1. Division of Allergy and Respiratory Medicine, Soonchunhyang University Bucheon Hospital, Bucheon, Korea.
2. Department of Pulmonary and Critical Care Medicine, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.
3. Department of Internal Medicine, Yonsei University College of Medicine, Seoul, Korea.
4. Department of Internal Medicine, Inha University College of Medicine, Incheon, Korea.
5. Division of Allergy and Respiratory Medicine, Soonchunhyang University Seoul Hospital, Seoul, Korea.