Department of Computer Science and Information Engineering, National Cheng Kung University, No 1. Da-Shueh Road, Tainan, Taiwan.|Department of Computer Science and Information Engineering, National Cheng Kung University, No 1. Da-Shueh Road, Tainan, Taiwan.|Department of Computer Science and Information Engineering, National Cheng Kung University, No 1. Da-Shueh Road, Tainan, Taiwan.|Department of Computer Science and Information Engineering, National Cheng Kung University, No 1. Da-Shueh Road, Tainan, Taiwan.