• 한국정밀공학회지
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• 제23권7호
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• pp.51-58
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• 2006

This study analyzes the uncertainty of the compensation method of a sensing error of three-DOF measuring system. This compensation method utilizes a reference coordinate system using a three point by moving a position of an endpoint of a three-DOF manipulator. The coordinate transformation between the three-DOF manipulator and the measuring system is identified by the reference coordinate system. According to the concept of this compensation method, each positioning error at any position of the end-point of the manipulator is derived. Uncertainty analyses of the compensation values on the basis of sensitivity analysis and Monte Carlo simulation are used to investigate a feasibility and effectiveness of the compensation method.

• Smart Structures and Systems
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• 제24권5호
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• pp.649-657
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• 2019

Recently, an advanced video deflectometer based on the principle of off-axis digital image correlation was presented and advocated for remote and real-time deflection monitoring of large engineering structures. In engineering practice, measurement accuracy is one of the most important technical indicators of the video deflectometer. However, it has been observed in many outdoor experiments that data drift often presents in the measured deflection-time curves, which is caused by the instability of imaging system and the unavoidable influences of ambient interferences (e.g., ambient light changes, ambient temperature variations as well as ambient vibrations) in non-laboratory conditions. The non-ideal unstable imaging conditions seriously deteriorate the measurement accuracy of the video deflectometer. In this work, to perform high-accuracy deflection monitoring, potential sources for the drift error are analyzed, and a drift error model is established by considering these error sources. Based on this model, a simple, easy-to-implement yet effective reference point compensation method is proposed for real-time removal of the drift error in measured deflections. The practicality and effectiveness of the proposed method are demonstrated by in-situ deflection monitoring of railway and highway bridges.

• Journal of Positioning, Navigation, and Timing
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• 제1권1호
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• pp.45-49
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• 2012

The flight performance evaluation of navigation system is very significant because the reliability of navigation data directly affect the safety of aircraft. Especially, the high-level navigation system such as DGPS/INS, need more precise flight performance evaluation method. The performance analysis is evaluated by comparing between the navigation system in aircraft and reference trajectory which is more precise than navigation system in aircraft. In order to verify DGPS/INS performance of m-level, the GPS receiver, which is capable post-processed Carrier-phase Differential GPS(CDGPS) method of cm-level, have to be used as reference system. The DGPS/INS is estimated the Center of Gravity (CG) point of aircraft to offer precise performance while the reference system is output the position of GPS antenna which is mounted on the outside of aircraft. Therefore, in order to more precise performance evaluation, it needs to compensate the lever arm and coordinates transformation. This paper use quaternion and Direct Cosine Matrix(DCM) methods as coordinate transformation matrix in lever arm compensation of CDGPS reference trajectory. And it compares NED errors of DCM and quaternion transformation in lever arm of reference trajectory via DGPS/INS result.

• 한국측량학회지
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• 제37권2호
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• pp.55-62
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• 2019

The stereo geometry establishment based on the precise sensor modeling is prerequisite for accurate stereo data processing. Ground control points are generally required for the accurate sensor modeling though it is not possible over the area where the accessibility is limited or reference data is not available. For the areas, the relative orientation should be carried out to improve the geometric consistency between the stereo data though it does not improve the absolute positional accuracy. The relative orientation requires conjugate points that are well distributed over the entire image region. Therefore the automatic conjugate point extraction is required because the manual operation is labor-intensive. In this study, we applied the method consisting of the key point extraction, the search space minimization based on the epipolar line, and the rigorous outlier detection based on the RPCs (Rational Polynomial Coefficients) bias compensation modeling. We tested different parameters of window sizes for Kompsat-2 across track stereo data and analyzed the RPCs precision after the bias compensation for the cases whether the epipolar line information is used or not. The experimental results showed that matching outliers were inevitable for the different matching parameterization but they were successfully detected and removed with the rigorous method for sub-pixel level of stereo RPCs precision.

• 제어로봇시스템학회논문지
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• 제22권10호
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• pp.826-832
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• 2016

A two-wheeled balancing mobile robot (TWBMR) has the characteristics of both nonlinear and underactuated system. In this paper, the disturbances acting on a TWBMR are classified into body disturbance and wheel disturbance. Additionally, we describe a nonlinear disturbance observer, which is suitable as a single input multi-output (SIMO) system for the longitudinal motion of TWBMR. Finally, we propose a reasonable disturbance compensation technique that combines the indirect reference input of equilibrium point and the direct torque compensation input. Simulations and experimental results show that the proposed disturbance compensation method is an effective way to achieve robust postural stability, specifically on inclined terrains.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2002년도 전력전자학술대회 논문집
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• pp.580-583
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• 2002

An improved MPPT converter with current compensation method for small-scaled PV-applications is presented in this paper. The proposed method implements maximum power point tracking (MPPT) by variable reference current which is continuously changed during one sampling period. Therefore, the power transferred to the load is increased above $9\%$ by the proposed MPPT converter with current compensation method. As a result, the utilization efficiency of Photovoltaic (PV)-panel can be increased. In addition, as it doesn't use digital signal processor (DSP), this MPPT method has the merits of both a cost efficiency and a simple control circuit design. Therefore, it is considered that the proposed MPPT method is proper to low power, low cost PV-applications. The concept and control principles of the proposed MPPT method are explained in detail and its validity of the proposed method is verified through several simulated results.

• 전력전자학회논문지
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• 제8권2호
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• pp.143-150
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• 2003

본 논문에서는 소규모 태양광 발전시스템에 적합한 전류보상기법을 갖는 개선된 최대전력 점 추적시스템을 제안하고자 한다. 제안된 전류보상기법을 갖는 개선된 최대전력 점 추적시스템은 한 샘플링 주기 동안에도 매 수위칭 주기마다 가변 레퍼런스 전류를 생성하여 최대전력 점 추적(MPPT)을 수행하는 방식이다. 이로 인해 세안한 방식은 기존 방식보다도 부하측으로 전달되는 출력전력이 약 9%정도 증가되었다. 그 결과 태양광 패널의 이용률이 상당히 증가될 것으로 사료된다. 또한 제안한 방식은 DSP를 사용하지 않기 때문에 제어회로가 단순하여 회로구성이 용이할 뿐만 아니라 저 비용의 특징을 가지고 있다. 그러므로 제안한 방식은 저 전적, 저 비용의 소규모 태양광 시스템에 적합한 방식으로 사려된다. 본 논문에 제안한 개선된 최대전력 점 추적시스템의 개념 및 제어원리가 자세히 설명되고 있고 또한 제안한 방식의 타당성을 검증하기 위해 시뮬레이션을 수행하였다.

• Journal of Electrical Engineering and Technology
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• 제1권2호
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• pp.153-160
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• 2006

This paper presents a new compensating system, which consists of a shunt active filter and passive components for mitigating voltage and current disturbances arising from an Electric Arc Furnace (EAF). A novel control strategy is presented for the shunt active filter. An extended method based on instantaneous power theory in a rotating reference frame is developed for extraction of compensating signals. Since voltages at the point of common coupling contain low frequency interharmonics, conventional methods cannot be used for dc voltage regulation. Therefore, a new method is introduced for this purpose. The passive components limit the fast variations of load currents and mitigate voltage notching at the Point of Common Coupling (PCC). A three-phase electric arc furnace model is used to show power quality improvement through reactive power and harmonic compensation by a shunt active filter using the proposed control method. The system performance is investigated by simulation, which shows improvement in power quality indices such as flicker severity index.

• 전기전자학회논문지
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• 제24권3호
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• pp.867-876
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• 2020

본 논문에서는 3레벨 인버터로 구동되는 IPMSM의 고주파 주입 센서리스 운전에서 중성점 전압 리플 저감을 제안한다. 고주파 전압 주입 기반의 센서리스 제어는 IPMSM의 저속 영역에서 일반적으로 사용하는 센서리스 제어 기법이다. 고주파 전압 주입을 이용한 IPMSM의 센서리스 제어 과정에서 중성점에서의 전압 리플이 증가하는 문제가 발생한다. 중성점에서의 큰 전압 리플은 출력 전류를 왜곡시킬 뿐만 아니라 직류단 커패시터의 수명을 단축시키므로 저감되어야 한다. 본 논문에서 제안하는 기법은 지령 전압에 적절한 값을 보상하여 중성점 전압 리플을 저감하며, 보상값은 지령 전압과 전류를 이용하여 간단히 계산한다. 제안하는 중성점 전압 리플 저감 기법의 타당성은 시뮬레이션을 통해 검증한다.

• 방송공학회논문지
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• 제22권2호
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• pp.240-252
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• 2017

기존의 High Efficiency Video Coding(HEVC)기반의 다시점 비디오 부호화 기법은 종속 시점의 픽쳐를 부호화 할 때, disparity compensation prediction(DCP)을 위해 추가적인 참조 영상을 사용하기 때문에 높은 부호화 복잡도를 가지고 있다. 본 논문에서는 MV-HEVC에서 변위 움직임 벡터 탐색 복잡도를 줄이기 위한 빠른 변위 움직임 벡터 탐색 방법을 제안한다. 제안하는 방법은 어파인 변환을 이용한 초기 탐색 지점 결정 방법과 적응적인 탐색 영역 크기 결정 방법을 포함한다. 실험 결과는 제안하는 방법이 부호화 효율의 저하가 거의 없이 변위 움직임 탐색 복잡도를 90.78%까지 줄일 수 있는 것을 보여준다. 또한, 실험 결과는 제안하는 방법이 다른 복잡도 감소 기술들 보다 효과적으로 복잡도를 줄이는 것을 보여준다.