1. Division of Pulmonary, Sleep and Critical Care Medicine, Department of Internal Medicine, Korea University Ansan Hospital, Ansan, Korea.
2. Department of Pathology, Korea University Ansan Hospital, Ansan, Korea.
3. Department of Dermatology, Korea University Ansan Hospital, Ansan, Korea.
4. Department of Thoracic and Cardiovascular Surgery, Seoul St. Mary's Hospital, The Catholic University of Korea College of Medicine, Seoul, Korea.