1. Department of Otorhinolaryngology, Yonsei University College of Medicine, Seoul, South Korea
2. Department of Otorhinolaryngology, National Health Insurance Corporation, Insan Hospital, Kyonggi-Do, Korea
3. Brain Korea 21 Project for Medical Science, Yonsei University College of Medicine, Seoul, South Korea
4. The Airway Mucus Institute, Yonsei University College of Medicine, Seoul, South Korea