• The Transactions of the Korean Institute of Electrical Engineers A
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• v.53 no.5
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• pp.249-256
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• 2004

This paper suggests a novel evaluation scheme of protective effectiveness in distribution systems. The adequacy of every parameter in a protective device is evaluated for the setting or correction rules. Then, the protective effectiveness of a device, device-wise effectiveness, is obtained by the combination of the parametric evaluation results. The coordination-wise effectiveness between devices can be calculated by evaluating the parameters which contribute the performance of coordination. The protective effectiveness of the whole system can be obtained by combining the device-wise and coordination-wise effectiveness values. The rules, in this paper, are categorized into three groups; rules for single parameter, rules for coordination between parameters, and rules for coordination between protective devices to form a hierarchical calculation model. The proposed method is applied to a typical distribution network to show its effectiveness.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.27 no.6
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• pp.75-81
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• 2013

In this paper, protection coordination between residual current devices and surge protective devices in low-voltage consumer's distribution systems are presented. In the case that a surge protrctive device(SPD) is located on the load side of an residual current device(RCD), when the surge is injected from the source side of the RCD, most of injected surge currents are split into the RCD and the protection coordination between the SPD and RCD is improper, three of 6 specimens experience unintended operation due to test impulse currents. Also when the surges is injected from the load side, a lot of the surge currents is split into the SPD, but a half of test specimens causes nuisance trip. Coordination between SPD and RCD is not valid. When installing SPD, it is important to select SPD after due consideration of the protection voltage level of metal oxide varistor embedded in RCD. It is expected that the results obtained from this work could be useful to improve the protection effects of SPD in low-voltage distribution systems.

• Proceedings of the KIEE Conference
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• 2001.05a
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• pp.129-131
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• 2001

In order to improve the reliability of power service and the effective management of distribution power system. DAS (Distribution Automation system) is widely used in KEPCO(Korea Electric Power Corporation) branch offices. Based on the present protective device coordination program which used in KEPCO. this study presents the new concept about both protective device coordination program maximizing the characteristics of DAS and development plan of protective device auto-coordination program with the merits of DAS.

• Proceedings of the KIEE Conference
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• 2003.07a
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• pp.363-365
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• 2003

Recently, the concern of power qualiaty problem is increasing. Especially, Voltage quality problem have been increased important problem. Electronic device was affected by voltage sag. So, sensitive load that included many electronic Device was affected by voltage sag. also, it may have economic loss. In this paper, we argue the coordination scheme considering the loss of sensitive load. The coordination device of distribution system for instaneous fault is recloser and sectionalizer, But, the fault clearing time of recloser is more than 2 seconds. So, voltage sag generates long time that affected sensitive load. HS(high speed switchgear) has fast fault clearing time(0.015s) that not affected sensitive load. Therefore, the coordination applied HS is used. The proposed schemes are proved and evaluated by a case study using PSCAD/EMTDC simulation.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2004.11a
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• pp.233-235
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• 2004

This paper studies protective coordination of utility interconnected multiple distirbuted generations(DG). The study of protective coordination interconnected DG has been conducted. A protective coordination of utility disturbed by reverse current of DG. Therefore, A protetive device is not operate when reverse current flows. In this paper, we use phase difference between V and I. Also, we studied protective coordination algorithm of utility interconnected multiple DG.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.48 no.9
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• pp.1103-1111
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• 1999

STACOM will be utilized to control substation voltage in the near future. Although STACOM shows good voltage regulation performance owing to its rapid and continuous response, it needs additional reactive power compensation device to keep control margin for emergency such as fault. ULTC transformer is one of good candidates. This paper presents a Kohonen Neural Network (KNN) based coordination control scheme of ULTC transformer and STACOM. In this paper, the objective function of the coordination control is minimization of both STACOM output and the number of switchings of ULTC transformer while maintaining substation voltage magnitude to the predefined constant value. This coordination, control is performed based on reactive load trend of the substation and KNN which offers optimal tap position in view of STACOM output minimization. The input variables of KNN are active and reactive power of the substation, current tap position, and current STACOM output. The KNN is trained by effective Iterative Condensed Nearest Neighbor (ICNN) rule. This coordination control applied to IEEE 14 bus system and shows satisfactory results.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.29 no.3
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• pp.81-87
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• 2015

In order to effectively protect electrical and electronic circuits which are extremely susceptible to lightning surges, multi-stage surge protection circuits are required. This paper presents the operational characteristics of the two-stage hybrid surge protection circuit in extra-low voltage DC power lines. The hybrid surge protective device consists of the gas discharge tube, transient voltage suppressor, and series inductor. The response characteristics of the proposed hybrid surge protective device to combination waves were investigated. As a result, the proposed two-stage surge protective device to combination wave provides the tight clamping level of less than 50V. The firing of the gas discharge tube to lightning surges depends on the de-coupling inductance and the rate-of-change of the current flowing through the transient voltage suppressor. The coordination between the upstream and downstream components of the hybrid surge protective device was satisfactorily achieved. The inductance of a de-coupler in surge protective circuits for low-voltage DC power lines, relative to a resistance, is sufficiently effective. The voltage drop and power loss due to the proposed surge protective device are ignored during normal operation of the systems.

• Journal of the Korean Society of Costume
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• v.56 no.8 s.108
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• pp.83-94
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• 2006

In this era of ubiquitous service, a computing device has functions similar with human beings. It influences all major fields of human life, such as clothing, dieting and housing. In order to use the coordination functions of the magic mirror, which might be a basic part of clothing in the era of ubiquitous service, this study concentrates on product information that should be inputted in RFID chip in detail in order to exercise virtual fashion coordination. Information should be inputted in RFID chip to use magic mirror for fashion coordination, a direction for doing this was also suggested. After coding the suggested clothing items, virtual fashion coordination was implemented as a fashion illustration. This study is as following, First, sorts standard code for suitable coordination in 4 images and presented to a proof. Code denoted by 10 characters. Each code literal special quality marks by two characters and divided by season, image, fabric, item, rotor, five items. Item middle of characters of 10 code, when agree on article more than 8, coordination is enabled. Secondely, It is presented by coordination to dressing action picture by suitable coordination classified apart in whole occasions, and coordination method by wearer inclination is remembered wearer's dressing action picture to Magic mirror including layered look. Thirdly, wardrobe of Magic mirror clothes that always buy newly in magic mirror, is washing and clothes that do not take to wardrobe did to be controlled. Fourth, Wealth and schedule is suggested firster than wearer's dressing action.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.59 no.1
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• pp.19-25
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• 2010

Most faults are single-phase-to-ground fault in ungrounded system. The fault currents of single-phase-to-ground are much smaller than detection thresholds of measurement devices, so detecting single-phase-to-ground faults is difficult and important in ungrounded system. The protection coordination method using SGR(Selective Ground Relay) and OVGR(Overvoltage Ground Relay) is generally used in ungrounded system. But this method only detects fault line and it has the possibility of malfunction. This paper proposed to advanced protection coordination method in ungrounded system. The method just using zero-sequence current can detect fault line, fault phase, fault section at terminal device. The general protection method is used to back up protection. In the case study, the proposed method has been testified in demo system by Matlab/Simulink simulations.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.8
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• pp.1479-1484
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• 2009

The introduction of the large transformer due to the large power demand has increased the fault current in power distribution system. The increased fault current can exceed the cut-off ratings of the circuit breaker. As the methods to solve this problem, the superconducting fault current limiter(SFCL) has been notified. However, the limited fault current by SFCL affects the operational characteristics of the protective device such as overcurrent relay. Therefore, the selection of the proper impedance for the SFCL is required to keep overcurrent relay's protective coordination with the SFCL when a large transformer is introduced into the distribution system. In this paper, the SFCL's impedance for protective coordination was investigates in that a large transformer is introduced.