• 한국전기전자재료학회논문지
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• 제17권1호
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• pp.16-20
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• 2004

We present the fabrication and performance of wavelength tunable butt coupled (BT) sampled-grating (SG) distributed bragg reflector (DBR) - planar buried heterostructure (PBH) laser diodes (LD). The fabricated LD showed the high optical output power due to the high coupling efficiency between active and passive components by the BT coupling methods. The series resistance and diode ideality factor of LD were measured to be 3.7 $\Omega$ and 1.35, respectively. The average threshold current was 25 ㎃. The output powers of BT-SG DBR-PBH-LD were obtained to be as high as 12.3 and 24.56 ㎽ at 100 and 200 ㎃, respectively. The maximum wavelength tuning range was about 31 nm and the side mode suppression ratio was about 37 dB.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1989년도 추계학술대회 논문집 학회본부
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• pp.83-86
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• 1989

Electrical conductivity, I - V and DLTS have been measured on polycrystalline samples of $\alpha-Fe_{2}O_{3}$ containing small deviation from stoichiometry and small amounts of added titanium. DLTS (Deep Level Transient Spectroscopy) in the current transient mode has been applied to the measurement of the trap density at the grain boundary. Titanium enters the $\alpha-Fe_{2}O_{3}$ lattice substitutionally as $Ti^{4+}$, thus producing an $Fe^{2+}$ and maintaining the average charge per cation at three. The $Fe^{2+}$acts as a donor center with respect to the surrounding $Fe^{3+}$ions.

• 전기학회논문지
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• 제58권12호
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• pp.2538-2541
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• 2009

H.264/AVC High 4:4:4 Intra/Predictive profiles supports RGB 4:4:4 sequences for high fidelity video. RGB color planes rather than YCbCr color planes are preferred by high-fidelity video applications such as digital cinema, medical imaging, and UHDTV. Several RGB coding tools have therefore been developed to improve the coding efficiency of RGB video. In this paper, we propose a new method to extract more accurate correlation parameters for inter-plane prediction. We use a searching method to determine the matched macroblock (MB) that has a similar inter-color relation to the current MB. Using this block, we can infer more accurate correlation parameters to predict chroma MB from luma MB. Our proposed inter-plane prediction mode shows an average bits saving of 15.6% and a PSNR increase of 0.99 dB compared with H.264 high4:4:4 intra-profile RGB coding. Furthermore, extensive performance evaluation revealed that our proposed algorithm has better coding efficiency than existing algorithms..

• 전력전자학회:학술대회논문집
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• 전력전자학회 2002년도 전력전자학술대회 논문집
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• pp.754-758
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• 2002

In the fuel-cell electric vehicle system, the low-voltage output of unit fuel-cell demands a number of cells to be stacked In series to produce a DC link voltage which is high enough to drive the vehicle inverter system. However, this increases the complexity of the fuel-cell control system. This paper presents a design of high-efficiency boost converter employing the average current-mode control, which is able to convert a low voltage of a fuel-cell generator with a small number of unit cells to a stable and high DC link voltage for electric vehicle applications.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2002년도 전력전자학술대회 논문집
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• pp.781-783
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• 2002

In this paper, the experiment results of the Boost converter for PFC(power factor correction) are presented. The performance of the 1kW class PFC rectifier with the average current mode control are evaluated. A 1kW, 100kHz system prototype was built and experimental results are presented to verify the design. As a results, power conversion efficiency above $95\%$ and power factor above $99\%$ were obtained.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1987년도 정기총회 및 창립40주년기념 학술대회 학회본부
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• pp.530-533
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• 1987

In high-frequency switched mode converters, Series Resonant Converter (SRC) is investigated using state-plane method. Phase plane trajectories of the SRC permit a direct closed form solution of the steady state operation and can make problems easy to solve. This paper describes steady state responses and characteristics of the SRC with respect to various circuit factors. The magnitute of steady state response and the average current through load are clearly related to how such the switching frequency differs from the resonant frequency. The results of the steady state analysis can be used to estimate the device and component stress on the power circuit.

• 전기학회논문지
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• 제60권3호
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• pp.560-565
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• 2011

This paper proposes the design of micro energy harvesting system by using thermoplastic polyurethane(TPU), which harvests electric energy from the kinetic energy of pedestrian and drives the desired load, and applied it to the self-generating shoes. Also, we designed the buck-boost converter in discontinuous conduction mode(DCM) which functions as a resistor emulator(RE) such that converter's average input current is proportional to input voltage, and it results in transfer of maximum power to buck-boost converter according to control behavior that converter's input resistance is matched with TPU's internal resistance. Therefore, this paper confirms the validity of proposed control scheme and possibility of application for self-generating shoes, from the obtained characteristic of designed micro energy harvesting system by using a TPU and buck-boost converter in DCM.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2001년도 전력전자학술대회 논문집
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• pp.368-371
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• 2001

In this paper, the experiment and simulation results of the Boost converter for PFC(power factor correction) using metal powder inductor are presented. The metal powder inductor used in the experiment was composed of Ni-Fe-Mo, Ni-Fe, Fe-Si-Al compound respectively The performance of the 500w class PFC rectifier with the average current mode control and the 300W class PFC rectifier with the variable frequency control, are evaluated.

• Journal of Information Processing Systems
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• 제18권6호
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• pp.822-829
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• 2022

According to existing study into the remote fault diagnosis procedure, the current diagnostic approach has an imperfect decision model, which only supports communication in a close distance. An Internet of Things (IoT)-based remote fault diagnostic approach for wind power equipment is created to address this issue and expand the communication distance of fault diagnosis. Specifically, a decision model for active power coordination is built with the mechanical energy storage of power generation equipment with a remote diagnosis mode set by decision tree algorithms. These models help calculate the failure frequency of bearings in power generation equipment, summarize the characteristics of failure types and detect the operation status of wind power equipment through IoT. In addition, they can also generate the point inspection data and evaluate the equipment status. The findings demonstrate that the average communication distances of the designed remote diagnosis method and the other two remote diagnosis methods are 587.46 m, 435.61 m, and 454.32 m, respectively, indicating its application value.

• 전력전자학회논문지
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• 제9권1호
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• pp.65-72
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• 2004

본 논문에서는 새로운 형태의 부스트 입력방식의 공진형 AC/DC 컨버터를 제안하였다. 제안된 컨버터는 교류 전원측의 역률개선과 컨버터 출력전압을 동시에 제어하는 단일단 역률 개선방식으로써 전류 연속모드 펄스폭 변조방식을 통해 99%의 고역률을 얻을 수 있으며, 변압기 누설 인덕턴스와 공진 커패시터간의 공진을 이용하여 영전압스위칭을 구현할 수 있기 때문에 스위칭 손실을 줄일 수 있다. 제안된 컨버터의 이론적 고찰을 위해 각 모드별 전류로를 통해 동작을 설명하였으며, 정상상태에서의 DC해석을 이용한 공진특성 분석을 하였다. 본 논문에서는 제안된 컨버터의 유효성 확인을 위해 입력 $120[V_AC],\; 출력\; 48[V_DC],\; 4[A]\; 200[W]$급 프로토타입 컨버터를 제작하였으며 실험을 통해 얻은 결과를 제시함으로써 이를 증명하였다.