• Journal of Electrical Engineering and Technology
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• v.1 no.1
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• pp.16-22
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• 2006

Selective ground relays (SGRs) are useful fur distinguishing a faulted feeder from the sound feeders in ungrounded systems. However, they sometimes mis-operate due to human or device errors. Particularly, the reversed polarity of zero-sequence current transducers (ZCTs) is the most frequent cause of mis-operation. This paper presents a modified SGR for reducing the probability of mis-operations caused by the reversed polarity of ZCTs. The modification is achieved by introducing an adaptive time delay, which depends on the magnitude of the zero-sequence current and the phase angle deviation from the reference. The modified SGR was successfully demonstrated on a sample ungrounded system without mis-operation.

• The Journal of Information Systems
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• v.3
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• pp.133-145
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• 1994

Performance evaluation is essential for the successful management and operation of MIS. The more MIS grows and relevant investment enlarges, the more performance evaluation grows in importance. However, MIS managers as well as top management still have difficulty in evaluating the performance of MIS. This arises from various reasons, such as the specialty of MIS, diversified influences of MIS, multidimensionality of evaluation items, and the difference between evaluation levels. In this paper, MIS is understood in a broad sense. MIS's scope is of a very wide range from each application system to system innovation view. The MIS should support the firm's objectives, and, consequently, MIS evaluation should be implemented at corporate level, not merely at application system level. The most critical problem of MIS evaluation is that a systematic frame covering various viewpoints and factors of MIS evaluation does not exist. Not a single measure covers all aspects of MIS evaluation. To help resolve this problem, this paper proposes an hierarchical approach for practical use that includes most aspects of evaluation approaches from previous studies, and, furthermore, emphasizes the evaluation of strategic aspects of MIS.

• Journal of the Korea Society of Computer and Information
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• v.5 no.4
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• pp.154-160
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• 2000

Recently, there are great variations on concepts and rolls of information system as the radical growth in information technology. A systematic MIS evaluation is requested for effective management and operation of information system. Although many researches on MIS evaluation have been progressed, the evaluation of the user satisfaction is limited by evaluating from the each system's result because of the diversity of view points and inclusion of MIS introduction. Therefore, in this paper, a conceptual framework is suggested to evaluate MIS synthetically that is changed by the result of existing MIS evaluation. So to speak, a new evaluation framework is suggested by synthesizing various view points and evaluation method that suggested from the existing MIS evaluation such as user satisfaction of results as the introduction of MIS and the satisfaction of variation of entire organization.

• Journal of Information Technology Applications and Management
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• v.25 no.2
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• pp.91-108
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• 2018

The purpose of this study is to examine the direction of the students' satisfaction improvement by comparison of related disciplines of undergraduate management information systems (MIS) majors. MIS is one of the academic disciplines that have become important as the demand for manpower for new industries in the 4th industrial revolution. We surveyed 3rd and 4th grade undergraduate students in the departments of management information systems, business administration (BA), computer engineering (CE) of C university. The results revealed that the students' satisfaction was influenced by the ability of the professor, the curriculum development, and the curriculum operation factors. Especially, it was found that the curriculum operating factors among the three departments had greater effect on the students' satisfaction. If the education environment is improved considering curriculum operating factors and the administrative and service factors and that are important in the CE departments, it will be helpful for the students' satisfaction improvement of MIS.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.10 no.5
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• pp.975-982
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• 2006

To cope with the recent developments of info-communication technology and information infrastructure, and in particular, to respond to the environment of wire and wireless communication integration, and also to overcome the limit of the existing web-based Port-MIS, the Ministry of Maritime Affairs and Fisheries is developing a mobile Port-MIS public service system (hereinafter referred to as a mobile Port-MIS). Accordingly, this study analyzes the current situation of the mobile Port-MIS that is under operation of the lust stage, finding out the problems, and suggesting new measures to activate the mobile Port-MIS. We expect this study will be able to suggest a guideline to the government institutions or other related organizations that plan to introduce a mobile technology in the near future.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.7-8
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• 2007

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.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2014.10a
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• pp.179-181
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• 2014

지금까지의 해상교통관제시스템(Vessel Traffic System: VTS)에서 관제를 수행함에 있어서 관제사들이 확인할 수 있는 선박에 대한 정보는 AIS(Automatic Identification System) 정보에 한정적이었다. 하지만 선박에서 전달받는 AIS 정적 정보는 한정적이며, 정확성 역시 신뢰할 수 없을 경우가 많은 실정이다. 그래서 관제사들은 선박의 정확한 정보 확인을 위해서 항만운영시스템(Port-MIS)에 별도로 접속하여 해당 선박에 대한 정보를 조회하여 활용하는 상황이다. 현재 ETRI에서는 Single Windows 개념을 적용한 차세대 해상교통관제시스템을 개발하면서 관제사들의 편의성 제공을 위해 추가적인 Port-MIS의 연동 없이 관제 화면을 통해 관제중인 선박에 대한 Port-MIS 정보를 조회하여 현시할 수 있도록 개발하고 있다. 본 논문에서는 관제사들의 VTS 현시용 선박 정보 필드에 대한 요구사항을 도출하고, 이를 제공하기 위한 시스템 설계 구조에 대해서도 기술한다.

• Proceedings of the KSR Conference
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• 2004.10a
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• pp.1303-1308
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• 2004

This paper proposes a reduction method for the mis-operation analysis of the DC High Speed Circuit Breaker(HSCB) in electric railway substation system. The analysis method is based on present condition of operation which is a method for accuracy level up. There is reason to operation of HSCB that it is mis-operation of fault detection relay(50F), operation of ground fault relay(64P), and trouble of electric car. A countermeasure is relay resetting through field test, induction of GTOCB(Gate Turn Off Thyristor Circuit Breaker), HSVCB(High Speed Vacuum Circuit Breaker), coordination with electric car. The results presented in the paper can be used as a reference for maintenance free in electric railway substation system.

• Journal of Advanced Marine Engineering and Technology
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• v.12 no.1
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• pp.28-36
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• 1988

Since the oil shocks of 1970s, the quality of the fuel oil for marine diesel engines has become more degarded than ever. When the poorer quality fuel is burned, carbon residues of the fuel oil cause blockage of the fuel injection valve nozzle and troubles of fuel injection system. The mis-firing of engine occurs due to the decrease of fuel quantity injected, the decrease of compression pressure in the slow speed range, the increase of fuel leaked and the high ignition temperature of degraded fuel etc. This paper is to investigate theoretically the effects of mis-firing on the crankshaft axial vibration of diesel engine. The cylinder pressure in operation is calculated by the computer aided simulation of closed cycle for a large two-stroke diesel engine and also the exciting force of axial vibration and the resonance amplitudes are calculated. And then, the condition of normal state, misfiring and one-cylinder cut-off operation are analyzed. The results of calculations show good agreements with those of the actual measurements.

• Proceedings of the KIEE Conference
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• 2003.11a
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• pp.337-340
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• 2003

This paper describes the operational characteristics of protection algorithm applied in distributed generations(DG) for faults occurred in the interconnected distribution networks. The DG can be Influenced by abnormal grid conditions such as disturbances occurring in the neighboring distribution feeders as well as the interconnected power line. Particularly, in case of the fault happening in the neighboring distribution feeders emanated from the substation to which DG is connected, the protective devices in the DG might mis-operate. The mis-operation of protective devices can be varied by the fault conditions. The simulation results for Hoenggye substation model composed of five feeders using PSCAD/EMTDC showed that the number of mis-operation of protective devices applied in DG is about 0.66 times per one year.