• Transactions on Electrical and Electronic Materials
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• 제18권3호
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• pp.169-175
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• 2017

A safe and reliable protection system in distribution networks, specifically, those hosting distribution generation units, needs a robust over-current protection scheme. To avoid unintentional DG disconnection during fault conditions, a protection system should operate quickly and selectively. Therefore, to achieve this aim, satisfying coordination constraints are important for any protection scheme in distribution networks; these pose a challenging task in interconnected and large-scale networks. In this paper, a new coordination strategy, based on the same non-standard time-current curve for all relays, in order to find optimal coordination of directional over-current relays, is proposed. The main aim is to reduce violations, especially miscoordination between pair relays. Besides this, the overall time of operation of relays during primary and backup operations should be minimized concurrently. This work is being tackled based on genetic algorithms and motivated by the heuristic algorithm. For the numerical analysis, to show the superiority of this coordination strategy, the IEEE 30-bus test system, with a mesh structure and supplemented with distributed generation, is put under extensive simulations, and the obtained results are discussed in depth.

• 한국화재소방학회논문지
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• 제4권2호
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• pp.3-13
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• 1990

Fire Protection System is facilities that Control the fire by mechanic means. Buildings Over a Certain Scale is required this system. As the small from the fire extinguisher as the large to the sprinkler system of automatic fire extinguishing equipment the kinds are various. With the development of architecture technique while modern higher buildings are increased. As fire is a first product that human make, it performed many profits and services for our mankind. Sometimes as it is profitable fire or harmful fire, it takes charge of human's life culture. Therefore fire protection system is facilities that control the ]after fire by mechanic means Building over a certain scale is required this system. As the small from the fire extinguisher as the large to the sprinkler system of automatic fire extinguishing equipment, the kinds are various. With the development of architecture technique while modern Higher buildings are increased high level and fire prevent facilities aren't reached to that level. The object of this study is present the problem which appear from the analysis of place standard for fire protection facility. This study described as a following order. First. We are going to look history of the fire protection system and change course of that with the year and facility. Second, We say the frame system and special nature of the foreign fire prevent Act. Third. We understand the control reality of fire protection system. Fourth. We took out the merit of foreign fire prevent law and the problem of our current domestic system. The placing standard of proper fire protection facilities that be presented from this study are followed next. 1) We have reinforce sprinkler system placing standard for the fire extinguishing and check the spread of fire. 2) We must to be ruled the standard for keeping fire prevention system that are received reality and people's idea. 3) We should prepare lawful basis which can be place fire prevention center. 4) We have to correct the standard of use about complex building without mainuse and we take increase the real effectiveness of this. 5) We ought to match the use of current fire prevention act and the use of architecture law.

• 한국화재소방학회논문지
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• 제5권1호
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• pp.5-14
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• 1991

Fire Protection System is facilities that Control the fire by mechanic means. Buildings Over a Certain Scale is required this system. As the small from the fire extinguisher as the large to the sprinkler system of automatic fire extinguishing equipment the kinds are various. With the development of architecture technique while modern higher buildings are increased. As fire is a first product that human make, it performed many profits and services for our mankind. Sometimes as it Is profitable fire or harmful fire, it takes charge of human's life culture. Therefore fire protection system is facilities that control the latter fire by mechanic means Building over a certain scale is required this system. As the small from the fire extinguisher as the large to the sprinkler system of automatic fire extinguishing equipment, the kinds are various. With the development of architecture technique while modern higher buildings are increased high level and fire prevent facilities aren't reached to that level. The object of this study is present the problem which appear from the analysis of place standard for fire protection facility. This study described as a following order. First, We are going to look history of the fire protection system and change course of that with the year and facility. Second. We say the frame system and special nature of the foreign fire prevent Act. Third. We understand the control reality of fire protection system. Fourth. We took out the merit of foreign fire prevent law and the problem of our current domestic system. The placing standard of proper fire protection facilities that be presented from this study are followed next. 1) We have to reinforce sprinkler system placing standard for the fire extinguishing and check the spread of fire. 2) We must to be ruled the standard for keeping fire prevention system that are received reality and people's idea. 3) We should prepare lawful basis which can be place fire prevention center. 4) We have to correct the standard of use count about complex building without mainuse and we take increase the real effectiveness of this. 5) We ought to match the use of current fire prevention act and the use of architecture law.

• Journal of Electrical Engineering and Technology
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• 제9권3호
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• pp.1104-1111
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• 2014

The digital substations are being built based on the IEC 61850 network. The cooperation and protection of power system are becoming more intelligent and reliable in the environment of digital substation. This paper proposes a novel method to prevent the malfunction caused by the Transformer Magnetizing Inrush Current(TMIC) using the IEC 61850 based data sharing between the IEDs. To protect a main transformer, the current differential protection(87T) and over-current protection(50/51) are used generally. The 87T IED applies to the second harmonic blocking method to prevent the malfunction caused by the TMIC. However, the 50/51 IED may malfunction caused by the TMIC. To solve that problem, the proposed method uses a GOOSE inter-lock signal between two IEDs. The 87T IED transmits a blocking GOOSE signal to the 50/51 IED, when the TMIC is detected. The proposed method can make a cooperation of digital substation protection system more intelligent. To verify the performance of proposed method, this paper performs the real time test using the RTDS (Real Time Digital Simulator) test-bed. Using the RTDS, the power system transients are simulated, and the TMIC is generated. The performance of proposed method is verified in real-time using that actual current signals. The reaction of simulated power system responding to the operation of IEDs can be also confirmed.

• 한국통신학회논문지
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• 제26권9A호
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• pp.1535-1541
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• 2001

TCP is the most widely-used transport layer protocol in current Internet, while ATM technology is used to increase the data communication speed at data link layer and network layer. In the TCP-over-ATM architecture, the most significant problems are (i) the partial packet discarding problem, and (ii) the TCP window timeout problem. Several approaches have been proposed to solve the partial packet discard problem and the timeout problem individually, but none of them considered the two problems together. In this paper, we propose an enhanced UBR+ scheme which supports fairness among the TCP connections using UBR+ scheme, and provides protection of damaged VC from the multiple packet losses in the same TCP sliding window. To analyze its performance, we simulate the proposed scheme using OPNET. The simulation results show that the proposed scheme supports fairness, and also increases the throughput by reducing the probability of multiple cell losses in the same TCP window.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2001년도 Proceedings ICPE 01 2001 International Conference on Power Electronics
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• pp.703-707
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• 2001

The demand for protection of power electronic applications has during the last couple of years increased regarding the high-power IGBT modules. Even with an active protection, a high power IGBT still has a risk of exhibiting a violent rupture in the case of a fault if IGBT Fuses do not protect it. By introducing fuses into the circuit this will increase the circuit inductance and slight increase the over-voltage during the turn-off of the diode and the IGBT. It is therefore vital when using fuses that the added inductance is kept at a minimum. This paper discuss three issues regarding the IGBT Fuse protection. First, the problem of adding inductance of existing High-Speed and new Typower fuses in DC-link circuit is treated, second a short discussion of the protection of the IGBT module is done, and finally, the impact of the high frequency loading on the current carrying capability of the fuses is presented.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2003년도 하계종합학술대회 논문집 V
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• pp.2927-2930
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• 2003

This paper has been studied the ballast for multiple lamps. Many fluorescent lamps are demanded in where industrial buildings and public buildings. Using the proposed ballast for multiple lamps, we can decrease the cost and the space for installing. Also in the paper, the protection circuit is introduced for over voltage and current. The general problem of the ballast for multiple lamps is to shut down the ballast circuit in the ease of one abnormal lamp. But the proposed method is not shut down all the circuit even if one lamp is in an abnormal condition.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2006년도 춘계학술대회 논문집 전기설비전문위원
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• pp.48-50
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• 2006

SC(Static Condenser) in KEPCO is used in voltage control and power factor compensation. Currently KEPCO uses SC to 154kv 50MVA and 23kv SMVA. It is not important in old days because a SC bank accident has no effect on power system. But we are interested in the SC bank for power quality in these days. The SC Bank has a reactor and a condenser using series connection. It is operated in critical point for resonance circuit normally. Therefore the SC bank has a small reliability against other Power instruments. If a 4th harmonic frequency as a resonance frequency is supplied in system, the condenser is damaged because of a resonance current. And a trip and a closing for CB(Circuit Breaker) in many times will have a big influence of SC bank destruction. General OCR(Over Current Relay) observing SC bank is not useful for this protection We think that protection relay must be have the SC bank characteristics. A solution for this problem is active Power, resonance frequency and impedance.

• 한국전기전자재료학회논문지
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• 제32권3호
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• pp.256-261
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• 2019

The use of military lithium batteries in this field accelerates the generation of internal pressure because the active materials, lithium and the electrolyte, react to form sulfur dioxide gas. This also reduces the amount of electrolyte. In this condition, batteries can 'vent' or 'explode' especially when completely discharged. Such venting and explosion can be regarded as a safety accident, as toxic gases and shrapnel are ejected from the batteries which can harm the user. A DTaQ was carried out in 2017 as a quality problem solution project to solve this safety issue. A protection circuit was thereby developed, which included a micro controller unit (MCU) which can stop battery usage when in an over-discharging state by sensing its low-voltage condition. In 2018, this concept was expanded to lithium batteries for the remote controlled ammunition system. This paper reports results of the improved performance.

• 한국정밀공학회지
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• 제15권7호
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• pp.78-84
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• 1998

The problem of autobody corrosion has been addressed over the past decade by the increasing use of zinc and zinc alloy coated steels in automotive application. This paper describes the evaluation of formability, weldability and painted corrosion performance of galvalume steel sheet. This paper presents an overview of the program and some initial test results on the weldability, lifetime of the electrode tip shape of the spot welding and corrosion protection. Galvalume steel sheet improved corrosion performance and spot weldability of galvalume steel sheet was not changed under the influence of the variation of welding current. And tip shape has influenced on the lifetime of tip for galvalume steel sheet.