• Proceedings of the Korean Vacuum Society Conference
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• 2010.08a
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• pp.102-102
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• 2010

수 Tera Watt급의 가속기 및 펄스파워 시스템은 다수의 스위치를 사용하고 있으며, 이와 같은 가속기 및 시스템의 성능은 기체방전 스위치의 성능에 직접적으로 관련되어 있다. 일반적으로 이와 같은 기체방전, 액체방전 고출력 스위치는 다목적으로 많은 연구와 개발에 응용되고 있다. 예를 들어 천둥 펄스전자빔 발생장치는 12개의 Marx gap 및 3개의 100 kV 펄스충전 전기트리거 gap을 가지고 있다. 기체 방전 또는 액체 방전 펄스 충전 갭 스위치의 음극에 펄스 고전압이 인가되면 이로 인하여 음극에서 전자빔이 발생한다. 내부에는 전자빔이 양극과 충돌하는 순간 양극표면에 플라스마가 형성된다. 이와 같은 플라스마 sheath는 축 방향 이극관 안에서 양극충전 에서 음극으로 팽창하면서 전파하며, 또한 거의 동시에 음극표면에도 플라스마가 형성되어 음극에서 양극으로도 팽창하여 전파하게 된다. 이와 같은 펄스충전 고출력 갭 스위치 안에서 발생되는 방전 플라스마의 특성에 관한 갭 breakdown 과정에 대한 특성연구를 한다. 고출력스위치의 특성 조건으로는 방전전압, 방전시간, jitter 등이 있다. 본 연구에서는 최대전압 600 KV, 최대전류 88 KA, 펄스 폭 60 ns의 특성을 가지는 고전압펄스 시스템 '천둥'을 이용하여 방전 챔버에 고전압 펄스를 인가하고 N2와 SF6 혼합기체 종류와 압력에 따른 방전 현상을 연구하였다. 전극은 구리텅스텐 합금재질의 표준전극을 사용하였고, 전극 간격은 20 mm로 고정하였다. 방전 챔버 압력을 100 torr에서 4 기압까지 변화시켜가며 실험을 진행하였고, N2에 대한 SF6의 혼합비율을 0%~100%까지 변화시키며 실험을 진행하였다. 방전 챔버에는 C-dot probe와 B-dot probe를 설치하여 전압과 전류를 측정하였고, C-dot probe 와 B-dot probe는 각각 Northstar사의 10000:1 고전압 probe와 rogowiski coil을 이용하여 시준 하였다. 실험결과 방전전압은 압력이 증가함에 따라 증가하다가 2 기압 이상에서는 완만히 증가하는 경향을 보였고, SF6 혼합비율은 0~10%까지 급격히 증가하고, 그 이상의 혼합비율에서는 완만히 증가하였다. 방전개시시간은 혼합기체 압력에 따라 증가하며 1기압 이상에서는 급격히 증가 하였다. SF6 혼합비율에 따라서는 1 기압 조건까지는 큰 차이가 없었으나 2 기압부터는 급격히 증가하였다. 안정성을 나타내는 jitter는 SF6 100%일 때 가장 컸으나 혼합기체의 변화에 따른 큰 차이는 없었다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.10
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• pp.16-23
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• 2018

Alternative technologies for sludge treatment and disposal need to be developed urgently because the amount of produced production has increased continuously. In this study, Pulsed Electric Fields (PEF) technique was applied for sludge solubilization and the performance was evaluated. The PEF equipped with electrodes coated by epoxy resin and teflon was inducted to the activated sludge suspension, and the effect of the coating materials on the solubilization was determined. In addition, the effect of the applied voltage on the solubilization yield was investigated as the applied voltage was increased from 6 to 12 and 15 kV. Sludge solubilization was not observed when the epoxy-coated electrode was used for PEF induction regardless of the applied voltage. However, sludge solubilization occurred when 12 and 15 kV were applied to the teflon-coated electrodes. The MLSS decreased to 9%, and the soluble-COD increased to 496% when the applied voltage was 15 kV. But sludge solubilization did not happen under 6 kV condition. The corona discharge was observed at applied voltages of 12 and 15 kV, (Ed- sorry but I cannot understand the following highlight) but if 6 kV, strongly indicating that the corona discharge make the sludge solubilized, which suggests that the critical voltage for sludge solubilization lies between 6 and 12 kV. Consequently, proper selection of electrode-coating materials and the applied voltage of PEF could lead to sludge solubilization by corona discharge.

• 한국신재생에너지학회:학술대회논문집
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• 2009.06a
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• pp.392-394
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• 2009

Direct Carbon Fuel Cells (DCFCs) generates electricity directly converting the chemical energy in coal. In the present study, effects of anode and current collector materials on the power density of DCFC are investigated experimentally. The adopted DCFC system is combined type of solid oxide fuel cells (SOFC) and molten carbonate fuel cells (MCFC) with the use of a liquid-molten salt anode and a solid oxide electrolyte, proposed by SRI. Power densities of 25 mm button cells with various combination of anode materials and current collector materials are measured.

• Proceedings of the KIEE Conference
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• 2008.10a
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• pp.101-102
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• 2008

SF6 widely used as insulating gas is rising as the environment problem. For decreasing this greenhouse gas, electrical breakdown characteristics of vacuum with air are studied in non-uniform field. The gap of needle to plane was 0.5mm. The pressure of vacuum the range of 10^-4${\sim}$10^-5torr. The diameter of a plane made of the stainless steel is 150mm. As a result of the experiment, the breakdown voltage is increased about degree of vacuum increased. The electrode material influenced breakdown voltage in vacuum.

• Electronics and Telecommunications Trends
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• v.29 no.6
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• pp.63-70
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• 2014

최근 사물인터넷 통신이 화두로 대두되고 있으며, 웨어러블 디바이스가 핵심기기중의 하나가 되고 있다. 본고에서는 스트레처블 디스플레이의 관점에서 웨어러블 기기, 의료기기 및 터치기술과의 융합 가능성에 대하여 정리하였다. 또한, 스트레처블 디스플레이를 구현하기 위한 기술은 아직은 기초 연구단계의 연구개발이 진행되고 있으며, 기판과 전극 재질의 입장에서 최근 기술들을 정리하였다. 향후 스트레처블 디스플레이가 구현된다면 그 시장 및 응용성은 급속히 확대될 것으로 전망된다.

• Proceedings of the KIEE Conference
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• 1998.07d
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• pp.1419-1421
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• 1998

Many kind of factors have influence on the electrical properties of polymer such as mechanical stress, impurity, additives, chemical blend, interfacial phenomena and so on. In this study, we lay emphasis on interfacial phenomena which is important part in insulating design of power cable. The electrical conduction characteristics of XLPE film are investigated as a function of different electrode materials in MIM Interfaces.

• KSBB Journal
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• v.11 no.3
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• pp.360-366
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• 1996

Electrodialysis of acetic acid was studied to find out the trend of the transport of organic acids through ultrafiltration and ion exchange membranes. The net transport rate of acetic acid was determined from the electro-migration velocity relative to the electro-osmotic flow rate through the membrane. Electro-osmosis flows through ultrafiltration membranes were from the anodic side to the cathodic side in the presence of electric field. The surface of ultrafiltration membrane was measured by the electro-osmotic flow to be charged negatively. Different transport behaviors of acetic acid were found with the ultrafiltration membranes of different materials. In general, regenerated cellulose membranes (YM series) were more effective than polysulfone membranes (PM series) for the transport of acetic acid. The transport of acetic acid was affected by electric strength, distance between the electrodes, surface area of electrode, temperature, and pore size of membrane. The transport rate through the ion exchange membrane was 1.5 to 3 times of those through the ultrafiltration membranes at the constant current of 150 mA in the experimental ranges. The transport rate of acetic acid through the ion exchange membrane increased by 10% with a pulse electric field of 10 sec/hr.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.3 no.2
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• pp.105-112
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• 2005

The electrolytic reduction of uranium oxide in a LiCl-Li$_{2}$O molten salt system has been studied in a 10 g U$_{3}$O$_{8}$ /batch-scale experimental apparatus with an integrated cathode assembly at 650$^{\circ}C$. The integrated cathode assembly consists of an electric conductor, the uranium oxide to be reduced and the membrane for loading the uranium oxide. From the cyclic voltammograms for the LiCl-3 wt$\%$ Li$_{2}$O system and the U$_{3}$O$_{8}$-LiCl-3 wt$\%$ Li$_{2}$O system according to the materials of the membrane in the cathode assembly, the mechanisms of the predominant reduction reactions in the electrolytic reactor cell were to be understood; direct and indirect electrolytic reduction of uranium oxide. Direct and indirect electrolytic reductions have been performed with the integrated cathode assembly. Using the 325-mesh stainless steel screen the uranium oxide failed to be reduced to uranium metal by a direct and indirect electrolytic reduction because of a low current efficiency and with the porous magnesia membrane the uranium oxide was reduced successfully to uranium metal by an indirect electrolytic reduction because of a high current efficiency.

• Resources Recycling
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• v.16 no.5
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• pp.51-56
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• 2007

Plastics are widely used in everyday life as very useful material. In Korea, about 4 million tons of plastic wastes are generated annually. However, recycling ratio is below 30%, and most of plastic wastes are disposed by landfill and incineration. Hence, the development of material separation technique that can recycle plastic wastes is a necessary situation. In this study, Triboelectrostatic separation for recovery of PET from final plastic wastes obtained from the sink product after wet-type gravity separation has been carried out. In the charging properties, the charge polarity and charge density of PET and PVC were very effective with the tirbo-charger made of PP and HDPE with the decrease in relative humidity. In material separation using HDPE cyclone charger, a PET grade of 96.80% and a recovery of 85.0% were achieved at 30 kV and the splitter position -2cm from the center. In order to obtain PET grade of 98.5%, PET recovery should be sacrificed by 24% with moving the splitter from the center to -6cm position.

• Journal of the Korean GEO-environmental Society
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• v.22 no.11
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• pp.31-37
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• 2021

To prevent accidents due to the cavities and loosened layers formed due to water leakage from the deteriorated buried pipes, evaluation of the changes in water contents around the buried pipes is required. As a method to evaluate the water contents of the soils, time domain reflectometry (TDR) system can be adopted. However, slender electrodes used in standard TDR probe may be damaged when buried in the ground. Thus, in this study, buried type TDR module was developed for the evaluation of the water contents with maintaining required shape of the electrodes in the ground. The TDR module is composed of three electrodes connected to the core conductor and outer conductor and a casing to prevent deformation and maintain alignment of the electrodes in the ground. For the verification of TDR waveforms measured using the TDR module, comparative analysis was conducted with the TDR waveforms measured using the standard TDR probe, and the relationship between the volumetric water content of the soils and the travel time of the guided electromagnetic wave was constructed. In addition, a model test was conducted to test the applicability of the buried type TDR module, and the experimental result shows that the TDR module clearly evaluates the changes in volumetric water contents due to the leakage from the modeled buried pipe. Therefore, the buried type TDR module may be effectively used for the health monitoring of the buried pipe and the evaluation of the water contents around the pipes buried in the urban pavements.