1. a Department of Computer Application Engineering , Far East University , Tainan, 744, Taiwan, R.O.C.
2. b Department of Mechanical Engineering , R.O.C. Military Academy , Kaohsiung, 830, Taiwan, R.O.C.
3. c Department of Engineering Science , National Cheng Kung University , Tainan, 701, Taiwan, R.O.C.
4. d Department of Engineering Science , National Cheng Kung University , Tainan, 701, Taiwan, R.O.C. Phone: Fax: E-mail: