• The Transactions of The Korean Institute of Electrical Engineers
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• v.63 no.7
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• pp.924-928
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• 2014

LLC resonant converter is used to control laser power density in ruby laser power supply. Zero voltage switching(ZVS) is implemented to minimize the switching loss by the LLC resonant converter. Laser output power is investigated and experimented by changing the output current. That current is controled by the charging voltage of capacitor. From those results, we obtained the maximum laser output of 1.94J at the discharge current of 860A and the pulse repetition rate of 1Hz.

• Proceedings of the KIEE Conference
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• 1999.11b
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• pp.67-69
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• 1999

ADD is under development for the high speed motor. This paper describes the test results for obtaining the maximum output by leading angle of encoder. So we carried out the test for obtaining the optimum leading angle of encoder. Maximum output 80[Kw] at 20,000[rpm] was obtained at leading angle of encoder at near $22^{\circ}$. We confirmed the maximum output 106[kw] of 25,000[rpm] at leading angle of encoder at $34.6^{\circ}$.

• Proceedings of the IEEK Conference
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• 2003.11c
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• pp.281-284
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• 2003

Multi-code CDMA is an appropriate scheme for transmitting high rate data. However, dynamic range of the signal is large, and power amplifier with good linearity is required. Code select CDMA (CS/CDMA) is a variation of multi-code CDMA scheme that ensures constant amplitude transmission. In CS/CDMA input data selects multiple orthogonal codes, and sum of these selected codes are MPSK modulated to convert multi-level symbol into different carrier phases. CS/CDMA system employs level clipping to limit the number of levels at the output symbol to avoid hish density of signal constellation. In our previous work we showed that by encoding input data of CS/CDMA amplitude of the output symbol can be made constant. With this coding scheme, level clipping is not necessary and the output signal can be BPSK modulated for transmission. In this paper we show that the constant amplitude coded(CA-) CS/CDMA transmitter can be implemented using only logic gates, and the hardware complexity is very low. In the proposed transmitter architecture there is no apparent redundant encoder block which plays a major role in the constant amplitude coded CS/CDMA.

• Proceedings of the KIEE Conference
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• 2000.07b
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• pp.1339-1341
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• 2000

This paper presents a new PWM DC/DC converter with multi-output using single secondary winding, which has two output characteristics of the isolation and non-isolation simultaneously. The proposed converter topology is consisted of the only one switch and single secondary winding. The proposed converter, therefore, has advantages not only low cost but also high power density. Operating principal of the proposed converter topology with conventional ZVT (Zero-Voltage-Transition) is illustrated in detail and the validity of the converter is verified with several interesting simulation results.

• Proceedings of the KIEE Conference
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• 2000.07b
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• pp.750-753
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• 2000

ADD is under development for the high speed motor. This paper describes simulation and test results for obtaining the maximum output by leading angle of encoder. So we carried out the test for obtaining the optimum leading angle of encoder. Maximum output 80[kW] at 20,000[rpm] was obtained at leading angle of encoder at near $22^{\circ}$. We confirmed the maximum output 106[kW] of 25,000[rpm] at leading angle of encoder at $34.6^{\circ}$.

• Journal of Electrical Engineering and Technology
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• v.12 no.3
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• pp.1082-1089
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• 2017

Negative output elementary super lift Luo converter (NOESLLC), which has the significant advantages including high-voltage transfer gain, high efficiency, high power density, and reduced output voltage/inductor current ripples when compared to the traditional DC-DC converters, is an attractive DC-DC converter for the field of negative DC voltage applications. In this study, in consideration of the voltage across the energy transferring capacitor changing abruptly at the beginning of each switching cycle, the improved averaged model of the NOESLLC operating in continuous conduction mode (CCM) is established. The improved DC model and transfer functions of the system are derived and analyzed. The current mode control is applied for this NOESLLC. The results from the theoretical calculations, the PSIM simulations and the circuit experiments show that the improved DC model and transfer functions here are more effective than the existed ones of the NOESLLC to describe its real dynamical behaviors.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.59 no.11
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• pp.2026-2031
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• 2010

The electrical characteristics of galvanic cell which is composed of the cathode electrode(graphite, carbon and copper) and the anode electrode(Zn and Mg) were investigated. For this research as electrolyte 2~12 wt% NaCl aqueous solution were used. At graphite cathode electrodes which use Zn and Mg with the anode electrode, the open circuit voltage was 1.3V most highly. The maximum output power increased as the electrolyte concentration increased, due to a increase in ion density. When Zn and Mg with the anode electrode, the maximum output power respectively was evaluated as 2.2mW and 5.5mW about the graphite cathode electrode in the NaCl 4wt%. The research results indicated that the output power of cell which is composed with graphite with the cathode and Mg with the anode was most excellent and the efficiency of the cell could be enhanced by increasing the electrolyte concentration.

• Proceedings of the KIEE Conference
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• 2009.04b
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• pp.156-160
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• 2009

This paper presents the interleaved active-clamping ZVS(Zero Voltage Switching) forward converter, which is mainly composed of two active-clamping forward converters. Only two switches are required, and each one is the auxiliary switch for the other. The circuit complexity and cost are thus reduced. The leakage inductance of the transformer or an additional resonant inductance is employed to achieve ZVS during the dead times. The duty cycles are not limited to be equal and within 50%. The complementary switching and the resulted interleaved output inductor currents diminish the current ripple in output capacitors. Accordingly, the smaller output chokes and capacitors lower the converter volume and increase the power density. Detailed analysis and design of this new interleaved active-clamping forward converter are described.

• Proceedings of the KIPE Conference
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• 2014.07a
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• pp.327-328
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• 2014

This paper presents a pulse density modulation (PDM) technique with a high frequency link for a dual output DC-DC converter. The proposed scheme consists of a fixed frequency AC link and independent PDM controllers for the output regulation, which provides a simple structure and higher efficiency. The simulation and experimental results are provided to show the effectiveness of the proposed method.

• Journal of the Korean Society for Library and Information Science
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• v.16
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• pp.243-279
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• 1989

Public library effectiveness is determined by a complexity of the internal and external environments of the library. The purpose of this article is to investigate community environments and library resources as determinants of the output measures of the 15 municipal libraries in Seoul and to cope with changes in the environments for the improvement of their performance. This study is based on the hypotheses that the library's output would be proportioned to the size of budget and library collection, and to the relationships between the characteristics of the library and of the community in which the library develops. The variables identified in this .study are population density, family size, institutions (social, cultural, financial and educational), presence of the mass media, size of service area, and economic level of the community. The output measures employed for analysis are: number of professional staff, expenditures, number of books in the collection, number of books added annually, total circulation, number of library visits, circullation per capita, library visits per capita, .and registration as a percentage of population. The recommendation made in this study is the innovation of the 15 libraries in organization.