1. Department of Rehabilitation Medicine, Jeju University Hospital, University of Jeju College of Medicine, Jeju 690-767, Korea.
2. Department of Physical Medicine and Rehabilitation, Myongji Hospital, Kwandong University College of Medicine, Goyang 412-270, Korea.
3. Department of Thoracic and Cardiovascular Surgery, Jeju University Hospital, University of Jeju College of Medicine, Jeju 690-767, Korea.
4. Department of Thoracic and Cardiovascular Surgery, Inha University School of Medicine, Incheon 402-751, Korea.