• Proceedings of the Korean Geotechical Society Conference
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• 2010.03a
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• pp.1286-1293
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• 2010

The ground anchor used in domestic area, which resists by adhesion between anchor body and the ground to the external force, seems not to be adequate for soft ground and urban area where the boundary between structures is close because the ground is disturbed and lost its strength during boring. In order to overcome such a shortcoming an expanded anchor system has been developed. The ground expansion is accomplished by means of Pulse Discharge Technology. In this technology, a high voltage of electricity is stored and discharged in milliseconds which induces high pressure acting on the ground. By making a couple of bulbs, a passive resistance as well as shaft resistance are mobilized, and therefore a higher pullout resistance comparing existing ground anchors is developed.In this study, a couple of full scale tests were conducted in order to figure out how much the resistance of an expanded anchor increases comparing to the straight. As a result, it was found that a remarkable increase in ultimate pullout capacity is observed for the soft ground and as the number of bulb increases. In addtion, as a result of applying to a cut slope reinforcement, it appeared that the length of fixed zone of anchor can be reduced effectively.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.51 no.10
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• pp.465-472
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• 2002

This paper presents a study on the aging and recovery of HTV (high temperature vulcanized) silicone rubber used for outdoor insulators. UV irradiation, corona discharge and water immersion were employed as factors of the artificial aging. The effects of changes derived from these stresses on the tracking and arc resistance of silicone rubber were examined. We have investigated the aging phenomena of HTV silicone rubber by the above stresses using the surface energy calculation with contact angle measurement, solvent-extraction, and surface/volume resistivity and so on. These results showed that UV irradiation and corona discharge lead to nearly the same surface oxidation, but the percentage change of mobile low molecular weight by these stresses was different. Furthermore, the oxidized layer induced under UV irradiation restricted the recovery of hydrophobic surface. Water immersion little lowered hydrophobicity level and leaded to a loss of tracking and arc resistance. The degradation mechanism based on our results was discussed.

• Transactions of the Korean Society of Automotive Engineers
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• v.14 no.1
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• pp.100-108
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• 2006

Time-resolved current and voltage measurements for an inductive automotive spark system were made. Also presented are measurements of the total energy delivered to the spark gap. The measurements were made in air for a range of pressures from 1-18atm, at ambient temperatures. The measured voltage and current characteristics were found to be a function of many ignition parameters; some of these include: spark gap distance, internal resistance of the spark plug and high tension wire, and pressure. The voltages presented were measured either at the top of the spark plug or at the spark gap. The measurements were made at different time resolutions to more accurately resolve the voltage and current behavior throughout the discharge process. This was necessary because the breakdown event occurs on a time scale much shorter than the arc and glow phases. The breakdown, are, and glow voltages were found to be functions of spark plug resistance, gas density, and spark plug gap as expected from the literature. Spark duration was found to decrease as either pressure or gap was increased. The transition from the arc to glow phase is usually distinguished by a sudden rise in the voltage across the gap. At pressures above about 7atm this transition was not observed suggesting that a glow phase was not present. Energy delivered to the gap increased with increasing pressure. The effective resistance of the spark gap during discharge was about twice as large for the glow phase as the arc phase.

• KIEE International Transactions on Electrophysics and Applications
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• v.3C no.3
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• pp.99-105
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• 2003

The influence of discharge conditions, including the resistance of the sparking circuit, the shape of the electrodes and the width of the falling dust on the ignitability of lycopodium streams were investigated. Discharge characteristics and the ignition phenomena were also explored. When a 100 ㏀ resistor was connected in series with the sparking circuit, the lowest level of minimum ignition energy (MIE) was attained for lycopodium streams. Simultaneously, the area where flammable gas generated increased and the duration of flammable gas generation decreased. That is, the ignita-bility of lycopodium streams depended strongly on the discharge power and discharge duration. Electrodes with sharp tips gave smaller MIEs than those with round tips in a capacitive-inductive sparking circuit, while shape made no difference in a capacitive-resistive circuit. Streams that were too narrow required a considerable amount of energy for ignition.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.10 no.1
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• pp.18-31
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• 2000

A stack must be designed to 1) reduce or eliminate rainfall or snowfall into a industrial exhaust system, 2) minimize a resistance to flow, 3) maximize the vertical dispersion of the contaminated air and 4) minimize maintenance. The weather cone stacks and the elbow-type stacks are very popular in Korea. But they add some resistance to the exhaust system resulting in reduction of air flow rate, but also deflect the noxious contaminants downward in undiluted form. To solve these problems, ACGIH (American Conference of Governmental Industrial Hygienists) suggested the vertical discharge stack with concentric space between the upper stack with larger diameter and the lower stack with smaller diameter. The preliminary test showed that the vertical discharge stacks did not have the good rainfall protection. The reversed cone were newly devised to satisfy the requirements for the good stack. Subsequently, the amount of rain being penetrated through the stacks was measured while the stacks were simultaneously and naturally exposed to rain in the same area outside. Test results indicate that none of the stacks tested completely exclude rain. The efficiency of rainfall protection and the pressure loss coefficient were compared. The temporary conclusion was reached to the point that the reversed cone stack is the best one. Further research is underway.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.05b
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• pp.124-127
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• 2000

The purpose of this study is to research and develop PAn-Carbon composite electrode for Supercapacitor. Supercapacitor cell of PAn-Carbon composite electrode with 1M $LiClO_{4}/IPC$ brings out good capacitor performance below 4.0V. The radius of semicircle of PAn-Carbon composite electrode adding 30wt% Acetylene Black was absolutely small. The total resistance of Supercapacitor cell mainly depended on internal resistance of he electrode. The discharge capacitance of PAn-Carbon on composite with 30wt% Acetylene Black in 1st and 50th cycles was 29 and 31F/g at current density of $1mA/cm^2$. The capacitance of PAn-Carbon composite with 30wt% Acetylene Black capacitor was larger than that of PAn capacitor without Acetylene Black. The coulombic efficiency of supercapacitor at discharge process of 1 and 50 cycles were 94 and 100%. respectively. PAn-Carbon composite Supercapacitor with 30wt.% Acetylene Black content showed good capacitance and stability with cycling.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.25 no.11
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• pp.73-82
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• 2011

The solid insulation system of stator windings in high voltage rotational machines is usually aging in accordance with long time operation. The partial discharge test have been known to check whether insulation deterioration exist or not, and the PD test can effectively diagnose a solid insulation condition regardless of during operation(on-line) or not(off-line). The on-line PD measurement have proven to be a successful technique in monitoring stator insulation condition nowadays. This paper describes the characteristics of comparing the on-line PD measurement data using PDMS-HG(Partial Discharge Monitoring System for Hydro-electric Generator) installed in field with the off-line diagnosis measurement data(insulation resistance, winding resistance, PI, ${\Delta}tan{\delta}$ and PD) on hydro generator(13[kV]) stator windings. These results make good use of managing rotational machines through evaluating the solid insulation condition of stator windings.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.11a
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• pp.231-232
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• 2007

Nickel oxide thin films were deposited by the DC magnetron reactive sputtering process under the conditions such as various oxygen flow rates(0, 3, 6, 8, 10 sccm) with constant 33 sccm argon flow rate for the sputtering time of 40 second with the power of 0.3 kW. Sheet resistances were measured by the four point probes. In order to observe discharge voltage characteristics according to the oxygen flow rates, the sputtering processes were performed under the powers of 0.2kW and 0.3kW. The feasibility of the coating system for high quality ferromagnetic thin films was tested through the electromagnetic simulation and the thin film thickness measurement from the experiment. It was shown that a discharge voltage was decreased under the low power and low oxygen flow rate, since the oxygen was quickly saturated on nickel target surface. The sheet resistance was increased as oxygen flow rate increased. The film thickness deposited by the coating system for ferromagnetic target was improved approximately 10% in comparison with previous coating systems.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.18 no.9
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• pp.870-875
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• 2005

We measured the optogalvanic signal and discharge voltage-current(V-I) curve under the two different discharge conditions with different buffer gases, Ar, and Ne. When the Gd was used as a cathode material at low discharge current less than 10mA, a significant change was observed in the current-voltage curve. Time resolved optogalvanic signal measurement were measured by the diode laser of which wavelengths correspond to metastable transition line of these gases (Ar, Ne). From these measurements, we found that the characteristics of the V-I curve strongly depend on the Penning ionization process.

• Proceedings of the KIEE Conference
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• 1989.07a
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• pp.642-646
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• 1989

We have developed analysis program of discharge chracteristics of KrF laser system with charge transfer type, that studied about deposited energy, nonlinear discharge, and electron number density in the laser tube. With this program, voltagr, current, and deposited energy was calculated 27 KV,32.6 KA,200 MW at total pressure 2 atm and charging voltage 33 KV, respectively. At this condition, circuit parameters are L1=150nH, R1=$0.3{\Omega}$, L2=15nH, R2= $0.3{\Omega}$. In addition, nonlinear discharge resistance and electron number density was calculated ${\infty}{\sim}0.17{\Omega}.1{\times}10^{16}cm^{-3}$, respectively.