• Journal of the Korean Society for Precision Engineering
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• v.19 no.4
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• pp.101-108
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• 2002

A specially-built EMM (Electrochemical Micro Machining) / PECM (Pulse Electrochemical Machining) cell, a electrode tool filled with non-conducting material, a electrolyte flow control system and a small & stable gap control unit are developed to achieve accurate dimensions of recesses. Two electrolytes, aqueous sodium nitrate and aqueous sodium chloridc arc applied in this study. The farmer electrolyte has better machine-ability than the latter one because of its appropriate changing to the transpassive state without pits on the surface of workpiece. It is easier to control the machining depth precisely by micrometer with pulse current than direct current. This paper also presents an identification method for the machining depth by in-process analysis of machining current and inter electrode gap size. The inter electrode gap characteristics, inc1uding pulse current, effective volumetric electrochemical equivalent and electrolyte conductivity variations, are analyzed based on the model and experiments.

• Journal of Advanced Marine Engineering and Technology
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• v.27 no.3
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• pp.429-436
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• 2003

The electrical discharge machining(EDM) with Si electrode instead of Gr or Cu electrode. made enormous effects on the surface. machining time, anti-caustic workpiece surface and so on In this paper. we experimented on the inter-role distance during discharge the electrical phenomenon of inter-pole, the distribution of discharge point. the distribution of off load time. etc., using Si electrode Cu electrode and Gr electrode under the same machining condition. As a result of a large quantity generated exclusive powders. the performance of the EDM using Si electrode. compared with EDM using others. is improved. We show that the quantities of those make far pole-gap discharge and discharge scatter under stable machining status possible.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2001.04a
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• pp.942-945
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• 2001

Pulse electrochemical micromachining offers significant improvements in dimensional accuracy as compared with conventional electrochemical machining. One primary issue in pulse electrochemical micromachining is to identify and control machining depth as well as interelectrode gap size. This paper presents an identification method for the machining depth by in-process analysis of machining current and interelectrode gap size. The inter electrode gap characteristics, including pulse current, effective volumetric electrochemical equivalent and electrolyte conductivity variations, are analysed based on the model and experiments.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.49 no.12
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• pp.679-684
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• 2000

Closing switch, key component of pulsed power system, is constructed simply and used frequently due to the easy control and manufacture of one. The kind of one are spark-gap, triggered vacuum switch, pseudo-spark switch and INPIStron. But the electrode of spark gap switch is damaged with the hot spot by Z-pinch and then the life of one become short. INPIStron with inverse pinch effect has long life but it is difficult trigger system to provide uniform discharge between cathode and anode. In this paper, the design and manufacturing of INPIStron with gas puffing trigger method in order to supply uniform discharge inter-electrode and the performance of the developed INPIStron applied to 500[kA]-2[MJ] pulsed power system is presented.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.1686-1687
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• 2011

A microfabricated chip with in-channel electrochemical cell using interdigitated gold electrode was fabricated for sensitive electrochemical analysis. The gold electrodes were fabricated on glass wafer using thermal evaporator and were covered using PDMS mold containing microchannel for analyte and electrolyte. The active area of each electrode was $250\;{\mu}m{\times}200\;{\mu}m$ with a gap of 200 ${\mu}m$ between the electrodes. Microelectrodes results in maximum amplification of signal, since the signal enhancement effect due to cycling of the reduced and oxidized species strongly depends on the inter electrode distance. Analytes such as methylene blue and guanosine were characterized using the fabricated electrodes and their electrochemical characteristics were compared with conventional bulk electrodes. The device so developed shall find use as disposable electrochemical cell for rapid and sensitive analysis of electroactive species.

• 한국정보디스플레이학회:학술대회논문집
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• 2004.08a
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• pp.55-58
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• 2004

High Xe-content PDP characteristics are discussed. A high efficacy, up to 5 lm/W for a 50% Xe in Ne gas mixture, is realized in 4-inch color PDP test panel designs with low cost stripe-type barrier rib structures, that are powder blasted in soda lime glass. Furthermore, for a high Xe-content a high luminance can be obtained with a relatively small electrode area. Therefore the inter cell gap and the driving margin can be increased in a stripe-type barrier rib structure. Finally, for a high Xe-content the panel lifetime increases, due to increasing luminance and firing voltage stability. Clearly, these findings may direct the design development for next generation PDPs towards a high Xe-content

• Proceedings of the KIEE Conference
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• 1989.11a
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• pp.139-141
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• 1989

The characteristics of the hollow cathode discharge were investigated. Temperature distribution of the hollow cathode was investigated and I-V curves of the hollow cathode discharge were obtained. In this paper variables are chamber pressure, Ar gas flow rate injected through the cathode tube and the gap distance between cathode and anode. The inter electrode electron temperature and density were measured by Langmuir probe.

• Proceedings of the KIEE Conference
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• 1994.07b
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• pp.1639-1642
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• 1994

The severe conditions such as rated voltage of 800kV, gas pressure of $5kg/cm^2$ and rated lighting impulse withstand voltage of 2400kV were adopted for the design of spacers in the 800kV GIS to give a sufficient design margin. The design criteria on the maximum electric field strength of the center conductor and the insulator surface were established by considering the insulator surface characteristics, electrode area and surface effects in the unequal electric field strength of the given gap. The design parameters such as inter/outer envelope degree, thickness, inter/outer inserts, triple junction gap were determined by calculating the electric field using FLUX-2D program package and by referring to the published papers. The mechanical stress analysis was conducted on the feasible model spacers that showed good electric field distributions to confirm the sufficient mechanical design margin. The 800kV spacer designed as described above is now in the process of manufacturing.

• Environmental Engineering Research
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• v.22 no.2
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• pp.141-148
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• 2017

Globalization, industrialization, mining, and uncontrolled population growth have fostered a shortage of potable water. Therefore, it has become imperative to understand an effective and reasonable water purification technique. A renewed interest in electrocoagulation (EC) has been spurred by the search for reliable, cost-effective, water-treatment processes. This paper has elucidated a technical approach for getting rid of heavy metals and total suspended solids (TSS) from synthetic water using an aluminum electrode. The effect of operational parameters, such as current density, inter-electrode distance, operating time, and pH, were studied and evaluated for maximum efficiency. This study corroborates the correlation between current density and removal efficiency. Neutral pH and a low electrode gap have been found to aid the efficacy of the EC setup. The outcome indicates that a maximum TSS removal efficiency of 76.6% occurred at a current density of $5.3mA/cm^2$ during a contact time of 30 min. In the case of heavy metals remediation, 40 min of process time exhibited extremely reduced rates of 99%, 59.2%, and 82.1%, for Cu, Cr, and Zn, respectively. Moreover, kinetic study has also demonstrated that pollutants removal follows first-and second-order model with current density and EC time being dependent.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.25 no.3
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• pp.529-536
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• 2001

We investigate a surface-micromachined capacitive accelerometer with the grid-type electrodes surrounded by a perforated proof-mass frame. An electromechanical analysis of the microaccelerometer has been performed to obtain analytical formulae for natural frequency and output sensitivity response estimation. A set of prototype devices has been designed and fabricated based on a 4-mask surface-micromachining process. The resonant frequency of 5.8$\pm$0.17kHz and the detection sensitivity of 0.28$\pm$0.03mV/g have been measured from the fabricated devices. The parasitic capacitance of the detection circuit with a charge amplifier has been measured as 3.34$\pm$1.16pF. From the uncertainty analysis, we find that the major uncertainty in the natural frequency of the accelerometer comes from the micromachining error in the beam width patterning process. The major source of the sensitivity uncertainty includes uncertainty of the parasitic capacitance, the inter-electrode gap and the resonant frequency, contributing to the overall sensitivity uncertainty in the portions of 75%, 14% and 11%, respectively.