1. Department of Multimedia Engineering, Dongguk University, Seoul 100-715, Republic of Korea
2. Department of Computer Science and Engineering, Seoul National University of Science and Technology, Seoul 139-743, Republic of Korea
3. Department of Computer Engineering, Sun Moon University, Asan 330-150, Republic of Korea
4. Department of Multimedia Engineering, Dankook University, Cheonan 330-714, Republic of Korea