1. Department of Thoracic and Cardiovascular Surgery, Kyungpook National University Hospital, Daegu, Korea
2. Department of Thoracic and Cardiovascular Surgery, School of Medicine, Kyungpook National University, Kyungpook National University Hospital, Daegu, Korea
3. Department of Surgery, School of Medicine, Kyungpook National University, Kyungpook National University Hospital, Daegu, Korea