• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.9 no.5
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• pp.58-64
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• 2000

This paper proposes a method for determining optimal EDM parameters based on discharge area from the physical model of a tool electrode. Main parameters, which affect the EDM performance, are peak value of currents, pulse-on time, and pulse-off time. Such parameters are closely dependent on the discharge area in EDM process. In this paper the discharge area is estimated from the CMM scanning data to the tool electrode. The method is very useful when any geometric information to the tool electrode is not provided from tool modeler or producer. The method consists of following four steps. First a triangulation mesh is constructed from the CMM data. Secondly, the z-map is modeled from the triangulated mesh. Thirdly, the discharge area is estimated from intersection between the z-map model and a z-height plane. Finally, the machining parameters are easily calculated by some known EDM equations to the discharge area. An example is introduced to show that the machining parameters are calculated from the CMM data to a tool electrode.

• Journal of the Korean Society for Precision Engineering
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• v.18 no.7
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• pp.127-133
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• 2001

The effects of triangular and rectangular discharge current waveforms on anode erosion in wire electric discharge machining is investigated based on heat transfer analysis of half-space subject to time and space-dependent heat flux. The thermal load on the anode is simulated by a hear flux that is calculated from time-dependent discharge channel radius and energy. Evolution of the melting front during discharge, the molten volume at the experimental result for qualitative verification of the analysis. It is demonstrated that the triangular current waveform is more efficient in eroding the anode than the rectangular one.

• Journal of the Korean Society for Precision Engineering
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• v.20 no.1
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• pp.70-78
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• 2003

The purpose of this study was to present the method to choose the optimization machining condition for the wire electric discharge machine. This was completed by examining the ever-changing quality of the material and by improving the function of the wire electric discharge machine. Precision metal mold products and the unmanned wire electric discharge machining system were used and then applied in industrial fields. This experiment uses the wire electric discharge machine with brass wire electrode of 0.25mm. In this experiment, we changed no-node voltage to 7 and 9, pulse-on-time to 6$mutextrm{s}$, 8$mutextrm{s}$ and 10$mutextrm{s}$, pulse-off-time to 8$mutextrm{s}$, 10$mutextrm{s}$ and 13$mutextrm{s}$, and experimented on wire tension at room temperature by 1000gf, 1200gf, and 1400gf, respectively.

• Journal of Korean Society for Atmospheric Environment
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• v.18 no.5
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• pp.337-344
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• 2002

In this study, we analyzed the NO removal efficiency by the pulsed corona discharge process and investigated the effects of several process variables such as initial concentrations of NO, $H_2O$, and NH$_3$, applied voltage, pulse frequency, diameter of the discharge electrode, and residence time. The removal efficiency of NO increased by the addition of $H_2O$ or NH$_3$, but the changes of initial NH$_3$ and $H_2O$ concentrations did not affect the removal efficiency of NO significantly. With the increases of the applied voltage or the residence time, the removal efficiency of NO increased. In addition, with the increases of the pulse frequency of applied voltage, or the diameter of the discharge electrode, the removal efficiency of NO increased. The experimental results can be used as a basis to design the pulsed corona discharge process to remove NO$_{x}$, SO$_{x}$ and VOCs.OCs.

• 한국정보디스플레이학회:학술대회논문집
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• 2007.08b
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• pp.1185-1188
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• 2007

The address discharge characteristics by the various scan-low and common-bias voltages are investigated based on measured address discharge time lags and $V_t$ close-curve analysis. The scan-low voltages are changed under the same voltage difference between the X and Y electrodes during an address period. As the voltage difference between the scan and address electrodes is increased during an address period, the address discharge time lag is shortened but the background luminance is increased. It is found that the improved address discharge characteristics is caused by the effect of the higher external applied voltage during an address period than the accumulated wall charges during a reset period and the high background luminance can be prevented by applying an address-bias voltage during a rising-ramp period and low reset voltage.

• 한국정보디스플레이학회:학술대회논문집
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• 2004.08a
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• pp.503-506
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• 2004

In this paper, we suggest a new driving waveform for stable address discharge in AC PDP without the reduction of contrast ratio. To analyze the influence of cross-talk between discharge and non-discharge cells and verify that proposed waveform shows a stable address discharge, we measured the address discharge delay time. The proposed waveform shows the reduction of the cross-talk and concurrently the improvement of address voltage margin compared with those of selective reset waveform having one reset period in 1TV-Field..

• Journal of Korean Society of Water and Wastewater
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• v.19 no.5
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• pp.619-624
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• 2005

This work is for examining a simplified equation based on the rational formula, which can easily decide storm-water detention volume in small urban catchments. The storm-water detention volume is determined by the inflow hydrograph flowing to detention basin and the outflow hydrograph discharged from the detention basin. The ratio of average outflow over the period of rainfall duration against allowable discharge was 0.5 in former simplified equation. But this research has found that the average outflow ratio depends on the storage methodology. In the case of the on-line storage method, the average outflow ratio is a function of the time of concentration of the catchments and rainfall duration, which ranged from 0.5~1.0. In the case of the off-line storage method, the average ratio is a function of peak discharge and allowable discharge except above time of concentration and rainfall duration, where its function value ranged from 1.0~2.0. When applying this equation to small catchment in Mokpo city, South Korea, we could easily calculate the relation curve between the storm-water detention volume and allowable discharge.

• Journal of Welding and Joining
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• v.15 no.6
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• pp.49-56
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• 1997

Effect of process parameters on the quality of condenser discharge weld for coated sheet steels was discussed. The welding specimens were coated with pure Zn of 20/20 g/m2 in the production line. Direct measurements of welding parameters such as the discharge current, the pressures and the voltage drop across the electrodes were carried out with welding process monitoring system. High speed camera was also utilized to analyze the weld formation process. Test results indicated that the relation between weld strength and applied energy was stabilized at the acceptable welding heat input range. It was thought that the acceptable welding heat input should be redefined based on the monitored data because the calculated value of the welding heat input could hardly be utilized if the discharge condition was changed. Mechanical test results and high speed photographs showed that expulsion deteriorated the weld quality and the strength at the same time especially when the size of the spatter was large enough to carry the molten metal, which should form the nugget, out of the welding spot. Results also demonstrated that the discharge current should be applied at the appropriate time during the process because sufficient nugget was not produced if the time was deviated from the optimum range.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.28 no.10
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• pp.636-641
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• 2015

In this study, the partial discharge degradation properties for 2-core PVC cable($2cores{\times}1.5mm^2$ cross section, length of 10 cm, 20 cm, 30 cm) following immersion with the salt water that the 2%, 4%, 8% of NaCl is dissolved in 100 g of distilled water for 48 and 96 hours has been measured. The results of this study are as follows. When the degradation time in salt water of 2% NaCl is 48 hours, it found that the number of partial discharge increased as about 40 pps, 50 pps, 90 pps with increasing the length of cable to 10 cm, 20 cm, 30 cm. In case the concentration and degradation time is same, the inception and extinction voltage decreased with increasing the length of cable. When the degradation time in salt water is 96 hours and the length of cable is 20 cm, it found that the number of partial discharge decreased as 3,000 pps, 500 pps, 100 pps with increasing the concentration of NaCl to 2%, 4%, 8%.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.52 no.10
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• pp.476-480
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• 2003

In this paper, we have performed 3-dimensional time-resolving measurement of the Ne light emitted from the cell of plasma display panel(PDP) as a function of the pressure using the scanned point detecting system. From the temporal behavior results, we could analyze the discharge behavior of panel with Ne-Xe(4%) mixing gas and 300 torr, 400 torr and 500 torr pressure. At the top view of panel, the discharge of 300 torr panel starts at the 634 ns and ends at the 722 ns. The emission duration time is about 90 ns. The discharge of 400 torr panel starts at the 682 ns and ends at the 786 ns. the emission duration time is about 100 ns. Also, the discharge of 500 torr panel starts at the 770 ns and ends at the 826 ns. the emission duration time is about 56 ns. The discharge moves from inner edge of cathode electrode to outer cathode electrode forming arc type. In the side view of 300 torr, 400 torr and 500 torr an emission shows that the light is detected up to 180${\mu}{\textrm}{m}$, 150${\mu}{\textrm}{m}$ and 70${\mu}{\textrm}{m}$ height of barrier rib and the emission distribution of the 300 torr is wider than 400 torr, 500 torr.