• Proceedings of the KIPE Conference
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• 2011.11a
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• pp.55-56
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• 2011

본 논문에서는 직류배전 시스템의 안정적이고 효율적인 운전을 위한 핵심요소인 양방향 충방전이 가능한 컨버터의 새로운 적응제어 기법을 제안한다. 제안한 방법은 소프트 스위칭을 위해 영전류를 검출하는 대신 계산을 통하여 동작 주파수를 결정한다. 따라서 다양한 입출력 조건에서 쉽게 소프트 스위칭이 가능하다. 효율 향상을 위해 다상 인터리빙 기법을 적용하였으며 이는 전류 리플 또한 줄일 수 있어 캐패시턴스를 줄이는 효과를 얻을 수 있다. 이와 같은 방법은 영전류 검출 회로가 필요하지 않기 때문에 양방향 구동 시 회로의 구성이 간편하며 전류 제어의 불안정성이나 노이즈 문제를 완화시킬 수 있다. 제안한 방법은 동작원리 분석을 바탕으로 200W 다상 벅-부스트 컨버터의 하드웨어 실험을 통해 효용성과 타당성을 검증하였다. 넓은 범위에서 고효율을 보였으며 최대 98.5%의 효율을 나타내었다.

• Proceedings of the KIPE Conference
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• 2018.07a
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• pp.478-479
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• 2018

본 논문에서는 무정전 CTTS 시스템에 적합한 영전력 투입과 영전류 차단이 가능한 알고리즘을 제안한다. 제안된 알고리즘은 이종전원에 크기와 위상차를 고정도로 검출하기 위해 이종전원의 차를 검출하였고 이를 통해 CTTS 투입 시 돌입전류를 감소시킬 수 있었다. 또한 순시 유무효전력 제어로 CTTS 차단 시 UPS 출력전류를 영전류로 제어하여 무아크 및 계통 안정화를 이룰 수 있었다. 또한 본 시스템은 UPS 동작뿐만 아니라 무효전력 보상기인 조상기로 사용 가능하며 특히 계통 전압안정화용으로 사용가능함을 확인하였다.

• The Transactions of the Korean Institute of Power Electronics
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• v.5 no.3
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• pp.254-260
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• 2000

일반적으로 3상 PWM AC/DC 컨버터는 정상상태에서의 효과적인 오차제거 및 빠른 과도응답 특성을 얻기 위해 동기좌표계상으로 모델링하여 제어한다. 그러나 이와 같은 제어기는 입력전압이 평형일 경우를 전제조건으로 하므로, 입력전압이 불평형일 경우 입력전류와 직류링크 전압에 2차 고조파 성분이 나타나게 된다. 본 논문에서는 불평형 입력전압 하에서 컨버터 시스템의 입력전류와 직류링크 전압에 발생하는 2차 고조파 성분을 최소화하기 위한 새로운 제어기법을 제안하였다. 입력측 역기전력 성분으로 간주할 수 있는 동기좌표계상의 전압을 입력전압의 상태에 따라 변동하였으며, 전류지령치를 무효전력과 2차 고조파 유효전력을 선택적으로 제거하도록 선정하였다. 입력전압의 분석은 동기좌표계상에서 수행되어지며, 각 상의 위상과 진폭의 검출이 불필요하다. 제안한 제어기법은 매우 간단하며 불평형 입력전압 상태에서 입출력 시스템의 고조파 왜란을 효과적으로 제어할 수 있다.

• Journal of the Korean Institute of Telematics and Electronics
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• v.6 no.1
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• pp.1-11
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• 1969

Reactor power frequency spectrum measurements at various power levela-OW, 1KW, 50KW, 100KW were made with TRIGA-MARK-II. An ion chamber was exposed to reactor flux, and the fluctions in its output current were analyed in a tunable bandpass filter to get the frequency spectrum of these fluctuation. The measured frequency spectrum of pile determined the modules of modules of zero power transfer function and indicated a prompt neutron mean life time of (7.90$\pm$1.62)X10 sec based on effective delayed neutron faction of 0.0075. The absolute value of reactor power obtained by noise analysis agreed within 5% with the power meter indication at the power below 10Kw.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.10 no.4
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• pp.325-332
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• 2017

In this paper, a survey of test sequence generation methods for testing the conformance of a protocol implementation to its specification is presented. The best known methods proposed in the literature are called transition tour, distinguishing sequence, characterizing sequence, and unique input/output sequence. Also, several variants of the above methods are introduced. Applications of these methods to the finite state machine model are discussed. Then, comparative analysis of the methods is made in terms of test sequence length. Finally, conclusions are given as follows. The T-method produces the shortest test sequence, but it has the worst fault coverage. The W-method tends to produce excessively long test sequences even though its fault coverage is complete. The problem with the DS-method is that a distinguishing sequence may not exist. The UIO-method is more widely applicable, but it does not provide the same fault coverage as the DS-method.

• Journal of the Korean Institute of Telematics and Electronics S
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• v.36S no.7
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• pp.124-133
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• 1999

In this paper, an event detection algorithm is proposed based on the statistics of subblock images. For an event of small size, we first divide each image into smaller subblocks and then for camera trembling, we use the statistics of three kinds of images such as the input image, reference image, and their difference image as features of the event. Simulation results show that the proposed algorithm is much more effective in event detection than the conventional cases based on only the difference image.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.46 no.3
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• pp.96-102
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• 2009

This paper deals with gate drive and power IC for high power devices(600V/200A and 1200V/150A). The proposed gate driver provides high gate driving capability (4 A source, 8 A sink), and over-current protected by means of power transistor desaturation detection. In addition, soft-shutdown function is added to reduce voltage overshoots due to parasitic inductance. This gate drive If is designed, fabricated, and tested using the Dongbu hitek 0.35um BCDMOS process.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.45 no.10
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• pp.75-82
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• 2008

In this paper, we propose an efficient symbol detection algorithm for multiple-input multiple-output spatial multiplexing (MIMO-SM) systems and present its design and implementation results. By enhancing the performance of the first detected symbol which causes error propagation, the proposed algorithm achieves a considerable performance gain as compared to the conventional sorted QR decomposition (SQRD) based detection and the ordered successive detection (OSD) algorithms. The bit error rate (BER) performance of the proposed detection algorithm is evaluated by the simulation. In case of 16QAM MIMO-SM system with 4 transmit and 4 receive ($4{\times}4$) antennas, at $BER=10^{-3}$ the proposed algorithm obtains the gai improvement of about 2.5-13.5 dB over the conventional algorithms. The proposed detection algorithm was designed in a hardware description language (HDL) and synthesized to gate-level circuits using 0.18um 1.8V CMOS standard cell library. The results show that the proposed algorithm can be implemented without increasing the hardware costs significantly.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.49 no.1
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• pp.8-11
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• 2012

Automated Vision Inspection (AVI) systems automatically detect any defect feature in a surface image. The performance of the system can be measured under a special circumstances such as ultimate defect detection. In this situation, the defect signal level is similar to noise level and it becomes hard to make a solid decision with AVI systems. In this paper, we propose an effective preprocessing technique to enhance SNR (Signal to Noise Ratio). The method is motivated by some principles of HVS (Human Visual System) and RLC (Run Length Coding) techniques is used for this purpose. The proposed preprocessing technique enhances SNR under ultimate defect conditions and improves overall performance of AVI system.

• Journal of the Korean Institute of Telematics and Electronics
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• v.11 no.2
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• pp.12-21
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• 1974

Perturbation thorpe for quantum mechanics is extended to the derivation of a power equation for microwave propagation in a rectangular waveguiad filled with N-type silicon which is transversely magnetized. This approximation evolves in a unified manner from the eigenvalue formulation of maxwell's equation wherein the wave numbers are tthe eigenvalues of a linear operator. TE10 wave at 9.61GHz is employed for the experimental investigation of the microwave propagation through a transversely magnetized semiconductor. Results from first order perturbation agree well with the experiment where the bridge method using two Magic Tees is employed.