1. Department of Computer Science and Information Engineering, National Taiwan University, Taipei, Taiwan (R.O.C)
2. Department of Computer Science, National Yang Ming Chiao Tung University, Hsinchu, Taiwan (R.O.C)
3. Institute of Information Science, Academia Sinica, Taipei, Taiwan (R.O.C)
4. Hong Kong and the Department of Computer Science and Information Engineering, College of Engineering, City University of Hong Kong, National Taiwan University, Taipei, Taiwan (R.O.C)