• Journal of Electrical Engineering and Technology
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• v.8 no.5
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• pp.969-974
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• 2013

Protection issues in distribution systems which are to be operated in open and closed-loop modes in a smart grid are studied and a generalized protection setting method is proposed to meet the new requirements. The developed setting method assumes a conventional over-current protection scheme for the system with reclosers and over-current relays. In a closed-loop mode, it identifies protective devices that have to be sacrificed in order to maximize protection coordination for bidirectional fault current flow. The proposed setting method has been tested on many systems with different complexity and is proved effective.

• Journal of Applied Reliability
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• v.9 no.1
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• pp.1-12
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• 2009

BLDC motors are stored in the devices such as CD-RW, COMBO, DVD-ROM and CD-ROM. It is indispensable to establish reliability assessment criteria for BLDC motors, especially in the world where IT grows rapidly. In this article, reliability certification procedure is given. The reliability certification procedure consists of two separate tests such as quality certification test and lifetime test. The former quality certification test comprises general performance test and environmental test. Items which pass the test undergo lifetime test which guarantees the extent of mean lifetime with certain confidence.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2018.05a
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• pp.175-176
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• 2018

We have developed liquis precursotr delivery system (LDS) for ultra thin film preparation in semiconductor devices. The LDS concists of 3 major parts : aerosol generator, vaporizer and vapor storage. By uaing LDS which was attached to plasma enhanced chemical vapor deposition system, thin Al2O3 layer was prepared at extremely low temperature and characterized.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.07a
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• pp.931-934
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• 2001

GaN nanowires has much interest as one-dimensional materials for blue light LED. GaN-based materials have been the subject of intensive research for blue light emission and high temperature/high power electronic devices. In this letter, the synthesis of GaN nanowires by the reaction of mixture of GaN nanowires by the reaction of mixture of Ga meta and GaN powder with NH$_3$ using thermal chemical vapor deposition is reported. X-ray diffraction, energy dispersive x-ray spectrometer, scanning electron microscopy, and transmission electron microscopy indicate that those GaN nanowires with hexagonal wurtzite structure were about 60nm in diameter and up to several hundreds of micrometers in length.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.07a
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• pp.373-376
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• 2001

When varistors for circuit protection is used at high voltage, it's operation properties were unstable because of leakage current and nonlinear coefficient with grain size. For the purpose of improving of ZnO varistor properties, high voltage ZnO varistor was fabricated with Y$_2$O$_3$addition. Electrical properties were investigated according to sintering conditions and mixing conditions. ZnO varistors was shown ohmic Properties when it's applied voltage was below critical voltage. It was shown non-ohmic properties over critical voltage, because current was increased with decreasing resistance.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1997.04a
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• pp.45-48
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• 1997

Enhancing the electrical conductivity of the ultrathin organic films is one of the important factors for the development of molecular electronic devices. The Langmuir-Blodgett(LB) technique has recently been attracted interest as the a method of deposition ultrathin films. We have fabricated N-docosyl-N'-methyl viologen-diTCNQ(DMVT) anion radical LB film and investigated the optical and electrical conductivity. We have measured UV/visible and FT-lR spectrum. In ESR spectrum, we confirmed that a half-amplitude linewidth is clearly dependent on both temperature and incident angle, which indicates conducting species change. The in-plane electrical conductivity of 21 layers is approximately 1.37$\times$10$^{-6}$ (S/cm).

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.07b
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• pp.752-755
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• 2002

Since Metallo-Porphyrin (MP) is very interesting compound due to its unique electronic and redox properties and it is also chemically and thermally stable, MP has been studied for potential memory and switching devices. In this study, thin films of 5,10,15,20 - Tetrakis - Octadecyloxymethylphenyl - Porphyrin - Zn(II) (Zn-TPP) were prepared by the Langmuir-Blodgett (LB) method and characterized by using UV/vis absorption spectroscopy and cyclic voltammetry. It was found that the proper transfer surface pressure for film deposition was 25 mN/m and the limiting area per molecule was $135{\AA}^2$/molecule. The current-voltage (I-V) characteristics of these films were investigated.

• Proceedings of the KIEE Conference
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• 2006.07a
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• pp.12-13
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• 2006

In this paper, RCF(Resistive Companion Form) analysis method which is used to analyze small signal stability problems of non-continuous systems including switching device. The RCF analysis method are applied to the power systems with the thyristor controled FACTS equipments such as TCSC. As a result of simulation, the RCF method is very powerful to calculate the oscillation modes exactly after the switching operations, and useful to analyze the small signal stability of power systems with switching devices such as FACTS equipments. As an applicable example of the RCF method in power system, the one machine infinite bus system including TCSC at generator terminal bus is investigated and the results proved that variations of oscillation modes after periodic switching operations of TCSC can be calculated exactly.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.11a
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• pp.341-342
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• 2006

A physical model for reduction of Electromagnetic Interference(EMI) or its predecessors, Radio Noise, Electrical Noise, or Radio-Frequency-Interference(RFI), is a rapidly expanding digital technology. It covers the frequency spectrum from DC to about 3 GHz EMI is the poisoner which does not allow radio, TV, radar, navigation, and a lot of electrical, electro-mechanical, and electronic and communication devices, apparatus and systems to operate compatibly in a common frequency spectrum environment EMI can result in a jammed radio, heart pacer failures, navigation errors and many other either nuisance or catastrophic events. Therefore, it follows that this spectrum pollution problem has reached international levels of concern and must be dealt with m proportion to the safety and economic impact Involved.

• 제어로봇시스템학회:학술대회논문집
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• 2005.06a
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• pp.778-781
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• 2005

In this paper, we describe a development of a Bluetooth Access Point for the WAN connection of home network devices. Especially, users can access the PSTN at home instead of expensive digital cellular network through the AP, using the 'one-phone', which is the Bluetooth enabled cellular phone. The simultaneous benchmark test about telephone service and LAN access service shows the perfect compatibility and reasonable performance of the access point. The one-phone service can become a convergence of wired and wireless communication through the AP.