• Journal of the Korean Institute of Telematics and Electronics B
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• v.31B no.3
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• pp.1-13
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• 1994

In this study under the distributed system for efficient distribution resource completely symmetic global scheduler was designed and implemented to obtain the general global scheduler, that is load balancing as sharing objectives. To balance the system's load efficiently each node must be designed to get right decision-making. Thus we considered computing time to estimate fault such as delay on communication network, communication period and other decision-making. Load balancing mechanism which suggested in this study was implemented in the distributed system which IBM PC/AT linked to and composed with Ethernet. The target operating system was composed of IBM PC/AT as a basic construction in which proper type of UNIX operating system were ported and communication layer chose communication type implemented from Amoeba. The method of IPC employing layered multilevel access method to avoid inefficient protocol using direct communication mode guarantees rapid response due to short ready time for IPC.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.475-476
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• 2011

전력공급의 안정성과 신회성을 높이기 위해 우리나라 배전선로에는 2002년부터 자동화가 추진되고 있으며 2010년을 기준으로 자동화 추진 대상 배전설비의 90% 이상이 자동화 설비로 교체되었다. 배전자동화는 고장의 조기검출과 고장복구 시간의 감소 등으로 배전선로의 전기 공급 신뢰도를 높인 것으로 평가되고 있지만 자동화 기기의 사용 증가로 인한 고장의 증가와 이에 따른 보수비용의 증가가 새로운 문제로 부각되고 있다. 본 논문에서는 우리나라 배전선로에서 사용되는 자동화용 단말장치에서의 고장현상에 대해 보고하고자 한다. 이를 위해 2009년부터 2009에 걸친 고장자료가 수집되었으며 이들 자료의 분석을 통해 주 고장모드를 확인하였다. 고장모드의 분석을 위해서는 제작자 및 운영자가 참여하여 FMEA(Failure mode and Effect Analysis) 방법을 사용하였으며 본 고에서는 이들에 대한 세부 내용을 기술하였다.

• 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.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.62 no.8
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• pp.1177-1183
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• 2013

In this paper, the analysis of inspection period bases on reliability is suggested in the field of traction power system. Even though there are several maintenance models, the most commonly used maintenance assessment has been focused on time based maintenance in real traction power systems. The maintenance intervals are selected on the basis of long-time experience. It ensures high availability and exact planning of staff. Reliability centered maintenance, which evaluates criticality and severity of each failure mode, achieves the operation, maintenance, and cost-effective improvement that will manage the risks of equipment. This paper deals with electrification in railway inspection frequency and applied reliability based inspection frequency instead of constant intervals. The distribution function of failure rate in traction power system belongs to Weibull function. Also, the fault data and the number of installed equipments for electrifications are collected. The failure history is investigated and classified in detail. Though these complicated procedures, it contribute to extend equipment lifetime and to reduce maintenance costs.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.36 no.9
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• pp.678-684
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• 1987

The identification problem of instrument faults in PWR pressurizer is considered. The instrument failure detection technique in this paper consists of two filters, a normal-mode Kalman filter which estimates plant states in normal operation and a bias estimator which estimates the magnitudes and directions of bias faults. The concept of threshold based on the residual of a Kalman filter in normal operation is introduced. The bias estimator is driven when the absolute value of residual exceeds the threshold. The suggested failure detection algorithm is applied to a PWR pressurizer. Computer simulations show that the prompt detection of bias fault can be performed very successfully when there exist instrument faults.

• Proceedings of the KIEE Conference
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• 2000.07a
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• pp.31-33
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• 2000

This paper discusses the operational characteristic analysis of distance relay depending on the power system parameters in transmission line including FACTS devices. Distance relay requires protective coordination because the FACTS devices change power system parameters to increase power transmission capacity. In this paper, the dynamic operational characteristics of distance relay are analyed for the effect of fault resistance and operation mode of FACTS devices according to the installed points of these devices.

• Journal of the Korean Institute of Telematics and Electronics
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• v.27 no.5
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• pp.699-708
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• 1990

This paper proposes two test procedures for detecting functional faults in semiconductor random access memories (RAM's) and a new testimg scheme to execute the proposed test procedures. The first test procedure detects stuck-at faults, coupling faults and decoder faults, and requires 19N operations, which is an improvement over conventional procedures. The second detects restricted patternsensitive faults and requires 69N operations. The proposed scheme uses Built-In Self Testing (BIST) techniques. The scheme can write into more memory cells than I/O pins can in a write cycle in test mode. By using the scheme, the number of write operations is reduced and then much testing time is saved.

• Journal of Applied Reliability
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• v.16 no.4
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• pp.347-355
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• 2016

Purpose: With the advance of miniaturization of electronic products, stacked packages of high density semiconductors are commonly used. Potential failure modes and mechanisms of stacked packages are identified. Methods: Failure modes and mechanisms of thin chip stacked packages are determined through the categorization and failure analysis: delamination, non-wet, crack, ESD, EMI and the process related damages. Results: Those failure modes are not easy to find and require excessive amount time and effort for analysis and subsequent improvement. Conclusion: In this study, a method of estimating the failure rate based on the strength measurement is suggested.

• Proceedings of the Korean Society for Quality Management Conference
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• 2010.04a
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• pp.67-73
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• 2010

This study began the study by instructing enterprises to change Batch Production into U-Line. This study suggested TPS U-Line building model process and applied it to some of their product line. By connecting concerned process elements into continuous operations. Outside orders were also switched to inside operations and executed in continuous operations, thereby about 100Km of transit distance became zero Km, Production lead Time was incredibly reduced. After all, 90% of Production Lead Time, 50% of handling fault, 3/4 of workers decreased and Productivity per Person enhanced which involves improving Batch Production into Continuous Production and applies it to the real world, so that small and medium enterprises can consult this study if the company is willing to make an improvement to their product line.

• Proceedings of the KIEE Conference
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• 1999.07c
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• pp.1035-1038
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• 1999

To improve the damping of all poorly damped oscillation modes, a control strategy of Static Synchronous Series Compensator (SSSC) based on energy method is presented in this Paper As a synchronous voltage-sourced inverter, SSSC is used to provide controllable series compensation. SSSC can provide controllable compensating voltage over an identical capacitive and inductive range. The damping effect of control strategy based on energy function is robustness with respect to loading condition, fault location and network configuration. Furthermore, the control inputs are based on local signals. In two area system, the effect of damping inter-area mode oscillation is demonstrated by the robust control strategy of SSSC.