1. Division of Pulmonology and Critical Care Medicine; Department of Internal Medicine; St. Vincent's Hospital; College of Medicine; The Catholic University of Korea; Suwon Korea
2. Research Institute of Medical Science; St. Vincent's Hospital; College of Medicine; The Catholic University of Korea; Suwon Korea
3. Department of Pathology; St. Vincent's Hospital; College of Medicine; The Catholic University of Korea; Suwon Korea
4. Division of Pulmonary; Critical Care and Sleep Medicine; Department of Internal Medicine; St. Paul's Hospital; College of Medicine; The Catholic University of Korea; Suwon Korea