1. Division of Pulmonary and Critical Care Medicine, Department of Medicine, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, South Korea
2. Department of Internal Medicine, Dongsan Hospital, Keimyung University School of Medicine, Daegu, South Korea
3. Division of Pulmonary, Allergy, and Critical Care Medicine, Hallym University Sacred Heart Hospital, Hallym University College of Medicine, Anyang, South Korea
4. Department of Internal Medicine, Kangbuk Samsung Hospital, Sungkyunkwan University School of Medicine, Seoul, South Korea
5. Department of Internal Medicine, College of Medicine, Kangwon National University, Chuncheon, South Korea
6. Department of Internal Medicine, Dongguk University Ilsan Hospital, Dongguk University College of Medicine, Gyeongju, South Korea
7. Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine and Lung Institute, Seoul National University College of Medicine, Seoul, South Korea
8. Department of Pulmonary and Critical Care Medicine, Dongguk University Gyeongju Hospital, Gyeongju, South Korea
9. Department of Internal Medicine, Eulji Hospital, Eulji University School of Medicine, Seoul, South Korea
10. Department of Internal Medicine, Chung-Ang University College of Medicine, Seoul, South Korea
11. Department of Internal Medicine, Konyang University Hospital, Daejeon, South Korea
12. Department of Multimedia, Seoul Women's University, Seoul, South Korea