1. Department of Internal Medicine, Ewha Womans University School of Medicine, Ewha Medical Research Institute, Seoul, Republic of Korea
2. Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine and Clinical Research Center for Chronic Obstructive Airway Diseases, Seoul, Republic of Korea
3. Department of Radiology, Asan Medical Center, University of Ulsan College of Medicine, Research Institute of Radiology, Seoul, Republic of Korea
4. Department of Radiology, East West Neo Medical Center, Kyunghee University School of Medicine, Seoul, Republic of Korea
5. Department of Internal Medicine, College of Medicine, Kangwon National University, Chuncheon, Republic of Korea
6. Department of Pulmonary and Critical Care Medicine, Ajou University School of Medicine, Suwon, Republic of Korea
7. Division of Pulmonology, Department of Internal Medicine, Hanyang University Guri Hospital, Hanyang University College of Medicine, Guri, Republic of Korea
8. Department of Internal Medicine, Bundang CHA Hospital, University of Pocheon Jungmoon College of Medicine, Seongnam, Republic of Korea
9. Division of Pulmonary and Critical Care Medicine, Department of Medicine, Kangbuk Samsung Hospital, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea
10. Department of Internal Medicine, Seoul National University Bundang Hospital, Seoul National University College of Medicine, Seongnam, Republic of Korea
11. Department of Internal Medicine, Kangnam Sacred Heart Hospital, Hallym University College of Medicine, Seoul, Republic of Korea
12. Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine, Seoul National University College of Medicine, Clinical Research Institute, Seoul National University Hospital, Lung Institute, Medical Research Center, Seoul, Republic
of Korea
13. Division of Respiratory and Critical Care Medicine, Department of Internal Medicine, College of Medicine, Korea University Anam Hospital, Seoul, Republic of Korea