1. Department of Internal Medicine, Pusan National University School of Medicine, Busan, Korea
2. Division of Pulmonary, Sleep and Critical Care Medicine, Department of Internal Medicine, Korea University Ansan Hospital, Ansan, Korea
3. Department of Internal Medicine, School of Medicine, Ewha Womans University, Seoul, Korea
4. Department of Internal Medicine, Yonsei University Wonju College of Medicine, Wonju, Korea
5. Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine, Yonsei University College of Medicine, Yonsei University Health System, Seoul, Korea
6. College of Medicine, Chung-Ang University, Seoul, Korea
7. Department of Internal Medicine, College of Medicine, Catholic University of Daegu, Daegu, Korea
8. Division of Pulmonary, Allergy and Critical Care Medicine, Chuncheon Sacred Heart Hospital, Hallym University School of Medicine, Chuncheon, Korea
9. Division of Pulmonary, Allergy and Critical Care Medicine, Department of Medicine, Hallym Medical Center, Hallym University School of Medicine, Anyong, Korea
10. Department of Pulmonary and Critical Care Medicine, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea