1. Department of Internal Medicine, Chonnam National University Medical School, Chonnam National University Hospital, Gwangju, South Korea
2. Division of Pulmonary and Critical Care Medicine, University of Ulsan College of Medicine, Asan Medical Center, Seoul, South Korea
3. Department of Chest Medicine, Masan National Tuberculosis Hospital, Masan, South Korea
4. Department of Internal Medicine, Pusan National University Yangsan Hospital, Yangsan, South Korea
5. Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine, Seoul National University College of Medicine, Seoul, South Korea