1. Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine, Mokdong HospitalCollege of Medicine, Ewha Womans University Seoul Republic of Korea
2. Division of Pulmonary and Critical Care Medicine, Department of Internal MedicineSeoul Hospital, College of Medicine, Ewha Womans University Seoul Republic of Korea
3. Bronchoscopy unitMokdong Hospital, Ewha Womans University Seoul Republic of Korea