1. Kongju National University,Div. of Info. & Comm. Eng,Cheonan,Korea
2. Pukyong National University,Dep. of Info. and Comm. Engineering,Busan,Korea
3. Electronics and Telecomm. Research Institute,Mobile Core Network Research Section,Daejeon,Korea
4. Kyung Hee University,Dep. of Electronic Eng,Yongin-si,Korea
5. Kongju National University,Dep. of Computer Science and Eng,Cheonan,Korea
6. Kyungnam University,School of Computer Science and Eng,Changwon,Korea