1. College of Computer Science and Engineering, Shandong University of Science and Technology, Qingdao 266590, China
2. Department of Information Management, Chaoyang University of Technology, Taichung 41349, Taiwan
3. Department of Electronic Engineering, National Kaohsiung University of Science and Technology, Kaohsiung 80778, Taiwan
4. Graduate School of Information, Production and Systems, Waseda University, Kitakyushu 808-0135, Japan