1. Department of Critical Care Medicine, Department of Medicine, Samsung Medical Center, Sungkyunkwan University School of Medicine
2. Department of Thoracic and Cardiovascular Surgery, Samsung Medical Center, Sungkyunkwan University School of Medicine
3. Division of Pulmonary and Critical Care Medicine, Department of Medicine, Samsung Medical Center, Sungkyunkwan University School of Medicine
4. Division of Cardiology, Samsung Medical Center, Sungkyunkwan University School of Medicine
5. Biostatistics and Clinical Epidemiology Center, Samsung Medical Center, Sungkyunkwan University School of Medicine
6. Department of Mathematical and Statistical Sciences, University of Alberta