• 대한전기학회:학술대회논문집
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• 대한전기학회 2007년도 추계학술대회 논문집 전력기술부문
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• pp.276-278
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• 2007

This paper describes the analysis to install an arrester for an underground distribution line effectively. Currently, the underground distribution cable is protected by the arrester connected with overhead distribution line. However, riser pole arrester can't protect all parts of cable like the end of the underground distribution cable. To solve this problem, we installed the arrester on each cable and have measured the overvoltage made by lightning surge in each situation. The location to get effective results has been decided from the measured voltage above.

• 제어로봇시스템학회논문지
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• 제15권8호
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• pp.804-811
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• 2009

This paper deals with the relationship between zeros and step response of the second and third order LTI(Linear Time Invariant) SISO(Single-Input and Single-Output) systems. As well known, if a system has a single unstable zero, it shows the step response with undershoot and, on the other hand, a stable zero slower than the dominant pole causes the system to have the step response with overshoot. Generally, in the case of a system with two unstable real zeros, it is known to have B type undershoot[7]. But there are many complex cases of the step response extrema corresponding to zeros location in third order systems. This paper investigates the whole cases depending on DC gains of the additive equivalence systems and they are to be classified by the region of zeros which are related to the shape of the step response. Moreover, monotone nondecreasing conditions are proposed in the case of complex conjugate zeros as well as the case of two stable zeros.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2002년도 하계학술대회 논문집 C
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• pp.1846-1849
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• 2002

A shorted-turn test was performed at the Sininchon combined cycle power plant on gas turbine generators. The test was conducted using a permanent flux probe and on-line diagnosis system. The flux probe installed in the generator air gap senses the field winding slot leakage flux and produces a voltage proportional to the rate of change of the flux. This pattern of flux variation is a signature unique to each field winding. We have also applied a voltage waveform analysis technique that can identify the pole location, slot number and number of shorted-turn with each slot.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1998년도 하계학술대회 논문집 E
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• pp.1721-1724
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• 1998

A shorted-turn test was performed at the Pyungtaek combined cycle power plant on gas. turbine generator #4. The test was conducted using a permanent flux probe and digital oscilloscope. The flux probe installed in the generator air gap, senses the field winding slot leakage flux and produces a voltage proportional to the rate of change of the flux. This pattern of flux variation is a signature unique to each field winding. We have also applied a waveform analysis technique that can identify the pole location, slot number, and number of shorted-Turns with each slot.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제48권11호
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• pp.742-747
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• 1999

On-line diagnosis system has been developed and is now applied the detection of shorted turns in the field winding of large generator. This system consists of data aquisition system and display PC. The data aquisition system detects voltage waveforms from flux probe sensor installed in the stator slot. The display PC shows theshorted-turn situation of generator rotor winding. A shorted-turn diagnosis test wasperformed on five gas turbine generators at the Seoinchon combined cycle power plant. The test was conducted using an new diagnosis system and digital oscilloscope which can identify the pole location, the slot number and the number of shorted turns within each slot. It is confirmed that results of two systems are very same in the field tests.

• Journal of Power Electronics
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• 제10권4호
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• pp.382-387
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• 2010

This paper presents a novel design method for determining the PID gains of a speed controller for a servo system compensating variations in bandwidth at a low speed. The variations in bandwidth of a speed controller are measured at a low speed and the relationship between the bandwidth and the damping ratio are verified by determining the location of the closed loop pole. The proposed algorithm uses the z-transform of a plant and speed controller and applies the time-varying sampling method for determining the PID gains of the speed controller at low speed. The magnitude and the phase condition are considered for finding a suitable control gain. The usefulness and effectiveness of the proposed method is demonstrated through experimental results such as low speed control and robust disturbance responses.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2006년도 제37회 하계학술대회 논문집 전기설비
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• pp.59-60
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• 2006

A shorted-turn test was performed at the Pyungtaek combined cycle power plant on gas turbine generators. The test was conducted using a permanent flux probe and on-line shorted-turn diagnosis system. The permanent flux probe installed in the generator air gap senses the field winding slot leakage flux and produces a voltage proportional to the rate of change signature unique to each field winding. We have also applied a voltage waveform analysis technique that can identify the pole location, slot number and number of shorted-turn with each slot.

• 센서학회지
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• 제33권4호
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• pp.209-215
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• 2024

Generally, a straight displacement meter is used to obtain displacement data to verify the safety of structural members and structures. A straight displacement meter is also used to measure the absolute displacement in research laboratories or safety inspection sites such as bridges and buildings. In this study, for structures in which the displacement sensor could not be fixed at the location where the displacement was to be measured, a circular displacement meter was manufactured to measure the displacement by installing a displacement gauge on the structure itself. In other words, when measuring the horizontal displacement of an upper part, such as a wind tower, a circular displacement meter was installed inside the wind tower to integrate it with the structure, applying the principle that the structure itself can be used as a displacement meter. This circular displacement meter can be installed and used inside a circular structure. Whereas in the case of a telephone pole, it can be installed outside to measure displacement. It can be manufactured in various sizes and used.

• 한국전자통신학회논문지
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• 제11권8호
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• pp.743-750
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• 2016

열차에서 지상차상통신은 데이터를 전송하기 위해 트랜스폰더 또는 발리스 (balise) 와 같은 무선장비를 일반적으로 사용하고 있다. 그러나, 이러한 종래의 방식에는 다중경로 페이딩, 대역폭소스 제한, 다른 사용자들로부터의 간섭 등 과같은 단점들이 있다. 게다가 이러한 장비가 많이 설치될 경우에는 비용이 많이 든다. 이러한 문제를 해결하기 위하여 적외선 통신 시스템을 제안하고자 한다. 적외선 시스템을 사용하여 열차의 위치 같은 데이타를 열차로 전송 할 수 있다. 적외선 통신 프로토콜은 direct dedication configuration에 실용적인 무선 데이터 통신을 제공할 수 있다. 뿐만 아니라, pole configuration경우에 적외선 시스템은 풍부한 대역폭 그리고 경제적 장비설치비용, 폭우 때 장비이용의 신뢰성까지 제공한다. 본 논문에서는 통신기능과 실행평가측정 (measurement performance evaluation)에 대한 분석을 다루었다. 제안된 지상차상통신 시스템에는 적외선 수신기 및 적외선 송신기 사이를 약 6미터 까지 전송가능하며, 송신기의 반각은 19.65도로, 수신각은 15도로 설정되었다.

• 한국위성정보통신학회논문지
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• 제11권4호
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• pp.44-47
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• 2016

TVWS에 대한 관심이 증가하고 있고, TVWS를 이용하는 통신시스템과 서비스에 대한 연구가 활발히 진행되고 있다. TVWS는 사용할 수 있는 주파수가 지역적으로 그리고 시간적으로 다르다. 때문에 TVWS를 이용하는 RF 시스템이 주파수가변 대역통과필터를 사용하면 시스템을 효과적으로 운용할 수 있다. 본 논문에서는 470 ~ 698MHz에서 동작하는 주파수가변 대역통과필터를 설계 및 구현하였다. 그리고 주파수가변 대역통과필터는 제어의 용이성과 크기를 고려해서 2-pole로 설계하였다. 구현한 주파수가변 대역통과필터는 제어전압을 1.58 ~ 3.93V 가변하면 470 ~ 698MHz에서 동작하며, 삽입손실은 최대 4.78dB, 반사손실은 10dB 이하를 갖는 것으로 측정되었다. 본 논문의 주파수가변 대역통과필터는 TVWS에서 동작하는 수신기에 직접 사용이 가능하며, 본 논문에서 사용한 주파수가변 대역통과필터의 설계 절차는 대전력 주파수가변 대역통과필터의 개발을 위한 기초 자료로 활용될 수 있다.