1. Respiratory Division, Department of Internal Medicine, Soonchunhyang University, School of Medicine, Gumi Hospital, Korea.
2. Department of Internal Medicine, Seoul National University Bundang Hospital, Seoul National University College of Medicine, Seongnam, Korea.
3. Respiratory Division, Department of Internal Medicine Soonchunhyang University, School of Medicine, Seoul Hospital, Seoul, Korea.
4. Department of Internal Medicine, Jeonbuk National University Medical School, Jeonju, Korea.
5. Department of Internal Medicine, Seoul National University Hospital, Seoul National University College of Medicine, Seoul, Korea.