1. Agency for Defense Development, P.O. Box 35, Yusung-gu, Taejon, 305-600 Korea
2. Department of Mechanical Engineering, ME3033, Korea Advanced Institute of Science and Technology, 373-1 Kusong-dong, Yusung-gu, Taejon, 305-701, South Korea,
3. Department of Mechanical Engineering, ME3033, Korea Advanced Institute of Science and Technology, 373-1 Kusong-dong, Yusung-gu, Taejon, 305-701, South Korea