• Title/Summary/Keyword: linguistic fuzzy system

Search Result 193, Processing Time 0.052 seconds

Complex LMS Fuzzy Adaptive Equalizer with Decision Feedback (판정궤환이 있는 복소 LMS 퍼지 적응 등화기)

  • 이상연;김재범;이기용;이충웅
    • The Journal of Korean Institute of Communications and Information Sciences
    • /
    • v.21 no.10
    • /
    • pp.2579-2585
    • /
    • 1996
  • In this paper, a complex fuzzy adaptive decision feedback equalizer(CFADFE) based on the LMS algorithm is proposed. The propoed equalizer is based on the complex fuzzy adaptive equalizer. The CFADFE isconstructed from a set of changeable complex fuzzy IF-THEN rules, where the 'IF' part of the rule is characterized by the state from a set of changealble complex fuzzy IF-THEN rules, where the 'IF' part of the rule is characterized by the state of the desision feedback. the role of decision feedback is to reduce the computational complexity. Computer simulation of the decision feedback. The role of decision feedback is to reduce the computational complexity. Computer simulation shosw that the CFADFE notonly reduces the computational complexity but also improves the performance compared with the conventional complex fuzzy adaptive equalizers. We also show that the adaptation speed is greatly improved by incorporating some linguistic information about the channel into the equalzer. It is applied to M-ary QAM digital communication system with linear and nonlinear complex channel characteristics.

  • PDF

Fuzzy estimation of minor flank wear in face milling (면삭밀링가공시 공구 부절삭날 마모길이의 퍼지적 평가)

  • Ko, Tae Jo;Cho, Dong Woo
    • Journal of the Korean Society for Precision Engineering
    • /
    • v.12 no.4
    • /
    • pp.28-38
    • /
    • 1995
  • The flank wear at the minor cutting edge significantly affects the geometric accuracy and surface roughness in finish machining. A fuzzy estimator based on a fuzzy inference algorithm with a max-min composition rule is introduced to evaluate the minor flank wear length. The features sensitive to minor flank wear are extracted from the dispersion analysis of a time series AR model of the feed directional acceleration signal. These features, dispersions, are used for constructing linguistic rules, and then the fuzzy inferences are carried out with test data sets collected under various cutting conditions. The proposed system turns out to be effective for estimating minor flank wear length.

  • PDF

Contingency Severity Ranking Using Direct Method in Power Systems (전력계통에 있어서 직접법을 활용한 상정사고 위험순위 결정)

  • Lee, Sang-Keun
    • The Transactions of the Korean Institute of Electrical Engineers P
    • /
    • v.54 no.2
    • /
    • pp.67-72
    • /
    • 2005
  • This paper presents a method to select contingency ranking considering voltage security problems in power systems. Direct method which needs not the detailed knowledge of the post contingency voltage at each bus is used. Based on system operator's experience and knowledge, the membership functions for the MVAR mismatch and allowable voltage violation are justified describing linguistic representation with heuristic rules. Rule base is used for the computation of severity index for each contingency by fuzzy inference. Contingency ranking harmful to the system is formed by the index for security evaluation. Compared with 1P-1Q iteration, this algorithm using direct method and fuzzy inference shows higher computation speed and almost the same accuracy. The proposed method is applied to model system and KEPCO pratical system which consists of 311 buses and 609 lines to show its effectiveness.

Development of an Evaluation System for Asphalt Pavement Condition Using Fuzzy Set Logic (모호집합(模糊集合)의 논리(論理)를 이용(利用)한 연성포장(延性鋪裝)의 평가기법개발(評價技法開發))

  • Kim, Kwang Woo;Park, Je Seon
    • KSCE Journal of Civil and Environmental Engineering Research
    • /
    • v.11 no.1
    • /
    • pp.125-134
    • /
    • 1991
  • Since comprehensive examination of flexible pavement is complex, evaluation of its condition has been based on subjective judgements. Especially, qualitative measure of pavement has been based on linguistic expressions which often cause misinterpretation. There has been no such a criterion that can appropiately assess pavement status. Therefore, this study was devised to develop an approach, using fuzzy set concept, for evaluation of current and expected service conditions of flexibel pavement surface course. An example study was conducted to verify its usefulness. Since arithematic operation of fuzzy set can quantify the linguistic values and translate them into illustrative models, the results shown in the example was easy for anyone to understand.

  • PDF

A Validity Verification of Human Error Probability using a Fuzzy Model (퍼지모델을 이용한 인적오류확률의 타당성 검증)

  • Jang, Tong-Il;Lee, Yong-Hee;Lim, Hyeon-Kyo
    • Journal of the Korean Society of Safety
    • /
    • v.21 no.3 s.75
    • /
    • pp.137-142
    • /
    • 2006
  • Quantification of error possibility, in an HRA process, should be performed so that the result of the qualitative analysis can be utilized in other areas in conjunction with overall safety estimation results. And also, the quantification is an essential process to analyze the error possibility in detail and to obtain countermeasures for the errors through screening procedures. In previous studies for the quantification of error possibility, nominal values were assigned by the experts' judgements and utilized as corresponding probabilities. The values assigned by experts' experiences and judgements, however, require verifications on their reliability. In this study, the validity of new error possibility values in new MCR design was verified by using the Onisawa's model which utilizes fuzzy linguistic values to estimate human error probabilities. With the model of error probabilities are represented as analyst's estimations and natural language expression instead of numerical values. As results, the experts' estimation values about error probabilities are well agreed to the existing error probability estimation model. Thus, it was concluded that the occurrence probabilities of errors derived from the human error analysis process can be assessed by nominal values suggested in the previous studies. It is also expected that our analysis method can supplement the conventional HRA method because the nominal values are based on the consideration of various influencing factors such as PSFs.

Phonetics and Language as a formal System

  • Port, Robert F.;Leary, Adam P.
    • Lingua Humanitatis
    • /
    • v.5
    • /
    • pp.221-264
    • /
    • 2003
  • This paper takes issue with the idea of language as a 'serial-time structure' as opposed to the 'real-time event' of speech, an idea entrenched in Chomskyan model of linguistic theory. The discussion centers around the leitmotif question: Is language constructed entirely from a finite set of apriori discrete symbol types, as the 'competence vs performance' dichotomy implies\ulcorner A set of linguistic patterns examined in this study, largely with regard to phonological considerations, points to the evidence to the contrary. That is, while the patterns may be said to be linguistically distinct, they are not discretely, different, i.e. not different enough to be reliably differentiated. It is demonstrated that much of current research in phonology, including the most recent Optimality Theory, is misdirected in that it falsely presupposes a discrete universal phonetic inventory. The main thrust of the present study is that there is no sharp boundary between 'competence' defined as the formal, symbolic, discrete time domain of language and human cognition on the one hand and 'performance' as the continuous, fuzzy, real-time domain of human physiology on the other.

  • PDF

Cost Risk Analysis for Preparing Budgets of Information Security using Fuzzy AHP (정보보안 예산 수립에서 퍼지 AHP의 적용을 통한 위험 비용 분석)

  • Ryu, Si-Wook;Her, Duk-Gyu
    • Journal of the Korea Safety Management & Science
    • /
    • v.14 no.3
    • /
    • pp.119-126
    • /
    • 2012
  • Recently, the breakdown of online banking servers and the leakage of customer information give rise to much concern about the security of information systems in financial and banking companies in Korea. The enforcement of security for information system becomes much more important issue than earlier. However, the security reinforcement of information system is restricted by a budget. In addition, the activities' cost to secure information system from threatening are under uncertain circumstances and should be established by a human decision maker who is basically uncertain and vague. Thus, making the budget for information system is exposed to any extent of the risk for these reasons. First, we introduce brief fuzzy set theory and fuzzy AHP (Analytic Hierarchy Process) methodology. Then, the cost elements that comprise yearly budget are presented and the priorities among the cost elements are calculated by fuzzy AHP. The cost elements that are exposed to risk are evaluated from the both perspectives of the risk impact and risk occurrence possibility which are expressed as linguistic terms. To get information on the risk profiles-pessimistic, most likely, and optimistic-for each cost element, the evaluation is accomplished and the result is presented. At last, the budget ranges-minimum, mode, maximum-for each cost element are estimated with the consideration of the risk profiles.

Adaptive Control of Nonlinear System Using Fuzzy and Compensating Controllers (퍼지와 보상 제어기를 이용한 비선형 시스템의 적응 제어)

  • Lee, Young-Woon;Lee, Young-Seog;Seo, Bo-Hyeok
    • Proceedings of the KIEE Conference
    • /
    • 1995.11a
    • /
    • pp.210-212
    • /
    • 1995
  • Its is proposed that a stable adaptive control system composed of a fuzzy and a compensating controller, is designed to control nonlinear systems. In fuzzy and proposed compensating controller, parameters of membership functions characterizing the linguistic terms change according to some adaptive law. The adaptive law are based on the Lyapunov systhesis approach. the closed-loop system using the adaptive control structure proposed in this paper is globally stable in the sense that the Lyapunov function decreases as time goes. the following simulation shows the results.

  • PDF

Optimization of Fuzzy Neural Network based Nonlinear Process System Model using Genetic Algorithm (유전자 알고리즘을 이용한 FNNs 기반 비선형공정시스템 모델의 최적화)

  • 최재호;오성권;안태천
    • Proceedings of the Korean Institute of Intelligent Systems Conference
    • /
    • 1997.11a
    • /
    • pp.267-270
    • /
    • 1997
  • In this paper, we proposed an optimazation method using Genetic Algorithm for nonlinear system modeling. Fuzzy Neural Network(FNNs) was used as basic model of nonlinear system. FNNs was fused of Fuzzy Inference which has linguistic property and Neural Network which has learning ability and high tolerence level. This paper, We used FNNs which was proposed by Yamakawa. The FNNs was composed Simple Inference and Error Back Propagation Algorithm. To obtain optimal model, parameter of membership function, learning rate and momentum coefficient of FNNs are tuned using genetic algorithm. And we used simplex algorithm additionaly to overcome limit of genetic algorithm. For the purpose of evaluation of proposed method, we applied proposed method to traffic choice process and waste water treatment process, and then obtained more precise model than other previous optimization methods and objective model.

  • PDF

Design of fuzzy PID controller for based on PI and PD parallel structure

  • Lee, Chul-Heui;Kim, Kwang-Ho;Seo, Seon-Hak
    • 제어로봇시스템학회:학술대회논문집
    • /
    • 1995.10a
    • /
    • pp.71-74
    • /
    • 1995
  • In this paper, a new PID fuzzy controller(FC) based on parallel operation of PI and PD fuzzy control is presented. First, two fuzzy rule bases are constructed by separating the linguistic control rule for PID FC into two parts : one is e-.DELTA.e part, and the other is .DELTAL.$^{2}$e-.DELTA.e part. And then two FCs employing these rule bases indivisually are synthesized and run in parallel. The incremental control input is determined by taking weighted mean of the outputs of two FCs. The proposed PID FC improves the transient response of the system and gives better performance than the conventional PI FC.

  • PDF