1. School of Computer and Information Engineering, Xiamen University of Technology, Xiamen 361024, China
2. School of Information Engineering, Changchun Sci-Tech University, Changchun 130600, China
3. Department of Computer Science and Information Engineering, Chaoyang University of Technology, Taichung 41349, Taiwan
4. Computer Center, National Taipei University, New Taipei 237303, Taiwan
5. School of Software Engineering, Xiamen University of Technology, Xiamen 361024, China