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정광석(Kwang-Seok Jung),박대원(Dae-Won Park),길경석(Gyung-Suk Kil),홍성준(Seong-Joon Hong),박찬용(Chan-Yong Park) 한국철도학회 2009 한국철도학회 학술발표대회논문집 Vol.2009 No.11월
This paper deals with the non-contact measurement of partial discharge (PD) in cast-resin transformers. The PD measurement system is composed of a planar-type capacitive antenna, a impedance coupler and a low-noise amplifier. Capacitance of the antenna is 2 ㎋, and the coupler attenuates the 60 ㎐ over 170 ㏈. Also, we designed and fabricated an amplifier having the frequency ranges of 500 ㎐ ~ 35 ㎒ at the gain of 60 ㏈. The fabricated antenna is installed in a cast-resin transformer. The sensitivity of the measurement system evaluated by a calibrator was 7 ㎷/pC for positive polarity and 9 ㎷/pC for negative polarity, respectively. In a laboratory experiment carried out for a cast-resin transformer, we could measure the positive signal of 185 pC and negative signal of 140 pC.
정광석(Kwang-Seok Jung),김선재(Sun-Jae Kim),박대원(Dae-Won Park),길경석(Gyung-Suk Kil),서동환(Dong-Hoan Seo) 한국마린엔지니어링학회 2010 한국마린엔지니어링학회 학술대회 논문집 Vol.2010 No.4
In this paper, we analyzed the frequency spectrum of radiated electromagnetic waves which is generated by series arc and corona discharges as a basic study to develop a online diagnostic technique for power facilities installed in a closed-switchboard. To simulate corona and series arc discharges, an arc generator specified in UL1699 and a corona generator were fabricated. The experiment was carried out in an electromagnetic shielding room, and the measurement system consists of a Ultra Log Antenna and a EMI Test Receiver. These results showed that the frequency spectrum of series arc and corona discharges exists in ranges from 30 to 500 [㎒], and the peak frequency of them were 40 [㎒], 80 [㎒], and 400 [㎒].
몰드변압기에서 용량성 프로브에 의한 부분방전 검출 기술
정광석,박대원,차현규,차상욱,길경석,Jung, Kwang-Seok,Park, Dae-Won,Cha, Hyeon-Kyu,Cha, Sang-Wook,Kil, Gyung-Suk 한국전기전자재료학회 2011 전기전자재료학회논문지 Vol.24 No.4
This paper dealt with a partial discharge (PD) detection method for insulation diagnosis in cast-resin transformers. To detect PD pulse, a planar-capacitive probe was designed and fabricated. The probe has no insulation problem and can be installed on cast-resin transformers even in operation since it does not connect with high voltage conductor. The PD measurement system consists of the capacitive probe, a coupling network of 100 [kHz] low-cutoff frequency, and an amplifier with a gain of 40 [dB] and a frequency bandwidth of 500 [Hz]~45 [MHz]. A plane-needle and a plane-plane electrode system were fabricated to simulate insulation defects in a cast-resin transformer. Sensitivity of the PD measurement system, which is evaluated by a standard calibrator was 0.35 [mV/pC] for positive and 0.45 [mV/pC] for negative, respectively. The PD detection by the capacitive probe was less sensitive than that by a coupling capacitor according to IEC 60270, but we could analyze the magnitude and the phase distribution of PD pulse.
정광석(Kwang-Seok Jung),박대원(Dae-Won Park),길경석(Gyung-Suk Kil),천상규(Sang-Gyu Cheon),김원(Weon Kim) 한국마린엔지니어링학회 2010 한국마린엔지니어링학회 학술대회 논문집 Vol.2010 No.10
본 논문에서는 미생물 살균효율 향상을 위한 UV-LED의 구동방법에 대하여 기술하였다. 구동방법에 따른 방사자외선의 세기를 비교하기 위해 소비전력이 4.5 W인 UV-LED 모듈과 20 ㎃의 정전류 회로 및 100 ㎃의 펄스폭 제어회로를 각각 제작하였다. 실험은 외부 자외선의 영향을 최소화하기 위해 암실애서 수행하였으며 스펙트럼 분석기(Avaspec-3648/Avantes)를 이용하여 거리에 따른 자외선의 세기를 측정하였다. 실험결과, 펄스 구동방법이 정전류 구동에 비해 약 5배 더 높은 자외선의 세기를 나타내었다.
Atomic Layer Deposition으로 증착된 Al-doped ZnO Film의 전기적, 구조적 및 광학적 특성 분석
임정수,정광석,신홍식,윤호진,양승동,김유미,이희덕,이가원,Lim, Jung-Soo,Jeong, Kwang-Seok,Shin, Hong-Sik,Yun, Ho-Jin,Yang, Seung-Dong,Kim, Yu-Mi,Lee, Hi-Deok,Lee, Ga-Won 한국전기전자재료학회 2011 전기전자재료학회논문지 Vol.24 No.6
Al-doped ZnO film on glass substrate is deposited by ALD in low temperature, using 4-step process (DEZ-$H_2O$-TMA-$H_2O$). To find out the optimal film condition for TCO material, we fabricate Al-doped ZnO films by increasing Al doping concentration at $100^{\circ}C$, so that the Al-doped film of 5 at% shows the lowest resistivity ($1.057{\times}10^{-2}{\Omega}{\cdot}cm$) and the largest grain size (38.047 nm). Afterwards, the electrical and physical characteristics in Al-doped films of 5 at% are also compared in accordance with increasing deposition temperature. All the films show the optical transmittance over 80% and the film deposited at $250^{\circ}C$ demonstrates the superior resistivity ($1.237{\times}10^{-4}{\Omega}{\cdot}cm$).
길경석,정광석,박대원,김선재,한주섭,Kil, Gyung-Suk,Jung, Kwang-Seok,Park, Dae-Won,Kim, Sun-Jae,Han, Ju-Seop 한국전기전자재료학회 2010 전기전자재료학회논문지 Vol.23 No.7
In this paper, we analyzed the frequency spectrum of radiated electromagnetic pulses generated by series arc- and corona- discharges as a basic study to develop an on-line diagnostic technique for power facilities installed inside closed-switchboards. To simulate series arc and corona discharges, five types of electrode system which consists of needle and plane electrodes were arranged. The experiment was carried out in an electromagnetic shielding room, and the measurement system consists of an ultra log antenna and an EMI receiver. From the experimental results, the frequency spectrum exists in ranges from 30 MHz to 2 GHz for a series arc discharge and 30 MHz to 1.2 GHz depending on defects for a corona discharge. The peak frequency of the series arc- and corona- discharges were 100 MHz to 160 MHz and 40 MHz to 80 MHz, respectively.
길경석,박대원,정광석,김선재,서동환,Kil, Gyung-Suk,Park, Dae-Won,Jung, Kwang-Seok,Kim, Sun-Jae,Seo, Dong-Hoan 한국전기전자재료학회 2010 전기전자재료학회논문지 Vol.23 No.5
Line to ground faults by deterioration of insulators has frequently occurred in power system, and the main cause is surface contamination of the insulators. The contamination of insulator is analyzed by monitoring the surface leakage current flowing them. The suspension insulator is monitored by installation of a zero-phase current sensor(ZCT), but the line-post insulator is impossible to apply the same method because of its large diameter structure. This paper proposed a detection method of surface leakage current for a line-post insulator, and it can easily be applied to new and/or built insulators. The leakage current is indirectly calculated from the potential difference between the metal electrode attached on the surface of insulator and the ground connector. To evaluate the performance of the proposed method, the leakage current is compared as a function of contamination condition controlled by the density of NaCl solution. The leakage current is proportioned to the density of NaCl solution, and the voltage detected by the electrode showed the same trend. From the experimental results, we designed and fabricated a monitoring device which is composed of a detection electrode, signal converter, microprocessor, and ZigBee, and its measurement range is $10{\mu}A{\sim}5mA$.