1. Division of Respiratory and Critical Care Medicine, Department of Internal Medicine, Korea University Ansan Hospital, Ansan, Korea.
2. Division of Endocrinology, Department of Internal Medicine, Korea University Ansan Hospital, Ansan, Korea.
3. Department of Pathology, Korea University Ansan Hospital, Ansan, Korea.
4. Department of Thoracic and Cardiovascular Surgery, Korea University Ansan Hospital, Ansan, Korea.