1. Associate Professor, Faculty of Mechanical and Aerospace Engineering, Sejong Univ., Seoul 143-747, Korea (corresponding author).
2. Graduate Student, School of Mechanical and Aerospace Engineering, National Creative Research Initiatives Center for Multiscale Design, and Advanced Automobile Research Center, Seoul National Univ., Seoul 151-742, Korea.
3. Professor, School of Mechanical and Aerospace Engineering, National Creative Research Initiatives Center for Multiscale Design, and Advanced Automobile Research Center, Seoul National Univ., Seoul 151-742, Korea.