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시지연과 SVPWM 영향이 고려된 새로운 제어 모델에 의한 3상 전압원 PWM 컨버터의 전류 제어
민동기,안성찬,현동석 전력전자학회 2000 전력전자학회 논문지 Vol.5 No.2
3상 PWM 컨버터의 디지털 전류제어기 디자인에 있어서 보편적인 방법은 이산화된 값을 사용한다. 그러나 이같은 시스템은 SVPWM의 특성과 시간연을 고려하지 않았기 때문에 에러를 갖는다. 본 논문은 이와 같은 문제점을 고려한 3상 PWM 컨버터의 새 좌표축 모델을 제시하였으며, 새 모델에 근거한 시지연 보상을 위한 별도의 알고리즘이 필요 없는 직접 디지털 전류제어기를 설계하였다. 또한 제안된 전류제어기를 위한 인덕턴스 불일치 문제를 간단한 알고리즘을 사용하여 보상하였다. 제안된 알고리즘의 타당성을 시뮬레이션과 실험을 통하여 입증하였다. In design of a digital current controller for a 3cP PWM converter, its conventional model is used in obtaining i its discretized version. But, it has errors since the characteristics of SVPWM and time delay are not taken i into consideration. In this paper, the new reference frame model of a 3c~ PWJVI converter is proposed C considering these problems. Also, the direct digital current controller based on this model is designed without a any extra algolithm. A simple tuning algorithm for the proposed current controller is given to compensate the i inductaηce mismatch problem. Then simulation and experimental results show the validity of the algolithm.
정상노인과 뇌졸중 환자의 우세측과 비우세측의 골밀도 비교
민동기 대한고유수용성신경근촉진법학회 2013 PNF and Movement Vol.11 No.2
Purpose : The purpose of this study of normal elderly and stroke patients by comparing the dominant side and recessive side was to evaluate the differents between each Methods : Thirty-two elderly participated in this study. They were classified two groups: stroke patients group and the normal elderly group. Outcome measures were: general characteristics and BMD. General characteristics included age, height, weight and body mass index. BMD was represented in the osteoporosis index, T-score and Z-score. The measurements of bone mineral density were evaluated on the calcaneus region of the dominant and recessive side, using OsteoPro. The data analyzed using SPSS 17.0 software and the Paired-sample T-test and the Independent-sample T-test Results : OI, T-score, Z-score showed no significant differences between dominant side and recessive side in normal elderly group. But stroke patients group showed OI, T-score, Z-score significant differences between paretic side and nonparetic side. Change score subtracted recessive side from dominant side was significant differences between stroke patients group and normal elderly group. Conclusion : There is positive relationship between physical activity and BMD in stroke patients. Therefore, improved physical activity can have a beneficial effect by reducing osteoporosis in stroke patients, considering a positive relationship between physical activity and BMD. .
만성요통환자의 한발서기 시 체간 안정화 근육의 활성화 변화
민동기,Min, Dong-ki 대한물리치료과학회 2014 대한물리치료과학회지 Vol.21 No.1
Purpose : The purpose of this study was to analyze and compare the surface electromyography(EMG) activity of trunk region muscle between normal subjects and chronic low back pain(CLBP) patients during one leg stance. Methods : The subjects were 27 people, were consisted of 12 subjects who don't have low back pain and 15 subjects who have low back pain from 19 to 28 year of age(mean age 22.22). We used surface EMG to evaluate the activity of the Rectus abdominis, External abdominal oblique, Quadratus lumborum, Gluteus medius muscle. We used independent two samples t-test for statistical data. Results : The result of this study showed that the maximal voluntary isometric contraction(%MVIC) ratio of the trunk muscles was higher in patients with CLBP than in normal subject. But there were no statistically significant differences. There were statistically significant differences of the activity of the Quadratus lumborum, Gluteus medius muscle(p<0.05).
중학교 3학년 기술·가정 교과에서 납땜식 전자키트와 블록식 전자키트의 수업 효과 비교
민동기,김진수 한국기술교육학회 2004 한국기술교육학회지 Vol.4 No.1
The purpose of this study was to investigate learning effects in practicing to make electronic products by using the electronic circuit block in the subject of Technology and Home Economics in middle school. The contents of study were to compare and analyze the academic achievements and practice time required in completing the electronic products between the learning group(experimental group) using the block-type electronic kit and another learning group(comparable group) using the soldering-type electronic kit. The results was as follows; First, the experimental group showed significant improvement compared with the comparable group in academic achievement test. Second, in the cognitive domain, the experimental group showed higher achievement than the comparable group, but it showed no statistical significance. Third, in the affective domain, the experimental group showed statistically significant academic improvement. Forth, in the psychomotor domain, the experimental group showed statistically significant academic improvement. Fifth, the measured time required to make the electronic bird was about 19 minutes for the experimental group and 77 minutes for the comparable group.