• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2001년도 하계학술대회 논문집
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• pp.628-631
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• 2001

Current lead is one of the first proposed devices for the application of High Temperature-Superconductor(HTSC). The current lead provides high current for electrical machine using superconductor from room temperature. Its characteristics that is zero resistance and low heat transfer rate under critical temperature lead to research for the replacement of existing current lead with HTSC. In this paper, we investigated the temperature distributions of stacking type and rod type current lead with each cross-section area and length using Nastran program and compared each temperature distribution. It is obtained from this paper that stacking type current lead has flat temperature gradient and than rod type one and more stable operation as current lead is closely related with its cross-section area and length.

• 조명전기설비학회논문지
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• 제22권8호
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• pp.45-51
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• 2008

본 논문에서는 2.5[kW]급 선박용 HID 탐사등 조명을 위한 Soft-start 개방회로 전압 및 정전류 순차 제어 방식을 제안한다. 제안된 제어회로는 HID 탐사등의 안정적인 점등을 위하여 개방회로 전압과 점등 전류를 순차적으로 제어하는 방식으로, 특히 전원투입 상태에서의 안정성을 위하여 일정한 입력전압에 대해서 Soft-start 기법을 적용하여 개방회로 전압 제어모드로 동작하도록 설계되었다. 또한, 점등개시 신호의 입력에 따라 제어모드를 전압제어에서 전류 제어모드로 변경하여 단일 PWM 제어소자에서 동시에 처리하도록 하였다. 한편, 입력 노이즈 및 개방회로 전압의 검출을 간단한 원칩 마이크로 프로세서로 구현하여, 오동작 및 점등 실패에 대한 강인성을 부가하도록 하였다. 제안된 제어기는 실제 선박용 HID 탐사등의 적용 시험을 통하여 그 안정성을 시험하였다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1994년도 하계학술대회 논문집 A
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• pp.369-372
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• 1994

In this paper, a voltage type dual PWM converter which achives the bidirectional power flow between a AC supply and a DC bus voltage is described. In PWM modulator, there exist a time difference between the sampling time and carrier wave, it achieves stable modulation even the disturbance in the synchronous AC source voltage. And this paper proposes the compensation method and the control method related a disturbance of synchronous signal using the low pass filter and phase shifter for the stable modulation. As a result the voltage type dual PWM converter makes the imput current wave as sinusoid, and performs the high power factor driving.

• 대한전기학회논문지
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• 제41권2호
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• pp.144-155
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• 1992

A design of a highly stable current-controlled power supply combining the phase-controlled rectifier (PCR), passive filter and active filter is investigated. A digital phase-looked voltage control (PLVC) with a capability of compensating the thyristor firing angles under unvalanced power source is proposed` otherwise the PCR output voltage has low-order subharmonics whose suppression requires a bulky passive filter. The digital PLVC has a fast dynamic characteristics as an inner control loop of the PCR. To suppress further the output ripple, an active filter using a transformer is introduced and its design is described through the frequency domain analysis. An optimal integral, proportional and measurable variable feedback (IPM) controller is designed using the time-weighted performance index based on the time domain analysis. The design method based on the time-weighted performance index gives better response characteristics than that based on the conventional performance index. It is also shown via experimental results that the proposed scheme gives better response characteristics than that based on the conventional performance index. It is also shown via experimental results that the proposed scheme gives good dynamic and static performances.

• Journal of Advanced Marine Engineering and Technology
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• 제28권4호
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• pp.641-647
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• 2004

By most sensorless speed control schemes for induction motor. the control performances in high speed range are good, but it is difficult to obtain satisfactory results in low speed region. This paper proposes a new method controlling the low and the high speed regions separately to attain the stable operation in the overall range. The current error compensation method, in which the controlled stator voltage is applied to the induction motor so that the error between stator currents of the numerical model and the actual motor can be forced to decay to zero as time proceeds. is used in the low speed region In the high speed region. the method with adaptive observer is utilized. This control strategy contains an adaptive state observer for flux estimation. The rotor speed can be calculated from the rotor flux and the motor currents. The experimental results indicate good speed and load responses from the very low speed range to the high, and also show accurate speed changing performance between the low and the high speed range.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2002년도 하계학술대회 논문집 B
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• pp.993-995
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• 2002

Switched Reluctance Generator attracts much attention because of high effciency, simple controllability with traction drive. But the theories that have been adopted as SRG control methods are complicated up to the present. This paper proposes reference current limitation strategy for stable generation of SRM and switching angle control. The proposed method is verified by simulation and experiments.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제52권10호
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• pp.425-430
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• 2003

A CMOS Voltage-Controlled Oscillator(VCO) for application at temperature stable system is designed. The VCO consists of bandgap voltage reference circuit, comparator, and voltage-to-current converter and the VCO has a temperature stable characteristics. The difference between simulated and calculated values is less than about 5% in output characteristics when the input voltage range is from 1V to 3.25V. The CMOS VCO has error less than about $\pm$0.85% in the temperature range from $-25^{\circ}C$ to $75^{\circ}C$.

• 한국초전도저온공학회:학술대회논문집
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• 한국초전도저온공학회 2002년도 학술대회 논문집
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• pp.219-220
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• 2002

In this paper, we propose non-soldered current lead was introduced which has low contact resistivity for fault current limiters of YBCO film. Carbon/Cu has good thermal conductivity, electrical conductivity and chemically stable, and so forth. Therefore it seems to be suitable material of current lead for current limiters of YBCO film. We have investigated electric field-current in field of 0-130 mT and quench characteristics of a YBCO film. Experimental results show that characteristics of transport is all right using Carbon/Cu-current lead.

• 한국수산과학회지
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• 제49권3호
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• pp.393-403
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• 2016

A steady, strong southward flow was observed in the lower layer beneath the Tsushima Warm Current in the deepest trough of the Korea Strait. Known as the Korea Strait Bottom Cold Water (KSBCW), this bottom current had a mean velocity of 24 cm/s and temperatures below 8–10℃. The direction of the bottom current was highly stable due to the topographic effects of the elongated trough. To determine the path of the southward bottom current, ADCP (Acoustic Doppler Current Profiler) data from 14 stations between 1999 and 2005 were examined. Persistent southward flows with average speeds of 4–10 cm/s were observed at only three places to the north of the strait where the bottom depths were 100–124 m. The collected data suggest a possible course of the southward bottom current along the southeast Korean coast before entering the deep trough of the Strait.

• 전력전자학회논문지
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• 제6권1호
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• pp.13-20
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• 2001

본 논문에서는 큰 출력 저항파 기준 전류와의 정합 특성이 우수한 새로운 전류 미러를 제안한다. CMOS 증폭기 회로에서 전원 전압이 작아지는 경우 출럭 전압의 스윙 폭이 전원 전압에 의해 제한되는 단점이 있으므로 제안된 회로는 이런 단점을 해결하기 위해 출력단의 스윙을 키우고, 안정된 동작올 할 수 있도록 한다. 출력단 부하가 큰 경우에 구동 능력을 증대시키고, 작은 전원 전압을 가질 때에도 큰 출력 스윙을 갖는 전류 미러를 시뮬레이션을 통해 가존의 캐스코드 전류 미러와 Regulated 전류 미러의 특성을 비교 및 고찰한다.