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