Department of Computer Science and Engineering, Yuan Ze University, Taoyuan 320, Taiwan. francis@saturn.yu.edu.tw|Department of Computer Science and Engineering, Yuan Ze University, Taoyuan 320, Taiwan. francis@saturn.yu.edu.tw|Department of Computer Science and Engineering, Yuan Ze University, Taoyuan 320, Taiwan. francis@saturn.yu.edu.tw|Department of Computer Science and Engineering, Yuan Ze University, Taoyuan 320, Taiwan. francis@saturn.yu.edu.tw|Department of Computer Science and Engineering, Yuan Ze University, Taoyuan 320, Taiwan. francis@saturn.yu.edu.tw|Department of Computer Science and Engineering, Yuan Ze University, Taoyuan 320, Taiwan. francis@saturn.yu.edu.tw|Department of Computer Science and Engineering, Yuan Ze University, Taoyuan 320, Taiwan. francis@saturn.yu.edu.tw