1. Department of Otorhinolaryngology-Head and Neck Surgery, Yonsei University Wonju College of Medicine, Ilsanro, Wonju, Korea;
2. Department of Otorhinolaryngology-Head and Neck Surgery, Seoul National University, Gwanak-gu, Seoul, Korea;
3. Department of Otorhinolaryngology, Yonsei University College of Medicine, Seodaemun-gu, Seoul, Korea;
4. Department of Otorhinolaryngology-Head and Neck Surgery, Soonchunhyang University College of Medicine, South Korea