1. Samsung Advanced Institute of Technology, Samsung Electronics, Yongin, Gyeonggi 446-712, Republic of Korea
2. Department of Computer Science and Engineering, IT Convergence Engineering, and Department of Creative IT Excellence Engineering, Pohang University of Science and Technology, Pohang 790-784, Korea
3. Department of Computer Science and Engineering, Texas A&M University, College Station, TX 77843, U.S.A.