[1] Yonsei University College of Medicine,Division of Pulmonology, Department of Internal Medicine, Institute of Chest Disease
[2] CHA University,Department of Internal Medicine, CHA Bundang Medical Center
[3] Hanyang University Guri Hospital,Division of Pulmonary and Critical Care Medicine
[4] Hanyang University College of Medicine,Biostatistics Collaboration Unit
[5] Yonsei University College of Medicine,Department of Pulmonary and Critical Care Medicine and Clinical Research Center for Chronic Obstructive Airway Diseases, Asan Medical Center
[6] University of Ulsan College of Medicine,undefined