1. Department of Computer Science & Technology, North China University of Technology, Beijing 100-144, China
2. Department of Multimedia Engineering, Graduate School of Dongguk University-Seoul, Seoul 100-715, Republic of Korea
3. Department of Multimedia Engineering, Dongguk University-Seoul, Seoul 100-715, Republic of Korea
4. Division of Electronics and Electrical Engineering, Dongguk University-Seoul, Seoul 100-715, Republic of Korea
5. Agency for Defense Development, Daejeon 305-152, Republic of Korea