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An exploration of the current challenges in social work education in Mainland China
Yuen‐han Mo Kitty,Tak‐Mau Chan Simon 한국사회복지학회 2021 Asian Social Work and Policy Review Vol.15 No.3
Social work education is facing multiple difficulties and challenges in Mainland China. Partly because of a dearth of national studies on the viewpoints of social work educators to explore the alternatives, this qualitative study tried to fill in the gap to interview 23 social work educators to investigate into the issue. Twenty-three cities, across two municipalities, two autonomous regions, and 11 provinces were covered to provide a full picture of national education practices and trends.
김연충,원충연,이상석,김영렬 성균관대학교 1998 학술회의지원논문목록집 Vol.1998 No.-
The conventional PI controller has been widely used in industrial applications. If a PI control gain is selected suitable. the PI controller shows very good control performance. But it is very difficult to find the optimal PI control gain. Therefore, in this paper, the 4-rule based fuzzy logic modifier of the conventional PI controller are presented. The fuzzy logic modifier which exhibits a stabilizing effects on the closed-loop system. has good robustness regarding the improperly tuned PI controller. The simulation are performed to verify the capability of proposed control method on vector controlled induction motor drive system.
전력전자 PSPICE 컴퓨터 시뮬레이션을 위한 스위치 모델
元忠淵,金淵俊,金世燦,金德憲 成均館大學校 科學技術硏究所 1990 論文集 Vol.41 No.2
PSPICE is widely used in analysis of general circuit and simulation in electric and electrical field is applied to power electronics circuit. The circuits used with thyristors will add significant complexity to PSPICE analysis, it is important that the thyristor model be as simple as possible. In order to solve this problem, an ideal voltage controlled switch and an ideal current controlled switch were added as circuit elements. Two typical power electronics circuits simulation using PSPICE program presented.
고속전철용 VVVF 인버터의 고조파 저감 기법에 관한 연구
박영진,김연충,김재문,원충연 成均館大學校 科學技術硏究所 1998 論文集 Vol.49 No.1
In the past inverter, the output voltage supplied to the motor is not a sinusoidal one. So, the harmonic currents clue to non-sinusoidal voltage cause excessive lose, heating and torque pulsations. In this paper, the several PWM methods for harmonics reduction in current and voltage of the VVVF inverter are described. The performance of the proposed harmonic reduction techniques is illustrated via experiments on V/F control of induction motor. It is proved that space-vector PWM is the best method in point of harmonic reduction.
퍼지 제어기를 이용한 브러시리스 직류전동기의 속도 제어에 관한 연구
김선욱,김재문,김연충,이상석,원충연 成均館大學校 科學技術硏究所 1997 論文集 Vol.48 No.2
This paper deals with the speed control of a BLDCM with rectangular back electromotive force using fuzzy logic controller. The fuzzy PI controllers make the many degrees of freedom in proportion to the number of the rule for input and its ability of adjustment for control input is excellent. Thus, the proper adjustment of the fuzzy rules can provide the good performance for the system. Above all, the advantage of the fuzzy controller has the characteristic of robustness for parameter variation, load change, noises. As a current controller, a hysterisis current controller is implemented, and in order to reduce torque ripple in low speed range, current controller detects the uncommutating mode current for every 60 electrical degree. The fuzzy speed controller is implemented by MCS80C196KC, a 16 bit one-chip microprocessor. The experimental results show that the performance of the fuzzy speed controller is superior to that of the conventional PI controller in terms of robustness for the change of load torque.
이정호,김재문,김연충,원충연 成均館大學校 科學技術硏究所 1998 論文集 Vol.49 No.1
In this paper, We proposed AC/DC boost converter with high power factor in TIG welder. The proposed power factor correction circuit with UC2854AN acting on constant switching frequency average current control have a three-loop control structure : the inner current loop, the line voltage feedforward loop, and the outer voltage loop. Also, We applied the constant current control strategy to stabilized the output current using the analog PI controller. To demonstrate the practical significance of the proposed methods, some simulation studies and experimental results are presented.
단일펄스 전압구동 방식에 의한 스위치드 리럭턴스 전동기의 속도제어에 관한 연구
김보형,안정준,김연충,김재문,원충연 成均館大學校 科學技術硏究所 1998 論文集 Vol.49 No.2
The conventional PI controller has been widely used in industrial applications. If it is selected suitable a PI control gain, the PI controller shows very good control performance. But it is very difficult to find the optimal PI control gain. This thesis deals with the speed control of switched reluctance motor using the PI controller with 4-rule based fuzzy logic modifier. Simulation and experimental results show that the fuzzy logic modifier which exhibits a stabilizing effects on the closed-loop system, has good robustness regarding the improperly tuned PI controller. The performance of the PI controller with fuzzy logic modifier is superior to that of the conventional PI controller.
Yuen-Chung Kim,Jeong-Joon Ahn,Jae-Mun Kim,Chung-Yuen Won,Young-Real Kim 전력전자학회 1998 ICPE(ISPE)논문집 Vol.- No.-
Because of simple control algorithm and easy implementation, the conventional PI controller has been widely used in industrial application. But, it is very difficult to find the optimal PI control gain. Therefore, in improperly tuned PI controller or parameter variation, to obtain optimal performance, the novel PI controller, which consist of conventional PI controller and 4-rule based fuzzy logic, are presented in this paper The novel PI controller which exhibits a stabilizing effects on the closed-loop system, has good robustness regarding the improperly tuned PI controller or parameter variation. The simulations are performed to verify the capability of proposed control method on induction motor.<br/>