• 충청수학회지
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• 제23권3호
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• pp.563-570
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• 2010

In this article, we take account of the fuzzy stability for generalized derivation in fuzzy Banach algebra.

• Korean Journal of Mathematics
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• 제22권4호
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• pp.659-670
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• 2014

In this paper, we prove the Hyers-Ulam stability of homomorphisms in fuzzy Banach algebras and of derivations on fuzzy Banach algebras associated to the Cauchy-Jensen functional equation.

• 한국지능시스템학회논문지
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• 제7권2호
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• pp.3-15
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• 1997

퍼지논리를 적용하기 위해서는 두가지 과제가 이루어져야 하는데 그것은 퍼지룰의 유도와 맴버쉽함수의 결정이다. 이 과제는 어렵고 또한 시간을 요하게 된다. 본 논문에서는 문제에 적용 가능한 멤버쉽함수와 퍼지룰을 자동으로 유도하기 위한 알고리즘적 방법을 제시하고 있다. 이 알고리즘적 방법은 샘플을 구분하는 엔트로피 최소화의 원리에 입각하고 있다. 멤버쉽함수는 샘플을 연속적으로 구분하여 이루어지며 퍼지룰 또한 엔트로피 최소화 원리에 의하여 이루어진다. 퍼지룰의 유도에서는 룰 비중 또한 같이 계산된다. 결정 문제에 적용을 위한 추론법 및 방법도 논의되었다.

• Journal of Electrical Engineering and information Science
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• 제2권6호
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• pp.191-196
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• 1997

Fuzzy clustering has been playing an important role in solving many problems. Fuzzy c-Means(FCM) algorithm is most frequently used for fuzzy clustering. But some fixed point of FCM algorithm, know as Tucker's counter example, is not a reasonable solution. Moreover, FCM algorithm is impossible to perform the on-line learning since it is basically a batch learning scheme. This paper presents unsupervised learning networks as an attempt to improve shortcomings of the conventional clustering algorithm. This model integrates optimization function of FCM algorithm into unsupervised learning networks. The learning rule of the proposed scheme is a result of formal derivation based on the gradient descent procedure of a fuzzy objective function. Using the result of formal derivation, two algorithms of fuzzy cluster analysis, the batch learning version and on-line learning version, are devised. They are tested on several data sets and compared with FCM. The experimental results show that the proposed algorithms find out the reasonable solution on Tucker's counter example.

• 한국지능시스템학회논문지
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• 제11권8호
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• pp.720-725
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• 2001

비선형 미분방정식으로부터 TSK(Takagi-Sugeno-Kang) 퍼지모델을 유도한느 것은 퍼지 제어의 이론분야에서는 매우 중요한 문제이다. 본 논문에서는 off-equilibrium에서 상수항을 가지는 부분 미분 방정식을 배제시키는 방법을 제안한다. 이는 전건부의 언어적 표현이 삼각형 소속함수들을 가지는 기본적인 TSK 퍼지모델에서 체계적으로 유도되어진다. 그리고, 유도된 TSK 퍼지모델의 전건부 소속함수들은 GA(Genetic Algorithm)를 이용하여 최적화함으로써 실제 미분방적식에 근사화한다. 아울러 이상의 제안된 방법의 우수성을 모의실험을 통하여 검증한다.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2002년도 ITC-CSCC -3
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• pp.1483-1486
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• 2002

In this paper, a new scheme of iterative loaming control of a robot manipulator is presented. The proposed method uses a fuzzy sliding mode controller(FSMC), which is designed based on the similarity between the fuzzy logic control(FLC) and the sliding mode control(SMC), for the feedback. With this, the proposed method makes possible fDr fast iteration and has advantages that no linear approximation is used for the derivation of the learning law or in the stability proof Full proof of the convergence of the fuzzy sliding base learning scheme Is given.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1992년도 한국자동제어학술회의논문집(국내학술편); KOEX, Seoul; 19-21 Oct. 1992
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• pp.441-446
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• 1992

We propose a control architecture for the fuzzy logic control of robot manipulators and a rule base derivation method for a fuzzy logic controller(FLC) using a neural network. The control architecture is composed of FLC and PD(positional Derivative) controller. And a neural network is designed in consideration of the FLC's structure. After the training is finished by BP(Back Propagation) and FEL(Feedback Error Learning) method, the rule base is derived from the neural network and is reduced through two stages - smoothing, logical reduction. Also, we show the performance of the control architecture through the simulation to verify the effectiveness of our proposed method.

• 한국지능시스템학회논문지
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• 제5권4호
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• pp.87-100
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• 1995

In order to control systems which contain nonlinearities of uncertainties, control strategies must deal with the effects of them. Since most of control methods based on system mathematical models have been mainly developed focused on stability robustness against nonlinearities or uncertainties under the assumption that controlled systems are linear time invariant, they have certain amount of limitations to smartly improve the transient responses of systems disturbed by nonlinearities or uncertainties. In this paper, a nonlinear fuzzy PID control method is suggested which can stably improve the transient responses of systems disturbed by nonlinearities, as well as systems whose mathematical characteristics are not perfectly known. Although the derivation process is based on the design process similar to general fuzzy logic controller, resultant control law has analytical forms with time varying PID gains rather than linguistic forms, so that implementation using common-used versatile microprocessors cna be achieved easily and effectively in real-time control aspect.

• Journal of Advanced Marine Engineering and Technology
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• 제36권7호
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• pp.927-934
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• 2012

This paper suggests a new fuzzy PID controller with variable parameters which improves the shortage of the fuzzy PID controller with fixed parameters suggested in [9]. The derivation procedure follows the general design procedure of the fuzzy logic controller, while the resultant control law is the form of the conventional PID controller. Therefore, the suggested controller has two advantages. One is that it has only four fuzzy linguistic rules and analytical form of control laws so that the real-time control system can be implemented based on low-price microprocessors. The other is that the PID control action can always be achieved with time-varying PID controller gains only by adjusting the input and output scalers at each sampling time.

• 한국마린엔지니어링학회:학술대회논문집
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• 한국마린엔지니어링학회 2001년도 춘계학술대회 논문집
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• pp.238-242
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• 2001

In this paper, we proposed an optimal identification method of the membership functions and the numbers of fuzzy rule base for the stabilization controller of the Thermal process control system by RVEGA. Although fuzzy logic controllers and expert systems have been successfully applied in many complex industrial process, they must rely on experts knowledges. So it is difficult in determination of the linguistic state space, definition of the membership functions of each linguistic term and the derivation of the control rules. To verify the validity of this RVEGA-based fuzzy controller, Thermal process control system, with strong nonlinear dynamics, was selected for application of this algorithm and compare with PI controller, and the empirically improved fuzzy controller.