1. Department of Pulmonary and Critical Care Medicine; Asan Medical Centre, University of Ulsan College of Medicine; Seoul Republic of Korea
2. Department of Clinical Epidemiology and Biostatistics; Asan Medical Centre, University of Ulsan College of Medicine; Seoul Republic of Korea
3. Department of Radiology and Research Institute of Radiology; Asan Medical Centre, University of Ulsan College of Medicine; Seoul Republic of Korea