• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1989년도 한국자동제어학술회의논문집; Seoul, Korea; 27-28 Oct. 1989
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• pp.200-205
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• 1989

The performance of conventional robot arms is inhibited by trade-off between speed and accuracy. Because these systems measure only joint angles, in spite of slow speed, they must rely on a stiff structure in order to attain positioning accuracy. Lightweight links would allow faster motion, but their flexibility would also produce positioning errors. This research is involved with the development and evaluation of an End-point Control System whose major goal is to compensate for link deflections and thus mitigate the speed versus accuracy conflict in conventional manipulator.

• 대한전기학회논문지:전력기술부문A
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• 제48권7호
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• pp.881-888
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• 1999

Target pointing guidance steers a vehicle to point at a target point at a given range Rs. In this paper, vehicle's motions relative to the target point are modeled by differential equations. Then a target pointing guidance law is derived using optimal control theories. In addition, it is shown that the proposed guidance law can achieve the goal of target pointing guidance whatever initial headings are.

• 한국해양공학회지
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• 제34권5호
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• pp.334-341
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• 2020

Most towfish systems do not have propulsive devices and cannot compensate for perturbation motion, which can affect the observation data. This paper discusses attitude control of a towfish with elevators on the left and right tail wings to improve the quality of the observational data. Specifically, we investigate the relationships between the towing point, the center of gravity, and the drag forces produced by the elevators to clarify whether the elevators can control the attitude of the towfish sufficiently for various positions of the towing point and center of gravity. The feasible positions of the towing point and center of gravity are defined by mechanical analyses, and simulations are conducted to verify that the elevators can provide attitude control in these positions. The simulation results show that at some positions, the elevators can control the attitude quickly and sufficiently even if disturbances exist.

• Journal of Electrical Engineering and Technology
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• 제13권2호
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• pp.752-760
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• 2018

In this paper, interior permanent magnet synchronous motor (IPMSM) design for sensorless drive, considering magnetic neutral point shift according to magnetic saturation, has been proposed. Sensorless control was divided into a method based on inductance and a method based on back induced voltage. Because induced voltage is very small at zero or low speed, error in rotor initial position estimation may occur. Using the ratio of saliency addresses this problem. When using high-frequency injections at low speed, the rotor's initial position is estimated at the smallest portion of the inductance. IPMSM has the minimum inductance at the d-axis. However, if magnetic saturation leads to magnetic neutral point variation, following the load current change, there is a change in the minimum point of inductance. In this case, it can lead to failure of initial rotor position estimation. As a result, it is essential that the blocking design has an inductance minimum point shift. As such, in this study, an IPMSM design method, by blocking magnetic neutral point change, has been proposed. After determining the inductance profile based on the finite element analysis (FEA), the results of proposed method were verified.

• 한국생산제조학회지
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• 제20권4호
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• pp.386-394
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• 2011

This paper is concerned with the application of the vision control scheme for robot's point placement task in discontinuous trajectory caused by obstacle. The proposed vision control scheme consists of four models, which are the robot's kinematic model, vision system model, 6-parameters estimation model, and robot's joint angles estimation model. For this study, the discontinuous trajectory by obstacle is divided into two obstacle regions. Each obstacle region consists of 3 cases, according to the variation of number of cameras that can not acquire the vision data. Then, the effects of number of cameras on the proposed robot's vision control scheme are investigated in each obstacle region. Finally, the practicality of the proposed robot's vision control scheme is demonstrated experimentally by performing the robot's point placement task in discontinuous trajectory by obstacle.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2003년도 ICCAS
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• pp.162-167
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• 2003

In this paper, a novel feasible real-time system was researched for a differential driven wheeled autonomous mobile robot so that the mobile robot can move in a smooth, safe and elegant way. Least Square Minimum Path Planning was well used for the system to generate a smooth executable path for the mobile robot, and the point-to-point tracking algorithm was presented as well as its application in arbitrary path tracking. In order to make sure the robot can run elegantly and safely, trapezoidal speed was integrated into the point-to-point path tracking algorithm. The application to guest following for the autonomous mobile robot shows its wide application of the algorithm. The novel design was successfully proved to be feasible by our experiments on our mobile robot Interactive Robot Usher (IRU) in National University of Singapore.

• 전기학회논문지
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• 제59권6호
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• pp.1075-1082
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• 2010

This paper analyzes a operating characteristic for maximum power point tracking (MPPT) of photovoltaic generation system. MPPT methods are used to maximize PV array output power by tracking maximum power point(MPP) continuously. To increase the output efficiency of PV system, it is important to have more efficient MPPT. MPPT algorithm is widely used the control method such as the perturbation and observation(PO) method, incremental conductance(IC) method and constant voltage(CV) method. In case of the radiation is changed, this paper proposes a response characteristic with MPPT control algorithms. Also, it proposes the direct for a novel MPPT control algorithm development through the analyzed data, hereby proves the effectiveness of this paper.

• Journal of Electrical Engineering and Technology
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• 제12권4호
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• pp.1471-1483
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• 2017

The low-frequency characteristics of four-switch three-phase (FSTP) inverter are investigated in this paper. Firstly, a general space vector pulse width modulation (SVPWM) directly involved the neutral point voltage of DC-link is proposed, where no sector identifications and trigonometric function calculations are needed. Subsequently, to suppress the DC offset in the neutral point voltage, the relationship between the neutral point voltage and the ${\beta}-axis$ component of the load current is derived, and then a new neutral point voltage control scheme is proposed where no low pass filter is adopted. Finally, the relationship between the load power factor and the maximum linear modulation index of the FSTP inverter is revealed. Since the operational region for the FSTP inverter in low frequency is reduced by the enlarged amplitude of the neutral point voltage, a linear modulation range enlargement scheme is proposed. A permanent magnet synchronous motor with preset rotary speed serves as the low-frequency load of the FSTP inverter. Experimental results verify that the new neutral point voltage control scheme is effective in the deviation suppression of the neutral point voltage, and the proposed scheme is able to provide a larger linear operational region in low frequency.

• 국제물리치료학회지
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• 제5권1호
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• pp.696-700
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• 2014

This study was carried out to identify the influence of continuous physical therapy on long-stay elderly patients. This study classified 92 patients who had been hospitalized for one year into experimental group who continued to perform physical therapy and control group who did not conduct physical therapy and these two groups were classified into 0.5 point-questionable group, 1 point-mild dementia group, and 2 point-moderate dementia group based on the Clinical Dementia Rating Scale(CDR) when they were hospitalized in order to analyze the changes at the early stage of hospitalization and after one year has passed. As a result, it was appeared that both in CDR 0.5-point subgroup of questionable group and in CDR 1-point subgroup of mild dementia group, CDR was statistically significantly reduced in the experimental group whose physical therapy was continuously performed than in the control group whose physical therapy was not performed(p<.05) and that there was no significant difference in changes in the CDR between experimental group and control group in CDR 2-point group, which is a moderate dementia group.

• 한국측량학회지
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• 제36권4호
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• pp.235-243
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• 2018

국가기준점은 국토에 관한 각종 개발 및 이용 계획 등의 입안을 위한 지도 제작 또는 건설, 토목 공사용의 도면 작성을 위한 기준으로써 매우 중요하다. 우리나라는 1910년대 이후로 국가 기준점인 삼각점과 수준점을 설치하여 관리하여 왔으며, 현재는 국가기준점 정보를 국토정보플랫폼을 통하여 서비스를 제공하고 있다. 우리나라의 국가기준점은 시대적인 사건과 환경에 의해 망실이나 재설, 이설 등의 과정을 거쳐 변화해 왔으며, 이러한 변화를 거친 국가기준점들을 시계열적으로 연계하여 정보를 제공하는 것은 매우 중요하다. 이에 본 연구에서는 삼각점을 시대별로 조선총독부 자료, 미군 YUCCA 사업 자료, 국립건설연구소 자료, 국립지리원 구 성과표 자료, 현재 자료로 구분하고, 각 시대별 동일 삼각점을 시계열적으로 연계하는 방안을 제시하였다. 최종적으로 제천시를 대상으로 시계열적 동일 삼각점을 정합하고, 삼각점의 시계열적 연계 가능성을 평가하였다.