• Journal of the Optical Society of Korea
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• v.11 no.4
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• pp.177-182
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• 2007

This paper discusses the errors associated with electric field cross talk for optical voltage sensors in a three-phase electric system and provides a solution to compensate the errors. For many practical conductor configurations, the electric field cross talk may cause errors unacceptable for the accuracy requirements of the sensors. We devised a real time compensation method for the cross talk and built an electronic circuits based on it. The mechanism of the compensation and the corresponding error reduction were discussed.

• Proceedings of the KIEE Conference
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• 2001.10a
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• pp.9-11
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• 2001

This paper deals with design and characteristic analysis of a permanent magnet linear synchronous motor for magnetic levitation stage of semi-conductor manufacture machine. In order to improve the control performance by detent force minimization, skew and PM offset method are used.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2010.06a
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• pp.189-189
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• 2010

The Improved flux-lock type superconducting fault current limiter(SFCL) is composed of a series transformer and superconducting unit of the YBCO coated conductor. The primary and secondary coils in the transformer were wound in series each other through an iron core and the YBCO coated conductor was connected with secondary coil in parallel. In a normal condition, the flux generated from a primary coil is cancelled out by its structure and the zero resistance of the YBCO thin films. When a fault occurs, the resistance of the YBCO coated conductor was generated and the fault current was limited by the SFCL. In this paper, we investigated the fault current limiting characteristics through the spot at the beginning of the fault current in the Improved flux-lock type SFCL. The experiment results that the fault current limiting characteristics was difference according to the point of a fault current started. Through the analysis, it was shown that shorter the time of a phase transition.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.65 no.5
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• pp.738-744
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• 2016

Current rating of a power cable can be calculated by the maximum allowable temperature in an insulating material considering the heat transfer from cable conductor. Therefore, it is very important to calculate the current rating using electrical equivalent circuit by calculated cable thermal circuit parameters but, it has not been fully investigated yet. In this paper, in order to determine the current rating of power cable, conventional calculation method has been reviewed considering the conductor resistance, loss factor of sheath, dielectric losses and thermal resistances based on the maximum allowable temperature of 345 kV $2500mm^2$ XLPE cable. To confirm the calculation result of the current rating, the conductor temperature should be examined whether it reaches the maximum allowable temperature by the thermal equivalent circuit of the cable. Then, utilizing EMTP (Electro-Magnetic Transient Program) which is a conventional program for electrical circuit, the thermal equivalent circuit was transformed to an electric equivalent circuit using an analogous relationship between thermal circuit and electrical circuit, and temperature condition including cable conductor, sheath, cable jacket could be calculated by the current rating of 345 kV $2500mm^2$ XLPE cable.

• Proceedings of the KIEE Conference
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• 2002.07a
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• pp.452-454
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• 2002

In case the overload of an existing power line is expected as the consumption of electric power increase, we substitute STACIR/AW which has better thermal characteristic for ACSR. That can approximately double the transmission capacity. In that case the mechanical characteristics of STACIR/AW should meet the design condition of the existing tower. However, the strength of invar in STACIR/AW is lower than that of steel in ACSR, which makes it difficult to keep the safety of a conductor specially in a long span In this regard, this paper presents the new conductor model using the AMC and the analysis of its characteristics.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2006.05a
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• pp.413-414
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• 2006

This study was aimed to verify the stable interruption characteristics between power collector and 3rd rail type conductor rail for the Korean-standardized rubber-tired AGT light rail vehicle. At the test track for the Korean-standardized rubber-tired AGT light rail vehicle, interruption ratios, stresses, vibrations, and contact force variations were measured by test conditions, having various train speed. As the results, it was verified that developed 3rd rail type conductor maintains interruption characteristics, which can supply stable electric power.

• Proceedings of the KSR Conference
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• 2004.10a
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• pp.1407-1412
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• 2004

Impedance calculations of electric railway traction systems is essential to define characteristics and to design it. The self impedance is defined voltage drop rate per unit length, the mutual impedance is represented as a voltage induced to transmission line from transmission line. The self and the mutual impedance are influenced by ground return currents. The earth is considered as a semi-infinitely extended non-ideal conductor. The current of transmission line produces earth current induced magnetically and it flow through a path having minimum impedance. Carson proposed the impedance calculation formula using wave equations and magnetic field equations. Though the formula have an improper equation, that is still used as a standard impedance calculation method. This paper introduced an impedance calculation method that the complex depth of earth return method assumes that the current in conductor returns through an imagined earth depth path located directly under original conductor at a depth of. In this paper, we showed that this proposed method has a closed form and is easier than Carson's.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.07a
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• pp.629-630
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• 2005

ACSR(Aluminum Conductor Steel Reinforced)가공송전선은 교류전류의 흐름에 의하여 코어 (Core)부에 자기장이 발생되어 전력손실을 발생시킨다. 이로 인한 전력손실을 최소화 하는 방법으로는 코어의 재질을 자성체인 고탄소강선 대신에 비자성강으로 교체하는 방법이 있다. 본 연구에서는 기존의 고탄소강선 대신에 고강도 비자성강을 코어(Core)에 적용한 ACNR(Aluminum Conductor Nonmagnetic Steel Reinforced) 가공송전선을 개발하였다. ACNR 가공송전선의 전기적 특성시험에서 약 9%정도의 손실저감효과를 나타내었다.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.17 no.3
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• pp.197-201
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• 2017

The demand for electric power is increasing every year in Korea. All the systems adopted at power stations in order to generate and transmit electric power should operate in perfect condition or reliability. The device for transmitting the generated high-voltage electric power is 6 kV CV single core cables. The manufacturing companies of the cables makes an official announcement that the operating lifetime of their cables is about 30years. But from the moment of operation the deterioration precesses of worsening the characteristics of cables starts. Since the reliability for the status of installed cables in deterioration has not been diagnosed, the cables can be broken at any unexpected moments. In order to prevent the abrupt cable accident by systematically monitoring the cable status, we have invented the first device in Korea. We have installed our device at Korea Western Power Co. Ltd. in order to diagnose the live cables. In this paper, we present our research results of measured temperatures of inner conductor and surface and the compared results of those data with other cable company. We also show that our results agree with those made by other company.

• Journal of Sensor Science and Technology
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• v.26 no.2
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• pp.101-106
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• 2017

A novel intravenous (IV) infusion monitoring sensor is presented to measure the drop rate in the drip chamber of an IV infusion set. It is based on a capacitive proximity sensor and detects the variation of the longitudinal electric field induced by the drop falling into the drip chamber. Unlike the conventional capacitor sensor with two semi-cylindrical conductor plates, the proximity sensor for IV monitoring is composed of a pair of conductor rings which are mounted on the outer surface of the drip chamber with a specific gap between them. The characteristics of the proximity sensor for IV monitoring were investigated through three dimensional electrostatic simulations. It showed quite superior performances in comparison with the conventional capacitor sensor. Especially, the proposed proximity sensor exhibits consistent sensitivity regardless of its mounting position on the drip chamber, operates normally though the drip chamber is tilted and shows robustness to the changes of the drop size and the drip factor of the IV infusion set. Thus, the proximity sensor for IV monitoring is more suitable for use in actual environment of IV therapy compared with the conventional capacitor sensor.