• Journal of the Korean Institute of Gas
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• v.11 no.1 s.34
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• pp.18-22
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• 2007

The fault current through the earth originated from a power line ground fault might cause arcing through the soil to an adjacent pipeline, which might bring about not only a catastrophic accident such as gas explosion and oil leakage but also a hazard to the safety of workers responsible for the maintenance and repair of the pipeline. In this paper we investigated the arcing phenomena through soil between a power line tower and a pipeline and outlined the standards for the separation distance of a buried pipeline adjacent to the power line tower.

• Journal of Electrical Engineering and Technology
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• v.7 no.5
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• pp.772-777
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• 2012

Accidents caused by water absorption in water-cooled generator stator windings often occur all over the world. The absorption into the insulator of the coolant, which is used to cool down the heat generated by stator windings during operation, leads to the deterioration of dielectric strength, and insulation breakdown. An insulation breakdown may cause not only an enormous economic loss but also a very serious grid accident that would compromise stable supply of electric power. More than 50 % of domestic generators have been in operation for more than 15 years, and water absorption tests performed on 50 water-cooled generator stator windings during a five-year planned preventive maintenance period beginning in 2006 identified water absorption problems in 10 of them, all of which required repair. Because the existing water absorption test detects this problem by utilizing stochastic methods after measuring the capacitances at the final positions of insulation breakdown, its accuracy is limited. This study demonstrates that water absorption can be more accurately diagnosed by utilizing method along with a more precise one.

• Journal of the Korean Society of Safety
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• v.32 no.6
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• pp.40-45
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• 2017

Chemical accidents generated during maintenance, repair, and normal operation, such as dispersion, fire, and explosions, can cause massive losses like a 2012 hydro fluorine leak in Gumi, South Korea. Since this accident, many researches have studied physical mitigation systems. However, due to many difficulties including potential costs and lack time, it is really hard for many companies to install mitigation systems without prior knowledge. Thus, the efficacy of mitigation system should be evaluated. This study assesses a dike design considering the fluid velocity at an open hole when a leakage accident occurs. It is assumed that leakage materials follow a free fall motion. Throughout case studies, a current KOSHA guide for a dike design was evaluated and new guidelines handling various conditions were proposed.

• 한국정보통신설비학회:학술대회논문집
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• 2007.08a
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• pp.390-393
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• 2007

The reliability as well as the power capability of the UPS system can be increased by replacing a single UPS unit with multiple small UPS units in parallel, resulting in a so-called module UPS. This module UPS system allows that a new module can be added or replaced while maintaining power to loads, which is a hot-swappable operation. In addition, it has desirable features such as ease of output power expandability, convenience of maintenance and repair, and high reliability. To realize the module UPS, load sharing without interconnection among parallel connecting modules as well as a small scale and lightweight topology is necessary. The frequency and voltage droop method is applied to parallel operation control to achieve load sharing. 5kVA modules are designed and implemented to confirm the effectiveness of the proposed approaches. Experimental results show that the module UPS system has a high power factor, a low distortion of output voltage and input current, hot-swappable operations and good load sharing characteristics.

• Korean Institute of Interior Design Journal
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• v.14 no.5 s.52
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• pp.218-225
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• 2005

In this apartment market, many apartments are being reconstructed within even less than 20 years from their first construction. This entails many problems in environmental and economical facets, for which many researches are under way in several institutions and universities. International cases show that the international trend goes for remodeling of maintenance, management, and repairing rather than new building. The purpose of this study is to investigate the factors of cost evaluation for establishing the time period of apartment based on durability of material and equipment while considering the economic feasibility of apartment, when remodeling as a concept of sustainability regarding building is being vitalized. This study investigates the proper period of remodeling in consideration of weight accruing to the LC(Life Cycle) and cost based on the standardized durability. The weight of cost, period establishment analysis, and LC according durability varies the data values of remodeling periods. The physical durability and cost from this data enable the investigation into not only the repair period of individual materials of the apartment but also remodeling period.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.67 no.11
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• pp.1523-1529
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• 2018

Electric vehicles that are currently in operation are being produced domestically. Therefore, there is no great difficulty in receiving or repairing the failed parts or in the overall repair. On the other hand, most of the electric locomotives are manufactured by introducing the parts and technology of foreign vehicle manufacturers. In this paper, conducted a study about life cycle cost analysis of developed auxiliary power unit in 8200 series electric locomotive and suggested cost down method. This confirms the economic benefits of the developed products of the auxiliary power supply compared to the existing products. In addition, a sensitivity analysis of MTBF was conducted to suggest a life cycle cost down method.

• Journal of Korean Library and Information Science Society
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• v.30 no.1
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• pp.243-255
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• 1999

In modem day Korea, the amount of records containing data, statistic etc are increasing dramatically. However, our country neglects to deal with these archives which include fields such as culture. Thus government documents, even modem documents less than 50 years old, are fading. becoming damaged and acidic. The purpose of this study is to research factors for prolongment the life of archival records, especially papers. Firstly, we want to maintain the document's original quality, which is a PH between 7 to 8.5, permanently. Secondly, our objective is to permanently maintain the records in a scientific environment. Thirdly, to execute proper repair methods by conservators. Permanent quality refers to the maintenance of a PH between 7 and 8.5 in a scientific environment whereby regulations are in effect to control the environment. These factors include constant temperature and humidity, breakors of various lights, Stable storage facilities which are fire resistent. A CCV control system as well as the dusting and fumigation of records. Finally, to conservate damaged papers based on exact diagnosis.

• Journal of the Korean Society of Safety
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• v.33 no.5
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• pp.35-41
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• 2018

Chemical accidents generated during maintenance, repair, and normal operation, such as dispersion, fire, and explosions, can cause massive losses like a 2012 hydro fluorine leak in Gumi, South Korea. Since this accident, many researches have studied physical mitigation systems. However, due to the lack of potential costs and time, it is really hard for many companies to install mitigation systems without prior knowledge. Thus, the efficacy of mitigation system should be evaluated. This study assesses a dike design considering the fluid velocity at an open hole when a leakage accident occurs. It is assumed that leakage materials follow a free fall motion. Throughout case studies, a current KOSHA guide for a dike design was evaluated and new guidelines handling various conditions were proposed.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.9 no.2
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• pp.366-373
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• 2005

In this paper, we propose the method of integrating the Book Lending Management System running either on local and web to develop Enterprise Application in distributed environment more easily and quickly using Sun's EJB based on the lava. We integrate the Book Lending Management System which is operated separately using EJB. And, by designing and implementing the Book Lending Management System separately according to its functions, it can reduce the cost of maintenance and repair. At all platforms where the Internet, Book Lending service is possible, because it provide Web based interface with JSP. Then, we can get platform independent implementation using EJB and JSP..

• Proceedings of the KIEE Conference
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• 2006.07a
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• pp.525-526
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• 2006

Recently, much research has been done and many improvements have been developed for islanding protection of distributed generation(DG). Anti-islanding protection for DG must be act very quickly to prevent equipment damage at the time of disconnection and for the safety of maintenance and repair personnel. DG-based detection methods have included both passive and active types, and now research has shifted towards new anti-islanding detection methods that make up for the defects of the previous types. Because differences occur between the utility grid and the DG when connecting and disconnecting depending on the phase difference, voltage, current, relative capacity of electric power, and system operation characteristics, voltage phase angle is an important consideration. In this paper, we simulated islanded operation characteristics comparing phase difference of DG and the connected utility grid, and analyzed various parameters (real power, reactive power, RMS voltage, RMS current, power factor angle, and frequency) by varying the DG's voltage phase angle. Using this information, we propose a suitable DG voltage phase angle for enhanced passive islanding detection techniques.