• Proceedings of the IEEK Conference
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• 2000.06e
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• pp.9-12
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• 2000

This paper describes the modeling and experimental results of coreless printed circuit board (PCB) based transformer that can be used for power conversion at high frequency operation. The principle of using coreless PCB based transformer in 2MHz, 10W class ZVS Flyback DC-DC converter has been successfully demonstrated. The maximum power conversion efficiency is 79%. Even for high operating frequency, an efficiency greater than 70% can be obtained with under 1% regulation error.

• Proceedings of the KIPE Conference
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• 1998.07a
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• pp.418-422
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• 1998

A new single stage AC/DC converter based on the forward converter is proposed. The proposed converter offers both the high power factor and the direct conversion from ac line to dc output voltage. Also, the proposed converter reduces the diode conduction loss, so improves the overall efficiency of the converter, compared with other alternatives. The principles of operation and the simulation results of the proposed converter are presented. A 100 W prototype was built and tested to show the potential of applications of the proposed converter.

• Proceedings of the KIPE Conference
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• 2007.07a
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• pp.147-149
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• 2007

A new half bridge converter without DC offset of magnetizing current is proposed. The proposed half bridge converter can realize no DC offset of magnetizing current as well as no circulating current, and guarantee ZVS operation. Therefore it has high efficiency and high power density, especially in wide input range. The operational principle, DC conversion ratio and ZVS analysis are presented. Experimental results demonstrate that the proposed converter can achieve a significant improvement in the efficiency.

• Journal of Korean Society on Water Environment
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• v.35 no.4
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• pp.332-339
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• 2019

A comparative study on the anaerobic digestion efficiency according to the temperature change was conducted considering the characteristics of domestic food wastes with high water content of about 80 % or more. The substrate was tested for anaerobic digestion efficiency in two substrates, a liquid component separated naturally from food waste and food waste itself. In the anaerobic digestion experiments, the digestion efficiency was the highest at $55^{\circ}C$ (thermophilic temperature). However, the digestion efficiency at $45^{\circ}C$(middle high temperature) was lower than that at $35^{\circ}C$(mesophilic temperature). The comparison of general food wastes anaerobic digestion requiring 30 days of hydraulic retention time to the liquid component indicated a stable digestion efficiency even after 15 days of hydraulic retention time.In the experiments conducted on food waste, the digestion efficiency at $55^{\circ}C$ was higher than that at $35^{\circ}C$. When the food waste, especially the liquid component originating from food waste, is treated by anaerobic digestion method, the mesophilic temperature and thermophilic temperature conditions are more favorable in the digestion efficiency than the middle high temperature ($45^{\circ}C$). However, when applying thermophilic or mesophilic temperature anaerobic digestion process operation in the field, the amount of energy input should be considered.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.34D no.11
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• pp.20-24
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• 1997

We have successfully fabricated high power (~20W) laser diode array, which are useful for pumping Nd:YAG lasers. The laser diode aray has 20 100.mu.m-wide cahnnels of which space was adjusted to 350.mu.m to improve thermal characteristics. And channel width is 100.mu.m. For an uncoated LD array, the output power of 15.66W has been obtained at 41A under quasi-CW operation, which results in about 0.42W/A slope efficiency. After aR(5%) and HR (95%) coatings on both facets, the output power was improved up to 21.18W at 40A under the same operation as above and the slope efficiency was 0.795W/A. On the other hand, by using a near field measurement system consisting of objective lens, eyepiece, CCD camera and image processing board, the typical near field patten of 1*20 LD array was observed.

• Journal of Fisheries and Marine Sciences Education
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• v.28 no.6
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• pp.1724-1738
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• 2016

This paper was researched on economic feasibility and sensibility of operation to offshore cage culture for cod. Offshore cage culture for cod needs to invest high budget what to construction and operation. And it was required variety methods about analysis of economic feasibility. Therefore, these were studied NPV, B/C and sensitivity for each by assuming a six scenarios considering the product performance according to the size of cod and culturing methods of fingerlings, etc. As a results, even though economy, if efficiency is low, it is a priority need the technical development to promote the feed efficiency to increase economic feasibility and should make efforts to enhance the business economy to strengthen the price competitiveness pricing with high quality products through quality control and brand recognition of cod. It expects to be used as a reference for related research in the future by deriving policy implications based on the method of analysis of the economic feasibility on offshore cage culture for cod.

• Proceedings of the KIPE Conference
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• 2010.11a
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• pp.173-174
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• 2010

In this paper, authors propose a new buck-boost converter of discontinuous conduction mode (DCM) added electric isolation. The proposed converter with DCM eliminates the complicated circuit control requirement and reduces the size of components. The general converters of high efficiency are made that the power loss of the used switching devices is minimized. To achieve the soft switching operation of the used control switches, the proposed converter uses a lossless snubber capacitor. The proposed converter achieves the soft-switching for all switching devices without increasing their voltage and current stresses. The result is that the switching loss is very low and the efficiency of converter is high. The soft switching operation of the proposed converter is verified by digital simulation and experimental results.

• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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• v.11B no.3
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• pp.64-69
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• 2001

Energy recovery in the regenerative region is very important when SRM is used in traction drive, This is to reduce en-ergy loss during mechanical braking and/or to have a high efficiency drive during braking To control excitation voltage in motor operation and regenerative voltage in the generator operation in the SRM multi-level voltage control is effective The paper sug-gests multi-level inverter which is useful for motoring and regenerative operation in SRM

• Proceedings of the KIEE Conference
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• 2000.11b
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• pp.294-296
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• 2000

Energy recovery in the regenerative region is very important when SRM(Switched Reluctance Motor) is used in traction drive. This is because that to reduce energy loss during mechanical braking and/or to have a high efficiency drive during braking. To control excitation voltage in motor operation and regenerative voltage in the generator operation in the SRM, multi-level voltage control is effective. This paper suggests multi-level inverter which is useful for motoring and regenerative operation in SRM.

• The Journal of Sustainable Design and Educational Environment Research
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• v.9 no.1
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• pp.41-51
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• 2010

It is high level of management activity for the fixed property of building to operating spaces for education in university campus. Therefore, this study is focused on definition of the factors for analyzing the actual conditions of space operation and application of them to C university campus in Gyeongbuk in the aspect of infrastructure of university and efficiency of space operation. These analytical factors are the rate of lecture and experimentation room, the rate of theoretical and experimental subject in curriculum and unit area for infrastructure and the rate of use, turnover rate and occupation rate per lecture for space operation. If the analytical factors of space operation are systemized as program module for space operation, the space management system of university campus will be characterized on the foundation of university information system. And it will be able to support the decision making about space management. It needs to integrate various type of information and data of university to increase the efficiency of decision making.