• Korean Chemical Engineering Research
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• v.49 no.6
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• pp.781-785
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• 2011

In this work, a nano-sized samaria-doped ceria(SDC) was prepared by a urea-based hydrothermal method and characterized by XRD, FESEM and TEM. It was observed that the increase in synthesis time and temperature gave rise to crystallity and particles size. Moreover, the synthesised powders had a excellent ion-conductivity(0.1 S/cm at 600~$800^{\circ}C$) which is suitable for electrolyte of intermediate temperature-solid oxide fuel cell(IT-SOFC). Subsequently for use as electrolyte for anode-supported IT-SOFC, we tried to deposit the SDC powder on a porous NiO-SDC substrate by electrophoretic deposition(EPD) method. From the FESEM observation, a compact

• Korean Chemical Engineering Research
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• v.48 no.2
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• pp.275-282
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• 2010

A characteristic study of aqueous chlorine dioxide generation from sodium chlorite($NaClO_2$) by an undivided electrochemical cell with different anode materials were performed. $IrO_2$-coated Ti, $RuO_2$-coated Ti and DSA were used as anode materials and Pt-coated Ti electrode was used as cathode. Various electrochemical cell operating parameters such as cell residence time($t_R$), initial feed solution pH, sodium chlorite and sodium chloride(NaCl) concentration and applied current for the generation of chlorine dioxide in an un-divided cell were investigated and optimized. Estimated optimal cell residence times in $IrO_2$-coated Ti, $RuO_2$-coated Ti and DSA anode material systems were around 2.27, 1.52 and 1.52 sec, respectively. Observed optimum initial feed solution pH was around 2.3 in all anode material systems. Optimum sodium chlorite concentrations in $IrO_2$-coated Ti, $RuO_2$-coated Ti and DSA anode systems were around 0.43, 0.43 and 0.32 g/L, respectively. Optimum electrolyte concentration and applied current were around 5.85 g/L and 0.6 A in all anode systems. Current efficiencies of $IrO_2$-coated Ti, $RuO_2$-coated Ti and DSA anode systems under optimum conditions were 79.80, 114.70 and 70.99%, respectively. Obtained energy consumptions for the optimum generation of chlorine dioxide were 1.38, 1.03 and $1.61W{\cdot}hr/g-ClO_2$, respectively.

• Resources Recycling
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• v.27 no.4
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• pp.29-35
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• 2018

In this study, the electrochemical redox behavior of neodymium in non-aqueous electrolytes was investigated to confirm the possibility of neodymium metallurgy at room temperature. The non-aqueous electrolytes include ionic liquids such as $[C_4mim]PF_6$, $[C_4mim]Cl$, and $[P_{66614}]PF_6$, ethanol which are highly soluble in neodymium salts, and mixed electrolytes based on carbonate with highly electrochemical stability. The electrochemical redox properties of neodymium were better than those of other electrolytes in the case of the mixed electrolyte based on ethylene carbonate (EC)/di-ethylene carbonate (DEC). Ethanol was added to improve the physical properties of the mixed electrolyte. Thorough the analysis about ionic conductivity of EC/DEC ratio, ethanol content and $NdCl_3$ concentration, the best electrolyte composition was 50 vol% content of ethanol and 0.5 M of $NdCl_3$. Using cyclic voltametry and linear sweep voltametry, a current peak estimated at -3.8 V (vs. Pt-QRE) was observed as a limiting current of neodymium reduction. Potentiostatic electrolysis for 18 hours at room temperature at -6 V (vs. Pt-QRE) confirmed that metallic neodymium was electrodeposited.

• Journal of the Mineralogical Society of Korea
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• v.15 no.2
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• pp.104-113
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• 2002

The sorption of Cd$^{2+}$ on calcite was studied in aqueous solutions of several electrolytes. The Cd$^{2+}$ concentration, 10$^{-8}$ M, was kept well below saturation with respect to CdCO$_3$(s). Sorption behavior of Cd$^{2+}$ in different ionic strengths of NaClO$_4$solutions shows that sorption is independent of ionic strength. This result suggests that Cd$^{2+}$ sorption on calcite surface is of a specific nature, and adsorption is controlled by an inner-sphere type of surface complex. Two stages in the sorption behavior could be identified: an initial rapid uptake, followed by slower uptake reaching a maximum steady state by 145 hrs. No evidence was observed for surface precipitation, although it can not be entirely ruled out. Desorption of Cd$^{2+}$ from the calcite surface after resuspension into Cd-free solution is initially very rapid, but depends partly on the previous sorption history. Desorption behavior of Cd$^{2+}$ show that an initial rapid desorption followed either by slow uptake reaching a maximum, as in the adsorption experiments, or slowing desorption to reach a steady state minimum. This irreversible behavior of Cd$^{2+}$ sorption and desorption may act as one of the controls for regulating the mobility of dissolved Cd$^{2+}$ natural aqueous systems. Calculated adsorption partition coefficients suggest that overall sorption and desorption process in the concentration range are controlled by d single mechanism.ingle mechanism.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.07b
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• pp.830-833
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• 2002

최근 나노 구조 (nano structure)를 만들기 위한 시도 중 하나로서 스스로 조직화(self organization)하여 나노 구조를 형성하는 물질을 나노 소자 제작을 위한 형틀 (template)로 이용하려는 시도가 활발히 진행되고 있다. 이러한 물질로서 주목을 받고있는 것 중 하나가 전해질 용액에서 알루미늄을 양극산화(anodization) 시켰을 때 형성되는 다공성 알루미나 박막이다. 본 연구에서는 고 순도 알루미늄을 기계적으로 연마(mechanical polishing)하고 공기 분위기에서 어닐링 (annealing)하여 알루미늄을 재결정화(recrystallization) 시키고 인가 전압이 40 V인 정 전압하에서 0.3 M의 수산(oxalic acid)을 전해질로 사용하면서 양극산화를 수행하여 평균 직경이 65 nm인 고도로 배열된 육방밀집구조의 나노 다공성 박막을 제작하였다. 또한 같은 방향의 육방밀집 배열은 크기가 수 ${\mu}m$인 영역(grain)을 형성하고 있었으며, 평균적인 pore의 밀도는 $1.1{\times}10^{10}/cm^2$였다.

• Nuclear Engineering and Technology
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• v.13 no.4
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• pp.254-263
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• 1981

Paper electrophoretic separation of fission products has been carried out by using the specially designed migration apparatus. In general, the isolation of rubidium, strontium, zirconium, ruthenium, cesium, cerium, molybdenum, and some short-lived fission products is more efficient under 0.1M HCl electrolyte as compared with 0.1M NaOH electrolyte. In addition to Np-239, 1-131∼135 were, in particular, observed with different iodine chemical species obtained by the paper-electrophoretic separation of short, neutron-irradiated uranyl nitrate solution.

• Journal of the Korean Chemical Society
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• v.14 no.3
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• pp.263-269
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• 1970

A theory of surface tension developed by using the approximation that the surface of liquids consists of a monomolecular layer has been applied to the molten salts (NaCl, KCl, NaBr, KBr) and the strong electrolyte solutions. By considering that the ionic forces are the long-range forces and with the use of the partition functions developed, the surface tension of molten salts and strong electrolyte solutions has been calculated. The results show good agreement between theory and experiment at various temperatures and over a wide concentration ranges (0.1-4.0m)

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2008.11a
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• pp.93-93
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• 2008

니켈도금은 각종 소지 상에 직접적이고 밀착성이 양호하고, 변색이 적고 방청력이 크며, 경도, 내식성, 내마모성 및 유연성이 우수하다. 또한 최근 활발히 진행되고 있는 광촉매 연구에 $TiO_2$는 우수한 광화학적 안정성, 효과적인 전하분리, 높은 산화 환원력 및 상업적 적용성을 갖기 때문에 니켈도금용액에 $TiO_2$를 첨가하며 복합도금을 행함으로써 니켈이 가지고 있는 기존의 우수한 특성에 $TiO_2$의 광분해 효과를 부과시킴 으로써 그 특성이 한층 더 향상되는 것을 알수있다. 본 연구에서는 수용액전해질과 비수용액 전해질에서의 Ni-$TiO_2$ 복합도금의 특성을 비교 분석해보았다. 동전위(Potentiodynamic)실험 및 순환전위(Cyclic Voltammetry)실험을 하였으며, 도금층의 특성 및 두께는 OM,SEM을 이용하여 분석하였다. 또한 복합도금 촉매 전극에 의한 광분해 효과를 보기 위해서 UV램프를 이용하여 분석하였다.

• Korean Journal of Soil Science and Fertilizer
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• v.24 no.2
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• pp.95-101
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• 1991

The results of relationships between colloidal stability and soil pH on three Hawaii's volcanic ash soils developed under the three different rainfall conditions can be summarized as follows: 1. The Hilo soil only revealed the increase of colloidal stability by becoming for from Z.P.C point to either side of pH. 2. Hilo and Kawaihae soils, however, showed the increase of colloidal stability only in the higher pH range than their Z.P.C. 3. $P_2O_5$ drying procers decreased colloidal stability kof these soils because of so called irreversible drying characteristics of amorphous materials and the decrement was in order of: Akaka>Hilo>Kawaihae expressing positive correlation with content of amorphous materials in them. 4. The difference of colloidal stability curves among three soils can easily be interpreted by DLVO theory considering 0.1N-HCl amount added to decrease their soil pH, respectively. The addition of large amount of 0.1N-HCl into Akaka and Kawaihae soils did not effectively develop the positive charge but resulted in the shrink of diffuse double layer thickness inducing large attraction forces among soil particles.

• Membrane Journal
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• v.20 no.3
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• pp.259-266
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• 2010

Porous poly(propylene) supported gel polymer electrolytes (GPE) were synthesized by thermal polymerization of DEGDMA [Di(ethylene glycol) dimethacrylate] in electrolyte solutions (1 M solution of $LiPF_6$ in EC/DEC 1 : 1 mixture) at $70^{\circ}C$. AC impedance spectroscopy and cyclic voltammetry were used to evaluate its ionic conductivity and electrochemical stability window of the GPE membranes. Lithium ion battery (LIB) cells were also fabricated with $LiNi_{0.8}Co_{0.2}O_2$/graphite and GPE membranes via thermal polymerization process. Through the thermal polymerization, self sustaining GPE membranes with sufficient ionic conductivities (over $10^{-3}\;S/cm$) and electrochemical stabilities. The LIB cell with 5% monomer showed the best rate-capability and cycleability.