• Publications of The Korean Astronomical Society
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• v.6 no.1
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• pp.62-75
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• 1991

The small sized telescope can be best used if the control and observation can be made remotely and fully automatically by the aid of computers. We discuss the possible ways of automating the existing telescopes of various designs using personal computers. 'We have specifically designed the parts necessary to automate 16 inch Cassegrain Telescope at Pusan University Observatory. The degree of automation we have set for the present work is the interactive. remote observation including opening and shutting down of dome slit. The observational modes we have in mind are photoelectric photometry and CCD imaging. The basic components of the hardware are interface card for 16 or 32 bit IBM PC family of computers, relay switches for the control of telescope movements, stepping motor controller card for the control of observational equipments, and AID converter unit that accepts signal from sensors for the environment conditions such as temperature, wind speeds, precipitation, etc. We also have designed and built a photoelectric photometer that can be fully controlled by the command of a computer. Such observational equipment is also essential in order that the remote observation can be realized.

• Proceedings of the KIEE Conference
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• 1994.07a
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• pp.528-531
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• 1994

In this paper, the resonant switch model applicable to the DC and small signal analysis of the resonant converter is studied because the conventional PWM switch model can't be applied to the analysis of the resonant converter. The charge control is superior to the peak current control in QRC because QRC is operated in FM mode. So the charge control technique is adopted and used to compose the ZVS-QRC boost with feedback loop.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2005.05a
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• pp.467-472
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• 2005

In this paper, design and control of the novel SEPIC-Flyback converter(SF converter) is developed as a possible converter for fuel cell system. This output characteristic of SF converter is similar to Buck-Boost converter in that it can step-up or step-down the voltage. With the small signal equivalent circuit modeling of SF converter, control-to-output transfer function is obtained. SF converter couples up the inductive type converter to capacitive type converter with one transformer, which has less ripple current than its respective one does. To verify the validity of the proposed converter, 500W, 100kHz converter is designed and tested. ZVS switching and active clamping are also tested in practice.

• Journal of Power Electronics
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• v.2 no.3
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• pp.212-219
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• 2002

A novel mode of parallel operation of a modular 3-phase AC-DC flyback converter for power factor correction along with tight regulation was recently analyzed and presented. The advantage of the proposed converter does not require expensive high voltage and high current devices that are normally needed in popular boost type 3-phase converter. In this paper tile detailed small signal analysis of the modular 3-phase AC-DC flyback converter is provided for control purpose and also experimental results are included to confirm the validity of the analysis.

• Proceedings of the KIPE Conference
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• 2010.07a
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• pp.129-130
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• 2010

For the high power demand and N+1 redundancy, this paper presents the digital load share (LS) controller design and the implementation of paralleled phase-shifted full-bridge converters (PSFBC) used in distributed power systems. By adopting the digital control strategy, separately used ICs for PSFBC and LS control functions in analog systems can be merged into a cost-effective digital controller. To compensate and stabilize both PSFBC and LS loops with the direct digital design approaches, small-signal model of the system is derived in discrete-time domain. The steady-state and dynamic load sharing performances are also investigated. Experimental results from two 1.2 kW paralleled PSFBC modules are shown to verify the proposed work.

• Proceedings of the KIEE Conference
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• 2001.04a
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• pp.324-328
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• 2001

This paper presents parallel operation and control loop design of ZVT(Zero Voltage Transition) Full Bridge DC/DC Converter. At parallel operation of ZVT Full Bridge Converter, dynamic current shared inductor devides the same current of unit converter and ZVT circuit and aids to high efficiency in the system. Base on the modeling of ZVT. Full Bridge Converter, the control loop is designed using a simple two-pole, one-zero compensation circuit. To show the validity of the design procedures, the small signal analysis of the closed loop system and open loop system is carried out and the superiority of the dynamic characteristics is verified through the experiment with a 2kW, 50kHz prototype converter.

• The Transactions of the Korean Institute of Power Electronics
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• v.17 no.1
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• pp.67-76
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• 2012

This paper proposes the aggregated modeling and control of integated boost-flyback converter (IBFC) for understanding of dynamics characteristic and designing of relevant controller. The basic concept of the aggregated modeling is to substitute the boost or the flyback converter with an equivalent current source. Since each converter with equivalent current source corresponds to the basic boost and flyback converters, the overall mathematical process is significantly simplified for the modeling. Afterwards each result is combined to construct the complete model of the IBFC, and the relevant controller is designed through the achieved small-signal model. Simulation and experimental results show excellent agreement with the theoretical expectations.

• Journal of Power Electronics
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• v.16 no.1
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• pp.102-110
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• 2016

Contactless power transfer technology is gaining increasing attention in city transportation applications because of its high mobility and flexibility in charging and its commensurate power level with conductive power transfer method. In this study, an inductively coupled contactless charging system for a 48 V light electric vehicle is proposed. Although this study does not focus on system efficiency, the generic problems in an inductively coupled contactless power transfer system without ferromagnetic structure are discussed. An active load matching method is also proposed to control the power transfer on the receiving side through a load matching converter. Small signal modeling and linear control technology are applied to the load matching converter for port voltage regulation, which effectively controls the power flow into the load. A prototype is built, and experiments are conducted to reveal the intrinsic characteristics of a series-series resonant inductive power charger in terms of frequency, air gap length, power flow control, coil misalignment, and efficiency issues.

• 한국연소학회:학술대회논문집
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• 2014.11a
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• pp.1-4
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• 2014

The present work focuses on the analysis of the pulverized coal combustion aerodynamics of the dual swirl burner by the control of the swirl-modes such as the outer swirl intensity (OSI). The detailed structure of pulverized coal swirling flames with swirl-mode was studied experimentally by particle image velocimetry and local flame colors based on $OH^*$, $CH^*$, and ${C_2}^*$ radicals. For all co-swirling conditions, the internal recirculation zone (IRZ) was observed near the inner shear layer with respect to the processing vortex core structure. Furthermore, a co-rotating vortex in the outer shear layer and the exhaust tube vortex (ETV) along the central axis were observed. The intensity of $CH^*$ signal was higher with small coal particle size, conversely, the size of the distribution of the $CH^*$ signal becomes larger. Therefore, the control of the aerodynamics with changing swirl intensities may play an important role in improving both environmental and combustion performances.

• Proceedings of the KIPE Conference
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• 2003.11a
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• pp.238-243
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• 2003

The solar cells should be operated at the maximum power point because its output characteristics are greatly fluctuated on the variation of insolation, temperature and load. The output power of solar cell is DC, therefore it is necessary to install an inverter among electric power converts. The inverter have to supply a sinusoidal current and voltage to the load and the interactive utility line. In the paper, the proposes a photovoltaic system designed with a step up chopper and single phase PWM voltage source inverter. Synchronous signal and control signal was processed by microprocessor for stable modulation. The step up chopper operates in continuous mode by adjusting the duty ratio so that the photovoltaic system tracks the maximum power point of solar cell without any influence on the variation of insolation and temperature because solar cell has typical dropping character. The single phase PWM voltage source inverter consists of complex type of electric power converter to compensate for the defect, that is, solar cell cannot be developed continuously by connecting with the source of electric power, from 10 to $20\%$. The single phase PWM voltage source inverter operates in situation that its output voltage is in same phase with the utility voltage. The inverter supplies an ac power with high factor and low level of harmonics to the load and the utility power system.