• 한국수자원학회논문집
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• 제47권4호
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• pp.357-370
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• 2014

본 연구에서는 격자기반의 공간분포 강우장에서 호우지속기간동안 지속시간별 면적최대강우량을 산정할 수 있는 탐색기법을 개발하여 DAD 분석을 실시하고 그 적용성을 평가하고자 한다. 우선, 세 가지 탐색기법(Box-tracking, Point-tracking, Advanced point-tracking)의 알고리즘을 구성하고, 가상의 강우장(1 hr 지속시간)을 대상으로 각 탐색기법의 성능을 검증하였다. 다음으로 용담댐 유역의 실제 강우사상을 선택하여 개발된 탐색기법과 GIS를 이용한 고전적인 방법을 사용하여 DAD 분석을 실시하고 그 결과를 비교 분석하였다. Box-tracking의 경우, Point-tracking과 Advanced point-tracking에 비하여 상대적으로 빠른 검색이 가능하지만, 강우장의 공간분포 형태를 고려하지 못하여 타 탐색기법에 비해 유역크기별 면적최대강우량이 과대 산정되었다. 반면, Point-tracking과 Advanced point-tracking은 강우장의 공간분포 형태를 적절하게 반영하여 면적최대강우량 산정이 가능하였으며, 특히 두개 이상의 호우중심이 존재할 경우 Advanced point-tracking은 Point-tracking보다 우수한 탐색성능을 보여주었다. 따라서 본 연구에서 제안하는 탐색기법은 DAD 분석 및 면적감소계수 계산을 위한 유용한 도구로 활용이 가능할 것으로 판단된다.

• 한국지리정보학회지
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• 제17권3호
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• pp.68-81
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• 2014

본 연구에서는 지점강우를 면적평균강우로 변환하는데 이용되는 DA(Depth-area)관계를 보다 효율적이고 정확하게 구축할 수 있는 자동 DAD분석기법을 국내의 유역에 적용하고 그 성능을 평가하는데 목적이 있다. 우선, 제안된 자동 DAD분석기법에는 격자기반의 공간강우분포를 호우중심으로부터 추적하는 방법으로 Box-tracking, Point-tracking, Advanced point-tracking으로 구분된다. 세 가지 방법을 용담댐 유역에서 발생한 호우 중 대표적인 10개의 호우사상에 대하여 적용한 결과, Advanced point-tracking을 적용하였을 경우가 다중호우중심을 가진 각 호우분포 형상을 정확히 고려하고, 보다 정확한 누적 시간별 누적 면적별 면적최대강우량(MAAR)을 산정할 수 있음을 확인하였다. 게다가, Advanced point-tracking이 선정된 여러 개의 호우중심으로부터 면적증가에 따른 각각의 MAAR을 동시에 산정하고 비교할 수 있어, 이에 따른 오차를 효과적으로 감소시킬 수 있음을 확인하였다. 마지막으로, 용담댐 유역의 10개의 호우사상에 대한 DAD 분석을 토대로 해당 유역의 DAD곡선을 누적시간별로 추출하였다.

• International Journal of Aeronautical and Space Sciences
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• 제10권2호
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• pp.86-94
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• 2009

This paper deals with the creation of a new, low-cost point/position tracking system that can measure deformations in engineering structures with simple commercially widespread cameras. Though point tracking systems do exist today, such as Stereo Pattern Recognition (SPR) and Projection Moir$\acute{e}$ Interferometry (PMI) systems, they are far too costly to use to analyze small, simple structures because complex optical components such as large flashes, high-resolution cameras and data acquisition systems with several computers are required. We developed a point tracking system using commercial cameras. This system used IR LEDs and commercial IR CCD cameras to minimize the interference posed by other extraneous light sources. The main algorithm used for this system is an optical point tracking algorithm, which is composed of the point extraction algorithm and the point matching algorithm for 3-D motion estimation. a series of verification tests were performed. Then, the developed point tracking system was applied to measure deformations of an acrylic plate under a mechanical load. The measured deformations of the acrylic plate matched well with the numerical analysis results. The results indicate that the developed point tracking system is reliable enough to measure continuous deformed shapes of various engineering structures.

• 전력전자학회논문지
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• 제24권2호
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• pp.111-119
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• 2019

In this study, constant power generation (CPG) algorithms are introduced for whole range power point tracking in photovoltaic systems. Currently, maximum power point tracking (MPPT) algorithm is widely used for high-power photovoltaic systems. However, MPPT algorithm cannot flexibly control such systems according to changing grid conditions. Maintaining grid stability has become important as the capacity of grid-connected photovoltaic systems is increased. CPG algorithms are required to generate the desired power depending on grid conditions. A grid-connected photovoltaic system is configured, and CPG algorithms are implemented. The performances of the implemented algorithms are compared and analyzed by experimental results.

• 전력전자학회논문지
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• 제21권6호
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• pp.497-505
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• 2016

Operating wind turbine generators at maximum power point requires maximum power point tracking (MPPT) control methods. However, conventional methods cannot track the appropriate maximum power point in situations involving wind turbine systems based on a series operation strategy. These systems comprise one or more local maximum power points, and conventional methods can detect only one local maximum power point closed by a current operation point. This study proposes an advanced MPPT method for the series operation strategy of a small, grid-connected wind turbine system. In determining the appropriate maximum point, operations at certain local maximum power points are analyzed. The results show one appropriate point, which is tracked by the proposed MPPT method. The effectiveness of the proposed method is verified by the experimental results.

• 대한기계학회논문집A
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• 제20권1호
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• pp.115-126
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• 1996

In the time optimal control problem, bang-bang control has been used becaese it is the theoretical time minimum solution. However, to improve tracking speed performance in the time optimal control, it is important to select a switching point accurately which makes the velocity zero near the target track. But it is not easy to select the swiching point accurately because of the damping coefficient variation and uncertainties of modeling an actual system. The Adaptive model following control(AMFC) is implemented to relieve the difficulty and inconvenience of this task. The AMFC and make the controlled plant follow as closely as possible to a desired reference model whose switching point can be calculated easily and accurately, assuring the error between the states of the reference model and those of the controlled plant appoaches zero. The hybrid control method composed of AMFC and PID is applied to a tracking actuator of the magneto optical disk drive(MODD) in random access devices to improve its slow tracking performance. According to the simulaion and experimental results, the average tracking time as small as 20ms is obtained for a 3.5 magneto-optical disk drive. The AMFC also can be applied for other random access devices to improve the average tracking performance.

• 제어로봇시스템학회논문지
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• 제22권2호
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• pp.133-138
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• 2016

This paper describes the track initiation and target-tracking filter for ship tracking in a marine environment by using Light Detection And Ranging (LiDAR). LiDAR with three-dimensional scanning capability is more useful for target tracking in the short to medium range compared to RADAR. LiDAR has rotating multi-beams that return point clouds reflected from targets. Through preprocessing the cluster of the point cloud, the center point can be obtained from the cloud. Target tracking is carried out by using the center points of targets. The track of the target is initiated by investigating the normalized distance between the center points and connecting the points. The regular track obtained from the track initiation can be maintained by the target-tracking filter, which is commonly used in radar target tracking. The target-tracking filter is constructed to track a maneuvering target in a cluttered environment. The target-tracking algorithm including track initiation is experimentally evaluated in a sea-trial test with several boats.

• Journal of Power Electronics
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• 제18권5호
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• pp.1470-1478
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• 2018

Recently, wireless power transfer (WPT) via coupled magnetic resonances has attracted a lot of attention owing to its long operation distance and high efficiency. However, the WPT systems is over-coupling and a frequency splitting phenomenon occurs when resonators are placed closely, which leads to a decrease in the transfer power. To solve this problem, an adaptive frequency tracking control (AFTC) was used based on a closed-loop control scheme. An improved particle swarm optimization (PSO) algorithm was proposed with the AFTC to track the maximum power point in real time. In addition, simulations were carried out. Finally, a WPT system with the AFTC was demonstrated to experimentally validate the improved PSO algorithm and its tracking performance in terms of optimal frequency.

• KIEAE Journal
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• 제14권2호
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• pp.21-28
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• 2014

This paper provides the up to date review of the shading effects on PV module performance and the associated detection algorithm related to the maximum power point tracking. It includes the brief explanations of the MMP variations due to the shading occurrence on the PV modules. Review of experimental and simulation studies highlighting the significant impacts of shading on PV efficiencies were presented. The literature indicates that even the partial shading of a single cell can greatly drop the entire module voltage and power efficiency. The MMP tracking approaches were also reviewed in this study. Both conventional and advanced soft computing methods such as ANN, FLC and EA were described for the proper tracking of MMP under shaded conditions. This paper would be the basic source and the comprehensive information associated with the shading effects and relevant MPP tracking technique.

• Journal of Power Electronics
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• 제15권4호
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• pp.929-938
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• 2015

Maximum power point tracking (MPPT) and battery charging control are two important functions for a solar battery charger. The former improves utilization of the available solar energy, while the latter ensures a prolonged battery life. Nevertheless, complete implementation of both functions can be complex and costly, especially for low voltage application such as standalone street lamps. In this paper, the operation of a solar battery charger for standalone street light systems is investigated. Using only one voltage sensor, the solar charger is able to operate in both MPPT and constant voltage (CV) charging mode, hence providing high performance at a low cost. Using a lab prototype and a solar simulator, the operation of the charger system is demonstrated and its performance under varying irradiance is validated.