• Proceedings of the KIEE Conference
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• 2002.04a
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• pp.112-115
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• 2002

Previous AC/DC PFC Boost Converter perceives feed forward signal of input and feedback signal of output for average current-mode control. Previous Boost Converter, the quantity of input current will be decreased by the decrease of output current in light load, and also power factor comes to be decreased. Also the efficiency of converter will be decreased by the decrease of power factor. The proposed converter presents the good PFC(Power Factor Correction), low line current hormonic distortions and tight output voltage regulations using non-dissipative snubber. The proposed converter also has a high efficiency by non-dissipative snubber circuit. To show the superiority of this converter is verified through the experiment with a 640W, 100kHz prototype converter.

• Journal of Electrical Engineering and information Science
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• v.2 no.3
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• pp.123-131
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• 1997

Design of single stage AC/DC converter with high power factor for low power level applications is proposed. The proposed converter gives the good power factor correction, low line current harmonic distortions, and tight output voltage regulations. This converter also has a high efficiency by employing an active clamp method and synchronous rectifiers. To verify the performances of the proposed converter, a 90W-converter has been designed. The modelling of this proposed converter is power formed using an averaging technique and based on this model a detailed analysis is carried out. This prototype meets the IEC555-2 requirements satisfactorily with nearly unity power factor and high efficiency.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.50 no.9
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• pp.473-478
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• 2001

In this paper a soft switching ZVT(Zero Voltage Transition) power factor converter using active snubbers is designed to improve efficiency and reduce voltage spike and parasitic ringing. The main switch achieves ZVT and the auxiliary switch operates with ZCS. A 2KW soft switching ZVT converter is designed with switching frequency 100kHz, output voltage 400VDC. Then the designed system is realized and experimental results show that the measured efficiency and power factor are over 97.45% and 0.997 respectively with an input current THD less than 3%.

• Proceedings of the KIEE Conference
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• 1995.07a
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• pp.371-375
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• 1995

This paper presents equipment for charging and discharging with high power factor and high efficiency. This equipment is consisted of $3{\phi}$ SPWM AC/DC converter for improving input current waveform and input power factor, and bidirectional DC/DC converter for electric isolation in the DC link Part. Therefore, Input power factor and the total efficiency in the proposed system can be increased more than in the conventional phase-controlled thyristor charging-discharging System.

• Journal of the Semiconductor & Display Technology
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• v.23 no.2
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• pp.50-54
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• 2024

In this paper, we propose a theoretical method to systematically analyze the power conversion efficiency of a single-phase PFC switching rectifier. Boost-type PFC was organized in order of highest correlation with load current using steady-state analysis results and introduced the concept of loss factor. The loss factors for each major element are summarized and presented in a table. This paper makes it easier to understand the internal loss and power conversion efficiency of the rectifier for loss factors. Lastly, to confirm the validity of the efficiency analysis results reflecting the loss factors, loss and efficiency analysis of the 2.5kW PFC rectifier was performed. The results were compared with data from a 2.5kW PFC circuit for evaluation. As a result, the usefulness of power conversion efficiency analysis reflecting the loss factors proposed in this paper was confirmed.

• The Research Journal of the Costume Culture
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• v.6 no.2
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• pp.92-108
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• 1998

The purpose of this study was designed a) to examine the relative importance for college students' clothing disposal causes and their factor structure: b) to test the effects of gender, clothing satisfaction and family income on clothing disposal determinants; and c) to assess the relationship between clothing purchase determinants and overall clothing satisfaction and clothing disposal determinants. Data (n=660) were collected from college students in Cheju Do. The survey questionnaire composed of a revised Clothing Disposal Determinants Scale, Clothing Purchase Determinants Scale and background variables. First, the most important reasons for clothing disposal were to unfit with body change, get washed our and raise nap on clothe, wornout with long-term use, do not ware for new purchasing clothe, uneasy on wear. Second, factor analysis of the revised Clothing Disposal Determinants Scale revealed five factors; unfitness, fashion change, quality dissatisfaction, product efficiency decrement, and maintenance/inconvenience. Third, female students perceived significantly higher in fashion change and unfitness than male students. Forth, unfitness and product efficiency decrement were significantly discriminated between between clothing satisfaction groups, unfitness and fashion change variables were significantly discriminated between family income groups. fifth, impulsive purchase factor was the best predictor of composite clothing disposal measure, followed by individuality, clothing satisfaction, practicality. The best predictors of each disposal factors were individuality oriented purchasing criterion in unfitness factor. Fashion in fashion change, impulsive purchase in quality dissatisfaction and product efficiency decrement factors, and practicality in maintenance/inconvenience factor. As a whole, the most consistent predictor of clothing disposal determinants was impulsive purchase factor.

• Progress in Superconductivity and Cryogenics
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• v.18 no.1
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• pp.46-49
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• 2016

The wireless power transfer (WPT) system using a magnetic resonance was based on magnetic resonance coupling of the transmission and the receiver coils. In these system, it is important to maintain a high quality-factor (Q-factor) to increase the transmission efficiency of WPT system. Our research team used a superconducting coil to increase the Q-factor of the magnetic resonance coil in WPT system. When the superconductor is applied in these system, we confirmed that transmission efficiency of WPT system was higher than normal conductor coil through a preceding study. The efficiency of the transmission and the receiver coil is affected by the magnetic shielding effect of materials around the coils. The magnetic shielding effect is dependent on the type, thickness, frequency, distance, shape of materials. Therefore, it is necessary to study the WPT system on the basis of these conditions. In this paper, the magnetic shield properties of the cooling system were analyzed using the High-Frequency Structure Simulation (HFSS, Ansys) program. We have used the shielding materials such as plastic, aluminum and iron, etc. As a result, when we applied the fiber reinforced polymer (FRP), the transmission efficiency of WPT was not affected because electromagnetic waves went through the FRP. On the other hand, in case of a iron and aluminum, transmission efficiency was decreased because of their electromagnetic shielding effect. Based on these results, the research to improve the transmission efficiency and reliability of WPT system is continuously necessary.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2007.05a
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• pp.15-20
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• 2007

In this paper we introduce the IP3003 which provides excellent Power Factor and Total Harmonic Distortion to the power system. It is developed by Interpion Semiconductor co. LTD. However, the efficiency of power factor correction system is very difficult to analyze mathematically. In this paper, we use the numerical simulation methods for analyzing PFC systems.

• Journal of Korea Trade
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• v.25 no.5
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• pp.93-109
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• 2021

Purpose - The logistics industry is often featured by its location relevance and industrial concentration. Industrial concentration is conducive to the effective transmission of information by reducing transaction costs and improving transaction efficiency, thus promoting the development of trade. The main purpose of this paper is to measure the spatial total factor productivity and location quotient of the logistics industry in Korea, and to study the impact of the logistics industry efficiency and agglomeration effect on import and export trade in Korea. Design/methodology - First, used the spatial stochastic frontier method to measure the spatial total factor productivity of the logistics industry in Korea, this serves as the efficiency index of the logistics industry in various regions of Korea. Second, calculated the location quotient (LQ) of the logistics industry to measure the industry's concentration degree. Third, employed a spatial econometric model to analyze the impacts of factors such as the efficiency and concentration levels of the logistics industry on import and export trade in Korea. Findings - This study's main findings can be summarized as follows: this study found that the overall efficiency of the logistics industry in Korea needs to be improved, even though it showed an upward trend in all regions of the country; Moreover, the agglomeration level of Korea's logistics industry needs to be improved; Finally, the positive spatial correlation and industrial agglomeration effect of Korea's logistics industry had a positive impact on the country's import and export trade. Originality/value - This study is innovative in terms of research perspective and methods. Most of the previous studies have measured the development level of the logistics industry using the logistics performance index (LPI), Fewer studies have assessed through the spatial total factor productivity and location quotient of the logistics industry in Korea to measure the efficiency index of the logistics industry in various regions of Korea and concentration degree, as well as there was almost no study on the impact of logistics industry efficiency and agglomeration effect on import and export trade in Korea. This study addresses this limitation by analyzing the impacts of the efficiency and agglomeration effect of the logistics industry on import and export trade in Korea.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.10 no.1
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• pp.170-178
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• 2000

Most of manufacturers try to produce the most efficient filter for respirators with the lowest breathing resistance. Filter performance depends on low penetration, i.e., high efficiency (%), and low pressure drop ($mmH_2O$). This study was performed to evaluate performance of respirator filters by quality factor ($q_F$) and suggest the direction for improvement of respirator filters of good quality in Korea. Two mechanical filters, S and K made in Korea, three filtering facepieces, S made in China, C made in Korea and M made in USA, which were widely used in the workplace, were selected and tested efficiency and pressure drop in accordance with flow rate, using with Automated Filter Tester Model 8110 (TSI, USA). The best quality factor within the same respirator filter categories was $0.0672cm^{-1}\;H_2O$ for mechanical filter S, $0.0698cm^{-1}\;H_2O$ for filtering facepiece M at flow rate of 32Lpm. Mechanical filter S would be the best suitable during heavy work since qulity factors decrease less sharply than any others as increased flow rates. It was necessary for mechanical filter S to lower pressure drop without increasing efficiency, but mechanical filter K should be increased efficiency and decreased pressure drop. While filtering facepiece M had the best quality performance of three ones, Sand C should get much higher efficiency and lower pressure for better performance.