1. Division of Pulmonary, Allergy and Critical Care Medicine, Department of Internal Medicine, Hallym University Sacred Heart Hospital, Anyang, Korea.
2. Lung Research Institute of Hallym University College of Medicine, Chuncheon, Korea.
3. Division of Pulmonary, Allergy and Critical Care Medicine, Department of Internal Medicine, Hallym University Kangdong Sacred Heart Hospital, Seoul, Korea.
4. Department of Internal Medicine, Konkuk University School of Medicine, Seoul, Korea.