• Transactions of the Korean hydrogen and new energy society
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• v.13 no.1
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• pp.65-73
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• 2002

Because of low flame ion density in hydrogen-air mixture, many residual electric energy could be existed in the ignition system of hydrogen engine, If these residual energy discharged abnormally during intake stroke, it may be the cause of backfire occurrence which is serious problem in development of hydrogen fueled engine but unsolved in spite of many concerned research on it. In this study, the possibility of backfire occurrence by abnormal electric discharge and countermeasure of that were investigated by using the experimental single cylinder hydrogen fueled engine with two types of ignition system. The results show that abnormal electric discharge appeared in low load with low ion density and then results in back fire occurrence, It is also seen that countermeasure method installing larger earth resistance in high tension code is effective to control abnormal electric discharge.

• Korean Journal of Materials Research
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• v.26 no.12
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• pp.696-703
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• 2016

In this study, we intensively investigated the effect of conductive additive amount on electrochemical performance of organic supercapacitors. For this purpose, we assembled coin-type organic supercapacitor cells with a variation of conductive additive(carbon black) amount; carbon aerogel and polyvinylidene fluoride were employed as active material and binder, respectively. Carbon aerogel, which is a highly mesoporous and ultralight material, was prepared via pyrolysis of resorcinol-formaldehyde gels synthesized from polycondensation of two starting materials using sodium carbonate as the base catalyst. Successful formation of carbon aerogel was well confirmed by Fourier-transform infrared spectroscopy and $N_2$ adsorption-desorption analysis. Electrochemical performances of the assembled organic supercapacitor cells were evaluated by cyclic voltammetry, galvanostatic charge/discharge, and electrochemical impedance spectroscopy measurements. Amount of conductive additive was found to strongly affect the charge transfer resistance of the supercapacitor electrodes, leading to a different optimal amount of conductive additive in organic supercapacitor electrodes depending on the applied charge-discharge rate. A high-rate charge-discharge process required a relatively high amount of conductive additive. Through this work, we came to conclude that determining the optimal amount of conductive additive in developing an efficient organic supercapacitor should include a significant consideration of supercapacitor end use, especially the rate employed for the charge-discharge process.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.26 no.7
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• pp.16-22
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• 2012

With the increase of consumption of new renewable energy, the use of Electric Double Layer Capacitor(EDLC) is being gradually widened as the next generation energy storage device. In order to expand the market of EDLC which is recently receiving a lot of attraction as a new promising area, development of a charge/discharge cycle tester to measure and test performance, is essential. Therefore, this research designed a circuit to measure capacity and internal resistance and a circuit to measure voltage maintenance properties, based on EDLC's basic charging/discharging properties so it is able to measure the state of charge and discharge at high speed. When evaluating performance characteristics, the 5[V]/100[A] prototype-EDLC charge/discharge testing system developed for this research showed ${\pm}0.1$[%] of accuracy of voltage and current measurement. It was also proved that the developed charge/discharge testing system for EDLC can be applied to the actual industry, when testing the entire system using a program produced for data monitoring and acquisition.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.20 no.6
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• pp.714-719
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• 2011

The surface roughness depending on the machining method is very important because is produce a finished product through riveting, sealing, bonding, and special paint in order to curb the turbulence and air resistance which occur between the sheets. Aluminum alloy 2024 which is widely used for interior and exterior material of aircraft are tested. Jin-young JW-60C wire cutting machine was used in this experiment. In this paper, the experimental investigation has been performed to find out the influence of the surface roughness and surface shape characteristics on the wire-cut EDM of discharge energy in aluminium alloy 2024. The selected experimental parameters are peak current, no-load voltage, off time and feed rate. The experimental results give the guideline for selecting reasonable machining parameters. The high discharge energy on the idle time, almost no change in surface roughness can be seen.

• Proceedings of the Korea Institute of Applied Superconductivity and Cryogenics Conference
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• 1999.02a
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• pp.26-29
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• 1999

Superconducting $YBa_{2}$$Cu_{3}$ $O_{7-x}$(YBCO) thin films were deposited on MgO(100) substrates using a hollow cathode discharge sputtering system. Influence of the sputtering conditions such as substrate temperature and discharge sputtering gas pressure on electrical and structural properties were investigated. It was found that YBCO thin films with zero resistance temperature higher than 85 K were obtained to the pressure 200 mToorr(Ar/O2=0.9), substrate temperature of $760^{\circ}C$, and target-substrate distance of 10 mm during film deposition. Homogeneous large area YBCO films with 2 inch diameter were also sucessfully fabricated by this method.

• Proceedings of the KIEE Conference
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• 1998.07d
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• pp.1511-1513
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• 1998

The purpose of this study is to research and develop PEO/PVDF electrolytes and $LiMn_2O_4$ composite cathode for all-solid state lithium rechargeable battery. We investigated AC impedance response and charge/discharge cycling of $LiMn_2O_4$/SPE/Li cells. The cell resistance was decreased so much initial charge process from 0% SOC to 100% SOC. The radius of semicircle of $LiMn_2O_4$/SPE/Li cell was so much from initial state to 20th cycling. The discharge capacity of the $LiMn_2O_4$ composite cathode was 144mAh/g based on $LiMn_2O_4$.

• Proceedings of the KIEE Conference
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• 1999.11d
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• pp.1096-1098
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• 1999

The performance of as plasma display panels (PDP) is influenced strongly by the surface glow discharge characteristics on the MgO thin films. This paper deals with the optimum preparation conditions of MgO Protecting layer by RF unbalanced magnetron sputtering(UBMS) in surface discharge type AC PDP. The samples prepared with the do bias voltage of -10V showed lower discharge voltage, lower erosion rate as a consequence of ion bombardment, higher optic transparency and higher crack resistance in annealing process than those samples prepared by conventional magnetron sputtering or E-beam eraporation.

• Proceedings of the KIEE Conference
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• 2000.07c
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• pp.1981-1983
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• 2000

In this paper, the arc resistance of INPIStron is presented. It is need to the design of Pulsed power system and simulation on the circuit of pulsed power system with INPIStron switch. It is also possible to use this parameter to the part of discharge characteristics of Xenon lamp and the device with electrical discharge.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.27 no.12
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• pp.841-846
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• 2014

It found that the maximum temperature of the arc discharge occurred on the Silicone rubber sample significantly decreased with increasing the reinforcing agent. It was confirmed that the current value decreased with increasing the aluminium trihydrate($Al(OH)_3$) and the current value increased with reducing the primary resistance over time. Regarding these results, may be it is because the degradation due to the electro-conductive carbonization was improved and the properties of dielectric breakdown was reduced by the flame retardant reinforcing agent. It found that the electro-conductive carbonized road has not happened by increasing the flame retardant reinforcing agent. Regarding to the arc discharge, this study show that the arc arising near the lower electrode of sample has disappeared.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.14 no.1
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• pp.51-56
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• 2015

This paper presents an investigation of abnormal wear of a contact jig between a nail and a nail fixture in electric resistance welding. To perform an analysis on the abnormal wear phenomenon, several methods are provided. Based on the theory of electric resistance welding, are analyzed. Using microscopic analysis, surface craters are observed. In the measurement of the electric current flow in the nail fixture, the current flow distribution is measured. From several analyses, the cause of abnormal wear in the contact jig is measured using the electric discharge of high current density at the inflow point of the electric supply to the nail fixture. An alternative shape for normal wear is proposed.