• 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 KIEE Conference
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• 1998.07d
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• pp.1459-1461
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• 1998

This paper provides the results of analysis of lightening arrester failed in the field. XRD was used for qualitative analysis and SEM for microstructure analysis of zinc oxide (ZnO) block. The failure of lightening arrester might occur due to the following reasons: the uneven size of zinc oxide grains and cement layers. the re-crystallization of zinc oxide grains resulting from electrical stress around impurities, and the presence of too large pores($\simeq$ 50 ${\mu}m$).

• Proceedings of the KIEE Conference
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• 2003.07e
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• pp.162-165
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• 2003

A resonant type voltage source and power device and a control method using Pulse Density Modulation(PDM) power control and Pulse Width Modulation(PWM)voltage control for plasma sterilization are described. For the stability of discharge in the generating tube, it is desirable that the peak apply voltage is constant. The PDM power control is employed for sustaining the voltage constant at any generating tube input power. Moreover, to avoid the influence of input AC voltage fluctuation etc., PWM voltage control with generating tube peak voltage feedback is used. Both functions were confirmed by the experiment with inverter and generating tube. The effect of input synchronous PDM method for input current stabilizing is confirmed also.

• Journal of Environmental Science International
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• v.7 no.3
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• pp.281-290
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• 1998

Thirty-eight sediment samples collected from the Youngsan River channel were analysed for Fe, Mn, Co, Cr, Cu, Nl, Zn and Pb to recognize the extent of contamination. Results showed that a wide range of contents was apparent far every metal over the study area. These differences have been mainly related to the textural variability of sediments. Exceptions to this were fecund in the contents of Cu, Zn, Pb and possibly Mn. The contents of Cu, Zn, Pb and Mn were particularly higher in the sediments loom the confluence of tributaries. Downstream profile of metal/Al ratios indicates that pollutant inputs from the Kwangju tributary are mainly responsible for enrichment of these metals in bed sediments of the Young-san River.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.30 no.11 s.254
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• pp.1123-1130
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• 2006

This study discusses about research efforts of hydrogen generation from hydrocarbon(e.g., diesel, gasoline, natural gas, and LPG), especially, butane reforming by using Autothermal Reforming Reaction (ATR) technology. Several catalysts were selected for butane ATR. Thermodynamic reactor conditions (temperature, $O_2$/C, S/C) are varied and reforming characteristics of 2 catalysts (Pt and Rh on ceramic supports) and 1 commercial catalyst (FCR-HC35) have been examined. To understand reaction behaviors in an ATR reactor comprehensively, temperature profiles of reactor were observed. By mass transfer limitation, fuel conversion decreases when GHSV increases. Significant temperature variation along the reactor was observed and it was mainly due reaction kinetics difference between exothermic oxidation and endothermic reforming reaction.

• Journal of the Korean Geotechnical Society
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• v.16 no.2
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• pp.5-12
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• 2000

The hazard of excavation may be very high until a supporting system is completely installed. In this paper, an excavation method which uses partially reinforced soldier pile($\square$-shape) inserted by a short length steel bar was proposed and simulated by the finite element method. The reinforcing steel bar is moved down along the stage of excavation to reinforce the stiffness of the supporting system. The result of analysis showed that the risk of failure by bending moment or shear stress could be significantly reduced by the reinforcing effect of the steel bar. The proposed method could be applied to the strut-supporting wall or the diaphragm wall.

• Proceedings of the KIEE Conference
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• 1996.07c
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• pp.1529-1531
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• 1996

Porcelain suspension insulators have teen used for a long time in distribution line. However, Puncture breakdowns in porcelain insulators caused by weaking cement between metal fitting nad porcelain material. There is little puncture breakdown in Epoxy casting insulator. This paper presents electrical test results for the development of suspension insulator used Cycloaliphatic Epoxy resin. Items of test results are as follow - Power Arc test - Aging test - Impulse flashover voltage tests - Puncture tests et.al.

• Proceedings of the KIEE Conference
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• 1996.07c
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• pp.1794-1796
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• 1996

In order to evaluate the soundness of 10 year service-aged XLPE-insulated 22.9 kV underground distribution cables, semiconductive shields have been characterized. The edge of insulation near the insulation shield shows a drastic decrease of OIT. Impurities such as Ca, Mg, Fe, Cu were detected in both conductor and insulation shields. Their concentrations at the insulation shield are much higher than those at the strand shield. All these facts suggest that the edge of insulation near the insulation shield is degraded considerably, which might be attributed to the oxidation reaction of insulation by a large amount of impurities in the insulation shield.

• Proceedings of the KIEE Conference
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• 1996.07c
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• pp.1791-1793
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• 1996

This paper describes Thermal-Mechanical performance and Ultimate Mechanical-Strength test for the purpose of aging analysis of suspension insulator. The temperature difference of insulator surface according to the aging of suspension insulator brought out about $2^{\circ}C$ to $7-8^{\circ}C$ difference comparing with the atmospheric temperature. Quality standard and Mechanical-Strength of used suspension insulator deteriorate more remarkably than that of new suspension insulator. It is required that Thermal-Mechanical performance test standard be revised in the future. And it is described about the development prospect of polymer insulators

• Proceedings of the KIEE Conference
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• 1996.07c
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• pp.1907-1909
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• 1996

In this paper, ultrsonic detection properties at a premolde joint utilized in a 23kV cables are studied. In a experiment a artificial defect within a joint and a measuring system are builded for generating discharges, gathering data about a detection properties, respectively. The experiment results show that one point detection is not allowed for monitoring a global status of a joint discharges and a detection sensitivity is less than 100pC. And also the attenuation and wave speed at the material of joint insulator are obtained.