• The Transactions of the Korean Institute of Electrical Engineers A
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• v.54 no.10
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• pp.487-495
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• 2005

This paper reviews the characteristic of thermal and temperature of oil field cable in transient state such as grounding fault and lightning surge. For analysis in various conditions, many actual underground power cable systems are modeled using ATP. These results are applied for the examination of temperature increase when the single line to ground fault by the breakdown of insulation part and hitting of lightning surge are occurred. The inner part temperature of OF cable is analysed according to the various kinds of cable using the thermal model of transient state. The temperature increase of sheath and crossbonded lead bv fault current is also analysed using IEC 60949.

• Tribology and Lubricants
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• v.23 no.5
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• pp.195-200
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• 2007

This paper presents the friction induced scuffing and wear defects analysis of a pin bushing bearing based on the chemical composition using a scanning microscopy (SEM) and an energy dispersive X-ray analyzer (EDX). The SEM/EDX system, which may provide good information on the surface thermal defects and chemical compositions, provides impurities such as an aluminum, a silicon, a ferrous component and an oxygen, especially. The EDX measured results show that the oxygen may reduce the strength and a hardness of a pin busing, which may lead to a scuffing and a seizure on the rubbing contact surface. The current technology fabricated by a sintering for a pin bushing bearing should be modified or changed to reduce the oxygen composition and the impurities in pin bushing materials.

• Proceedings of the Korea Institute of Applied Superconductivity and Cryogenics Conference
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• 2003.02a
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• pp.163-166
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• 2003

Maintaining low temperature is very important in operating HTS cable termination in which Joule heat is generated at current lead. In this study, numerical analysis using FLUENT is performed to find an optimized flow conditions for effective cooling of HTS cable terminal system using subcooled liquid nitrogen (L$N_2$) as refrigerant. The variables considered here are mass flow rate of L$N_2$, location of inlet and diameter of inlet and outlet. Simplified models are investigated under these variables. Based on maximum temperatures in the cryostat, the configuration for effective cooling of HTS cable was determined.

• Hwankyungkyoyuk
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• v.15 no.2
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• pp.14-29
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• 2002

The environment of the world becomes deteriorated rapidly as the result of the development of technology, the increase of the standard of living, and the growth of population. These circumstances called for environmental education in Korea, creating an environment course in the middle and high school in 1995. Despite the increasing importance of environmental education, however, the situation has not developed in its favor because of the current system of the university entrance examination. The school has failed to develop the curriculum of environmental education in the secondary education. This paper solves this problem internally in terms of the improvement of the contents, organization, teaching method (role-playing game), and teaching materials of environmental education, with a case study of the “noise” unit in 10th grade. This case study expects to change the attitude toward noise, increase the interest and knowledge in environment, and lead to responsible environmental behavior.

• Journal of the Korea Society for Simulation
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• v.16 no.3
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• pp.39-48
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• 2007

This study suggests a method of command and control in modeling a combat situation. In particular, it presents the structure of an intelligent agent that may substitute for the current system of decision making in the military operation to lead a troop. Today the Korean military war game simulations emphasize on engagements, instead of command and control. This suggested principle will be a good foundation for the today and the future Korean warfare.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.22 no.50
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• pp.33-44
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• 1999

This paper describes the Autonomous Vehicles (AV) which are operated for their own tasks. There are chances of conflict resolution such as sharing the same path which can lead to the risk of a collision. This research represents some ways of negotiating the conflict resolution by generating cooperative actions. Negotiation while traveling the path is accomplished by using priority and by announcing the start time of the task. When there is a risk of collision, the AV tries to dissolve the situation of conflict resolution by concurrently adjusting mutual speed and by performing the algorithm of passing. If the speed of the AV cannot be adjusted, it measures the distance between the counterpart of the AV and an obstacle along the path. Then it judges either to proceed by passing the counterpart of the AV or to turn back after observing the current circumstances. The performance of the algorithm described above was proven by a simulator.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.22 no.3
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• pp.59-65
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• 2008

High-speed electrical motor has been studied for several applications, i.e. for direct-drive systems of centrifugal compressors and turbo blowers. This paper deals with a design consideration of electromagnetic, mechanical and thermal limits of high-speed induction motor for turbo blower. Basic design concept of high-speed motor was proposed. As the motor is to be operated at high speed, the losses are quite different from conventional low-speed machines. Especially, the increases of rotor eddy current and friction losses could lead to an overheated motor. So, we suggested a special cooling system to reduce temperature rise. And, based upon this design concept, the prototype induction motor(37[kW], 45,000[rpm]) for high-speed turbo blower was designed and 2-D electromagnetic field analysis was implemented. Finally, criteria to evaluate the characteristics of high-speed induction motor have been proposed and tested.

• Proceedings of the KIEE Conference
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• 1998.07a
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• pp.140-142
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• 1998

The major part of SMES (Superconducting Magnetic Energy Storage) system consist of the superconducting coil, cryostat and current lead, power converter. The 0.7MJ SMES coil was a design and manufacture by using SMES device that we developed a design code. A SMES coil was wound with high winding tension in order to prevent wire motion from Lorentz force. This paper described optimum design for the SMES coil.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.34 no.3
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• pp.57-70
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• 2011

To address global climate change, various governments are investing in electric vehicle research and, especially in Korea, the application of electric vehicles to public transportation. The lithium batteries used in electric vehicles typically have an expected life cycle of 2-5 years. If electric vehicles become commonly used, they will generate many discarded batteries that could be harmful to the environment. Additionally, lithium batteries are potentially explosive and should be handled appropriately. Thus, reverse logistics issues are involved in handling expired batteries efficiently and safely. Reverse logistics includes the collection, recycling, remanufacturing, and discarding of waste. This study developed a reverse logistics process for electric vehicle batteries after analyzing the as-is process for lead and lithium batteries. It also developed possible disposal regulations for electric vehicle batteries based on current laws regarding conventional batteries.

• Proceedings of the Korean Vacuum Society Conference
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• 1999.07a
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• pp.78-78
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• 1999

Experimental studies of laser micromachining on Mo metal using piezo Q-switched Nd:YAG laser have been performed. Miniaturized microcolumn electron gun arrays as a potential electron beam lithography or portable mini-scanning electron microscope application have recently extensively examined. For these purpose, the electro-static electron lens and deflector system called microcolumn has to be assembled. The conventional microcolumn fabrication technique would gave a limitation on the minimization of aberration. The current technique of a 1 $\mu$m misalignment would lead to ~1.3 nm coma. In order to reduce aberration, assembling the microcolumn component followed by laser drilling should be very beneficial. In this report, we will address the preliminary report of laser micromachining on Mo substrate using piezo Q-switched Nd:YAG laser. The geometrical figures, such as the diameter and the depth of the frilled aperture are dependent upon the total energy of the laser pulse train, laser pulsewidth, and the diameter of laser beam in addition to the materials-dependent parameters.