1. Department of Otorhinolaryngology, Yonsei University Wonju College of Medicine, Wonju, South Korea;
2. Department of Otolaryngology, Yonsei University College of Medicine, Seoul, South Korea;
3. Research Center for Human Natural Defense System, Yonsei University College of Medicine, Seoul, South Korea;
4. The Airway Mucus Institute, Yonsei University College of Medicine, Seoul, South Korea