Sungkyunkwan University - Division of Pulmonary and Critical Care Medicine, Jeonbuk National University, affiliation not provided to SSRN, Dongguk University, Hanyang University, Chungbuk National University - Chungbuk National University Hospital, Hallym University, Konkuk University - Konkuk University Medical Center, affiliation not provided to SSRN, Jeonbuk National University - Research Institute of Clinical Medicine and Hanyang University - Division of Pulmonary Medicine and Allergy