• Transactions on Control, Automation and Systems Engineering
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• 제3권3호
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• pp.170-175
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• 2001

Q-learning is a kind of reinforcement learning where the agent solves the given task based on rewards received from the environment. Most research done in the field of Q-learning has focused on discrete domains, although the environment with which the agent must interact is generally continuous. Thus we need to devise some methods that enable Q-learning to be applicable to the continuous problem domain. In this paper, an extended fuzzy rule is proposed so that it can incorporate Q-learning. The interpolation technique, which is widely used in memory-based learning, is adopted to represent the appropriate Q value for current state and action pair in each extended fuzzy rule. The resulting structure based on the fuzzy inference system has the capability of solving the continuous state about the environment. The effectiveness of the proposed structure is shown through simulation on the cart-pole system.

• 전기학회논문지
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• 제56권8호
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• pp.1405-1411
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• 2007

In this paper, a new speed sensorless control based on a fuzzy compensator are proposed for the interior permanent magnet synchronous motor (IPMSM) drives. The conventional proportional plus integrate(PI) control are very sensitive to step change of the command speed, parameter variations and load disturbance. To cope with these problems of the PI control, the estimated speeds are compensated by using the fuzzy logic controller (FLC). In the FLC used by the speed compensator of the IPMSM, the system control parameters are adjusted by the fuzzy rule based system, which is a logical model of the human behavior for process control. The effectiveness of algorithm is confirmed by the experiments.

• Journal of Power Electronics
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• 제3권2호
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• pp.115-123
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• 2003

This paper presents analysis, design and simulation for the indirect field orientation control (IFOC) of induction machine drive system. The dynamic performance of the IFOC under nominal and detuned parameters of the induction machine is established. A conventional proportional plus integral-derivative (PI-D) two-degree-of-freedom controller (2DOFC) is designed and analysed for an ideal IFOC induction machine drive at nominal parameters with the desired dynamic response. Varying the induction machine parameters causes a degredation in the dynamic response for disturbance rejection and tracking performance with PI-D 2DOF speed controller. Therefore, conventional controllers can nut meet a wide range of speed tracking performance under parameter variations. To achieve high- dynamic performance, a proposed robust fuzzy logic controllers (RFLC) for d-axis rotor flux, d-q axis stator currents and rotor speed have been designed and analysed. These controllers provide robust tracking and disturbance rejection performance when detuning occurres and improve the dynamic behavior. The proposed REL controllers provide a fast and accurate dynamic response in tracking and disturbance rejection characteristics under parameter variations. Computer simulation results demonstrate the effectiveness of the proposed REL controllers and a robust performance is obtained fur IFOC induction machine drive system.

• 한국정보처리학회논문지
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• 제6권4호
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• pp.977-987
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• 1999

현행 교통 신호 제어기는 사전에 계획된 신호 시간 체계 또는 시간대별로 선택되는 방법을 취하고 있다. 이와 같은 신호 체계는 교통 상황 변화에 적절하게 대응하기 어려운 문제점을 갖고 있다. 특히, 혼잡 상황과 같은 문제들은 이진 논리로써 해결하기 어렵다. 따라서, 본 논문에서는 교통 혼잡 상황에 신속하게 대처할 수 있는 신호기 제어 시스템을 제안하였다. 본 논문에서 제안한 제어기는 불확실성 및 퍼지환경에서 작동한다. 따라서, 도로의 혼잡 상황을 퍼지 논리를 사용하여 표현하고 퍼지 추론기에 의해 신호 시간을 결정하도록 하였다. 본 논문에서 제안한 신호기 제어 시스템의 타당성을 검증하고자 페트리네트를 이용하여 모델링 하였다.

• 한국정보처리학회논문지
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• 제5권11호
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• pp.2908-2914
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• 1998

본 논문은 교통량이 변하는 복수 교차로망의 신호등 제어에 적합한 지능형 신호 제어기를 제안한다. 교차로망이란 하나의 교차로가 사방으로 연결된 교차로이다. 기존의 교차로 제어방법들은 주로 단일 교차로를 대상으로 연구가 수행되었다. 하지만 단일 교차로 제어는 현실의 교통 상황과는 차이가 있다. 본 논문에서는 교통량과, 녹색 신호시 교차로로 진입하는 차량수와 적색 신호동안 대기하는 차량수를 퍼지 제어의 입력변수로 사용하여, 현재 녹색 현시의 확장시간을 조정하는 퍼지 교통망 제어기를 개발한다. 제안된 방법은 기존의 교차로 신호 주기 제어 방법들과 시뮬레이션을 수행하여 비교하였다. 실험결과는 제안된 퍼지 논리 제어기가 기존의 방법들에 비하여 차량당 지체시간과 논문에서 제안된 비용함수 면에서 우수함을 보여준다.

• 대한전기학회논문지:시스템및제어부문D
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• 제50권7호
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• pp.318-324
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• 2001

Efficiency optimization of an indirect vector controlled induction motor drive is proposed. The loss models are used in the validation of the fuzzy logic based on-line efficiency optimization control. At steady state, the fuzzy controller adaptively changes the excitation current on the basis of measured input power, until the maximum efficiency point is reached. The pulsating torque, due to flux reduction, has been compensated by an ingenious feedforward scheme. During transient state, rated flux is established to get the best transient response. Through a comprehensive simulation study, the results confirmed the validity of the proposed method.

• 한국경영과학회:학술대회논문집
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• 대한산업공학회/한국경영과학회 2006년도 춘계공동학술대회 논문집
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• pp.1235-1239
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• 2006

Fractal manufacturing system (FrMS) distinguishes itself from other manufacturing systems by the fact that there is a fractal repeated at every scale. A fractal is a volatile organization which consists of goal-oriented agents referred to as AIR-units (autonomous and intelligent resource units). AIR-units unrestrictedly reconfigure fractals in accordance with their own goals. Their goals can be dynamically changed along with the environmental status. Since goals of AIR-units are represented as fuzzy models, an AIR-unit itself is a fuzzy logic controller. This paper presents a goal regulation mechanism in the FrMS. In particular, a reinforcement learning method is adopted as a regulating mechanism of the fuzzy goal model, which uses only weak reinforcement signal. Goal regulation is achieved by building a feedforward neural network to estimate compatibility level of current goals, which can then adaptively improve compatibility by using the gradient descent method. Goal-oriented features of AIR-units are also presented.

• Journal of Power Electronics
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• 제13권3호
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• pp.369-380
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• 2013

Direct torque control based on space vector modulation (SVM-DTC) protects the DTC transient merits. Furthermore, it creates better quality steady-state performance in a wide speed range. The modified method of DTC using SVM improves the electrical magnitudes of asynchronous machines, such as minimizing the stator current distortions, the stator flux with electromagnetic torque without ripple, the fast response of the rotor speed, and the constant switching frequency. In this paper, the proposed method is based on two new control strategies for direct torque control with space vector modulation. First, fuzzy logic control is used instead of the PI torque and a PI flux controller to minimizing the torque error and to achieve a constant switching frequency. The voltages in the direct and quadratic reference frame ($V_d$, $V_q$) are achieved by fuzzy logic control. In this scheme, the switching capability of the inverter is fully utilized, which improves the system performance. Second, the close loop of stator flux estimation based on the voltage model and a low pass filter is used to counteract the drawbacks in the open loop of the stator flux such as the problems saturation and dc drift. The response of this new control strategy is compared with DTC-SVM. The experimental and simulation results demonstrate that the proposed control topology outperforms the conventional DTC-SVM in terms of system robustness and eliminating the bad outcome of dc-offset.

• 한국정보처리학회논문지
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• 제4권10호
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• pp.2485-2492
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• 1997

오늘날 자동차의 급격한 증가에 따른 교통 체증을 완화시키기 위해 효율적인 교차로 신호 제어기의 필요성이 대두되고 있다. 최근에는 신호등의 주기를 적응적으로 제어하기 위하여 퍼지 논리가 도입되었다. 일반적인 퍼지 제어 방식은 녹색신호에 교차로로 진입하는 차량 수와 적색신호 동안 대기하는 차량 수를 퍼지 제어의 입력 변수로 사용하여 확장시간을 조정한다. 그러나 이 방법은 가변 교통량을 갖는 교차로에는 부적합하다. 본 논문에서는 대칭적인 소속함수를 갖는 기존의 퍼지 논리 제어기들보다 적은 수의 제어규칙들을 가지면서도 교통 흐름을 보다 잘 반영하는 비대칭적인 소속함수를 갖는 새로운 퍼지 논리 제어기를 제안한다. 제안된 방법의 효율성은 단일 교차로 시뮬레이션을 통해 테스트되었다. 실험결과는 제안된 방법이 평균 지체시간, 통과 대수, 포화도면에서 우수한 성능을 보여주었다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2011년도 제42회 하계학술대회
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• pp.1392-1393
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• 2011

This paper proposes fuzzy logic control maximum power point tracking(FLC MPPT) of photovoltaic(PV) pump system using IPMSM. Conventional MPPT controller was unstable by reason of the ripple-current of DC link in three phase inverter. Thus in this paper the control algorithm of IPMSM using $i_q$ current is composed to improve the insecurity of conventional MPPT controller. Proposed algorithm is operated by simulation with variation radiation condition. And analyze the response characteristic of IPMSM. The validity of this paper is proved by analyzed data.