1. Department of Internal Medicine, Yondong Severance Hospital, Yonsei University College of Medicine, Yongdong P.O. Box 1217, Seoul 135-720, Korea.
2. Department of Internal Medicine, Yonsei University College of Medicine, Seoul, Korea.
3. Department of Mechanical Engineering, Soongsil University, Seoul, Korea.
4. Department of Mechanical and Control System Engineering, Handong University, Seoul, Korea.
5. Department of Mechanical and Aerospace Engineering, Seoul National University, Seoul, Korea.
6. Department of Mechanical Engineering Mechanical Engineering & Design, Hankuk Aviation University, Seoul, Korea.