1. Department of Otorhinolaryngology—Head and Neck Surgery, Chung-Ang University College of Medicine, Seoul, Korea
2. Department of Otorhinolaryngology, Yonsei University College of Medicine, Seoul, Korea
3. The Airway Mucus Institute, Yonsei University College of Medicine, Seoul, Korea
4. Research Center for Human Natural Defense System, Yonsei University College of Medicine, Seoul, Korea