1. Asan Medical Center and collaborating hospitals, Department of Pulmonary and Critical Care Medicine, University of Ulsan College of Medicine, Seoul, Korea
2. Department of Pulmonary and Critical Care Medicine, Asan Medical Center, University of Ulsan College of Medicine.
3. Department of Anesthesiology and Critical Care Medicine, Yonsei University College of Medicine.
4. Department of Internal Medicine, Ulsan University Hospital, University of Ulsan College of Medicine.
5. Department of Pulmonary and Critical Care Medicine, Pusan University Hospital, Pusan National University College of Medicine, Pusan.
6. Department of Pulmonary and Critical Care Medicine, Gangneung Asan Hospital, University of Ulsan College of Medicine, Kangneung.
7. Department of Pulmonary and Critical Care Medicine, Inha University Hospital, Inha University College of Medicine, Incheon.
8. Department of Pulmonary and Critical Care Medicine, Ewha Womans University Mocdong Hospital, Ewha Womans University School of Medicine.
9. Department of Pulmonary and Critical Care Medicine, Chuncheon Sacred Heart Hospital, Hallym University School of Medicine, Chuncheon.
10. Department of Pulmonary, Allergy and Critical Care Medicine, Hallym University Sacred Heart Hospital, Hallym University School of Medicine.
11. Department of Pulmonary and Critical Care Medicine, Samsung Medical Center, Sungkyunkwan University School of Medicine.
12. Department of Anesthesiology and Critical Care Medicine, Ajou University Hospital, Ajou University School of Medicine, Suwon.