1. School of Mechanical and Aerospace Engineering, Building 301, Room 1205, Seoul National University, San 56-1, Shinlim-dong, Kwanak-ku, Seoul 151-742, Korea
2. School of Mechanical and Aerospace Engineering, Building 301, Room 1205, Seoul National University, San 56-1, Shinlim-dong, Kwanak-ku, Seoul 151-742, Korea;
3. Agency for Defence Development, Yuseong PO Box 35, Daejeon 305-600, Korea