• Proceedings of the IEEK Conference
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• 2002.07a
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• pp.433-436
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• 2002

Most of electric distribution utilities have their reliability performance measured by reliability indices such as SAIFI and SAIDI to evaluate customer satisfaction. Adding protective devices in electrical distribution system can increase the system reliability by protecting public customers from local faults. In large-scale distribution system, it is difficult to determine the positions of these protective devices, which can efficiently protect customers within utilities' investment. In this paper, we propose an optimization technique to identify types and positions of protective devices to minimize SAIFI and SAIDI indices according to system requirement constraints.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.61 no.4
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• pp.214-219
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• 2012

In this paper, the method of protective coordination is studied to install Superconducting Fault Current Limiter (SFCL) to power distribution system. If SFCL is installed, the protective coordination is not operated well because of the decreased fault current. Thus, the resetting method of protective devices is presented to coordinate protection system in power distribution system with resistor-type SFCL. The presented methods are divided into three parts; OCR, OCR-Recloser, OCR-Recloser-Recloser. The presented methods are proved through case studies using PSCAD/EMTDC simulation.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.16 no.2
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• pp.90-97
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• 2002

In this paper we study the performance test items and improvement plans of surge protective devices for low-voltage power circuits used in railway system. Above of all, the sources of electromagnetic interference in railway system are researched. And then we compared domestic railway standard with IEC and IEEE standards far the test items and methodologies of surge protective devices. Through the investigations, we found that the domestic standard is behind in the number of test items and methods on surge protective devices. As the countermeasures, we suggest removing component tests of surge protective devices, separating standards for power and signal standards, and using international surge waveform. In applying to domestic railway surge protective devices, surge limiting voltage measuring and surge endurance tests by international standard methods are good result.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.54 no.9
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• pp.427-433
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• 2005

In DC tracking power supply system, ground faults are currently detected by the potential relay, 64P. Though 64P relay detects ground fault, it cannot Identify the faulted region which causes long traffic delays and safety problem to passengers. Two new ground fault protective relay schemes that can identify the faulted region are presented in this paper. One is bus differential protective relay and the other is ground overcurrent protective relay. Both type of relays is similar in principle to the ordinary bus differential protective relay and the ground overcurrent relay used in other power system. In DC traction power supply system, since it is ungrounded, ground fault current is not big enough to operate those relays. To solve the problem, a current control device, called device 'X', is newly introduced in both system, which enables large amount of ground fault current flow upon the positive line to ground fault. Algorithms for these relays are developed and their validity are verified by EMTP simulation.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.9 no.3
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• pp.658-663
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• 2008

In this study, we estimated the influence of electrical pole by FEM(Finite Element Method) and developed protective system by designing and interpreting protective system for electrical pole and overhead optical communication line when abnormal strength worked on messenger wire. Protective system did not shed messenger wire under wind pressure and discontent load but did assign a part to preventing rupture of electrical pole and disconnection of optical communication line through automatically shed messenger wire over fixed strength. Structure of protective system analysis by FEM and prove property by measuring tensile strength for practical product.

• Journal of the Korea Institute of Construction Safety
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• v.2 no.1
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• pp.16-20
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• 2019

About 50% of disasters occurring at domestic construction sites are caused by the accidents not wearing personal protective equipment. Under the current statutes, employers are required to provide personal protective equipment and workers are required to wear personal protective equipment. However, there is insufficient compliance with wearing personal protective equipment on site. This study is about the measure of improving the system to the way of purchasing, wearing and managing personal protective equipment by individual workers, and refunding the cost of personal protective equipment to workers. It is expected that this thesis will improve the system of personal protective equipment effectively, and contribute to the prevention of disasters by settling the culture of wearing personal protective equipment.

• Journal of the Korean Society of Clothing and Textiles
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• v.37 no.8
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• pp.1117-1129
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• 2013

The sizing system for Korean Standard of Disposable Protective Coveralls (DPC) uses the ISO sizing system without modification even though the user suitability for Koreans is unverified. This study provides useful information to improve the size standard of Korean DPC by analyzing measurement DPC data from Korean men and women. The distribution of Korean measurements shows that the size sections were unsuitable for Korean men and women for a protective clothing size standard. Body types were categorized into five types based on a cluster analysis of representative men's and women's measurement factors. Two clusters mostly consisted of men, two other clusters mostly consisted of women, and the other cluster relatively evenly consisted of men and women. Therefore, characteristic body measurements and measurement distribution differences were identifiable for men and women. In conclusion, an unmodified ISO protective clothing size standard is unsuitable for Korean men and women and may cause fit problems. This study shows that a Korean Standard of protective clothing is beneficial for protective clothing manufacturers and wearers if smaller size intervals are added for women and the difference in the distribution of men and women is reflected in the current sizing system. ISO is appropriate to use a Korean Standard in this global era, however, it should be reviewed to provide improved Korean data.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.48 no.6
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• pp.712-718
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• 1999

When a fault occurs in power transmission systems, protective relays play a roles of protecting the power system according to there setting values. Therefor, it is important that protective relays have high selectivity and sensitivity by correct setting the involves a large volume of data and is a complicated and very tedious, therefore vulnerable to the human errors. Also, it is very difficult to verify that the relays have correct operating parameters before the fault occurs. This paper porposed a method to testify the reliability of realys by showing the operation response to faults in the simulation of the real power system operation environment.

• Proceedings of the KAIS Fall Conference
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• 2006.05a
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• pp.302-306
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• 2006

In this study, we analyzed the influence of electrical pole by FEM(Finite Element Method) and developed protective system by designing and interpreting protective system for electrical pole when abnormal strength worked on messenger wire. Protective system did not shed messenger wire under wind pressure and discontent load but did assign a part to preventing rupture of electrical pole through automatically shed messenger wire over fixed strength. Structure of protective system analysis by FEM and prove property by measuring tensile strength for practical product.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.52 no.1
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• pp.50-57
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• 2003

In this paper, the protective relay setting rules of Korean electric power system are studied by analysis of errors to be considered. An accurate operation of protective relays with accurate settings are important in power system reliability. The setting rules are used from the first establishment in 1982 and revision in 1990 Therefore, it needs revise and analysis of the setting rules because of environmental changes such as voltage raise or applied new technology of power system. Two major setting rules are studied. One is the rule for Zones of distance relay for transmission lines. The other is the one of differential current in a differential relay for power transformers. The range of errors in the setting rules accepted in the field experience is studied in simulation of case study. Also some guide lines for the range of errors in the setting rules are presented from the case study using Matlab simulation.