• 한국운동역학회지
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• 제22권3호
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• pp.373-378
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• 2012

The purpose of this study was to develop an electric riding machine for cycle fitting to control riding posture easily, to measure frame size quantitatively, and to overcome disadvantages of the traditional systems. The electric riding machine consisted of actuator, load controller, and display & control unit. The actuator unit by BLDC(BrushLess Direct Current) motor drives the saddle height up and down, the crank forward and backward, the handlebar up and down, and the handlebar forward and backward. The load controller unit controls loads by Eddy current controller with electromagnet and aluminum circular plate. The display & control unit consisted of frame size controller and display panel which shows top tube length(485~663mm), head tube length(85~243mm), seat tube length(481~671mm), and seat tube angle($62.7{\sim}76.4^{\circ}$). The range of frame size control for developed electric riding machine did not have difference compared to traditional commercial systems, but quantitative and precise control with 0.1 mm length and $0.1^{\circ}$ angle was possible through digital measurement. Unlike traditional commercial systems, frame size control was possible during riding through motor driven method, thus fitting duration decreased. It is necessary for further improvement to have feedback from users. It is believed that developed electric riding machine can help to develop domestic fitting system.

• International Journal of Advanced Culture Technology
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• 제7권1호
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• pp.231-236
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• 2019

Background/Objectives: This paper proposes a dual mode feedback-controlled cycling system for children with spastic cerebral palsy to rehabilitate upper extremities. Repetitive upper limb exercise in this therapy aims to both reduce and analyze the abnormal torque patterns of arm movements in three- dimensional space. Methods/Statistical analysis: We designed an exercycle robot which consists of a BLDC motor, a torque sensor, a bevel gear and bearings. Mechanical structures are customized for children of age between 7~13 years old and induces reaching and pulling task in a symmetric circulation. The shafts and external frames were designed and printed using 3D printer. While the child performs active/passive exercise, angular position, angular velocity, and relative torque of the pedal shaft are measured and displayed in real time. Findings: Experiment was designed to observe the features of a cerebral palsy child's exercise. Two children with bilateral spastic cerebral palsy participated in the experiment and conducted an active exercise at normal speed for 3 sets, 15 seconds for each. As the pedal reached 90 degrees and 270 degrees, the subject showed minimum torque, in which the child showed difficulty in the pulling task of the cycle. The passive exercise assisted the child to maintain a relatively constant torque while visually observing the movement patterns. Using two types of exercise enabled the child to overcome the abnormal torque measured in the active data by performing the passive exercise. Thus, this system has advantage not only in allowing the child to perform the difficult task, which may contribute in improving the muscle strength and endurance and reducing the spasticity but also provide customizable system according to the child's motion characteristic. Improvements/Applications: Further study is needed to observe how passive exercise influences the movement characteristics of an active motion and how customized experiment settings can optimize the effect of pediatric rehabilitation for spastic cerebral palsy.

• 한국인터넷방송통신학회논문지
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• 제22권6호
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• pp.21-30
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• 2022

본 논문에서는 소형 추적 레이더에 적용 가능한 서보의 설계, 제작, 시험에 대해 기술하였다. 우선 1장에서는 본 연구의 필요성에 대해 기술하였다. 2장에서는 향후 소형 유도무기용 추적 레이다에 적용 가능한 서보 개발에 대해 기술하였다. 3장에서는 브러쉬 직류전동기, 브러쉬리스 직류 전동기, 영구 자석 동기 전동기의 전류 제어를 위한 설계 및 시험 결과를 대해 기술하였다. 그리고 4장에서는 시험 휠의 속도 제어를 위한 설계 및 시험 결과를 기술하였다. 그리고 5장에서는 앞선 시험들의 결과를 정리하였다. 본 논문에서는 보안상의 이유로 일부 그림을 의도적으로 흐림(blur) 처리 하였으며, 개발된 짐벌과의 시험이 아니라 별도의 시험 휠의 제어 결과를 기술하였다.

• 생물환경조절학회지
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• 제28권4호
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• pp.454-460
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• 2019

이 연구에서는 염수를 증발냉각법을 이용하여 담수를 생산할 목적으로 회전형 미세입자 분무장치를 설계 제작하여 회전체의 표면조도, BLDC 시로코 팬의 회전수 그리고 염수 공급량의 변화에 따른 분무입자의 크기와 분포 특성을 실험적으로 분석하고자 하였다. 회전체의 표면조도 $Ra=0.27{\sim}7.65{\mu}m$인 경우 분무입자 크기는 $0.117{\sim}1.360{\mu}m$ 였고, 분무입자의 90% 가 $0.50{\mu}m$ 이하인 것으로 나타났다. $Ra=12.70{\sim}22.84{\mu}m$인 경우에는 분무입자 크기가 $2.51{\sim}184.79{\mu}m$의 범위에 분포하였고, 분무입자의 98%가 $13.59{\mu}m$ 이하인 것으로 나타났다. BLDC 시로코 팬의 회전수가 분무입자의 크기와 분포에 미치는 영향을 분석하기 위하여 표면조도 $Ra=0.27{\mu}m$로 고정한 상태에서 염수 공급량을 일정하게 유지하면서 팬의 회전수를 3,800~5,600rpm 로 변화시켜가며 실험을 수행한 결과 염수 공급량이 2.77~8.28mL/min 인 경우에는 분무입자의 크기가 $0.314{\sim}0.541{\mu}m$의 범위에 분포하였다. 또한 염수공급량이 9.74mL/min 이고 회전수가 5,600rpm인 경우에는 분무입자의 98.23% 이상이 $2.51{\sim}13.59{\mu}m$의 범위에 분포하였다.

• 한국생산제조학회지
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• 제26권1호
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• pp.89-99
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• 2017

This paper describes the development of a thigh wearable robot for power assistance during stair climbing. In the wearable robot developed in this study, high-power BLDC motors and high-capacity harmonic reduction gears are used to effectively assist the thigh muscle during stair climbing. In particular, normal ground and stair are distinguished accurately by using wireless smart shoes, and the stair climbing assistance is performed by activating the actuators at an appropriate time. Impedance of the hip joint was effectively reduced by performing friction compensation of the gears, and a wearing adjustment mechanism was designed to fit the robot to the thigh by conveniently modifying the width and tilting angle of the robot using set collars. Consequently, the performance of the developed thigh wearable robot was verified through stair climbing experiments with EMG measurement.

• 전기학회논문지
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• 제66권5호
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• pp.792-799
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• 2017

The real time unmanned monitoring system of an equipment's internal parts and condition requires the monitoring device to be able to stop at a set location on the rail. However, due to the slip between the driving surface and the roller, an error occurs between the actual position and the command position. In this paper, a method to compensate the position error due to the roller slip is proposed. A proximity sensor located at both ends of the rail detects the starting point and the maximum position pulse, linearly compensating the error between the angular position of the motor and the mechanically fixed starting and maximum position pulse of the rail in forward and reverse direction. Moreover, unlike the existing servo position controller, the motor adopts the position detection method of Hall sensor in BLDC (Brushless DC) and applies an algorithm for low-speed driving so that a stable position control is possible. The proposed rail guided unmanned monitoring system with driving slip compensator was tested to verify the effectiveness.

• 전력전자학회논문지
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• 제17권3호
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• pp.246-251
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• 2012

This paper proposes a new position compensation method for misaligned Hall-effect sensors of BLDCM(Brushless DC Motor). If the Hall-effect sensors are installed at wrong position, the exact rotor position cannot be obtained. Therefore, when the BLDCM is controlled with this wrong position, the torque ripple can be increased and the average torque also decreases. The back-EMF of BLDCM can be obtained by using the voltage equation and by multiplying the back-EMF constant and rotor speed. At a constant speed, the estimated back-EMF by using the multiplication of the back-EMF constant and rotor speed is constant, but the estimated back-EMF from the voltage equation decreases at the commutation point because the line-to-line back-EMF of two conducting phases is start to decrease at this point. Therefore, by using the difference between these two estimated back-EMFs, the commutation point of the phase current can be determined and position compensation can be carried out. The proposed position correction method doesn't require additional hardware circuit and can be easily implemented. The validity of the proposed position compensation method is verified through several experiments.

• 한국정보통신학회논문지
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• 제3권3호
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• pp.639-650
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• 1999

본 논문에서는 정현파형 브러시리스 직류 전동기의 속도제어를 위해 두 개의 스위칭 라인에 의해 구성된 채터링 둔감영역을 갖는 가변구조 속도제어기를 설계한다. 슬라이딩 모드 과정 중 과도상태에서 발생하는 고주파 채터링을 저주파로 한정시키기 위해 데드 존(Dead Zone) 함수의 도입을 제안하고, 정상상태에서의 채터링 및 정상상태 오차를 제거하기 위해서는 제어입력에 시변이득을 적용한다. 제안된 데드 존 함수는 두개의 스위칭 함수로 구성된 슬라이딩 영역을 표시하며 이 영역에 시스템의 상태가 존재 시제어 구조를 PI제어기로 변경하여 채터링이 발생하지 않으며 이 영역의 이탈 시만 가변구조제어를 적용하므로 채터링이 발생하게 되어 과도상태의 고주파 채터링을 저주파로 감소시킬 수 있다. 설계된 속도 제어기에 대해 컴퓨터 시뮬레이션과 실험을 통하여 그 성능을 보인다.

• 전기학회논문지
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• 제58권10호
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• pp.1930-1935
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• 2009

This paper deals with the torque ripple reduction of permanent magnet synchronous motor using harmonic current injection. Torque ripple of electric motor reduces system stability and performances, therefore efforts to reduce torque ripple are exerted in the design process. Torque ripple can be reduced by appropriate pole/slot combination, skew of rotor or stator, design of magnetic circuit, etc. In addition, torque ripple can be also reduced by input voltage and current, and many researches have been conducted to reduce torque ripple for six-step drive. Torque ripple reduction for current vector controlled permanent magnet synchronous motor also have been conducted and verified by investigating back emf wave form. Torque ripple reduction in this paper started from getting torque profile according to input current and electrical angle calculated by FEA, then instantaneous currents at each electrical angles for constant torque are calculated and applied to experiments. Therefore, 0% of torque ripple can be obtained theoretically with harmonic current injection. In order to maximize the effect of torque ripple reduction, a BLDC motor having high harmonic component of back emf is chosen. With sinusoidal current drive, over 100% of torque ripple is obtained initially, then 0.5 % of torque ripple is obtained by FEA using harmonic current injection. The effect is verified by experiment and the presented method can be effectively applicable to Electric Power Steering(EPS).

• 조명전기설비학회논문지
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• 제19권5호
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• pp.54-59
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• 2005

브러시리스 직류 전동기(Brushless U Motor : BLDCM)는 기존의 직류 전동기의 단점인 브러시를 제거한 것으로 제어가 간단하면서도 넓은 범위에서 속도 제어가 가능하고 효율이 높으며 경제적으로 제어기 제작이 가능하여 산업용 뿐 아니라 가전에까지 널리 사용된다. 그러나 BLDCM을 구동하는데 필수적인 센서는 제품 가격을 증가시킬 뿐만 아니라 운전 환경이 열악한 곳에서는 동작 오류를 발생하는 원인이 되고 있다. 본 논문에서는 BLDCM의 센서리스 구동에서 정상상태 운전뿐만 아니라 안정된 초기 구동에 관한 연구를 수행한다. 정상상태 운전은 측정된 역기전력을 이용하여 회전자의 위치를 결정함으로써 이루어지며, 초기 구동을 개선하기 위해 환류 다이오드로부터 측정된 전류 신호를 이용하여 초기 구동을 하게 된다. 이것은 실험을 통해 타당성을 확인하였다.