• Journal of Electrical Engineering and Technology
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• 제6권5호
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• pp.595-604
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• 2011

A three-phase three-level shunt active filter controlled by fuzzy logic current controller which can compensate current harmonics generated by nonlinear loads is presented. Three-level inverters and fuzzy controllers have been successfully employed in several power electronic applications these past years. To improve the conventional pwm controller performance, a new control scheme based on fuzzy current controller is adopted for three-level (NPC) shunt active filter. The scheme is designed to improve compensation capability of APF by adjusting the current error using a fuzzy rule. The inverter current reference signals required to compensate harmonic currents use the synchronous reference detection method. This technique is easy to implement and achieves good results. To maintain the dc voltage across capacitor constant and reduce inverter losses, a proportional integral voltage controller is used. The simulation of global system control and power circuits is performed using Matlab-Simulink and SimPowerSystem toolbox. The results obtained in transient and steady states under various operating conditions show the effectiveness of the proposed shunt active filter based on fuzzy current controller compared to the conventional scheme.

• 한국과학교육학회지
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• 제18권4호
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• pp.503-516
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• 1998

본 연구는 형식적 조작기의 초기에 형성되며, 형식적 사고와 과학적 추론의 기초가 되는 비례 논리의 형성에 미치는 학습자 요인과 비례 논리 향상을 위한 프로그램의 적용효과를 분석하는데 그 목적이 있다. 비례 논리 형성에 미치는 요인 분석을 위하여 형식적 사고기의 초기에 해당하는 중학교 1, 2, 3학년 학생 790명을 대상으로 하였다. 표집된 학생들에게 과학적 사고력 검사, WCST, 설계기능검사, 정신용량 검사, 인지양식 검사, 뇌기능 분화 검사, 동시적/연속적 처리 검사, 과학적 추론 검사를 실시하였다. 한편, 비례논리 향상을 위한 프로그램의 적용을 위해서 비례논리가 형성되지 않은 학생 133명에게 처치하여 그 효과를 분석하였다. 본 연구의 결과 학습자의 연령, 과학적 추론 능력, 정신용량, 동시적/연속적 정보처리 점수가 높을수록 비례논리 형성 정도가 높았다. 반면에 보속적 오류가 적을수록 비례논리 형성 정도가 높았다. 비례논리 형성에 높은 예언력을 가지고 있는 대표적인 변인으로는 과학적 추론, 정보처리, 보속적 오류, 연령의 학습자 요인이다. 형식적 사고기의 연령에 있는 학생 중 비례논리가 형성되지 않은 학생을 위해서 비례 논리 형성을 위한 프로그램이 효과가 있는 것으로 나타났다. 본 연구결과를 바탕으로 논리적 사고 형성에 미치는 요인에 대한 분석과 비례논리의 형성이 기타의 논리 형성과 과학 교과목의 성취도에 미치는 영향에 대한 연구가 계속되기를 기대한다.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1993년도 한국자동제어학술회의논문집(국내학술편); Seoul National University, Seoul; 20-22 Oct. 1993
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• pp.1183-1187
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• 1993

The objective of this study is to design a fuzzy logic controller(FLC) which controls the position of excavator's attachment a noble FLC is proposed, which is based on simple control rules while offering easy tuning of control parameters by utilizing real operation characteristics of an operator. The proposed FLC consists of two parts, the proportional controller part and the FLC part. Experiments are carried out on a test bed which is built around a commercial excavator. The controller is applied to bhe leveling of excavator's bucket tip, which is one of the main functions in an excavator's operation.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1993년도 한국자동제어학술회의논문집(국내학술편); Seoul National University, Seoul; 20-22 Oct. 1993
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• pp.1080-1085
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• 1993

A nonlinear control algorithm for the depth control of underwater vehicles is presented. In order to consider the deadzone effect of the flow control valve, a nonlinear fuzzy logic controller (FLC) is synthesized and combined with a linear proportional-derivative-acceleration (PDA) controller, which is called, the PDA/FLC controller. And, to show the effectiveness of the PDA/FLC control system, it is compared with the linear PDA control system through computer simulation. It is found that the PDA/FLC control scheme is a suitable one to maintain the desirable depth of underwater vehicles with deadzone.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1993년도 한국자동제어학술회의논문집(국내학술편); Seoul National University, Seoul; 20-22 Oct. 1993
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• pp.224-227
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• 1993

In this paper, a new LMS algorithm with a variable step size (VVS LMS) is presented. The change of step size .mu. at each iteration, which increases or decreases according to the misadaptation degree, is computed by a proportional fuzzy logic controller. As a result the algorithm has very good convergence speed and low steady-state misadjustment. The norm of the cross correlation between the estimation error and input signal is used. As a measure of the misadaptation degree. Simulation results are presented to compare the performance of the VSS LMS algorithm with the normalized LMS algorithm.

• 산업기술연구
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• 제13권
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• pp.33-41
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• 1993

In this paper, a new LMS algorithm with a fuzzy variable step size (FVS LMS) is presented. The change of step size ${\mu}$, at each iteration which is increases or decreases according to the misadaptation degree, is computed by a proportional fuzzy logic controller. As a result the algorithm has very good convergence speed and low steady-state misadjustment. As a measure of the misadaptation degree, the norm of the cross correlation between the estimation error and input signal is used. Simulation results are presented to compare the performance of the FVSS LMS algorithm with the normalized LMS algorithm.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1995년도 Proceedings of the Korea Automation Control Conference, 10th (KACC); Seoul, Korea; 23-25 Oct. 1995
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• pp.135-137
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• 1995

A new design method is proposed for a fuzzy PD controller. By analyzing phase plane characteristics we can build and optimize the rule base of fuzzy logic controller. Also, a new gain tuning method is used to improve performance in the transient and steady state. The improved performance of the new methodology is shown by an application to the design of control system with a highly nonlinear actuator.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1996년도 하계학술대회 논문집 C
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• pp.1963-1967
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• 1996

This paper describes the analysis, design, and silicon-fabrication of a fluidic proportional amplifier, which is the most important element of fluidic logic circuits. First, FEM(finite element method) analyses were performed, using the Fluent computational fluid dynamics program, and design geometries were optimized. Then, a $40\;{\mu}m$-deep amplifier was fabricated in silicon using anisotropic dry etching.

• Journal of Electrical Engineering and Technology
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• 제13권5호
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• pp.1886-1900
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• 2018

This paper proposes a confronting feedback control structure and controllers for positive output elementary super lift Luo converters (POESLLCs) working in discontinuous conduction mode (DCM). The POESLLC offers the merits like high voltage transfer gain, good efficiency, and minimized coil current and capacitor voltage ripples. The POESLLC working in DCM holds the value of not having right half pole zero (RHPZ) in their control to output transfer function unlike continuous conduction mode (CCM). Also the DCM bestows superlative dynamic response, eliminates the reverse recovery troubles of diode and retains the stability. The proposed control structure involves two controllers respectively to control the voltage (outer) loop and the current (inner) loop to confront the time-varying ON/OFF characteristics of variable structured systems (VSSs) like POESLLC. This study involves two different combination of feedback controllers viz. the proportional integral controller (PIC) plus sliding mode controller (SMC) and the fuzzy logic controller (FLC) plus SMC. The state space averaging modeling of POESLLC in DCM is reviewed first, then design of PIC, FLC and SMC are detailed. The performance of developed controller combinations is studied at different working states of the POESLLC system by MATLAB-Simulink implementation. Further the experimental corroboration is done through implementation of the developed controllers in PIC 16F877A processor. The prototype uses IRF250 MOSFET, IR2110 driver and UF5408 diodes. The results reassured the proficiency of designed FLC plus SMC combination over its counterpart PIC plus SMC.

• International Journal of Aeronautical and Space Sciences
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• 제7권2호
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• pp.137-144
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• 2006

The objective of this paper is to present trajectory guidance and control system with a dynamic inversion for a small unmanned aerial vehicle (UAV). The UAV model is expressed by fixed-mass rigid-body six-degree-of-freedom equations of motion, which include the detailed aerodynamic coefficients, the engine model and the actuator models that have lags and limits. A trajectory is generated from the given waypoints using cubic spline functions of a flight distance. The commanded values of an angle of attack, a sideslip angle, a bank angle and a thrust, are calculated from guidance forces to trace the flight trajectory. To adapt various waypoint locations, a proportional navigation is combined with the guidance system. By the decision logic, appropriate guidance law is selected. The flight control system to achieve the commands is designed using a dynamic inversion approach. For a dynamic inversion controller we use the two-timescale assumption that separates the fast dynamics, involving the angular rates of the aircraft, from the slow dynamics, which include angle of attack, sideslip angle, and bank angle. Some numerical simulations are conducted to see the performance of the proposed guidance and control system.