• The Transactions of the Korean Institute of Electrical Engineers C
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• v.54 no.9
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• pp.407-413
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• 2005

The optical current transformer was developed for 170 kV GIS using optical fiber. The sensor optimized on the optical CT was wound 3 turns and twisted 4 times per a turn at the pipe with a diameter of 130 m. To optimize the optical CT, the output signal was measured according to the setting angle of polarizer and analyzer, The asymmetry and distortion of the output signals were improved when the parallel polarized light was incident to the fiber sensor and under the angle of analyzer was $45^{o}$. The measurement error for the linearity was only $\pm{0.42}\;\%$ to 1,000 A in the case of reflection type.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.54 no.2
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• pp.55-62
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• 2005

The optical CT was developed to use twisted fibers for 170 kV GIS. The fiber sensor optimized on the optical CT was wound 3 turns and twisted 4 times per a turn at the pipe with a diameter of 130 mm. The measurement error for the linearity which was satisfied the criterion of 'IEC Class-1.0' was less than ± 0.44 % at the transmission type and ± 0.82 % at the reflection type to 2,000 A. At a low current to 200 A, the measurement error was ± 0.69% at the transmission type and ± 1.38 % at the reflection type.

• Proceedings of the KIEE Conference
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• 1992.07a
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• pp.491-494
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• 1992

This paper described the development example of optical CT(Current Transformer) and optical PT (Potential Transformer) which is measurement system of current and voltage of electric power line using Electro-Optic effect and Magneto-Optic effect. We designed the optical CT of 22KV class and 154KV class and an optical PT of 22KV class. And now the filed testing is in progress in a KEPCO's substation.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.24 no.11
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• pp.9-16
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• 2010

This paper examines the temperature characteristics of an Optical CT (optical current transformer) using the Faraday effect for measuring high current in a super high voltage-power apparatus. It is performed as follows by the sensor for embodying Faraday effect. $\cdot$ A single-mode optical fiber capable of maintaining a polarization state is used. $\cdot$ A light source is applied at 1310[nm] to a Laser Diode. $\cdot$ The Linear of Faraday effect to a large current is evaluated and $\cdot$ A possible application using an Optical CT was shown. An Influence of Faraday effect to the surrounding temperature measured -40~50[$^{\circ}C$], and the characteristic of the current sensitivity was reported. An application using the results of the temperature compensation system was used in order to compensate for surrounding temperatures. A possibility of applying Optical CT for electric power apparatus was advanced further. We were able to confirm that this temperature calibration method can minimize the fluctuation of the output signal depending on the temperature conditions.

• Journal of the Optical Society of Korea
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• v.13 no.3
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• pp.304-309
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• 2009

We tested the feasibility of measuring fat thickness using a miniaturized chip LED sensor module, testing 12 healthy female subjects. The module consisted of a single detector and four sources at four different source-detector distances (SD). A segmental curve-fitting procedure was applied, using an empirical algorithm obtained by Monte-Carlo simulation, and fat thicknesses were estimated. These thicknesses were compared to computed-tomography (CT) results; the correlation coefficient between CT and optical measurements was 0.932 for bicep sites. The mean percentage error between the two measurements was 13.12%. We conclude that fat thickness can be efficiently measured using the simple sensor module.

• Proceedings of the Optical Society of Korea Conference
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• 2007.02a
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• pp.289-290
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• 2007

• Journal of radiological science and technology
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• v.46 no.2
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• pp.107-114
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• 2023

The purpose of this study was to compare the basic radiological characteristics of in-house polymer gel and commercially-available gel (BANG^TM) gel dosimeters with a spectro-photometer to use a optical computed tomography (CT) scanner. We investigated the radiological characteristics including dose linearity, absorbance spectrum, dose rate dependency and inter-and intra-reproducibility at wavelengths of 590, 600 and 630 nm. The optimal dose linearities of two gel dosimeters showed R² value of 0.939 and 0.948 at wavelengths of 590 nm and 600 nm, respectively. For two polymer gel dosimeters, there is no peak sensitivity within the range of all wavelengths in absorbance spectrum. For in-house gel dosimeter, the dose rate dependency were within 5% for all wavelengths except for the dose rate of 100 MU/min. For BANG^TM gel dosimeter, the dose rate dependency showed an error range of ±5% for all wavelengths. The inter-and intra-reproducibility of two gel dosimeters were within the range of 2.5%. We have confirmed that the two gel dosimeters was appropriate for use with a optical CT scanner.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2006.05a
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• pp.418-421
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• 2006

현재 국내 외에서 GIS(Gas Insulated Switchgear)용 광 CT(optical current transformer)가 활발히 연구 개발되고 있다. 이러한 광 CT는 전력선에 발생하는 자기장에 의해 레이저 빛의 파장 각도가 변하는 현상인 Faraday Effect를 기련 원리로 한 전류측정용 기기이다. 본 논문에서는 GIS용 광 CT 개발을 목적으로 한 기초적 연구로써 자기장이 발생하는 전력선에 장착되는 센서부가 도선을 중심으로 해서 어떻게 위치하느냐에 따른 광 CT의 출력신호를 측정하여 연구하였다.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.17 no.6
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• pp.47-53
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• 2003

In this paper, we described the laboratory layout of the optical CT in connection with the measurement of large current based on Magneto-Optic Effects. It was used He-Ne laser for light source and was used PIN-Photodiode for light receiver. The sensing section was organized by winding optical fiber around conductor on the concept that the rotation angle of polarizing axis by Faraday Effect is proportional to the applied current in to conduction. The optical signal passed through optical fiber sensor was induced to analyzer arranged in the direction of $\theta$ for input polarization, and then analyzed its rotation angle and researched on operating characteristics of optical CT for 60[Hz] AC current measurement from l00[A] to 1000[A] was carried out. In this results, the output signals induced linearly with the current and proved that the intensity is increased with increasing turns of fiber through output differences which in accordance with turns of fiber and we verified that there is not only difference of the output with the medium between electric field and optical fiber, but also the lineality. Measuring the references and output intensities of the optical CT, ratio errors were within $\pm$7%. This confirmed that error rate will be improved by each medium and turns.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.18 no.3
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• pp.109-113
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• 2004

In this paper, we took the basic experiment in order to explore the optical CT(optical current transformer) for measuring high current in a superhigh voltage condition. It is based on the faraday effect that changes the polarization characteristic of optical signals by the magnetic field. We used 1310[nm] laser diode for a light source and comprised a sensing part with the optional fiber of 5[m], 10[m], 20[m] length each. The range of current was from 400[A] to 1300[A]. We observed the characteristic of output that changes according to the length of the optical fiber composing the sensing part. The optical fiber of 5[m] length used for the sensing part had -11.1% of the maximum ratio of error and 10[m] and 20[m] length had -3.5% and 1.7% each. This means that the power and linearity of output increase in proportion to the length of optical fiber and applied current in the same experimental condition.