• Journal of Magnetics
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• 제21권2호
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• pp.298-302
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• 2016

In bone density examinations, a change in the measured BMD occurs owing to the differences between the measured areas. To address this problem, we aimed to develop a new auxiliary device that could be rotated by $15^{\circ}$ by fixing the ankle to the distal femur neck. Dual energy X-ray absorptiometry (DXA) of BMD examinations were performed once a year, but 10 patients were examined over three sessions to analyze the area for measuring the femur neck BMD. The goal of this test was to determine the device's reliability, and the results were expressed in terms of the standard deviation of measurements. After performing bone density measurements using the new auxiliary device on 10 normal patients, with three measurements for each patient, the obtained standard deviation was 0.03. The standard deviation of the measured BMD was 0.19 when using the currently existing auxiliary device, while the standard deviation of the measured BMD was 0.03 when using the new auxiliary device. By using the new auxiliary device, the standard deviation could be reduced by ~80%. Accurate rotation of the femur neck was possible in all examinations, and the standard deviation of BMD measurements could be reduced by up to 80% compared with the measurements performed using the currently existing auxiliary device. We hope that this advantageous new design can be used as a standard auxiliary device for measuring the femur neck BMD.

• 공학기술논문지
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• 제10권2호
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• pp.203-208
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• 2017

Due to global climate change issues, there is a growing demand for systems throughout the industry. In the case of power conversion, studies have been actively conducted to change the structure of the power conversion circuit and to apply new power devices. In particular, the WBG (Wide Band Gap), which is newly emerged device in the market for developing semiconductor technology, has demonstrated advantages in applying for various aspects in comparison to the existing Si (Silicon) Semiconductor. Recent research centers in the railway industry are focusing on developing technologies suitable for railway vehicles by utilizing these new developments in railway countries such as Japan and Europe. This paper researches the WBG device that is applicable to the auxiliary power supplies (APS) in railway system, and analyzes the downsizing effects to APS in high-speed railway by conducting a theoretical analysis and simulation.

• 한국철도학회:학술대회논문집
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• 한국철도학회 1999년도 추계학술대회 논문집
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• pp.267-272
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• 1999

The auxiliary power supply system fur passenger service of railway car has been developed from MA(Motor-Alternator) to CVCF Inverter (Static Inverter). Generally, a customer wants to apply tile new control method and device for auxiliary power supply of railcar However, if the auxiliary power supply is supplied to extended existing line, the maintenance cost of the old system is less expensive than new developed system, so, the customer specifies that the auxiliary power supply has compatibility with existing one completely. At that time, the hardware is nearly same as existing system except small changes of accessories for better performance. This paper describes the flicker control using feed-forward method of auxiliary power supply system for new 50 electric railcars, which are delivered to Korean National Railroad (KNR) Kwa-chon Line. The existing power supply system has damping resistor box to stabilize the DC input (1.5 ㎸). At this time, for better system efficiency the new system has not include resistor box but new control method including feed-forward control is applied. This control algorithm realizes the better stabilization of input power compared to the result of the existing system, which includes resistor box

• 한국전자통신학회논문지
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• 제13권2호
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• pp.377-382
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• 2018

현재 운용되고 있는 전기기관차(8200호대) 전장품의 부분적 국산화를 위해서는 전기기관차내의 장치간 MVB 통신프로토콜에 대한 분석이 우선 진행되어야 한다. 그 중에서도 신규 개발된 보조전원장치가 적용되었을 때 우려되는 사항인 고장발생 시 동작에 대한 분석이 필요하다. 본 논문에서는 분석된 통신프로토콜을 적용한 신규 개발 통신제어장치를 통해 신규 보조전원장치를 기존 전기기관차에 적용하였을 때 정상동작 뿐만 아니라 고장발생 시 동작에도 문제없이 작동하도록 고장코드에 대한 MVB 통신프로토콜을 분석하였다.

• 조명전기설비학회논문지
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• 제17권4호
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• pp.100-105
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• 2003

본 논문은 새로운 보조 공진 DC 링크 스너버 회로를 제안하였으며, 실제적인 스위칭 소자 모듈의 유도 손실특성을 근거로 하여 전력손실의 저감에 대해 다루었다 보조 공진 DC 링크 스너버 회로를 이용하여 전압형 소프트 스위칭 3상 인버터의 회로정수값을 추종하였다. 그리고 실험과 시뮬레이션 결과에 의해서 3상 하드스위칭과 소프트스위칭 인버터의 전력 손실 해석을 하였다.

• 해양환경안전학회지
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• 제21권6호
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• pp.759-769
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• 2015

본 논문에서는 12펄스 정류기의 커패시터 중앙 DC버스에 개선된 보조전원장치를 설치하는 방법을 제안하였다. 11차 및 13차 고조파가 감소하는 이론적인 배경을 다루었으며 부하전류의 크기, 전원전압의 위상 및 크기, 커패시터 전압에 따라 개선된 보조전원의 파형 및 크기가 어떻게 제어되어야 하는지를 제시하였다. 기존의 구형파 보조전원장치를 적용한 경우는 전 영역에서 고조파 왜형률이 6~60[%]로 큰 편차를 보이지만 본 눈문에서 제안하는 개선된 보조전원장치를 적용한 경우 저 부하에서 고 부하에 이르는 전 영역에서 57~71[%] 라는 안정되고 뛰어난 고조파 왜형율 저감 효과를 보인다. 특히 10[%] 부하상태에서 기존방식은 고조파 왜형율 저감 효과가 6[%]로 효과가 거의 없지만 제안된 방식은 71[%]라는 놀라운 저감성능을 보여주고 있다. 소프트웨어 PSIM을 활용하여 컴퓨터 시뮬레이션을 통해 제안된 방식의 유효성을 입증하였다.

• 설비공학논문집
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• 제18권9호
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• pp.707-713
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• 2006

To improve heating performance of the heat pump in winter season, refrigerant heating device was applied to conventional heat pump. The refrigerant heating device operates at the heating capacity does not enough to the heating load requirement of the conditioning space. When the discharge air temperature of the indoor heat exchanger goes down to below $40^{\circ}C$ which is criterion for comfort of the occupants in the conditioning space, the system also starts. The refrigerant heating system has new concept of auxiliary heating device for heat pump in winter. In this study, the system performance was analyzed through experiments and parametric study was conducted to improve the COP and control strategies.

• 전력전자학회논문지
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• 제10권5호
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• pp.518-525
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• 2005

제안된 회로는 하나의 보조스위치를 이용하여 주 스위치와 정류용 다이오드가 턴-온/턴-오프 시 동시에 영전압과 영전류 조건을 만족시킨다. 그리고 이 회로에 사용되는 주 스위치는 다수 캐리어 소자뿐만 아니라 소수 캐리어 반도체 소자까지 사용할 수 있는 장점을 가지고 모든 PWM 컨버터에 적용 가능하다. 그리고 제안된 보조 스위치와 공진회로가 주 전력 경로에 존재하지 않으므로 주 스위치와 다이오드에 더 이상의 전압/전류 스트레스가 없게 된다. 제안된 컨버터의 유효성을 이론적 분석과 실험을 통하여 입증하였다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2002년도 하계학술대회 논문집 B
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• pp.1064-1066
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• 2002

This paper proposes a new prototype auxiliary resonant DC link(ARDCL)snubber circuit and deals with its power loss on the basis of actually measured conduction loss characteristic of switching device module. Voltage type soft switching three phase inverter using proposed ARDCL snubber circuit is presented along with its performance evaluations. And, the power loss analysis of three phase hard and soft switching inverter are carried out from the point of simulation and experimental results.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2002년도 춘계학술대회 논문집
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• pp.428-431
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• 2002

Yard cranes are very useful equipments for handling of heavy containers. But rope-driven yard cranes must have a little of sway and skew motion because ropes are passive mechanical device. So many researches have been concentrated on anti-sway algorithm controlling trolley speed. But control algorithm of trolley speed is not practical in windy weather. In this paper, we are going to propose a new structure for anti-sway. This structure uses aux. ropes. The control strategy with auxiliary rope is very useful to sway control of yard crane because rope length is shorter than quay-side container cranes. In this paper, we derive equations of motion of trolley system which have anti-sway controller to use auxiliary rope. And main schemes are introduced and explained briefly.