1. Brain Korea 21 Project for Medical Science, Yonsei University, Seoul 120-752, Republic of Korea
2. Division of Computer and Electronic Systems Engineering, Hankuk University of Foreign Studies, Yongin 449-791, Republic of Korea
3. Division of Cardiology, Department of Internal Medicine, Severance Cardiovascular Hospital, Yonsei University College of Medicine, Seoul 120-752, Republic of Korea
4. Cardiovascular Research Institute, Yonsei University College of Medicine, Seoul 120-752, Republic of Korea