1. Department of Thoracic and Cardiovascular Surgery, Pusan National University Hospital, Busan, Korea
2. Biomedical Research Institute, Pusan National University Hospital, Busan, Korea
3. Department of Thoracic and Cardiovascular Surgery, Pusan National University School of Medicine, Yangsan, Korea
4. Department of Thoracic and Cardiovascular Surgery, Mokpo Hankook Hospital, Mokpo, Korea