• 대한전기학회:학술대회논문집
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• 대한전기학회 2000년도 하계학술대회 논문집 C
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• pp.1850-1852
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• 2000

In this paper, new Partial Discharge (PD) detection technique using Pockels cell was proposed and considerable apparent chaotic characteristics were discussed. For this purpose, PD was generated from needle-plane electrode in air and detected by optical measuring system using Pockels cell, based on Mach-Zehnder interferometer, consisting of He-Ne laser, single mode optical fiber, 50/50 beam splitter and photo detector. A qualitative analysis was carried out by drawing Return map for the normalized time series of the detected PD signals. The results are as follows:(a) Fixed points, between 0.7 and 1.0, are appeared clearly in the right upper area of the return map as the increase in the number of obtained data.(b) Considerable periodicity have been remarked even though exact period and length can not be determined.(c) The self-similarity can be also observed inasmuch as the late paths do not follow the previous ones. Accordingly, exact quantitative analysis such as embedding dimension, fractal dimension, and Lyapunov exponents should be carried out for deducing the quantitative properties regarding PD phenomena.

• 한국광학회:학술대회논문집
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• 한국광학회 1998년도 제15회 광학 및 양자전자 학술발표회 논문집
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• pp.144-145
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• 1998

• 대한전기학회:학술대회논문집
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• 대한전기학회 2004년도 하계학술대회 논문집 C
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• pp.1997-1999
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• 2004

In this paper, a novel method has been proposed by use of HY-Pockels sensor for the detection of PD in GITR(Gas Insulated Transformer) in order to improve reliability and to overcome the shortcomings of other techniques which are currently employed. For this work, different types of the test specimen, simulating the winding of the real GITR, have been designed and fabricated to generate the PD. And then, the detection of PD has been realized by conventional methods according to IEC 270 and also the proposed novel sensor as well. Afterwards, their results are well compared to understand the correlation between the nature of the defects in the winding and their PD pattern.

• Journal of Electrical Engineering and Technology
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• 제2권3호
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• pp.396-400
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• 2007

A novel technique has been proposed and related experimental works have been performed in order to detect the partial discharges and the location of the possible defects introduced into the Gas Insulated Switchgear. For this purpose, a prototype HY Pockels sensor has been developed and then employed in order to investigate its field applicability for finding the location of the defects using a 170kV GIS mock-up. Our proposed sensor enables us to measure the electric field variation due to the PD occurrence. In addition, the different PD patterns are observed, which might be dependant on the location and the distance of the sensor with respect to the PD source. Throughout this work, its linear response has been proved to be admissible as a function of the applied voltage. And also the position of the PD source might be distinguished by comparing the PD patterns.

• 전기의세계
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• 제29권5호
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• pp.321-328
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• 1980

The Q-switching oscillator of TE $M_{00}$ mode was constructed in order to improve the properties of energy focusing and amplification, and prevent laser materials from breakdown. The Q-switching was done by means of electro-optical effect using Glan prism and KDP Pockels cell. Sharp laser pulse of risetime-1 ns and variable pulse width 2-10 ns was obtained from Q-switching laser pulse by PTM method using a laser triggered spark gap (LTSG), Glan prism and Pockels cell. A single ultra-short pulse (picosec order in pulse width) was obtained from mode-locked pulse train in combination of a mode-locked oscillator using saturable dye cell with pulse shaping system using PTM method.d.

• The Korean Journal of Ceramics
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• 제5권4호
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• pp.409-413
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• 1999

A two-beam polarization (TBP) interfermeter with a reflection configuration for measuring the linear electroptic coefficient is described and investigated experimentally and theoretically. It is shown that a TBP interferometer can be used for measuring the Pockels coefficient of thin film with a strong Fabry-Perot effect. The TBP interferometer technique is used to measure the effective differential linear electro-optic coefficient $re=r_{33}-(n_0/n_0)^3r_{13}$of lead zirconate titanate (PZT) thin film. The results are in agreement with known data.

• 한국광학회:학술대회논문집
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• 한국광학회 1988년도 광학 및 양자전자학 워크샵
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• pp.9-16
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• 1988

음향 광학 변조기와 BDN/iodoethane 용액을 이용한 결합형으로 펄스형 Nd:YAG 레이저의 모드 록킹을 수행하여 그 특성을 조사하였고 pockels cell을 이용하여 모드 록킹된 펄스 train 으로부터 단일 펄스를 선택하였다.

• 한국전기전자재료학회논문지
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• 제13권8호
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• pp.688-693
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• 2000

In this paper an optical voltage sensor and an optical current sensor which can be used for the measurement of impulse voltage and current are implemented. BSO single crystal is utilized as a voltage sensor(Pockels effect cell). An rare earth doped YIG is used as a current sensor(Faraday effect cell). A new signal processing technique is adopted not only to avoid the influences o external optical fiber pertubations of transmitting optical fiber but also to improves the frequency response characteristics of the fiber-optic voltage and current sensors. Experimental results show that optical voltage sensor has maximum 2.5% error within the voltage range from 0V to 500V. and optical current sensor has maximum 2.5% error within the current range and that of optical current sensor is about 1.5% within temperature range from -2$0^{\circ}C$ to 6$0^{\circ}C$. The proposed optical sensors have good frequency response characteristics within the frequency range from DC to 10MHz.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2007년도 제38회 하계학술대회
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• pp.1273-1274
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• 2007

In this paper, a Optical Voltage Transformer has been designed and fabricated to improve temperature stability caused by materials properties and insulation in measuring system, using single crystal $Bi_{12}SiO_{20}$ as Pockels effect cells for Gas Insulated Switchgear[GIS] System. LD[wavelength: 850nm] was used as optical source, InGaAs as optical detector to measure optical power, Polarizing Beam Splitter as Polarizer and Analyzer, and Multi-mode Optical-fiber[62.5/$125{\mu}m$] as Light transmission line. OPT was assembled in order to pockels effect, and adopted direct electric field type. The linearity of OPT maintains variation for applied voltage range from 100V - 3000V during the test of electric property, As the temperature was changed from $25^{\circ}C$ to $60^{\circ}C$. the result of this study shows that characteristics of OPT are good, and it can be reflected for practical optical sensors in GIS system.

• Transactions on Electrical and Electronic Materials
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• 제9권2호
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• pp.84-88
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• 2008

In this paper, we analyze the errors associated with electric field interference for fiber-optic voltage sensors working in a three-phase electric system. For many practical conductor arrangements, the electric filed interference may cause errors unacceptable for the accuracy requirements of the sensors. We devised a real time compensation method for the interference by introducing geometric and weight factors. We realized the method using simple electronic circuits and obtained the real time compensated outputs with errors of 1 %.