• Nuclear Engineering and Technology
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• v.21 no.3
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• pp.151-164
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• 1989

Since in the KMRR the neutron spectrum is hardened in comparison with the conventional power reactors, and the absorber is in a tube-form which may contain the neutron multiplying media inside it, the reactor physics characteristics of the KMRR absorber are much different. The characteristics of the hafnium control absorber are studied under the several kinds of the environmental conditions. The environmental conditions include the inner materials inside the absorber shroud, the absorber thickness, the absorber burnout, and the fuel burnup. Investigated are nuclear characteristics such as the dependence of the spectral, regional, and isotopic contribution to the neutron absorption, and the dependence of the reactivity worth. Many important absorber characteristics are identified and presented from the analysis.

• Journal of the Korea Safety Management & Science
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• v.16 no.2
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• pp.185-192
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• 2014

The production type of foundry industry is a small quantity batch production methods that require the highly skilled technology in the global competition in the variety of customer needs and directly under the influence of fluctuations characteristic. Therefore suitability for small quantity batch production and flexible production capacity and price competitiveness is needed more than anything. To do this, we need transcription and comprehensive innovation activities to maximize the revenue structure of the organization and field survival foundation should be developed the TPI(Total Profit Innovation) process in all aspects of the organization and all employees are involved in order to create a cost, quality, time, and service part of the overall aim how to achieve those effects within a short period of time. We applied the TPI process for S company in the foundry business innovation and productivity through cost reduction. We will expect the productivity improvement and financial performance improvement and then continually accumulate and review the results.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09a
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• pp.480-481
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• 2006

The n-type $(95%Bi_2Te_3-5%Bi_2Se_3)$ compound was newly fabricated by gas atomization and hot extrusion, which is considered to be a mass production technique of this alloy. The effect of powder size on thermoelectric properties of 0.04% $SbI_3$ doped $95%Bi_2Te_3-5%Bi_2Se_3$ alloy were investigated. Seebeck coefficient $({\alpha})$ and Electrical resistivity $(\rho)$ increased with increasing powder size due to the decrease in carrier concentration by oxygen content. With increasing powder size, the compressive strength of $95%Bi_2Te_3-5%Bi_2Se_3$ alloy was increased due to the relative high density. The compound with ${\sim}300\;{\mu}m$ size shows the highest power factor among the four different powder sizes. The rapidly solidified and hot extruded compound using $200[\sim}300{\mu}m$ powder size shows the highest compressive strength.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.64 no.10
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• pp.1411-1417
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• 2015

The installation of PV system to the power distribution system is being increased as one of solutions for environmental pollution and energy crisis. However, the efficiency of PV system is getting decreased because of the aging phenomenon and several operation obstacles. Therefore, The technology development of aging diagnosis of PV modules are required in order to improve operation performance of PV modules. This paper proposes evaluation algorithm for aging state in PV modules by using the electrical characteristics of PV modules and environmental factors. And also, this paper presents a operation evaluation system of PV modules based on the proposed aging diagnosis algorithm of PV modules. From the simulation results of proposed evaluation system, it is confirmed that the proposed algorithm is a useful tool for aging diagnosis of PV systems.

• Proceedings of the KIPE Conference
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• 2015.11a
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• pp.205-206
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• 2015

케이블 및 버스바는 전원을 공급하는 부대 장치로 산업 전반에 걸쳐 널리 사용되고 있다. 대부분의 경우 일정 주기로 점검 및 교체 등의 유지 보수를 진행하나 ITER IVC 버스바 및 지중케이블 등의 특수한 경우에서는 접근성 및 작업성의 이유로 유지 보수를 진행 할 수 없다. 이러한 경우, 절연물 내부에 전기 트리가 발생했을 때에는 대책이 없다. 전기 트리는 부분적인 고전계에 의한 진성파괴, 전하의 주입 또는 추출에 의한 파괴 및 전기-기계적 응력(맥스웰 응력)에 의한 파괴, 미소 부분 방전에 의한 파괴의 가장 큰 고장요인이 되는 현상이며, 다양한 사고 사례가 알려져 있다. 본 연구에서는 유한요소해석법을 이용하여 전기 트리를 가지는 사각 버스바에 대한 전계해석을 진행하였고, 전기 트리를 방지 할 수 있는 사각 버스바의 절연 설계에 대한 방안을 제시한다. 이 설계 방안은 향후 전기 트리를 고려한 사각 버스바의 절연 설계 기초 데이터로 활용 될 것이다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.9
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• pp.42-51
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• 2017

This paper deals with the power supply facility providing wireless power transmission for a type of electric vehicles called the on-line electric vehicle(OLEV) and proposes optimal protection coordination methods which analyze the faultsin the 60Hz and 20kHz bands using PSCAD/EMTDC, which is the typical commercial software for the distribution system. The simulation results show that the proposed methods can reduce the fault current by introducing an NGR (Neutral Ground Resistor) in the 60Hz band and prevent the malfunctioning of the protection device by installing a CT in the neutral wire in the 20kHz band when a ground fault occurs.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.8
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• pp.5550-5558
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• 2015

Recently, fuel cell with high energy efficiency and low CO2 emission is energetically interconnected with power system. Especially, FCGS(Fuel Cell Generation System) which usually operates at high temperature, is being developed and installed in the form of large scale system. However, it is reported that power system disturbances related to surge, harmonic and EMI have caused several problems such as malfunction of protection device and damage of control device in the large scale FCGS. In order to solve these problems, this paper presents a modeling of operation characteristics of FCGS by PSCAD/EMTDC, ETAP, P-SIM software. And also, this paper proposes countermeasure algorithms to prevent power system disturbances. From the simulation results, it is confirmed that the proposed algorithm is useful method for the stable operation of large scale FCGS.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.12
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• pp.77-86
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• 2020

Power quality problems caused by feeder voltage drop and extension construction cost problems can occur with the increasing utilization rates of the existing fixed-type EV (electric vehicle) charger. Moreover, EV users might not be able to access the EV charger due to a lack of EV charging facilities. Therefore, this paper proposes an MPSD (movable power supply device) for EVs to overcome user inconvenience caused by the insufficient number of chargers and extension cost issues. The proposed MPSD was mainly composed of a PV (photovoltaic) system, ESS (energy storage system), EV charging system, and monitoring and control system. Furthermore, there are three operation modes available to enhance the flexibility of the MPSD application, depending on the situation. This paper also presents an economical evaluation modeling using the present worth method to consider the cost and benefit elements. The simulation results based on proposed modeling showed that MPSD is more economical than the existing EV charger. Moreover, its profit can be increased significantly depending on the distance to the installation point.

• The Korean Journal of Pain
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• v.14 no.1
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• pp.51-55
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• 2001

Background: Oral mucositis is a common complication of anticancer chemotherapy. The sequelae of this consist of an increased risk of infection, moderate to severe pain, compromised oral function, and bleeding. This study was performed to evaluated the effects of the He-Ne laser and the Ga-Al-As laser on oral mucositis caused by anticancer chemotherapy in pediatric patients. Methods: There were 3 cases of osteosarcoma and 6 cases of leukemia. All patients received He-Ne laser (632.8 nm wavelength, power 60 mW) application on 400-600 Hz scanning for 5-20 minutes and Ga-Al-As laser (904 nm wavelength, power 40 mW) application by fiberoptic hand piece placed in immediate proximity to the tissue without direct contact with it for 30 seconds per point for 5 days per week. During the application patients wore wavelength-specific dark glasses and were instructed to keep their eyes closed. Results: The mean number of treatments with oral intake was $4.89{\pm}0.64$. The mean number of total treatments was $9.44{\pm}2.59$. There were no significant side effects during and after the laser treatments. Conclusions: He-Ne laser and Ga-Al-As (IR) laser treatment were well tolerated and reduced the severity and duration of chemotherapy-induced oral mucositis in pediatric oncologic patients.

• Journal of Korean Physical Therapy Science
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• v.12 no.4
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• pp.43-55
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• 2005

This study was performed to investigate the effects of low-power Helium Neon Infra Red(He-Ne IR)laser irradiation and exercise on the regeneration of experimentally cut sciatic nerve in rats. The thrity Sprague-Dawley adult mail rats were assigned to the 6 groups : normal group(1), injured control groups(2), experimental groups(3). There was made artificial injured in the sciatic nerve of rats the each experimental laser group and exercise group were treated from 3 days after being injured for the 5 minutes(laser group), 10 minutes(exercise group), and 15 minutes(exercise and laser group) everyday during 2 weeks. There were measured the changes of amplitude of compound muscle action potential and histological change by the light microscopy on the sciatic nerve injured rats. The results obtained as follows : 1. In the control groups, the regeneration were slowly and slightlly progressed to compared with the experimental groups. Inflammation were much more observed, and fibrous adhesion was also observed around the sutured region of the cut sciatic nerve. 2. The amplitude of compound muscle action potential in the experimental groups were significantly increased to the injured control groups at 1 week(p<.05). The compound muscle action potential of the exercise and lased group was significantly decreased to be similar to normal group at 2 weeks(p<.05). 3. In histologic finding, in the experimental groups were observed the proliferation of the schwann cells, the infiltration of inflammatory cells and the extent of destruction at adjacent tissue were remarkably decreased on the 2 weeks. From these experimental results, it may be suggested that the laser and exercise were effected the heeling process of peripheral nerve injuried rats.