• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1997.11a
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• pp.258-261
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• 1997

The sealing integrity is related to the safe operation of arrester the prime failure reason of porcelain housed arresters is moisture ingress. To be a meaningful tests a polymer arrester sealing test must be a realistic acceleration of field service. We think the test should be an accelerating course of actual temperatures, the enduring property to mechanical load and temperatures should be considered together. A union test method consisting of the thermal mechanical test and thermal cycling test is proposed to test the sealing integrity of polymeric arresters, which uses dielectric loss, leakage current 1mA DC voltage and partial discharge as the diagnostic techniques, and the test results were presented. The comparison states that the TMTCUT method is suitable fur the test of sealing integrity of polymeric arresters. .

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.59 no.4
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• pp.364-371
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• 2010

In this paper, we propose the landscape lighting power control system with solar sell generator equipment for energy saving, and also which is included the landscape lighting power transformation device. The power transformation device can check inverse current in the power of the solar cell module and control the power of the battery. And we present the design of landscape lighting power control system. The power control system uses microprocessor with charging system and power transformation device. And also it can control the power of loads under consideration intensity of illumination. The landscape lighting loads are composed of LED(Lighting Emitting Diode) and HID(High Intensity Discharge)lamps. To evaluate property, we installed the solar cell array which generate three kilo watt power. Experimental results show that the proposed system can have stability and energy saving on the mixed configuration of electric loads with DC and AC lamps.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.06a
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• pp.545-546
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• 2006

This study was performed to investigate the surface properties of electrochemically oxidized pure titanium by anodic spark discharging method. Commercially pure titanium plates of $10{\times}20{\times}1[mm]$ in dimensions were polished sequentially emery paper. Anodizing was performed at current density of $76.2\;[mA/cm^2]$, application voltage of 290, 350, 400 [V] using a regulated DC power supply, which allowed automatic transition constant current when a preset maximum voltage has been reached. The Ti surface oxided films was characterized by scanning electron microscope(SEM). The precipitation of HA(Hydroxyapatite) crystals on anodized surface was greatly accelerated by hydrothermal treatment. The concentrations of DL-$\alpha$-Glycerolphosphate Magnesiurn(DL-$\alpha$-GP-Mg) salt and Ca acetate in an electrolyte was highly affected the precipitation of HA crystals converted by Ti Anodized oxide films by Shape of Impulse Voltage.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.02a
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• pp.437-437
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• 2010

DC Hollow cathode 방전은 약 100여 년 전, Paschen에 의해 실험된 이후로 광원, 스퍼터링 공정, 이온빔 소스 등 다양한 분야에 이용되어 왔다. 최근 태양전지용 마이크로 결정질 실리콘 증착 시, RF CCP의 전극에 복수의 홀 혹은 트렌치 구조를 두어 Hollow cathode 방전 효과를 이용하여 향상된 공정 속도로 공정을 진행한다. 그러나 RF-MHCD (Multi hole cathode discharge) 공정을 위한 최적 규격의 홀 기에 관한 연구는 그 중요성과 응용성에도 불구하고 깊게 이루어지지 못한 바 있다. 그러므로 저자는 Capacitively Coupled Plasma (전극 간격 : 4cm, 전극 직경 : 14cm) 장비에서 평면 전극과 10mm 깊이와 각각 3.5mm, 5mm, 7mm, 10mm 직경의 홀이 있는 4개의 전극을 이용하여 Argon RF-MHCD 방전을 관찰하여 조건 별 최적의 홀 전극 디자인을 도출하였다. 실험 조건은 64.5mTorr ~ 645mTorr압력 범위/ 1A~9A이며, 플라즈마는 전극 사이 중앙에 설치한 RF-compensated Langmuir Probe와, 전극과 전기적으로 접촉하는 1000:1 Probe 와 Voltage-Current Probe를 이용하여 측정되었다. 실험 결과 압력 조건 별로, 최적의 전자 밀도를 유도하는 전극 상 홀의 직경이 달라짐을 확인하였다.

• Bulletin of the Korean Chemical Society
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• v.15 no.5
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• pp.353-356
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• 1994

The $CN(B^2{\Sigma}^+)$ radical was produced in a jet using an electric dc discharge of the precursor $CH_3CN$ with inert carrier gases. The rotationally resolved Fourier transform emission spectra of the 0-0 band of the $(B^2{\Sigma}^+{\to}X^2{\Sigma}^+)$ transition of CN have exhibited different distribution of the intensity for the carrier gases He and Ar, respectively. From the analysis of intensity distribution in the spectra, the mechanism for rotational cooling process of CN radical in a supersonic expansion has been suggested.

• Journal of Korean Society of Environmental Engineers
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• v.22 no.2
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• pp.211-216
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• 2000

In this paper, experimental investigations were carried out to remove NOx, SOx simultaneously from a simulated combustion flue gas [$NO(0.02%)-SO_2(0.08%)-CO_2-Air-N_2$] by using a pulse corona induced plasma chemical processing. Discharge domain of wire-cylindrical plasma reactor was separated from a gas flow duct to avoid unstable discharge by aerosol particle deposited on discharge electrode and grounded electrode. The NOx, SOx removal was experimentally investigated by a reaction induced to ammonium nitrate, ammonium sulfate using a low price of aqueous NaOH solution and a small quantity of ammonia. Volume percentage of aqueous NaOH solution used was 20% and $N_2$ flow rate was $2.5{\ell}/min$ for bubbling aqueous NaOH solution. Ammonia gas(l4.82%) balanced by argon was diluted by air and was introduced to a main simulated flue gas duct through $NH_3$ injection system which was in downstream of reactor. The $NH_3$ molecular ratio(MR) was determined based on [$NH_3$] and [$NO+SO_2$]. MR is 1.5. The NOx removal rates increased in the order of DC, AC and pulse, but SOx removal rates was not significantly effected by source of electricity. The NOx removal rate slightly decreased with increasing initial concentration. but SOx removal rate was not significantly affected by initial concentration. The NOx, SOx removal rates decreased with increasing gas flow rate.

• Journal of Korean Neurosurgical Society
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• v.49 no.6
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• pp.355-358
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• 2011

Objective : Subdural hygroma (SDG) is a complication occurring after head trauma that may occur secondary to decompressive craniectomy (DC). However, the mechanism underlying SDG formation is not fully understood. Also, the relationship between the operative technique of DC or the decompressive effect and the occurrence and pathophysiology of SDG has not been clarified. Purpose of this study was to investigate the risk factors of SDG after DC in our series. Methods : From January 2004 to December 2008, DC was performed in 85 patients who suffered from traumatic brain injury. We retrospectively reviewed the clinical and radiological features. For comparative analysis, we divided the patients into 2 groups : one group with SDG after craniectomy (19 patients; 28.4% of the total sample), the other group without SDG (48 patients; 71.6%). The risk factors for developing SDG were then analyzed. Results : The mean Glasgow Outcome Scale (GOS) scores at discharge of the groups with and without SDG were 2.8 and 3.1, respectively (p<0.0001). Analysis of radiological factors showed that a midline shift in excess of 5 mm on CT scans was present in 19 patients (100%) in the group with SDG and in 32 patients (66.7%) in the group without SDG (p<0.05). An accompanying subarachnoid hemorrhage (SAH) was seen in 17 patients (89.5%) in the group with SDG and in 29 patients (60.4%) in the group without SDG (p<0.05). Delayed hydrocephalus accompanied these findings in 10 patients (52.6%) in the group with SDG, versus 5 patients (10.4%) in the group without SDG (p<0.05). On CT, compression of basal cisterns was observed in 14 members (73.7%) in the group with SDG and in 18 members of the group without SDG (37.5%) (p<0.007). Furthermore, tearing of the arachnoid membrane, as observed on CT, was more common in all patients in the group with SDG (100%) than in the group without SDG (31 patients; 64.6%) (p<0.05). Conclusion : GOS showed statistically significant difference in the clinical risk factors for SDG between the group with SDG and the group without SDG. Analysis of radiological factors indicated that a midline shifting exceeding 5 mm, SAH, delayed hydrocephalus, compression of basal cisterns, and tearing of the arachnoid membrane were significantly more common in patients with SDG.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2011.11a
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• pp.540-543
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• 2011

This work is devoted to an experimental investigation on conceptual design of dual consecutive stage micro plasma thruster (${\mu}PT$). Optimization study on the thruster configuration has been performed for various electrode gap distances from 1 mm to 2 mm and the hole diameter from 0.3 mm to 2 mm depending on desired operating conditions and corresponding nozzle design requirement. The operation of ${\mu}PT$ at low pressure from $10^{-1}$ Torr to $10^{-4}$ Torr and at various argon flow rates ranging from 5 sccm to 300 sccm has been studied to understand the physic of plasma and the gas dynamics in details. The specific impulse can reach up to 3000-4000 seconds at low power consumptions from 1 to 5 W. Image of exhaust plume from ${\mu}PT$ will be provided and electrical characteristics is also mentioned in this paper.

• Proceedings of the KSME Conference
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• 2003.04a
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• pp.1678-1683
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• 2003

DBD(Dielectric Barrier Discharge) plasma in air is well established for the production of large quantities of ozone and is more recently being applied to aftertreatment processes for HAPs(Hazardous Air Pollutants). Although DBD high electron density and energy, its potential use as nano and sub-micron sized particle charging are not well known. Aim of this work is to determine design and operating parameters of a two-stage ESP with DBD. DBD and ESP are used as particle charger and precipitator, respectively. We measured particle precipitation efficiency of two-stage ESP and estimated ozone decomposition of both pelletized $MnO_2$ catalyst and pelletized activated carbon. To examine the particle precipitation efficiency, nano and sub-micron sized particles were generated by a tube furnace and an atomizer. AC voltage of $7{\sim}10$ kV(rms) and 60 Hz is used as DBD plasma source. DC -8 kV is applied to the ESP for particle precipitation. The overall particle collection efficiency for the two-stage ESP with DBD is over 85 % under 0.64 m/s face velocity. Ozone decomposition efficiency with pelletized $MnO_2$ catalyst or pelletized activated carbon packed bed is over 90 % when the face velocity is under 0.4 m/s in dry air.

• Transactions of the Korean hydrogen and new energy society
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• v.28 no.3
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• pp.238-245
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• 2017

Mg-Ni nanoparticles were synthesized by a physical vapor condensation method (DC arc-discharge) in a mixture of argon and hydrogen atmosphere, using compressed mixture of micro powders as the raw materials. The crystal phases, morphology, and microstructures of nanoparticles were analyzed by means of X-ray diffraction (XRD) and high-resolution transmission electron microscopy (HRTEM). It was found that the intermetallic compounds of $Mg_2Ni$ and $Mg_2Ni$ formed with existence of phases of Mg, Ni, and MgO in Mg-Ni nanoparticles. After one cycle of hydrogen absorption/desorption process (activation treatment), Mg-Ni nanoparticles exhibited excellent hydrogen absorption properties. $Mg_2Ni$ phase became the main phase by aphase transformation during the hydrogen treatments. The phenomenon of refinement of grain size in the nanoparticle was also observed after the hydrogen absorption/desorption processes, which was attributed to the effect of volume expansion/shrinkage and subsequent break of nanoparticles. Maximum hydrogen absorption contents are 1.75, 2.21 and 2.77 wt.% at 523, 573 and 623 K, respectively.