• 유공압시스템학회논문집
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• 제3권4호
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• pp.1-7
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• 2006

A water hydraulic pump is likely to have serious problems of high leakage, friction and low energy efficiency. A water hydraulic pump has commonly a fixed displacement type and its outlet flow is adjusted by controlling rotation speed of the pump, which can be implemented by using an electric inverter. This study aims to investigate energy efficiency of the water hydraulic pump system which is driven by an electric inverter. The study is based on the experimental results. The pump which is used in the study shows relatively good efficiency and low leakage, low friction as well. The reasons for the good performance of pump is also investigated.

• Journal of Power Electronics
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• 제12권3호
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• pp.418-428
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• 2012

It is very important to improve the overall efficiency of systems with a source of power that has low-voltage high-current terminal characteristics such as fuel cells. A resonant converter is required for high efficiency systems. However, the peak value of the switches current is large in a resonant converter. This peak current requires a large number of switches and results in system failures. In this paper, an analysis and experiments of a resonant isolation push-pull converter are performed. A switching loss analysis is performed in order to compare losses between a resonant push pull converter and a hard switching push-pull converter. Specially, the conduction loss is studied based on the ratio between the resonant frequency and the switching frequency. In addition, a method for improving the efficiency is implemented with conventional HF insolation converters.

• The Journal of Asian Finance, Economics and Business
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• 제9권2호
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• pp.313-324
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• 2022

The Chinese outward foreign direct investment (OFDI) involves various bilateral trade agreements and regional agreements signed between China and other countries. This study examines the impact of Chinese OFDI in ASEAN-5 countries through ASEAN-China Free Trade Agreement (ACFTA) namely Indonesia, Malaysia, Philippines, Singapore, and Thailand from 2000 to 2016. This study attempts to address three research objectives. The first is to examine the motives for China's investment in ASEAN-5. The second is to explore the different impacts of China's investment across countries. The third is to investigate whether the OFDI conducted by state-owned enterprises (SOEs) will produce different impacts on the firm's efficiency score. Using the DEA approach, this study finds evidence that the overall Chinese OFDI is relatively efficient. We find that the estimated efficiency score of this OFDI has improved in pre- and post ACFTA where a higher overall efficiency score was reported when comparing pre- and post ACFTA signing for both SOEs and NSOEs. Finally, China's parent firms' efficiencies showed higher scores among NSOEs compared to SOEs after the signing of ACFTA for all ASEAN countries except Malaysia. We highlight that the country's institutional infrastructure, earlier investment presence, and diplomatic ties help in shaping an effective trade agreement.

• 한국입자에어로졸학회지
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• 제18권4호
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• pp.97-107
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• 2022

The geometry of popular wave plate type mist eliminator for the wet flue gas desulfurization process was improved, fabricated, and experimentally evaluated. A Mist eliminator is a type of inertial particle collector which collection efficiency is proportional to the velocity of the gas phase. However, as the amount of re-entrainment is also proportional to the gas phase velocity, there is a limitation for the gas phase flow rate. Re-entrainment is one of the most important issues in a mist eliminator and is likely to occur as the input of the liquid phase and flow rate of the gas phase increase. In order to resolve this problem, the projection angle of the improved mist eliminator is set to 30° from the conventional one while maintaining the cross-section. With low flow rate conditions, the modified mist eliminator showed a similar pressure drop and overall collection efficiency. However, with conditions in which re-entrainment is obviously occurring, the modified mist eliminator showed better performance in draining droplets than the conventional one. As a result, the modified mist eliminator showed higher overall collection efficiency.

• 한국병원경영학회지
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• 제17권4호
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• pp.1-20
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• 2012

The purpose of this study is to find out the job satisfaction of the korean medical clinic workers, and understand the factors that affect the satisfaction thereby increasing the efficiency of human resource management and providing the basic data to establish the management strategy. We visited 50 korean medical clinics which were chosen randomly from the korean medical clinics in the city of Changwon, Gyungnam. First, we explained the purpose of the study and survey contents to the surveyees, then distributed the Questionnaire and collected them. The data analysis was done statistically using the SPSS WIN IBM 20.0 program. The results were as follows: Professional career, interpersonal relationship, work autonomy, and overall job satisfaction showed significant differences depending on ages. While satisfaction of interpersonal relationship showed significant difference depending on final education. Depending on marriage status, while married persons showed significantly high satisfaction on professional career, interpersonal relationship, work autonomy, administration, and overall job satisfaction, there is no significant difference on income satisfaction. The number of years worked in the current clinic showed significant difference on administration satisfaction. Also, daytime working hours showed significant difference on administration and overall job satisfaction. The work area showed significant difference on overall job satisfaction. The income level showed significant differences on professional career, administration, and overall job satisfaction. From this study, it was confirmed that demographic characteristics and work environment factors showed significant differences on overall job satisfaction of workers in korean medical clinics. Therefore, in order to facilitate efficient manpower utilization and organization efficiency maximization, and motivation of human resources, a detailed plan should be developed to improve working environment and take demographic characteristics into consideration.

• 한국유기농업학회지
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• 제23권4호
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• pp.615-641
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• 2015

This study analyzes an economic efficiencies of apples, pears, and grapes farming. We evaluate an annual economic overall efficiency (OE), allocative efficiency (AE), technology efficiency (TE), pure technology efficiency (PTE), and scale efficiency (SE) using data envelopment analysis (DEA). We also measure returns to scale of farms, and the change of technical efficiency of frontier farms. Lastly we estimate the effects of some explanatory variables on allocative, pure technical, and scale efficiencies.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1997년도 하계학술대회 논문집 F
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• pp.2098-2100
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• 1997

The present paper investigates the optimal operation of a switched reluctance motor such that overall drive efficiency is maximized under a variable supply voltage. The operation under a variable supply voltage exhibits the improved drive efficiency in the full range of operating torque and speed, and exhibits the expanded range of operating torque and speed. Furthermore a variable supply voltage may be utilized in reducing torque ripple.

• Journal of Advanced Marine Engineering and Technology
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• 제22권6호
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• pp.836-843
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• 1998

In this paper effects of resonator within intake manifold system on volumetric efficiency were investigated n the 4-cylinder and 4 stroke Diesel Engines. The effects of resonator system were analyzed on resonant speed and on volumetric efficiency for a complicated intake system with resonator was confirmed. And the optimum design method of the resonant system which had the overall high and flat characteristic of volumetric efficiecncy was proposed.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2005년도 전력전자학술대회 논문집
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• pp.526-528
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• 2005

Nowadays, more than ever before, many researchers are paying attention to raising the efficiency of a Power converter. In Flyback converter, the resistor of RCD snubber consumes the stored energy in leakage inductor. It play a role in degrading the overall system efficiency Thus, In this paper, a novel energy recovery circuit of Flyback converter is proposed to improve the efficiency. The operational principle of the proposed circuit is explained in detail. And, it is verified through the simulation results.

• 신재생에너지
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• 제5권3호
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• pp.32-39
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• 2009

The Samcheonpo ocean small hydropower plant (SHP) has a special feature of using marginal hydraulic head of circulating water system of fossil fuel power plant as a power source and having the characteristics of general hydropower generation and tidal power generation as well. Also, it contributes to reducing green house gases and developing clean energy source by recycling circulating water energy otherwise dissipated into the ocean. The efficiency of small hydropower plant is directly affected by effective head and flow rate of discharged water. Therefore, the efficiency characteristics of ocean hydropower plant are analyzed with the variation of water level and flow rate of discharged water, which is based on the accumulated operation data of the Samcheonpo hydropower plant. After the start of small hydropower plant operation, definite rise of water level was observed. As a result of flow pattern change from free flow to submerged flow, the instability of water surface in overall open channel is increased but it doesn't reach the extent of overflowing channel or having an effect on circulation system. Performance evaluation result shows that the generating power and efficiency of small hydropower exceeds design requirements in all conditions. Analysis results of CWP's water flow rate verify that the amount of flowing water is measured less and the highest efficiency of small hydropower plant is achieved when the effective head has its maximum value. In conclusion, efficiency curve derived from water flow rate considering tidal level shows the best fitting result with design criteria curve and it is verified that overall efficiency of hydropower system is satisfactory.