1. Division of Pulmonary, Allergy, and Critical Care Medicine, Department of Internal Medicine, Pusan National University School of Medicine, Busan, Korea.
2. Department of Trauma Surgery, Pusan National University School of Medicine, Busan, Korea.
3. Department of Thoracic and Cardiovascular Surgery, Pusan National University School of Medicine, Busan, Korea.
4. Department of Internal Medicine, Wonkwang University Sanbon Hospital, Gunpo, Korea.