• 대한기계학회논문집A
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• 제38권8호
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• pp.893-898
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• 2014

펄스 레이저를 적용한 실버나노와이어의 접합 영향이 연구되었다. 조사된 레이저 펄스 에너지는 실버나노와이어 네트워크에서 실버나노와이어간에 접합을 유도하였으며 이로 인해 투명 기저위의 실버나노와이어 네트워크 박막에 전기 저항값을 조절할 수 있었다. 특히 이러한 나노네트워크에서의 접합은 개별 나노와이어의 접촉점의 형태로 발생되었고 접합의 효과는 전체 실버나노와이어 네트워크의 전기저항 변화 측정으로 평가하였다. 또한 레이저 빔 펄스폭 및 레이저 평균 출력이 나노와이어 접합 비율 평가에 적용되어 연구되었다. 실버나노와이어 네트워크의 광학 특성도 관찰되었으며 이에 레이저 공정 요소 대비 효과도 연구되었다. 최적화된 레이저빔 적용 재료처리는 특화된 국부 재료 특성 개선에 장점을 보였다. 펄스 레이저를 이용한 실버나노와이어의 재료처리의 적용과 그 효과에 대해서도 논의한다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2004년도 제26회 학술발표회 초록집
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• pp.121-121
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• 2004

• 한국세라믹학회지
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• 제48권6호
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• pp.487-492
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• 2011

The effect of the application of lanthanum strontrium manganite and yttria-stabilized zirconia (LSM-YSZ) nano-composite fabricated by pulsed laser deposition (PLD) as a cathode of solid oxide fuel cell (SOFC) is studied. A gradient-structure thin-film cathode composed of 1 micron-thick LSM-YSZ deposited at an ambient pressure ($P_{amb}$) of 200 mTorr; 2 micron-thick LSM-YSZ deposited at a $P_{amb}$ of 300 mTorr; and 2 micron-thick lanthanum strontium cobaltite (LSC) current collecting layer was fabricated on an anode-supported SOFC with an ~8 micron-thick YSZ electrolyte. In comparison with a 1 micron-thick nano-structure single-phase LSM cathode fabricated by PLD, it was obviously effective to increase triple phase boundaries (TPB) over the whole thickness of the cathode layer by employing the composite and increasing the physical thickness of the cathode. Both polarization and ohmic resistances of the cell were significantly reduced and the power output of the cell was improved by a factor of 1.6.

• Food Science and Biotechnology
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• 제18권6호
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• pp.1537-1540
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• 2009

Enterobacter sakazakii is a representative microorganism whose presence in infant foods can cause serious disease. The purposes of this study were to determine the inactivation effects of intense pulsed light (IPL) on E. sakazakii and the commercial feasibility of this sterilization method. The inactivation of E. sakazakii increased with increasing electric power and treatment time. The cells were reduced by 5 log cycles for 4.6 and 1.8 msec of treatment at 10 and 15 kV of electric field strength, respectively. The sterilization effects on commercial infant foods were investigated at 15 kV. The cell population in an infant beverage, an infant meal, and an infant powdered milk product inoculated with E. sakazakii were inactivated exponentially as a function of time and reduced by 4.0, 2.5, and 1.5 log cycles for 9.4, 7.0, and 7.0 msec of treatment time, respectively.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2008년도 제39회 하계학술대회
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• pp.904-905
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• 2008

In this paper, a novel 60kV, 300A, 3kHz pulsed power supply based on IGBT stacks is proposed. Proposed scheme consists of series connected 9 power stages to generate maximum 60kV output pulse and 15kW series resonant power inverter to charge DC capacitor voltage. Each power stages are configured as 8 series connected power cells and each power cell generates up to 830VDC, 300A pulses. Finally pulse output voltage is applied using total 72 series connected IGBTs. The synchronization of gating signal is important of series operation of IGBTs. For gating signal synchronization, full bridge inverter and pulse transformer generates on-off signals of IGBT gating and specially designed gate power circuit was used.

• Nuclear Engineering and Technology
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• 제51권3호
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• pp.776-783
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• 2019

Laser welding is usually a more effective method than electron-beam one since a vacuum chamber is not required. It is important for joining Zr-1%Nb (E110) alloy in a manufacturing process of nuclear fuel rods. In the present work, effect of energy parameters of pulsed laser welding on properties of butt joints of sheets with a thickness of 0.5 mm is investigated. The most efficient combination has been found (8-11 J pulse energy, 10-14 ms pulse duration, 780-810 W peak pulse power, 3 Hz pulse frequency, 1.12 mm/s welding speed). The results show that ultimate strength under static loading can not be used as a quality criterion for zirconium alloys welds. Increased shielding gas flow rate does not allow to protect weld metal totally and contributes to defect formation without using special nozzles. Several types of imperfections of the welds have been found, but the major problem is branching microcracks on the surface of the welds. It is difficult to identify the cause of their appearance without additional research on improving the welding zone protection (gas composition and flow rate as well as nozzle configuration) and studying the hydrogen content in the welds.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2001년도 Proceedings ICPE 01 2001 International Conference on Power Electronics
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• pp.816-821
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• 2001

The generation of isolated grids by pulsed converters with characteristics close to the mains of the utility companies is a pretentious task. For generation of three-phase four-wire isolated grids are presented possible topologies and the demands on the system control are processed. For control of all conceivable load and error conditions, an extensive control technology is necessary. This must permit unsymmetrical operating conditions for an unlimited period but recognize errors simultaneously and therefore an overloading the consumer and the power semiconductors reliable may prevent. Measurement results on an experimental plant show the problems to be solved.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제51권11호
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• pp.628-634
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• 2002

A capacitor-charging power supply using high frequency inverter technology is strongly recommended for the charging section of the pulsed power supplies. A high frequency inverter swiching makes the overall system size small. The command-charging feature can guarantee the higher reliability of switching function. The protection circuit can be easily included in the system and the good regulation of charging voltage can be acieved by the feedback system. Several modules can be stacked to supply required output power and a failed module can be easily replaced. A 50-kV, 35-kW capacitor charging power supply is developed. In this paper the detailed design and test results of a prototype unit are presented.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1995년도 추계학술대회 논문집
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• pp.125-128
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• 1995

The remote sleeve repair-welding technology using the pulsed Nd:YAG laser for increasing the lifetime of the steam generator tube in the nuclear power plant has been developed. The laser welding has many advantages on deep penetration depth and narrow heat affect zone(HAZ). The inconel 600 tube and inconel 690 sleeve used high temperature and high pressure service have been welded as round lap welds. It is found that the relation between the connection width and welding parameters. It is found that the shear strength in proportion to the connection width by conducting tensile-shear tests.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2006년도 제37회 하계학술대회 논문집 C
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• pp.1550-1551
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• 2006

An L-band linear accelerator system for e-beam sterilization is under design for bio-technology application. The klystron-modulator system as RF microwave source has an important role as major components to offer the system reliability for long time steady state operation. A PFN line type pulse generator with a peak power of 71.5-MW, $7{\mu}s$, 285 pps is required to drive a high-power klystron. The high power pulse transformer has a function of transferring pulse energy from a pulsed power source to a high power load. The pulse transformer producing a pulse with a peak voltage of 275 kV is required to produce 30-MW peak and 60 kW average RF output power at the frequency of 1.3-GHz. We have designed the high power pulse transformer with 1:13 step-up ratio. The peak and average power capability is 71.5-MW (275 kV, 260 A at load side with $7{\mu}s$ pulse width) and 130 kW, respectively. In this paper, we present a system overview and initial design results of the high power pulse transformer.