• Journal of Power Electronics
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• 제17권2호
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• pp.346-357
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• 2017

The Modular Multilevel Converter (MMC) is particularly attractive for medium and high power applications such as High-Voltage Direct Current (HVDC) systems. In order to reach a high voltage, the number of cascaded submodules (SMs) is generally very large. Thus, in the applications with hundreds or even thousands of SMs such as MMC-HVDCs, the sorting algorithm of the conventional voltage balancing strategy is extremely slow. This complicates the controller design and increases the hardware cost tremendously. This paper presents a Two-Way Merge Sort (TWMS) strategy based on the prediction of the capacitor voltages under ideal conditions. It also proposes an innovative Insertion Sort Correction for the TWMS (ISC-TWMS) to solve issues in practical engineering under non-ideal conditions. The proposed sorting methods are combined with the features of the MMC-HVDC control strategy, which significantly accelerates the sorting process and reduces the implementation efforts. In comparison with the commonly used quicksort algorithm, it saves at least two-thirds of the sorting execution time in one arm with 100 SMs, and saves more with a higher number of SMs. A 501-level MMC-HVDC simulation model in PSCAD/EMTDC has been built to verify the validity of the proposed strategies. The fast speed and high efficiency of the algorithms are demonstrated by experiments with a DSP controller (TMS320F28335).

• Journal of Communications and Networks
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• 제8권1호
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• pp.8-12
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• 2006

Master-slave (M-S) strategies implemented with chain circuits are the main option in order to distribute clock signals along synchronous networks in several telecommunication and control applications. Here, we study the two types of masterslave chains: Without clock feedback, i.e., one-way master-slave (OWMS) and with clock feedback, i.e., two-way master-slave (TWMS) considering the slave nodes as second-order phase-locked loops (PLL) for several types of loop low-pass filters.

• 한국ITS학회 논문지
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• 제16권6호
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• pp.16-28
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• 2017

본 연구에서는 운수종사자시스템과 운행기록분석시스템을 활용하여 시내버스 고령운전자 운전적성정밀검사의 신규검사결과, 사고 및 벌점현황, 운행기록자료를 분석하였다. 분석결과 시내버스 고령운전자를 사고수가 많은 관심대상 운수회사와 관리가 잘 되고 있는 교통안전 우수회사와 비교했을 경우 운전적성정밀검사의 결과는 비슷하였으나 최근 5년 동안 운행하면서 발생한 총 벌점은 상당한 차이를 보였고 사고의 경우 평균 중상자수와 경상자의 수도 적은 것으로 확인됐다. 또한 운행 100km당 위험운전행동 횟수를 비교해보면 우수회사의 고령운전자는 다른 고령운전자와 비고령운전자와 비교해서도 위험운전행동 횟수가 상당히 적은데 잘못된 운전습관의 교정결과에 따른 것으로 나타났다.