• Proceedings of the Korea Society for Energy Engineering kosee Conference
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• 1995.05a
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• pp.230-235
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• 1995

염-암모니아계 화학열펌프기술의 핵심인 전도성 블록의 특성파악을 위한 기초단계 연구로서 전도성 블록의 제조 및 기초물성분석에 관한 연구를 수행하였다. 황산이 함유된 천연흑연을 열처리하여 팽창흑연을 준비하고 특성을 분석하였다. 이 팽창흑연을 압축, 성형하여 흑연지지체를 제조하였으며, 성형된 지지체에 진공기법을 이용하여 염을 함침하고 건조과정을 거쳐 전도성 블록을 제조하였다. 전도성 블록의 특성분석으로서 염의 입자내에 분산정도는 EPMA/EDS, 기공율 및 기공크기 분포는 헬륨침투법과 수은 침투법, 기체투과도는 Darcy's law를 적용하고, 열전도도 측정은 전이 일차원 열류기법을 이용하였다. 전도성 블록이 암모니아와 반응 했을때 부피팽창을 관찰하였으며, 반응기에서 전도성블록의 온도분포를 관찰하였다. 본 연구에서 제조된 블록은 염이 균일하게 분산되어 있었으며 기공율은 제조조건에 따라 0.4 ∼ 0.83, 기체투과도는 0.01 ∼ 10 Darcy, 열전도도는 흑연지지체의 겉보기 밀도가 110 kg/㎥ 인 경우, 반지름방향의 열전도도, λr은 20 W/mK, 축방향의 열전도도, λa는 17 W/mK 이였다. 겉보기밀도가 150 kg/㎥ 인 경우, λr은 22 W/wK, λa는 20 W/wK 이였다. 전도성 블록의 부피팽창은 비가역적이었으며 대부분이 반지름 방향보다 축방향에서 팽창이 일어났다. 온도분포는 초기 반응의 kinetics가 내부온도를 지배하였으나, 시간이 경과후 반응기 내부온도는 외부열전달에 의해 지배되었다.

• Applied Chemistry for Engineering
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• v.18 no.4
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• pp.361-365
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• 2007

The precipitation reaction of some rare earth chlorides ($Ce/Nd/GdCl_3$) in a LiCl-KCl molten salt has been carried out by reaction with oxygen. Identification of rare earth precipitates by reaction with oxygen and effects of oxygen sparging time (max. 420 min) and molten salt temperature ($450{\sim}750^{\circ}C$) on conversion were investigated. In this study, regardless of the oxygen sparging time and the molten salt temperature, oxychlorides (REOCl) for $NdCl_3$ and $GdCl_3$, and an oxide ($REO_2$) for $CeCl_3$ are formed as a precipitate, which are identical with the estimation results of Gibbs free energy of reaction (${\Delta}G_r$). The conversion of rare-earth chlorides into insoluble precipitates was described by using a conversion ratio. The conversion ratio increased exponentially with the oxygen sparging time and finally showed asymptotic value, over 0.999 at $750^{\circ}C$ of the molten salt temperature and over 300 min of sparging time conditions. The conversion ratios were increased with the molten salt temperature. In case of $CeCl_3$, when the sparging time exceed 60 min, the values of the conversion ratio were nearly constant over 0.999 in all experimental temperature conditions.

• 한국연소학회:학술대회논문집
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• 1999.10a
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• pp.1-9
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• 1999

The NOx production and combustion characteristics are experimentally compared with an offset with counter-orifice configuration. The offset-opposed impinging flame creates stronger vortex around the stagnation point than the opposed flame. The thermal and mass mixtures be improved and the delay of turbulence dissipation be occurred by the strong vortex. In result, the turbulent flame structure transferred from the wrinkled flame and the corrugated flame to the distributed reaction flame. It was found that the offset-opposed impinging flame decreased more NOx and improved the combustion efficiency than the opposed flame. The principal objective of this study is to develop the low NOx combustor by distributed reaction flame.

• Korean Chemical Engineering Research
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• v.47 no.4
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• pp.465-469
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• 2009

Characteristics of oxidation reaction of four lanthanide chlorides(Ce, Nd, Pr and $EuCl_3$) in a oxygen-eutectic(LiCl-KCl) salt bubble column was investigated. From the results obtained from the thermochemical calculations by HSC chemistry software, the most stable lanthanide compounds in the oxygen-used rare earth chlorides system were oxychlorides(EuOCl, NdOCl, PrOCl) and oxides($CeO_2$, $PrO_2$), which coincide well with results of the Gibbs free energy of the reaction. In this study, similar to the thermochemical results, regardless of the sparging time and molten salt temperature, oxychlorides for Eu, Nd and Pr and oxides for Ce and Pr were formed as a precipitant by a reaction with oxygen. The structure of the rare earth precipitates was divided into two shapes : small cubic(oxide) and large tetragonal (oxychloride) structures. The conversion efficiencies of the lanthanide elements to their molten salt-insoluble precipitates(or compound) were increased with the sparging time and temperature, and Ce showed the best reactivity. In the conditions of $650^{\circ}C$ of the molten salt temperature and 420 min of the sparging time, the conversion efficiencies were over 99% for all the investigated lanthanide chlorides.

• Applied Chemistry for Engineering
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• v.20 no.4
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• pp.381-385
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• 2009

A basic objective is the preparation and surface studies of supported molten salt catalysts because molten salts can stay as the liquid phase in the range of the ordinary reaction temperature. Many kinds of metal salt mixtures for the formation of molten salt phase are appliable but CuCl and KCl were selected in this study because Cu is considered catalytically reactive in many reactons. The loading of the molten salt was selected as 25 vol% of the total pore volume of ${\gamma}-alumina$ to provide reasonable exposed surface area. The surface structure of catalysts containing molten salts in the ${\gamma}-alumina$ was studied using scanning electron microscopy (SEM) and energy-dispersive spectroscopy (EDS). CuCl and KCl were added into the ${\gamma}-alumina$ using concentrated hydrochloric acid solution by the impregnation technique. The surfaces of the prepared catalysts before and after heat treatments were compared and they suggested that the heat treatment of catalysts helped the formation of molten-salt although the surface compositions of CuCl and KCl were not uniform.

• Economic and Environmental Geology
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• v.34 no.2
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• pp.175-192
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• 2001

We have collected hydrogeochemical data of shallow groundwaters in the Uljin area located at eastern coastal area of Korea. Geostatistical analysis (ANOVA test, cluster analysis, and factor analysis) of the collected data sets was pert'onned, in order to evaluate both the spatial and/or temporal variation of water quality data and the groundwater contamination, as weJl as the principal reactions occurring in the aquifer. Results of the ANOVA test show that regional water chemistry are not significantly changed spatially in eight watersheds. However, some ions such as $Ca^{2+}$, $HCO_{3}^{-}$ and $SO_{4}^{2-}$ show a meaningful watershed variation. Water chemistry variation according to sampling time (season) is not shown, except for $SO_{4}^{2-}$. The cluster analysis shows that significant water chemistry variation is eXplained by the distance from the coast. Factor analysis indicates that the water chemistry is changed according to various factors as follows: in the order of decreasing importance, water-rock interaction (mainly, carbonate dissolution), sea-salt spraying, and then contamination by fertilizers and agrochemicals.

• Applied Chemistry for Engineering
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• v.10 no.5
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• pp.754-760
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• 1999

The properties of the catalyst for a direct internal reforming type molten carbonate fuel cell were examined by ICP, BET, CHN, EDS, and $H_2$ chemisorption. Potassium and lithium, the components of carbonate electrolyte, were transported to the catalyst during the operation of fuel cell, and the amounts of the deposited alkali elements were reduced in the order of inlet, outlet, and the middle. From the direct correlation between the amount of alkali and the physical properties such as BET surface area and Ni dispersion, and from the observation of the lump of the alkali species on the poisoned catalyst, it was confirmed that the physical blocking of the catalyst by alkali deposition was the main reason for the deactivation. Although the amount of alkali species was greater at the inlet than at the oulet, the catalyst sampled from the outlet had lower activity. This was caused by the chemical interaction between the alkali species and the catalyst at the outlet where temperature was highest in the cell body, which was detected by FT-IR analyses.

• 한국신재생에너지학회:학술대회논문집
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• 2009.11a
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• pp.133-133
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• 2009

연료전지는 연료의 화학적 에너지를 전기화학 반응을 통하여 직접 전기로 변환하기 때문에 에너지 전환효율이 높고 공해물질을 배출하지 않는 환경친화적인 고효율 발전방식으로, 특히 용융탄산염 연료전지(MCFC) 및 고체산화물 연료전지(SOFC)같은 고온형 연료전지의 경우 분산전원이나 중앙집중발전 같은 발전용에 적합한 연료전지로 평가받고 있다. 현재 MCFC 및 SOFC등의 발전용 연료전지 시스템의 효율은 약 50% 정도이며, 시스템의 발전효율을 높이기 위한 여러 연구가 진행되고 있다. 그 중에서 고온의 배열을 이용하여 연료전지 발전시스템의 효율을 향상시키기 위해 FuelCell Energy, Ansaldo Fuel Cells 및 Simens Westinghouse 등에서 수백 kW급의 fuel cell - gas turbine hybrid system에 대한 상용화 수준의 실증연구가 진행되었다. 본 연구에서는 발전용 연료전지 시스템의 발전효율을 높이기 위한 방안 중 하나로 배열을 이용하여 steam을 발생시켜 air amplifier에 사용함으로써 연료전지 시스템의 MBOP(Mechanical Balance of Plant)중 전력을 소비하는 air blower를 대체하여, 시스템 효율을 향상시키고 시스템의 가용성을 높일 수 있는 설계안에 대하여 논하고자 한다.

• Applied Chemistry for Engineering
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• v.10 no.4
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• pp.581-585
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• 1999

The surface treated hydroxypropyl methylcellulose(HPMC) which could adjust the soluble time was synthesized when 40 wt % glyoxal solution and $KH_2PO_4$ were sprayed and reacted. And also, the solution dynamic at different ratios of two adding agents were identified If the surface of HPMC was treated with only glyoxal, the dispersion characteristics at different ratios of two adding agents were identified If the surface of HPMC was treated with only glyoxal, the dispersion was observed in the neutral solution and the viscosity was increased after directly dissolved as the solution become alkali condition. But the fine-powder type of HPMC which reacted with glyoxal and $KH_2PO_4$ was dispersed regardless of pH of solution and observed that it was dissolved and its viscosity increased after elapsing some time. With increasing amount of glyoxal and $KH_2PO_4$, the soluble time was delayed. The reaction condition was about 60 min at $75{\sim}85^{\circ}C$. Especially, the removal process of organic solvent after reaction was not required due to reaction under water solution without organic during glyoxal and $KH_2PO_4$ treatment. And also, the HPMC which could adjust the soluble rate in water or organic solvent by changing the degree of substitution of HPMC was synthesized.

• Applied Chemistry for Engineering
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• v.10 no.4
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• pp.615-619
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• 1999

Polyether-clay nanocomposite was not polymerized with stearyltrimethylammonium ion exchanged montmorillonite, but it was self-polymerizable when heated with both stearyltrimethylammpmoim and m-phenylenediammonium ions intercalated montmorillonite to form polyether-clay nanocomposites. Molcular disperion of montmorillonite within the crosslinked epoxy matrix verified using X-ray diffraction and transmission electron microscopy found that the final product contains a uniform dispersion of exfoliated $10{\AA}$ thin clay layers seperated by $250{\sim}500{\AA}$of polyether polymer, thus verifying the nanocomposite structure.