1. Ph.D. Candidate, Dept. of Aerospace Engineering, Pusan National Univ., Busan 609-735, Republic of Korea.
2. Associate Professor, Industrial Liaison Innovation Center, Pusan National Univ., Busan 609-735, Republic of Korea.
3. Professor, Dept. of Aerospace Engineering, Pusan National Univ., Busan 609-735, Republic of Korea (corresponding author).