• The Transactions of the Korean Institute of Electrical Engineers B
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• v.48 no.8
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• pp.400-407
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• 1999

This paper treated the design, manufacture and the performance characteristics under each mode of high speed motor/generator for an electro-mechanical battery(EMB). This machine is employed as an integral part of a flywheel energy storage system(FESS), i.e., a modular flywheel system to be used as a device for storing electrical or mechanical energy. In this machine, the magnetic field system is constructed by using special magnet array, dipole Halbach array with 16 permanent magnet segments and the armature is composed of a plastic bobbin and multi-phase windings with Litz wire. The magnet array produces a highly uniform dipole field without back iron. The motor/generator is 3-phase machine in which the dipole Halbach array surrounding the winding is rotating. Since there are no iron laminations, this field system offers some unique advantages for the simplicity of the design and the theoretical prediction of characteristics of a high speed electric machine. This paper describes the results obtained when EMB system was tested in the laboratory.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.54 no.12
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• pp.601-608
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• 2005

This paper presents a novel single-stage high-power-factor electronic ballast for fluorescent lamps operating in critical conduction mode. The proposed topology is based on integration of boost converter as power factor corrector(PFC) and a half-bridge high frequency parallel resonant inverter into a single stage. The input stage of the boost converter is operating in critical conduction mode for positive and negative half cycle voltage respectively at line frequency(60Hz). So that a boost converter makes the line current follow naturally the sinusoidal line voltage waveform. The simulated and experimental results for 100W fluorescent lamps operating at 42kHz switching frequency and 220V line voltage have been obtained. This proposed inverter will be able to be practically used as a power supply in various fields as induction heating applications, fluorescent lamp and DC-DC converter etc.

• Proceedings of the KIPE Conference
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• 2017.07a
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• pp.339-340
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• 2017

본 논문은 에너지 저장시스템(ESS)과 무정전 전원장치(UPS)를 하나로 통합한 새로운 하이브리드 ESS-UPS 시스템을 제안한다. 제안하는 시스템은 ESS와 UPS를 하나로 통합함으로써 전력변환 시스템(PCS)의 가격을 줄이고 배터리의 이용률을 높일 수 있다. 또한 기존의 on-line UPS와는 달리 두 종류의 중요부하를 구성할 수 있어 PCS의 용량대비 비상발전 용량을 증대시키는 것이 가능하다. 본 논문에서는 제안하는 하이브리드 ESS-UPS 시스템의 운영 전략 및 급속 모드전환 알고리즘을 제안하며, 5kW급 축소 시작품을 통한 실험 결과로 타당성을 입증하였다.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.12a
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• pp.81-86
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• 2006

In this paper, we designed the cylindrical type light source that had a electromagnetic principle of inductively coupled plasma, and measured its electrical-optical properties. Using the principle of transformer, electrically equivalent circuit of cylindrical type light source was analyzed. According to the parameters of electromagnetic induction which were diameter of coil with 0.3~1.2 mm, number of turns with 4~12 turns, distance with 40~120 mm and RF power with 10~150 W, the electrical and optical properties were measured. When diameter of coil was 0.3 mm, number of turns was 8 turns and distance was 40 mm, the highest brightness of 29,730 $cd/m^2$ was shown with RF power 150 W. The relationship between electromagnetic induction and plasma discharges was shown by mode transition from E-mode to H-mode.

• Bulletin of the Korean Space Science Society
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• 2010.04a
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• pp.25.2-25.2
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• 2010

MIRIS는 과학기술위성 3호의 주 탑제체로 우주 및 지구의 적외선 관측을 위한 두 개의 카메라 시스템을 가지고 있으며 이를 위한 적외선 검출용 이미지 센서가 각각 장착되어 있다. 이미지 센서를 통해 검출된 이미지 데이터를 읽기 위해 고속의 데이터 처리가 요구되어 FPGA 구성방식으로 전용 제어기를 구성하였다. 우주 및 지구의 적외선 관측용 이미지 센서는 구성 및 동작방법이 달라 요구기능을 만족하는 각각의 전용 이미지 센서 제어기를 개발했다. FPGA를 이용한 이미지 센서 제어기에는 검출된 이미지를 읽기위한 센서 제어 신호발생기, 아날로그 이미지 신호를 디지털 정보로 변환하는 ADC 제어용 신호 발생기, ADC의 출력 신호를 고속의 직렬 통신선로로 출력 하는 기능 외에 동작 모드 및 동작 상태 입력용 DSP 인터페이스, 고속의 직렬 통신 선로에 MIRIS 상태정보 삽입 기능, 제어기의 기능을 원격지에서 확인 할 수 있는 이미지 패턴 생성기능 등을 가지고 있다. 특히, 이미지를 읽기 위한 동작 시에만 클록 주파수를 인가하는 방법으로 FPGA 내부 회로를 구성하여 전류의 소모량을 최소화 하였다.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2009.10a
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• pp.325-328
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• 2009

In this study, A Magnetic stimulation Pulse Train control technique is introduced and applied to Flyback converter operating in discontinuous conduction mode. In contrast to the conventional pulse width modulation control scheme, the principal idea of a Magnetic stimulation Pulse Train is to achieve output voltage regulation using high and low power pulses. The proposed technique is applicable to any converter operating in discontinuous conduction. However, this work mainly focuses on Flyback topology. In this paper, the main mathematical concept of the new control algorithm is introduced and simulations as well as experimental results are presented.

• Journal of the Society of Naval Architects of Korea
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• v.53 no.6
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• pp.482-493
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• 2016

The identification of modal damping of a segmented hull model with torsional response is difficult task due to the coupling of modal response. This is because the 1st and 2nd torsional vibration modes are closely spaced in frequency domain leading to the situation that the modal decomposition is difficult to achieve by simple band-pass filter. Present study applied several different modal decomposition methods to derive the damping ratio of different modes. The modal decomposition methods considered in this study are simple band-pass filter, Hilbert vibration decomposition, Wavelet transform and proper orthogonal decomposition. Coupled free decay signal obtained from the torsional hammering test on a segmented hull model was processed with four different methods and the derived damping ratios were compared with each other. Discussions also have been made on the pros and cons of the different methodologies.

• Journal of IKEEE
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• v.23 no.2
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• pp.407-412
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• 2019

Many industrial regions has used and extended the application of LED driver because of many advantage. Specially, due to the simplicity, miniaturization and power density, the flyback converter is selected by a lot of power engineer. Also, the electrolytic capacitor in this converter is used for the constant DC voltage of the converter because of the sufficient capacitance and the economic price. However, because of the characteristics of the electrolytic capacitor and ripple currents on the converter. the expected lifetime of the LED driver is more and more shorted. In this paper, a single-stage CCM PFC flyback converter with the film capacitor is suggested to extended the lifetime of the LED driver. In addition, the proposed converter with the LC filter is decreased the ripple current of the converter output.

• Proceedings of the Korea Information Processing Society Conference
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• 2013.11a
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• pp.1525-1527
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• 2013

본 논문에서는 저시력자의 개선된 독서 환경을 제공하는 시각보조기기를 위한 실시간 영상처리 SoC(System on Chip) 하드웨어 구조 설계에 대해서 기술한다. 기존의 시각보조기기는 화면 영상이 실제 움직임보다 늦게 출력되는 잔상 현상이 발생하며, 색 변환 기능도 제한적이다. 따라서 본 논문에서 제안하는 실시간 영상처리 SoC 하드웨어 구조는 데이터 연산을 최소화함으로써 잔상 현상이 감소되며, 저시력자를 위한 다양한 색상 모드를 지원한다. 제안하는 영상처리 SoC 하드웨어 구조는 Core-A 모듈, Memory Controller 모듈, AMBA AHB bus 모듈, ISP(Image Signal Processing) 모듈, TFT-LCD Controller 모듈, VGA Controller 모듈, CIS Controller 모듈, UART 모듈, Block Memory 모듈로 구성된다. 시각보조기기를 위한 실시간 영상처리 SoC 하드웨어 구조는 Virtex4 XC4VLX80 FPGA 디바이스를 이용하여 검증하였으며, TSMC 180nm 셀 라이브러리로 합성한 결과 동작주파수는 54MHz, 게이트 수 197k이다.

• The Transactions of the Korean Institute of Power Electronics
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• v.27 no.4
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• pp.356-366
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• 2022

This paper presents a mode transition method that applies frequency compensation technique of an LLC resonant converter for stable mode transition. LLC resonant converters used in various applications require high efficiency and high power density. However, because of circuit property, a wider voltage gain range equates to a greater circuit loss, so maintaining high efficiency at all voltage gain ranges is difficult. In this case, full bridge-half bridge mode transition method can be used, which maintains high efficiency even in a wide voltage gain range. However, this method causes damage to the circuit through overcurrent by the mode transition. This study analyzes the cause of the problem and proposes a mode transition method that applies frequency compensation technique to solve the problem. The proposed method verifies the stable transition through simulation analysis and experimental results.