1. School of Mechanical and Aerospace Engineering, Seoul National University, 314-308 Dae-Hak Dong Gwan-Ak Gu, Seoul 151-744, Korea
2. National R&D Coordination and Evaluation Center, Korea Institute of Science and Technology Evaluation and Planning (KISTEP), Dong Won Industrial Building 275 Yang-Jae Dong Seo-Cho Gu, Seoul 137-130, Korea
3. School of Mechanical and Aerospace Engineering, Seoul National University, 301-1507 Dae-Hak Dong Gwan-Ak Gu, Seoul 151-744, Korea