• Journal of Power Electronics
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• 제9권5호
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• pp.809-821
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• 2009

This paper proposes a new phase-shift full-bridge DC-DC converter by applying energy recovery circuits to a conventional full-bridge DC-DC converter in plasma display panel applications. The converter can achieve soft-switching in main-switches by an extra auxiliary resonant network even with the wide operating condition of both output load and input voltage. The un-coupled design guidelines to the main bridge-leg component parameters for soft-switching operation contribute to conduction loss reduction in the transformer primary side leading to efficiency improvement. The auxiliary switches in the resonant network also operate in zero-current switching. This paper analyzes the operation modes of the proposed scheme and presents the key design guidelines through steady state analysis. Also, the paper verifies the validity of the circuits by hardware experiments with a 1kW DC/DC converter prototype.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2001년도 추계학술대회(한국공작기계학회)
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• pp.99-104
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• 2001

The neural network method has been introduced to design a controller for linear motor feed system and system operation status was monitored. It is most difficult to achieve controller gain tuning because of the information limit. Regardless of the system structure, conventional control gain could be adjusted minimizing the resulting error for both position and velocity using the proposed method. Slight performance deterioration was observed at the small value of training epoch. Different controller performance for position was observed with respect changed sampling time. Actuated system performance was monitored using neural network signal processing and operational status was predicted with the rate of 80% approximately.

• 한국공작기계학회논문집
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• 제10권3호
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• pp.75-82
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• 2001

The continuous chip in turning operation deteriorates the precision of workpiece and can cause a hazardous condition to operator. Thus the chip form becomes a very important task for reliable turning process. The chip form is identified using the neural network of supervise data Through the measurement of energy radiated from the chip. The feed mechanism os adjusted in order to break continuous chip according to the result of the chip form recognition and it shows a good approach for precision turning operation.

• Journal of Electrical Engineering and Technology
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• 제12권4호
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• pp.1435-1441
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• 2017

Distributed generation (DG) in the future will play an important role in the electricity supply systems, in wich can provide DG capacity from a few hundred kW to tens of MW. However, it is connected to the local power grid, DG will have certain influence on the power quality of the power grid. One of the most significant effects is that they will change the configuration of the local power grid as well as affecting the operation mode of the grid. This paper presents a method of finding the optimal open loop, analyzing and selecting the appropriate mode of operation to reduce power losses of power distribution networks that includes DG.

• 한국응용과학기술학회지
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• 제26권2호
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• pp.151-160
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• 2009

At this study, we are developing a possible control system through remote monitoring for fire protection in various chemical factory facilities. It's possible to do real time confirmation of a normal operation presence of the various equipment installed in a chemical factory through the internet network at a fire fighting head office, an area fire department and a chemical factory situation room using this remote monitoring control system. When occurring, abnormal operation is the remote monitoring control system, which can check this immediately and notify the situation room administrator. After it was tested using developed remote monitoring control system, the remote monitoring for which the internet network was used confirmed possible.

• 대한전기학회논문지:전력기술부문A
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• 제49권1호
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• pp.26-30
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• 2000

Switching of the transmission lines(T/L) is one of the methods for wuppressing the short circuit capacity. This paper presents the T/L switching operation by using the Hopfield neural network(HNN). The switching of T/L can make the line powers and the bus voltages deteriorated, as well as the fault current decreased. Such an insecure state should be avoided when the T/L is operated to be open. In this studies, the inequality constraints are formulated into the objective function to be incorporated with the HNN. Test results show that the convergence characteristics of HNN lead to the adequate solution of T/L switching.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2000년도 하계학술대회 논문집 A
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• pp.564-566
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• 2000

To provide more noiseless upstream service on the HFC(Hybrid-Fiber Coaxial) Access Network, we should conduct upstream band analysis and have related operation skill. In this paper, we studied the upstream signal measurement to get goof transmission quality, effective operation and maintenance, also showed the method of noise analysis and that of upstream band frequency selection. Finally we tested the signal in the field and showed the analyzed result.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2000년도 하계학술대회 논문집 A
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• pp.125-127
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• 2000

Multiple faults are hard to diagnose correctly because the operation of circuit breakers tripped by former fault changes the topology of power systems. The information including operating time of actuated relays and tripped circuit breakers is used for considering changes of the network topology in fault section diagnosis. This paper presents a method for fault section diagnosis using a set of matrices which represent changes of the network topology due to operation of circuit breakers. The proposed method uses fuzzy relation to cope with the unavoidable uncertainties imposed on fault section diagnosis of power systems. The inference executed by the proposed matrices provides the fault section candidates in the form of a matrix made up of the degree of membership. Experimental studies for real power systems reveal usefulness of the proposed technique to diagnose multiple faults.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2006년도 추계학술대회 논문집 전력기술부문
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• pp.12-14
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• 2006

This paper presents an vulnerability index for hidden failure of protective relays in transmission system. The bad influence can be quantized by an vulnerability index. When there is mis-operation, no-operation or mis-setting, power flow can be quantized by an index. According to the index, relays can be resetting. So the wide area blackout can be prevented.

• Journal of international Conference on Electrical Machines and Systems
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• 제1권2호
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• pp.98-104
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• 2012

This paper presents a novel transformer isolated parallel connected full-bridge dc-dc converter using recently developed trans-Z-source network. Unlike the traditional voltage -fed or current-fed converters, the proposed converter can be open- and short-circuited without damaging switching devices. Therefore, the desired buck and boost function can be achieved and the converter reliability can be greatly improved. A 6 kW prototype dc-dc converter is built and tested to verify performances of the proposed converter.