International Journal of Fuzzy Systems ADVISORY BOARD Z. Zenn Bien Wei-Ling Chiang Bor-Sen Chen Toshio Fukuda Han-Pang Huang Korea Advanced Institute of Science andTechnology, Korea National Central University, Taiwan National Tsing Hua University, Taiwan Nagoya University, Japan National Taiwan University, Taiwan James M. Keller Laszlo T. Koczy Tsu-Tian Lee H.T. Nguyen Enrique Ruspini University of Missouri-Columbia, USA Budapest University of Technology and Economics, Hungary National Taipei University of Technology, Taiwan New Mexico State University, USA SRI International, USA Jeffrey J. P. Tsai Gwo-Hshiung Tzeng Hsiao-Fan Wang Ronald Yager John Yen University of Illinois at Chicago, USA National Chiao-Tung University, Taiwan National Tsing Hua University, Taiwan Iona College, USA Pennsylvania State University, USA EDITORIAL BOARD Honorary Editor: Lotfi A. Zadeh Editor-in-Chief: Wen-June Wang Managing Editor: Wei-Yen Wang Area Editors: Dept. of Electrical Engineering and Computer Science, Computer Science Division, University of California, 729 Soda Hall # 1776, Berkeley, CA 94720-1776, USA e-mail: zadeh@cs.Berkeley.EDU Department of Electrical Engineering National Central University, Taiwan e-mail: wjwang@ee.ncu.edu.tw Department of Applied Electronics Technology, National Taiwan Normal University, Taiwan e-mail: wywang@ntnu.edu.tw National Taiwan University of Science and Technology, Taiwan e-mail: su@orion.ee.ntust.edu.tw Shun-Feng Su C.W. Tao National Ilan University, Taiwan e-mail: cwtao@mail.niu.edu.tw Associate Editors Bao Rong Chang Wen-Jer. Chang Shyi-Ming Chen Jyh-Horng Chou Hung-Yuan Chung Meng Joo Er National University of Kaohsiung, Taiwan National Taiwan Ocean University, Taiwan National Taiwan University of Science and Technology, Taiwan National Kaohsiung First University of Science and Technology, Taiwan National Central University, Taiwan Nanyang Technology University, Singapore János Fodor Robert Full´er Kaoru Hirota T.P. Hong Chen-Chien Hsu Yo-Ping Huang Obuda University, Hungary A° bo Akademi University, Finland Tokyo Institute of Technology, Japan National University of Kaohsiung, Taiwan National Taiwan Normal University, Taiwan National Taipei University of Technology, Taiwan Yaochu Jin Chia-Feng Juang H.K. Lam Chang-Shing Lee Pei-Jun Lee T.H.S. Li Univ. of Surrey, UK National Chung Hsing University, Taiwan King’s College London, UK National University of Tainan, Taiwan National Chi Nan University, Taiwan National Cheng Kung University, Taiwan C. L. Lin C. M. Lin Chin-Teng Lin Honghai Liu Kyung Chan Min Witold Pedrycz National Chung Hsing University, Taiwan Yuan-Ze University, Taiwan National Chiao-Tung University, Taiwan Univ. of Portsmouth, UK Yonsei University, Korea University of Alberta, Canada Henri Prade Mu-Chun Su Shun-Feng Su C.W. Tao J. S. Taur Shaocheng Tong Université Paul Sabatier, France National Central University, Taiwan National Taiwan University of Science and Technology, Taiwan National Ilan University, Taiwan National Chung Hsing University, Taiwan Liaoning University of Technology, China Ching-Chih Tsai Shian-Shyong Tseng Rong-Jyue Wang Ching-Chang Wong Peitsang Wu Chen-Tung Chen National Chung Hsing University, Taiwan National Chiao-Tung University, Taiwan National Formosa University, Taiwan Tamkang University, Taiwan I-Shou University, Taiwan National United University, Taiwan Ping-Feng Pai National Chi Nan University, Taiwan Luis Martínez López University of Jaén, Spain Cengiz kahraman Istanbul Technical University, Turkey English Consultant An-Chien Huang Webmaster I-Hsum Lee Lee-Ming Institute of Technology e-mail: ijfs@orion.ee.ntust.edu.tw or i-hsum@orion.ee.ntust.edu.tw PUBLISHER Taiwan Fuzzy Systems Association Society President: S.-F. Su Professor of National Taiwan University of Science and Technology, Taipei, Taiwan Tel: +886-2-27376704 Email: su@orion.ee.ntust.edu.tw URL: http://www.ijfs.org.tw/ The International Journal of Fuzzy Systems (IJFS) is published quarterly each year by the Taiwan Fuzzy Systems Association (TFSA). Institutional subscription rate: US$140 annually; individual annual subscription rate: US$50 for nonmembers, US$25 for members (including postage). Note that another US$ 100 is needed if the express mail is required.