• Journal of the Korean Ceramic Society
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• v.36 no.9
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• pp.930-936
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• 1999

For LiMn2O4 based spinel structures the stoichiometric reaction conditions need be considered carefully because the electrical properties depend on the structural stability. In order to obtain the homogeneous compound the Pechini process was chosen which could obtain a stoichiometry phase even low temperature and dependency of the synthetic condition on structural stability and electrochemical performance was investigated. X-ray diffraction studies showed that the compounds doped with transition metal have smaller lattice constants than those un doped. The dc conductivity was evaluated by a four probe method in the low and high temperature region respectively. The variations of basal spacings for the cathode were detected to be dependent on the extent of current flows (under dc)

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.16 no.12
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• pp.1150-1154
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• 2003

The voltage profile during discharge of the zinc air battery has very flat pattern until reach to end of discharge voltage. But, when zinc air battery is discharged by high current, the discharge voltage and energy becomes low. Therefore, we focused on effects of catalyst size to solve this problems by increasing active sites of oxygen reduction reaction. The size of catalyst was reduced from 27 to l${\mu}{\textrm}{m}$ and we examined average discharge voltage, capacity, energy, resistance and characteristics during GSM pulse discharge of zinc air battery with change of current density. And we also measured porosity of the cathode according to the ASTM. So we have got improvement of average discharge voltage and energy when catalyst was minimized and we have got optimum size of catalyst at 5${\mu}{\textrm}{m}$.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2003.09a
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• pp.158-161
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• 2003

Removal of phenanthrene by electrokinetic method combined with Fenton-like process was studied in a model system. The scale of reactor was 100cm in length, 100cm in width, and 70cm in height. The distance between electrodes was 70cm. Indonesia kaoline was selected as a model soil. When constant voltage of 100 V was applied to this system, current decreased from 200 mA to 100 mA for 14 days. Total accumulated EOF was about 55,000 mL. The concentration of phenanthrene near anode was very low because direction of electroosmosis was from anode to cathode and hydrogen peroxide was supplied to anode reservoir. Phenanthrene concentration was increased as the location was far from anode because hydrogen peroxide was gradually decomposed and then the rate of hydroxyl radical production was decreased.

• Journal of Advanced Marine Engineering and Technology
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• v.39 no.8
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• pp.833-837
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• 2015

Li-air batteries have a promising future for because of their high energy density, which could theoretically be equal to that of gasoline. However, substantial Li-air cell performance limitations exist, which are related to the air cathode. The cell discharge products are deposited on the surfaces of the porous carbon materials in the air electrode, which blocks oxygen from diffusing to the reaction sites. Hence, the real capacity of a Li-air battery is determined by the carbon air electrode, especially by the pore volume available for the deposition of the discharged products. In this study, a simple and fast method is reported for the large-scale synthesis of carbon nanoballs (CNBs) consisting of a highly mesoporous structure for Li-air battery cathodes. The CNBs were synthesized by the solution plasma process from benzene solution, without the need for a graphite electrode for carbon growth. The CNBs so formed were then annealed to improve their electrical conductivity. Structural characterization revealed that the CNBs exhibited both an pore structure and high conductivity.

• Journal of Surface Science and Engineering
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• v.28 no.4
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• pp.199-206
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• 1995

A kinetic study on the electrodeposition of Ni-Zn-P ternary alloys onto a steel in chloride solutions was carried out using a rotating disc electrode. The coatings were characterized using SEM/EPMA and A. A. analysis. The results showed that the plating rates of three components were increased with applied potential, disc rotating speed and temperature. The activation energies of Ni, Zn and P of the coatings were 6.1, 5.1 and 8.0 kcal/mole respectively. Therefore, the deposition rates were controlled partly by surface electrochemical reaction and partly by mass transport. As the potential, temperature of bath and rotating speed of cathode disc were raised, the vol. % ratios of Ni and P of coating layer were increased but that of Zn decreased. The effect of coating parameters on the surface morphology was also examined.

• Journal of environmental and Sanitary engineering
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• v.12 no.3
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• pp.131-138
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• 1997

In this study, the effect of the various operating conditions on the removal of $Cr^{6+}$ from $Cr^{6+}$ containing wastewater which has strong toxicity by using electrolysis with iron electrode as anode and aluminum electrode as cathode was investigated. The removal efficiency of $Cr^{6+}$ was increased as the pH was decreased, as the distance of electrode was decreased and the voltage was increased. The reaction temperature slightly affected the removal efficiency. The optimum conditions for the treatment of $Cr^{6+}$ containing wastewater were initial pH 3, 5 volt and the distance of electrode was 1cm. The feasibility of the electrochemical treatment to the $Cr^{6+}$ containing industrial wastewater was verified from this study.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2003.04a
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• pp.310-313
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• 2003

Removal of phenanthrene by electrokinetic method combined with Fenton-like process was studied in a model system. The scale of reactor was 120 cm in length, 10 cm in width, and 50 cm in height. Sand was selected as a model soil. Bentonite was filled in the space between reservoir and contaminated soil to control the flow rate of water. When constant voltage of 100 V was applied to this system, current varied from 1000 mA to 290 mA for 28 days. pH of anode and cathode reservoirs became to 2 and 13, respectively. Removal efficiency of phenanthrene was more than 60 %.

• Proceedings of the Materials Research Society of Korea Conference
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• 2012.05a
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• pp.71.1-71.1
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• 2012

Proton Exchange Membrane Fuel Cells (PEMFCs) have been of great interest particularly in the automobile industries because of their high energy density and low pollutant emission. However, some of the issues such as, the necessarily high contents of Pt catalysts and their slow kinetics of cathode oxygen reduction reaction remain as obstacles in the commercialization of the PEMFC. In this presentation, after brief explanation on basic principles of PEMFC and its application to FC vehicles, recent researches to improve the activity and durability of Pt-based nano catalysts toward oxygen reduction will be introduced. It covers size and shape control of Pt nano particle, binary and ternary Pt-M alloys, novel core-shell nano structures of Pt, and a little bit about non-Pt catalysts. Strategies and methodologies for design and synthesis of novel catalysts will also be included.

• Journal of the Korean Ceramic Society
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• v.42 no.12 s.283
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• pp.860-864
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• 2005

In this study, we fabricated honeycomb type Mixed-Gas Fuel Cell (MGFC) which has advantages of stacking to the axial direction and increasing volume power density. Honeycomb-shaped anode with four channels was prepared by dry pressing method. Two alternative channels were coated with electrolyte and cathode slurry in order to make cathodic reaction sites and the others were filled with partial oxidation (POX) catalyst to increase fuel conversion. Furthermore we employed the sol-gel technique which can increase cell performance and decrease carbon coking.

• Bulletin of the Korean Chemical Society
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• v.35 no.10
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• pp.2901-2905
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• 2014

The hierarchical-structured $LiFePO_4$ cathode materials were synthesized by one-step microwave synthesis, and their electrochemical properties were investigated. Addition of citric acid during the reaction lead to the formation of hierarchical structured $LiFePO_4$, which has both nano- and micron-characteristics advantageous for energy density and electrode fabrication. Adjusting the molar ratio of Fe to citric acid enhanced the electrochemical properties of $LiFePO_4$.