• The Journal of the Korea institute of electronic communication sciences
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• v.19 no.4
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• pp.661-668
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• 2024

Based on the topology of the direct-drive permanent magnet synchronous wind power grid-connected system based on the power electronics full-power converter, the wind turbine model and the grid-side inverter model were studied, and the machine-side rectifier control based on current and speed double closed loops was designed. strategy, as well as a grid-side inverter control strategy based on current and voltage double closed loops, implementing a two-level back-to-back double closed-loop full control strategy. A system simulation model was built using Matlab/Simulink, and the operation of the unit was simulated when the wind speed changed step by step. The grid-connected current with the same phase and good sinusoidal nature of the grid voltage was output. The grid-connected system ran stably and efficiently. The simulation results The validity and rationality of the model, as well as the correctness and feasibility of the control strategy were verified.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2016.06a
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• pp.237-239
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• 2016

본 논문에서는 HEVC (High Efficiency Video Coding) 복호화기의 SAO (Sample Adaptive Offset)를 효율적으로 병렬화하기 위한 방법을 제안한다. HEVC 는 주관적 화질 향상 및 압축 효율 향상을 위해 디블록킹 필터 (de-blocking filter)와 샘플 적응적 오프셋 (SAO)이라는 두 가지 인-루프 필터를 사용한다. 두 종류의 인-루프 필터의 사용은 HEVC 복호화기의 복잡도를 증가시키는 요인이며, 인-루프 필터에 데이터레벨 병렬화를 적용하여 고속으로 복호화를 수행할 수 있다. 본 논문에서는 SAO 의 병렬화를 위해 CTU (Coding Tree Unit)의 행 단위로 병렬화를 수행함으로써, 병렬화로 인한 추가적으로 발생하는 라인 버퍼 사용을 줄여 SAO 병렬화 효율을 향상시켰다. 실험결과 제안하는 SAO 병렬화 방법을 사용하여 균등분할 SAO 병렬화 방법에 비해 91%의 속도를 향상시켰다.

• 한국디지털정책학회:학술대회논문집
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• 2004.05a
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• pp.593-608
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• 2004

우리나라의 경우 교통정보수집용 검지기는 루프검지기가 주종을 있으며, 지금까지 한국에서 루프검지기를 대체할 수 있는 영상 및 초단파검지기와 같은 대체검지기에 대한 평가는 단속류 보디는 연속류 상황에 대한 평가로 제한되어 왔다. 한편 최근들어 점차 고속도로를 중심으로 영상검지기의 설치개소수가 급속히 증가하고 있는 추세이다. 이 영상검지기의 경우 연속 교통류 상황의 15 분 혹은 5 분 단위의 점유율, 교통량, 속도등의 교통변수 측정정확도는 검지시스템의 요구사항을 충족하는 것으로 나타났다. 본 연구에서는 한국의 장래 교통관리 첨단화에 요구되는 교통자료 수집수준을 시가지도로 및 고속도로를 중심으로 파악하고, 루프검지기의 대체 검지기로서 영상검지기에 대한 성능평가 및 분석을 실시하였다.

• Proceedings of the Korea Association of Information Systems Conference
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• 2000.05a
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• pp.195-199
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• 2000

본 논문에서는 인터넷 상의 영상에 기반한 교통 감시 시스템을 구현한다. 영상 기반의 교통 감시 시스템은 루프 감지기 등의 센서를 이용한 방법에 비해 비용과 설치, 유지, 보수면에서의 장점으로 인하여 많이 연구되고 있다. 제안한 시스템은 인터넷상에서 FPA(Field Processing Agent)와 TSM(Traffic Surveillance Manager)으로 구성되며, FPA는 TSM에게 도로 영상과 차량의 속도, 도로 점유율과 같은 교통 정보를 제공한다. 차량의 평균 속도와 도로 점유율은, 도로색 영상과 연속된 입력 영상간의 샘플링 지점의 색상 차이변화를 이용하여 추출한다. 제안한 방법은 근사적인 교통정보를 추출해 주며, 입력 영상 전체에 대한 처리 과정 없이 제한된 영역만을 처리하기 때문에, 실시간 감시 시스템을 구축하는데 용이하다.

• Proceedings of the KIPE Conference
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• 2019.07a
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• pp.489-490
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• 2019

본 연구에서는 태양광 벅 컨버터 제어기에 P&O 알고리즘을 이용하면서 MPPT 알고리즘의 추적 속도를 올리기 위한 최적 태양전지 전압 제어기 설계방법에 대해 제안한다. 제안된 제어기에서는 외부 루프의 MPPT 제어기의 수행 속도를 얼마나 빠르게 하는지에 대한 이론적인 방법을 제시하고 업데이트 주기를 0.1[sec] 이하로 줄이는 것을 목표로 전압제어기는 오버슈트가 업고, 빠른 상승시간을 갖도록 설계하여 MPPT 제어기의 추적 속도를 향상시키는 제어기법을 제안하고, 설계된 제어기 이득을 PSIM 시뮬레이션을 통해 제어기 성능을 검증한다.

• Journal of the Korean Institute of Intelligent Systems
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• v.23 no.4
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• pp.281-285
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• 2013

In this paper, a design scheme of a cruise control system for an electric vehicle using piece-wised PD control is proposed. Cruise control of electric vehicles is one of the major performance elements. Drive motors having linear characteristics ideally is required in order to achieve the cruise driving. But practical motors have nonlinear characteristics and the performance of the motors can be improved by the closed-loop control to compensate it. In this paper, we improved the performance of by applying piece-wised PD control because the driving motors having nonlinear characteristics are difficult to obtain adequate performance only using closed-loop control. In order to test the proposed method, the experiments were carried out by applying the proposed method after setting up an electric vehicle equiped with a driving motors having large nonlinear characteristics. The experiment results of the proposed piece-wised PD control shows better performance than that of closed-loop control.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.42 no.10 s.340
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• pp.1-8
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• 2005

This Paper Proposes the algorithm for improving the Performance or symbol timing synchronization in hoc terrestrial DTV system. The Gardner algerian is used for symbol timing synchronization has good performance in multipath fading environment but degradation of performance is caused by jitter. Though the amount of jitter becomes more little as narrow bandwidth of loop Inter, convergence speed becomes slower. This paper propose the algorithm that averages out values of loop filter every certain time and gradually reduces the bandwidth of loop filter after estimating offset using this average for the high speed of convergence and reducing the met of jitter. The proposed algorithm has better performance with high speed of convergence and the amount of jitter than conventional method.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.17 no.1
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• pp.116-123
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• 2003

In this paper, interleaved boost converter is applied as a pre-regulator in switched mode power supply. The pre-regulator plays a role to improve power factor. Interleaved Boost Power Factor Corrector(IBPFC) can reduce input current ripple as a single voltage control loop only without inner current loop, because input current is divided each 50% by two switching devices. Each converter cell is also operated in discontinuous current mode and inductor current of each converter is discontinuous. Total input current which is composed by each converter cell is continuous current. Thus, IBPFC is able to improve input current ripple. IBPFC operating in discontinuous current mode can be classified as six modes from switching state and be carried out state space averaging small signal modeling. A control transfer function is obtained according to the modeling. Single voltage control loop is also constructed by the control transfer function. From experimental result, improvement of power factor and input current ripple are verified.

• Korean Journal of Optics and Photonics
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• v.16 no.1
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• pp.27-33
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• 2005

In this paper, a new wavelength converter using an SOA(Semiconductor Optical Amplifier)-loop-mirror for NRZ(NonReturn to Zero) optical data has been proposed and experimentally demonstrated. Conventional nonlinear fiber-loop-mirror methods can perform RZ-to-RZ, NRZ-to-RZ, and RZ-to-NRZ data format conversion, but NRZ-to-NRZ conversion has not been demonstrated until now. The experiment for the conversion from a 1300 nm NRZ data signal at 1.5 Gbps to a 1550 nm NRZ data one is successfully performed using a fiber-loop-mirror with 1300 nm-SOA.

• Journal of the Korea Convergence Society
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• v.6 no.3
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• pp.51-57
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• 2015

This paper proposes an efficient method such as Extended Three Region Partitioning Method for nested loops with irregular dependences for maximizing parallelism. Our approach is based on the Convex Hull theory, and also based on minimum dependence distance tiling, the unique set oriented partitioning, and three region partitioning methods. In the proposed method, we eliminate anti dependences from the nested loop by variable renaming. After variable renaming, we present algorithm to select one or more appropriate lines among given four lines such as LMLH, RMLH, LMLT and RMLT. If only one line is selected, the method divides the iteration space into two parallel regions by the selected line. Otherwise, we present another algorithm to find a serial region. The selected lines divide the iteration space into two parallel regions as large as possible and one or less serial region as small as possible. Our proposed method gives much better speedup and extracts more parallelism than other existing three region partitioning methods.