1. Division of Pulmonary and Critical Care Medicine, Bundang Hospital, Seoul National University College of Medicine, Seoul, Republic of Korea
2. Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine, Seoul Metropolitan Government Seoul National University Boramae Medical Center, Seoul, Republic of Korea
3. Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine and Lung Institute of Medical Research Center, Seoul National University College of Medicine, Seoul, Republic of Korea