• Journal of the Korean Society for Precision Engineering
• /
• v.8 no.3
• /
• pp.27-43
• /
• 1991

연소 가공은 고품질 고정도를 필요로 하는 경우 매우 유효한 가공방법이지만 그 공정이 많은 Parameter에 의해 구성되기 때문에 동일한 조건에서도 정량적인 평가가 어려우므로 작업현장 에서는 과학적 원리와 공학적 지식 보다는 숙련자의 경험과 기능에 의존하고 있는 실정이다. 본 연구에서는 이와 같은 국면에 대처한 문제 해결을 위해 Computer가 인간사고에 근접 할 수 있도록 Fuzzy 이론과 Default 이론을 도입하고 전문가의 이론적 지식과 숙련자의 감각적 지식을 적극 수용 하여 연소용 Expert system (최적 가공 조건의 설정 System과 Trouble shooting system)을 개발하였다. 또한 연소 가공 Data의 불확실한 애매성을 효과적으로 이용 할 수 있도록 Fuzzy 가능성이론에 의해 가공 Datad을 회귀 분석하여 실가공 Data base에 축적시켜 재활용토록 설계하었으며 개발된 본 System 의 실행 결과 그 활용성이 높음을 입증하였다.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.60 no.7
• /
• pp.1314-1323
• /
• 2011

The maintenance of generating units is implicitly related with power system reliability and has a tremendous bearing on the operation of the power system. A technique using a fuzzy search method which is based on fuzzy multi-criteria function has been proposed for GMS (generator maintenance scheduling) in order to consider multi-objective function. In this study, a new technique using combined fuzzy set theory and genetic algorithm(GA) is proposed for generator maintenance scheduling. The genetic algorithm(GA) is expected to make up for that fuzzy search method might search the local solution. The effectiveness of the proposed approach is demonstrated by the simulation results on a practical size test systems.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 1999.11a
• /
• pp.282-286
• /
• 1999

This paper describes the implementation of a fuzzy temperature measuring & control system to control the water temperature in plant. This system consisted of mainly three parts; sensing part, control part that includes a control algorithms introduced the fuzzy theory, and actuating part. The control algorithms of control part are utilized a look-up table method and firmware technique using one-chip microprocessor(89C52). For evaluating the performance of a fuzzy control system, the experiment results of a fuzzy controller are compared with these of a conventional PID controller which provides an auto-tuning function. The experiment results show that the proposed controller has a good control performance and is robust to external disturbance.

• Transactions of the Korean Society of Mechanical Engineers
• /
• v.18 no.1
• /
• pp.113-120
• /
• 1994

The dynamic characteristics of turning processes are complex, non-linear and time-varying. Consequently, the conventional techniques based on crisp mathematical model may not guarantee cutting force regulation. This paper presents a fuzzy controller which can regulate cutting force in turning process under varying cutting conditions. The fuzzy control rules are extablished from operator experience and expert knowledge about the process dynamics. Regulation which increases productivity and tool life is achieved by adjusting feedrate according to the variation of cutting conditions. The performance of the proposed controller is evaluated by cutting experiments in the converted conventional lathe. The results of experiments show that the proposed fuzzy controller has a good cutting force regulation capability in spite of the variation of cutting conditions.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2006.05a
• /
• pp.788-791
• /
• 2006

Fuzzy theory has been used effectively to control the nonlinear system since Mamdani successively adopted fuzzy theory in the steam-engine control problem in 1973. Truckbacker-upper control problem originally proposed by Nguyen and Widrow become a standard highly nonlinear control problem. In this paper, we designed adaptive fuzzy membership functions for speed control as well as steering control. In other words, an adaptive fuzzy control system for truck backer-upper problem useful for practical adaptation is proposed. Experimental results by simulations prove the effectiveness of the proposed system.

• Honam Mathematical Journal
• /
• v.38 no.4
• /
• pp.783-794
• /
• 2016

The notions of hesitant fuzzy left (resp., right, bi-, quasi-) ideals are introduced, and several properties are investigated. Relations between a hesitant fuzzy left (resp., right) ideal,a hesitant fuzzy bi-ideal and a hesitant fuzzy quasi-ideal are discussed. Characterizations of hesitant fuzzy left (resp., right, bi-, quasi-) ideals are considered.

• Journal of the Korean Institute of Intelligent Systems
• /
• v.22 no.3
• /
• pp.394-398
• /
• 2012

Based on the theory of a bipolar fuzzy set, the notion of a bipolar fuzzy subring/ideal of a Near ring is introduced and related properties are investigated. Characterizations of a bipolar fuzzy subnear ring and a bipolar fuzzy ideal in near ring are established. Relations between a bipolar fuzzy ideal and a level cut are discussed. Using bipolar fuzzy ideals, we discuss characterizations of Noetherian Near ring.

• Journal of applied mathematics & informatics
• /
• v.40 no.5_6
• /
• pp.1043-1052
• /
• 2022

Our goal in this paper is to propose the advancement proposed by Alsina, Klement and other researchers in the area of fuzzy logic applied to the area of fuzzy graph theory. We introduce the notion of complete Hamacher fuzzy graphs and the notion of balanced Hamacher fuzzy graphs and discuss their properties. Moreover, several operations on these fuzzy graphs are explored via the complete notion.

• Journal of Information Processing Systems
• /
• v.15 no.3
• /
• pp.655-669
• /
• 2019

Supplier evaluation is of great significance in green supply chain management. Influenced by factors such as economic globalization, sustainable development, a holistic index framework is difficult to establish in green supply chain. Furthermore, the initial index values of candidate suppliers are often characterized by uncertainty and incompleteness and the index weight is variable. To solve these problems, an index framework is established after comprehensive consideration of the major factors. Then an adaptive weight D-S theory model is put forward, and a fuzzy-rough-sets-AHP method is proposed to solve the adaptive weight in the index framework. The case study and the comparison with TOPSIS show that the adaptive weight D-S theory model in this paper is feasible and effective.

• International Journal of Quality Innovation
• /
• v.5 no.1
• /
• pp.52-67
• /
• 2004

Successful implementation of statistical process control techniques requires for operational definitions and precise measurements. Nevertheless, very often analysts can dispose of process data available only by linguistic terms, that would be a waste to neglect just because of their intrinsic vagueness. Thus a hybrid approach, which integrates fuzzy set theory and common statistical tools, sounds useful in order to improve effectiveness of statistical process control in such a case. In this work, a fuzzy approach is adopted to manage linguistic information, and the use of a Chi-squared control chart is proposed to monitor process performance.