• The Transactions of the Korean Institute of Electrical Engineers P
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• v.56 no.3
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• pp.142-147
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• 2007

Infrared thermography is one of the most valuable and cost-effective diagnostic techniques for predictive maintenance on electrical systems. For the electric installations, the thermographies can identify major problems, which if left unattended could lead to breakdowns. The result thermal images depend upon operator skills, inspection technique, and load and weather conditions. When the thermographer is applied to remote monitoring, the conditions of the systems are not perfectly analyzed because operators are hard to know the weather's effects of the installed place. Therefore, this paper defines the effects by weather conditions which will influence the final results. The purpose of this paper is to define the weather effects that a thermographer needs to consider for successful condition analysis.

• Management Science and Financial Engineering
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• v.3 no.1
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• pp.57-74
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• 1997

An EOQ-like inventory model for a manufacturing process is studied. The system is assumed to deteriorate during the production process. The results are either the production of a number of defective items, or the breakdown of the production machine. The optimal production lot size is derived. The model is extended to the case in which the probabilities of making defective items and machine breakdowns are a function of both the quantity (amount) and quality (performance) of the consumed setup cost (including the preventive maintenance cost). We further assume that the setup performance can be improved by investing in the performance improvement program. Hence, the same or a better setup outcome can be achieved with a lower setup cost. We then investigate the optimal setup cost and investment policy simultaneously, thereby achieving a better process quality and setup cost reduction concurrently.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2008.11a
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• pp.151-154
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• 2008

In today's agriculture, there has been an increase in the construction of agricultural facilities due to the need to maximize land usage and many customer demands for products. But many agricultural facilities are constructed by not qualified construction company so it often causes many accidents like breakdowns and repairs. this study is to understand the construction process of agricultural facilities. The results of this research are that greenhouse is lack of the law of contract and the performance and need for the construction process supervision. Vinyl House is needed to supervise the design of the structure.

• Proceedings of the KIEE Conference
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• 1996.07c
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• pp.1529-1531
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• 1996

Porcelain suspension insulators have teen used for a long time in distribution line. However, Puncture breakdowns in porcelain insulators caused by weaking cement between metal fitting nad porcelain material. There is little puncture breakdown in Epoxy casting insulator. This paper presents electrical test results for the development of suspension insulator used Cycloaliphatic Epoxy resin. Items of test results are as follow - Power Arc test - Aging test - Impulse flashover voltage tests - Puncture tests et.al.

• Proceedings of the KIEE Conference
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• 1997.11a
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• pp.544-549
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• 1997

Injector of high voltage or linear ion accelerator is intended to generate, extract and form beam of certain species with required parameters at the entrance of accelerating structure or, for low energy case, directly in the processing chamber (end station). Injector is the main part defining the ion accelerator performance and reliability. Its power supply and control system (PSCS) features are conditioned by placing the injector equipment at high voltage potential and by complexity of the plasma-beam load. The injector's PSCS should provide: - Transmission of electric power onto high voltage (h/v) terminal; - Obtaining of required output characteristics for injector equipment operation; - Transmission of the operational data and start/stop signals from h/v terminal to control cabinet; - Rremote control of injector; - Withstanding the high voltage breakdowns and X-ray radiation; - Compatibility with other equipment. The paper is concerned with analysis of injectors' PSCS structure and description of the system developed for 50 keV, 20 mA heavy ion injector.

• Proceedings of the KIEE Conference
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• 1995.11a
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• pp.411-413
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• 1995

Porcelain insulators have been used for the almost all of the suspension insulators in distribution line. However, Puncture breakdowns in porcelain insulators caused by westing cement between metal fitting and porcelain material. There is little puncture breakdown in Epoxy casting insulator. This paper presents a new design technique for the development of suspension insulator used Cycloaliphatic Epoxy resin. The design was performed on the basis of two conditions (weather conditions for the past 30 years and the existing installation conditions of KEPCO) and was proven of its adaptability by FEM method.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 1999.11a
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• pp.174-178
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• 1999

This paper describes an investigation on bearing failure due to spragging that has been continuously occurred in turbine hearings. The spragging is defined as the damage found on the leading edge of unloaded pads in the tilting pad journal bearing, In general, the damage mechanism by spragging is classified into fatifgue failure, The principle cause of spragging could be thought as the self-excited vibration by the absence of a stable static equilibrium position of upper pads with no preload. Because of serious consequences of system breakdowns due to bearing failures, determination ar the causes of failure and effective method for countermeasures are very important. This paper describes both the causes of spragging and countermeasures for prevention of such failure, which are taken place in the electric power plants.

• Proceedings of the KSR Conference
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• 2008.06a
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• pp.900-907
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• 2008

All electric trains in the city should be run without any troubles of the equipments in order to offer good services to the passengers. But some breakdowns occur when they are operated due to the long time uses. There are mechanical troubles and electrical troubles included reactors. Most of them, the reason of the troubles can be found out easily after breakdown. But it is difficult to find out the reasons of the reactor troubles which disappear after operation. The reactors of the train filter the current which supplied from electrical lines and supply the current to the inverter and block the ripple of the current. Partial discharge occur from the reactor by the heat. accordingly, If the signals of discharge were perceived, it could be anticipate the deterioration degree of insulation. In this paper, on-monitoring system for reactor's troubles in trains is established and the output results of monitoring system are investigated.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.29 no.1
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• pp.109-115
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• 2006

Exact solutions for practical-size problems in job shop will be highly inefficient. Scheduling heuristics, therefore, are typically found in the literature. If we consider real-life situations such as machine breakdowns, the existing scheduling methods will be even more limited. Scheduling against due-dates addresses one of the most critical issues in modern manufacturing systems. In this paper, the method for weighted tardiness schedule using a graph theoretic decomposition heuristic is presented. It outstands the efficiency of computation as well as the robustness of the schedule.

• Proceedings of the Korea Society for Simulation Conference
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• 1998.10a
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• pp.128-132
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• 1998

This research is concerned with buffer management in a multi-cell FMS(Flexible Manufacturing System) with an AGVS(Automated Guided Vehicle System). To reduce blocking and starving caused by breakdowns, variablility in process times, and diversity of part routing, buffer is needed. Due to the high per unit buffer cost, which primarily consists of floor space and equipment cost, the total capacity of buffers in an FMS is very limited. Therefore, proper buffer management can provide a high system efficiency. This paper presents a buffer management model for a multi-cell FMS with an AGVS and a simulation study to compare the proposed model to a conventional buffer management model in a job shop FMS.