into the amorphous state is distinctly observed from the structural factor and radial distribution by X-ray diffraction. Amorphization has been observed in all two types of samples after the milling for 120 hrs. DSC spectrum of $V_{50}Co_{50}$ powder sample milled for 60 hrs indicates a sharp exothermic peak from the crystallization at $600^{\circ}C$. The structure factor, S(Q) and radial distribution function, RDF(r), observed by X-ray diffraction gradually change into a structure characteristic of an amorphous state with increasing MA time.