• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2005년도 춘계학술대회
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• pp.59-63
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• 2005

The 800-kW PM (permanent magnet) synchronous generator is developed as a wind power generator. The matching converter is designed to control the torque and power depending on the wind speed regime. The generator starts to generate the power at the speed of 9 rpm and the rated output is generated at the speed of 25 rpm. The rated output power of an inverter is 750 kW when the PM synchronous generator is delivering 800 kW to the inverter. The inverter is specially designed to perform the maximum power point tracking (MPPT) at the low wind speed regime that is typical wind environment in Korea. The inverter test was done with a 2 MW M-G system at KERI (Korea Electric Research Institute). The M-G set has a 2 MW motor driver and a 38:1 gear to match the speed between the motor and the PM generator. The torque simulating the wind is applied to the PM generator by a DC motor. The test results show the inverter efficiency of $94.3\%$ at the rated power generating condition. The measured values show that the MPPT algorithm is working well. Overall reliability will be verified through the long-term site test.

• 한국산학기술학회논문지
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• 제16권7호
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• pp.4855-4862
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• 2015

본 논문에서는 전력설비의 동작 상태를 주기적으로 감시 및 기록함으로써 전기안전사고를 예방하고 사후 원인 분석을 지원하기 위한 저가형 전력 성분 측정 및 기록 시스템을 제안한다. 제안된 시스템에서는 정밀한 전력 성분의 측정과 기록, 원격 측정이 가능하면서도 비용을 줄일 수 있도록 부품을 선정하여 제작하였다. 특히, IEEE 1459-2010에 정의된 전력 성분을 계산하기 위해 MAXIM사의 78M6631을 이용함으로써 저비용 고성능 시스템 구현이 가능하였다. 개발된 시스템은 공인 시험기관에서 사용하고 있는 YOKOGAWA 전력분석기 WT1600 과 같은 표준 장비를 이용하여 측정 성능 시험을 실시하였다. 그 결과 측정 오차가 0.5%이하로 나타났고 6개월 이상 현장에 설치하여 동작 신뢰성과 원격 측정 성능 시험을 실시하여 그 성능을 입증하였다.

• 대한물리치료과학회지
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• 제12권4호
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• pp.79-87
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• 2005

The purposes of this study were to test the effects of the low power laser and exercise on the recovery in the cerebellar injured rats by 3-Acetylpyridine. Cerebellar injury was induced by 3-Acetylpyridine chemoablation of the inferior olive. Thirty Sprague-Dawley rats were assigned to the normal control and 3AP control and 3 experimental groups. Each experimental group was treated from 5 days after being injured for the 5 min(laser group), 10 min(exercise group) and 15min(exercise with laser) everyday during the 2 weeks. The Hindlimb splay test, Vestibular drop test, Hindlimb stride width test, Maximal Height Vertical Jump test were examined at pre-treatment on 1st day and 5th, 10th, 14th days after treatment on the cerebellar injured rats by 3AP. The results of this experiment were as follows; There were significantly increased exercise on the 3 experimental groups comparied with the 3AP control group, in the Hindlimb splay test, Vestibular drop test, Hindlimb stride width test, and Maximal Height Jump test(P<.05).

• 비파괴검사학회지
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• 제24권4호
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• pp.325-330
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• 2004

원자력발전소에는 여러 종류의 케이블이 전력공급, 감시 및 제어신호의 전달을 위해 열악한 환경하에서 이용되고 있다. 발전소의 안전한 운전을 위해서 이 케이블이 어느 정도 열화 되었는지 확인할 필요가 있다. 특히, 원자력발전소의 수명 연장과 더불어 저압 케이블을 장기간 사용함에 따라서 저압케이블의 열화를 평가하기 위한 방법이 필요하게 되었다 저압케이블의 열화를 측정하는 파라미터로는 주변 온도, 절연재질의 경도, 파단시 연신률(EAB, Elongation At Breaking Point) 등이 있다. 그러나, 온도나 경도를 계측하는 검사는 정량적인 판단기준의 설정이 곤란하고 진단의 정밀도가 낮으며, 부분적으로 샘플링하는 방법은 샘플링되는 케이블에 연결된 부하를 정전시켜야 하고 장소와 시간적인 제약이 있으며, 전기적 측정법은 노화 초기부터 중기까지의 열화정도를 확인하기 어렵다. 본 연구에서는 재료의 열화에 따라서 초음파의 음속이 변화한다는 이론적인 배경(1,2)을 바탕으로 저압 케이블 재료의 열화에 따른 초음파의 음속을 측정하였다. 이를 위해, 원자력발전소에서 사용되는 저압케이블을 가속 열화시켰으며, 저압케이블의 피복재에서 초음파의 음속을 측정할 수 있는 장비를 개발하여, 초음파의 음속측정 후 인장시험을 통해 파단시 연신률을 측정하였다. 파단시 연신률이 증가함에 따라서 음속이 선형적으로 감소하였으며, 초음파의 음속은 열화의 정량적 평가 파라미터로서의 사용 가능성을 확인할 수 있었다.

• 설비공학논문집
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• 제11권2호
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• pp.193-204
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• 1999

Performance of a variable-speed, roller-type vane compressor was evaluated at low evaporating temperature. First, an experimental investigation was conducted to examine the performance variation as functions of both outdoor temperature and rotating speed. For this purpose, a typical heat pump was implemented as a test apparatus to measure mass flow rate and power input. Secondly, computational investigations corresponding to the heat pump test conditions were performed to predict compressor performance using ORNL Map-Based compressor model. Results obtained from the heat-pump experiments showed that both mass flow rate and power consumption were sensitively dependent on both evaporating temperature and compressor speed as was predicted from the computational results. From the comparisons of both experimental and computational results, it was well recognized that the ORNL model was subjected to larger error in the accuracy of prediction as outdoor temperature decreased. When the outdoor temperature was above $-5^{\cire}C$, errors of predicted values corresponding to both mass flow rate and power consumption were estimated as $\pm$10% and $\pm$ 15%, respectively. Finally, it is suggested that the ORNL model needs to be re-evaluated if compressor map data tested below $-5^{\cire}C$(in evaporating temperature) are available.

• KIEE International Transactions on Power Engineering
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• 제5A권3호
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• pp.293-299
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• 2005

Automatic reclosing is a typical protection method in power distribution systems for the clearing of temporary faults. However, it has a fatal weakness in regards to voltage sags because it produces repetitive voltage sags. In this paper, we explored the repetitive impact of voltage sag due to the automatic reclosing of power distribution systems. The actual tests of low voltage loads were carried out for obtaining the susceptibility of voltage sags. The final results of the tests yielded power acceptability curves of voltage sag, and the curves transformed the 3-dimensional CBEMA (Computer Business Equipment Manufacturer Association) format. For the quantitative evaluation of the impact of repetitive voltage sags, an assessment formulation using the voltage sag contour was proposed. The proposed formulation was tested by using the voltage sag contour data of IEEE standard and the results of the test. Through the case studies, we verified that the proposed method can be effectively used to evaluate the actual impact of repetitive voltage sags.

• 에너지공학
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• 제21권1호
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• pp.26-32
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• 2012

본 연구에서는 PV(photovoltaic)모듈에서 경년에 따른 효율 저하의 원인을 분석하기 위해 셀 레벨에서의 열충격 시험을 수행하였다. 열충격 시험의 조건은 $-40^{\circ}C$에서 $85^{\circ}C$로 각각 15분씩 30분을 1사이클로 하였으며, 열충격 시험 500 사이클 동안 100 사이클 간격으로 EL분석 및 I-V분석을 수행하였다. 효율 감소율은 단결정 Bare Cell이 8%, Solar Cell이 9%였으며, 다결정 Bare Cell이 6%, Solar Cell이 13%의 감소율을 보였다. 열충격 시험 후 Solar Cell은 표면 손상으로 인한 효율저하를 확인할 수 있었다. Bare Cell의 경우 표면의 손상이 없었지만, 효율이 저하된 것을 확인할 수 있었다. 이는 Fill Factor 분석에 의해 경년 시 나타나는 누설전류에 의한 소모전력 증가로 효율 저하에 영향을 준 것으로 판단된다. 또한, Bare Cell보다 Solar Cell에서의 효율 감소율이 상대적으로 높게 나타난 결과는 표면 손상 및 소모 전력의 증가로 인해 Solar Cell 효율에 큰 영향을 미치는 것으로 판단된다. 향후 단면 분석법 및 다양한 조건의 시험 기법을 활용하여 PV모듈 뿐 아니라 Cell 레벨에서의 불규칙한 효율 및 Fill Factor의 감소 원인을 검토하고, Solar Cell에서의 효율 저하가 가속되는 원인에 대한 대책 방안 연구가 수행되어야 할 것이다.

• 설비공학논문집
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• 제24권11호
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• pp.777-783
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• 2012

The hardness and strength test was performed to make the manufacturing process of SA213 P92 boiler pipe steel. And the microstructure change was studied to find out the cause of room temperature property of P92 steel, ie, low hardness and strength property. The room temperature property of P92 steel depends on the improper normalizing and cooling rate. Especially, Ferrite was formed and the steel had low hardness when the temperature was decreased slowly under the cooling rate $1^{\circ}C$/min after normalizing at the temperature around $A_{c1}$ to $A_{c3}$. The critical heat treatment temperature and cooling rate was over $900^{\circ}C$ and over $10^{\circ}C$/min to satisfy the minimum yield and tensile stress which was laid down by ASME Code.

• 드라이브 ㆍ 컨트롤
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• 제11권4호
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• pp.25-31
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• 2014

This paper details application of a DLC(Diamond Like Carbon)-coating to the swash plate and the ball joint of pistons that make sliding contact with the piston shoes of an axial piston pump. This process, aimed to reduce the frictional and leakage power losses of the hydrostatic piston shoe bearings at the low speed range. At lower speeds than 100rpm, the positive effects of the DLC-coating on the power loss reduction of the hydrostatic piston shoe bearings could be confirmed. These effects resulted in little improvement in volumetric efficiency of the test pump, but the mechanical efficiency could be raised by up to 5% at 100rpm; here, the DLC-coated swash plate played a more dominant role than the DLC-coated ball joint.

• Journal of Radiation Protection and Research
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• 제34권2호
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• pp.77-81
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• 2009

An Area Radiation Monitoring System (ARMS) ionization chamber, which had an 11.8 L active volume, was fabricated and performance-tested at KAERI. Low leakage currents, linearities at low and high dose rates were achieved from performance tests. The correlation coefficients between the ionization currents and the dose rates are 1 at high dose rate and 0.99 at low dose rate. In this study, an integration-type ARMS ionization chamber was tested over a year for an evaluation of its long-term stability at a radioisotope (RI) repository of the Young-gwang nuclear power plant. The standard deviation of dose rate of 1 day data and over a 100-days mean value were 6.2 $\mu$R/h and 2.9 $\mu$R/h, respectively. The fabricated ARMS ionization chamber showed stable performance from the results of the long-term tests. Design and performance characteristics of the fabricated ionization chamber for the ARMS from performance-tests are also addressed.