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BLDC 전동기에서 PWM 방식에 따른 토크리플 저감에 관한 연구
김상훈,권경준 江原大學校 産業技術硏究所 2004 産業技術硏究 Vol.24 No.A
This paper presents a current control strategy to reduce torque ripple of Brushless DC Motor in commutation period with PWM pattern. The torque ripple is mainly caused by the inequality in the rate of change between rising current and decaying one during commutation. And also it is influenced by the shape of real back EMF. Therefore, in the proposed control strategy, considering real back EMF a compensation voltage is generated to equalize the rate of change in these commutating currents. And then, by providing the compensation voltage in commutation period with PWM pattern, the torque ripple can be reduced. The simulation and experimental results verify that the proposed method can reduce the torque and the current rippies significantly.
교류 서보 전동기 속도센서리스 제어를 위한 퍼지 동조 고이득 관측기 설계
김상훈,김낙교 대한전기학회 2005 전기학회논문지 D Vol.54 No.12-D
This paper deals with speed-sensorless control of an AC servo motor using Fuzzy-Tuning High Gain Observer(FTHGO). Resolver or encoder can be used to measure a rotor speed, but it has a limit to detect motor speed precisely. To solve this problem, it is studied to measure a speed of an AC servo motor without sensor. In this paper, the gain of an observer to estimate motor speed is properly set up and designed using the fuzzy control theory. It calculates the differentiation of the rotor current of the AC motor and estimates the rotor speed using it. Proposed speed sensorless control is performed using the estimated speed as the control variable. Designed FTHGO is applied to AC servo motor to verify the feasibility of the proposed observer. Feasibility of the FTHGO proposed in this paper is proven comparing the experimental results with/without the speed sensor.
김상훈,조청운,홍현기 한국정보과학회 2003 정보과학회논문지 : 소프트웨어 및 응용 Vol.30 No.12
Registration is the process aligning the range data sets from different views in a common coordinate system. In order to achieve a complete 3D model, we need to refine the data sets after coarse registration. One of the most popular refinery techniques is the iterative closest point (ICP) algorithm, which starts with pre-estimated overlapping regions. This paper presents an improved ICP algorithm that can automatically register multiple 3D data sets from unknown viewpoints. The sensor projection that represents the mapping of the 3D data into its associated range image is used to determine the overlapping region of two range data sets. By combining ICP algorithm with the sensor projection constraint, we can make an automatic registration of multiple 3D sets without pre- procedures that are prone to errors and any mechanical positioning device or manual assistance. The experimental results showed better performance of the proposed method on a couple of 3D data sets than previous methods. 대상 물체의 3차원 모델을 구축하기 위해서는 여러 시점에서 측정된 거리정보 데이타들을 하나의 좌표계로 통합하는 정합(registration) 과정이 필수적이다. 3차원 데이타의 정합을 위해 가장 널리 사용되는 ICP(Iterative Closest Point) 알고리즘은 거리정보 데이타 간에 겹치는 영역 또는 일치점 등에 대한 사전 정보가 필요하다. 본 논문에서는 임의의 시점에서 측정된 데이타를 반복적인 방법에 의해 자동으로 정합하는 개선된 ICP 방법이 제안된다. 3차원 데이타가 거리정보 영상으로 맺히는 관계를 나타내는 센서 사영조건(projection constraint), 데이타의 공분산(covariance) 행렬, 교차(cross) 사영 등을 이용하여 정합과정을 자동화하였으며, 유저의 개입이나 3차원 기계 보조 장치 등을 사용하는 별도의 초기값 측정 없이 3차원 모델을 정확하게 구성할 수 있다. 다양한 거리정보 데이타에 대한 실험을 통해 제안된 방법의 우수한 성능을 확인하였다.
김상훈,김학렬,박상학,김재민,박찬원 朝鮮大學校 附設 醫學硏究所 2002 The Medical Journal of Chosun University Vol.27 No.2
Background and Objectives : As the authors experienced 2 cases of male genital self-mutilation while psychotic, investigated with psychiatric points of view including general and psychiatric characteristics, family background, Psychodynamics of genital self-mutilation in Korea. Materials and Methods : Among total 20 cases of the genital self-mutilation, 4 accident-caused cases were excluded. Results : Epidemiological data showed that the most of the genital self-mutilation cases are twenties(56.3%); most are sing1e(68.5%) and the lower socio- economic c1asses(43.8%), the proportion of believers(31.2%) are somewhat larger than of those don't have any religions; most(50.0%) have no occupation. The familial background appeared that the most of them have grown up under widow mother's care(45.5%) and in some other places than their own homes(45.5%) and that there are relatively more first son (45.5%) among them. In terms of the mutilation types and instruments, transection of penis type were committed most frequent1y(93.8%), mostly by knives(68.8%). The formal diagnoses were mainly schizophrenia(87.5%) and schizoid personality disorder(12.5%). Major symptoms at the time of the act were delusion and/or hallucmation(62.5%) and depressive state(43.7%). Psychodynamically, lots of cases could be explained as to punish failures in the male ro1e(21.9%), related to re1igiosity(15.6%), and the wish to be or delusion of being fema1e(12.5%). Conclusion : Psychiatric investigation on the cases of genital self-mutilation reported in Korea suggests that the risk factors for the selfUmutilation on the genitalia are the deprivation of the early experiences required for personality development, Presence of psychotic disorder or depression, identity confusion, and the guilty feelings toward sexual aggression.