• 한국전기전자재료학회논문지
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• 제23권10호
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• pp.809-813
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• 2010

Frequency domain measurement of propagation loss for ultra high frequency (UHF) partial discharge in the winding of power transformer using a spectrum analyzer and pulse generator is presented. We compared the performance of the method using a network analyzer with and without a winding. Using a network analyzer simplifies the measurement and offers better dynamic range and frequency range. It also provides precise propagation loss within the winding in frequency domain at UHF range. We applied this method to measure UHF propagation loss of transformer mock-up, modeled 154 kV 20 MVA power in KEPCO substation.

• 한국정보통신학회논문지
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• 제17권11호
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• pp.2479-2485
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• 2013

본 논문에서는 순차 바이어스를 이용한 반도체 레이더용 SSPA를 설계 하였다. 전력증폭기의 상승/하강 바이어스 지연에 의해 발생되는 신호의 왜곡을 제거하기 위하여 가변확장 펄스 생성기를 적용하였다. 최적화된 임피던스 매칭회로는 GaN-전력 소자의 높은 효율을 갖기 위하여 로드-풀 방식을 통한 마이크로파 특성 측정으로 설계되었다. 설계된 SSPA는 X밴드 반도체 레이더에 적용하기 위하여 전치 증폭기, 구동 증폭기 그리고 주 증폭기의 3개의 단으로 구성되었다. 그 결과로 200W 출력 펄스 최대 53.67dBm을 가지고 평균 52.85dBm의 SSPA를 만들 수 있었다. 본 논문에 제시된 반도체 펄스 압축 레이더 트랜시버 모듈의 최적화 설계는 추가적인 디지털 레이더에 대한 연구를 통해 소형화와 동작향상이 가능하다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2008년도 추계학술대회 논문집 전기기기 및 에너지변환시스템부문
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• pp.53-55
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• 2008

In high speed applications, the slotless permanent magnet(PM) motors appear an attractive solution, being almost insensitive to magneto-motive force harmonics and to pulse width modulation(PWM) current ripple and exhibiting lower stator iron losses and rotor losses (significant with square wave current control). So, this paper deals with methods for design of permanent magnet synchronous motor/generator.

• 전자공학회논문지
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• 제50권2호
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• pp.174-184
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• 2013

LED 기반 그린에너지 조명 시스템의 성공적인 연구 개발과 원만한 설치 운영을 위해서는 펄스 파, 스파이크 파를 비롯한 비선형신호와 고조파, sag, swell 등을 포함한 불요신호에 대한 실시간 전력품질측정이 요구된다. 본 논문에서는 그린에너지 조명시스템 응용을 타깃으로 기존 저주파수 대 (60Hz~수KHz)는 물론 수십 KHz 이상의 고주파수 대에 발생하는 각종 전원 신호 분석이 가능한 저가형 전력품질측정 (power quality measurement: PQM) 방안을 제안하고, 이를 TI 320F28335 MCU(micro-controller unit) 기반 PQM 테스트 베드로 구현한다. 제안된 알고리즘은 CCS (Code Composer Studio) 3.3 환경에서 C언어로 작성하였으며, 임의 신호 발생기(NF-WF1974)로부터 발생된 모의 신호를 활용하여 구현된 알고리즘을 검증한다. 테스트 베드를 이용하여 LED SMPS로부터 발생되는 각종 비선형 전류 신호 측정, FFT를 이용한 고조파 신호의 분석이 가능할 뿐 아니라 이산 웨이블렛 변환을 이용한 sag, swell, interruption 등의 고품질 전력신호 측정도 가능하다.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2019년도 전력전자학술대회
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• pp.248-250
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• 2019

입자가속기는 물질의 미세 구조를 밝히기 위해 기본 입자를 가속, 충돌시키는 장치로 최근 암치료 등 의학적 용도로도 이용되고 있다. 그러나 고속으로 고압을 인가시켜야 하는 장치인 만큼 기존에 명확히 설립된 회로가 없다. 이에 본 논문에서는 Ion gate를 등가회로로 구성하여 Fast Switch 장치의 기본 회로를 제안 및 분석, 실험하였다. 또한 기본 회로에서 발생하는 문제들을 개선하고자 RC Input filter와 기타 파라미터들의 설계와 Fast switch와 Ion gate를 잇는 wire 내의 기생성분을 고찰하였고 Ion gate 구동을 위해 기준이 되는 명확한 Fast switch 회로를 제안한다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2001년도 하계학술대회 논문집 C
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• pp.1694-1696
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• 2001

Partial discharge(PD) tests are used to evaluate the insulation condition of stator windings in six 6.6kV motors. These tests were conducted using a conventional partial discharge detector (PDD), turbine generator analyzer(TGA) and partial discharge analyzer(PDA). Off-line PD measurements were performed on six 6.6kV motors. PD magnitudes ranged from 740 pC to 5,100 pC at the normal line-to-ground voltage. Six 6.6kV motors have been equipped with eighteen 80pF epoxy-mica couplers(one per phase) on the motor terminal boxs. The PD pulse from sensors were measured with the TGA and PDA instruments on a normally operating motors. The PDD, TGA and PDA test results showed that internal discharge was detected in voids of the groundwall insulation.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2006년도 제37회 하계학술대회 논문집 C
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• pp.1554-1555
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• 2006

We have studied the backward wave oscillator, a power pulsed generator oscillator at 20 GHz has higher frequency then current one. An absolute instability linear analysis was used for the purpose of designing the slow wave structure. A large diameter of the slow wave structure was adopted to prevent the breakdown brought about by the increase of power density.

• Current Optics and Photonics
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• 제5권5호
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• pp.544-553
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• 2021

A 40-W 200-ns 300-kHz thulium-doped fiber laser at 2050 nm with a master oscillator power amplifier configuration was developed, for application to lithium-isotope separation. The master oscillator generated a 5.35 W continuous-wave beam, which the pulse generator then broke into 200-ns pulses at 300 kHz. Then, the laser beam was amplified by passing through a two-stage amplifier. The output power finally obtained was 42.0 W at 2050 nm, and was stable for a long time, over 2 hours. In spite of this achievement, mode instability was observed in the output beam. This can be solved in the future by using a method such as tight coiling.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 하계학술대회 논문집 C
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• pp.1828-1830
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• 2003

Partial discharge(PD) tests are used to evaluate the insulation condition of stator windings in two 4.16kV and three 6.6kV motors. These tests were conducted using a conventional partial discharge detector(PDD) and turbine generator analyzer(TGA). Off-line PD measurements were performed on five high voltage motors. PD magnitudes ranged from 1000 pC to 5400 pC at the normal line-to-ground voltage. Five high voltage motors have been equipped with 80pF epoxy-mica coupler on the motor terminal box. The PD pulse from sensors were measured with the TGA instrument. TGA summarizes each plot with two Quantities such as the peak PD magnitude(Qm) and the total PD activity(NQN). The defect mechanisms of high voltage motor can be associated with PD patterns such as internal, slot and conductor surface discharges. The PDD and TGA test results of No. 4 motor showed that internal discharge was detected in voids of the groundwall insulation.

• 한국의학물리학회:학술대회논문집
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• 한국의학물리학회 2002년도 Proceedings
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• pp.400-403
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• 2002

The fundamental experiments for measuring soft x-ray characteristics from the vacuum capillary are described. These experiments were primarily performed in order to generate line spectra such as x-ray lasers. The generator consists of a high-voltage power supply, a polarity-inversion ignitron pulse generator, a turbo-molecular pump, and a radiation tube with a capillary. A high-voltage condenser of 200 nF in the pulse generator is charged up to 20 kV by the power supply, and the electric charges in the condenser are discharged to the capillary in the tube after closing the ignitron. During the discharge, weakly ionized plasma forms on the inner and outer sides of a capillary. In the present work, the pump evacuates air from the tube with a pressure of about 1 mPa, and a demountable capillary was developed in order to measure x-ray spectra according to changes in the capillary length. In this capillary, the anode (target) and cathode elements can be changed corresponding to the objectives. The capillary diameter is 2.0 mm, and the length is adjusted from 1 to 50 mm. When a capillary with aluminum anode and cathode electrodes was employed, both the cathode voltage and the discharge current almost displayed damped oscillations. The peak values of the voltage and current increased when the charging voltage was increased, and their maximum values were -10.8 kV and 4.7 kA, respectively. The x-ray durations observed by a 1.6 ${\mu}$m aluminum filter were less than 30 ${\mu}$s, and we detected the aluminum characteristic x-ray intensity using a 6.8 ${\mu}$m aluminum filter. In the spectrum measurement, two sets of aluminum and titanium electrodes were employed, and we observed multi-line spectra. The line photon energies seldom varied according to changes in the condenser charging voltage and to changes in the electrode element. In the case where the titanium electrode was employed, the line number decreased with corresponding decreases in the capillary length. Compared with incoherent visible light, these rays from the capillary were diffracted and diffused greatly after passing through two slits.