1. School of Mechanical and Aerospace Engineering, Seoul National University, Seoul 151-742, Republic of Korea
2. Samsung Electro-Mechanics, Suwon-si, Gyeonggi-do 443-743, Republic of Korea
3. Construction Equipment System Research Department, Hyundai Heavy Industries, Ulsan 682-792, Republic of Korea
4. Department of Aerospace Engineering, Pusan National University, Busan 609-735, Republic of Korea
5. School of Mechanical and Aerospace Engineering and Institute of Advanced Aerospace Technology, Seoul National University, Seoul 151-742, Republic of Korea