1. Division of Cardiology, Department of Internal Medicine and Catholic Research Institute for Intractable Cardiovascular Disease, College of Medicine, The Catholic University of Korea, Seoul, Korea.
2. Division of Cardiology, Department of Internal Medicine, Heart Vascular Stroke Institute, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea.
3. School of Mechanical Engineering, University of Ulsan, Ulsan, Korea.