1. Division of Gastroenterology, Department of Internal Medicine, School of Medicine, Kyungpook National University, Daegu, Korea.
2. Division of Gastroenterology, Department of Internal Medicine, Kyungpook National University Hospital, Daegu, Korea.
3. Department of Thoracic and Cardiovascular Surgery, School of Medicine, Kyungpook National University, Daegu, Korea.
4. Department of Thoracic and Cardiovascular Surgery, Kyungpook National University Hospital, Daegu, Korea.
5. Medical Institute, Daegu, Korea.