1. Department of Otorhinolaryngology–Head and Neck Surgery, Dankook University Hospital, Cheonan, South Korea
2. Department of Otorhinolaryngology–Head & Neck Surgery, Asan Medical Center, University of Ulsan College of Medicine, Seoul, South Korea
3. Department of Otorhinolaryngology–Head and Neck Surgery, Soonchunhyang University College of Medicine, Bucheon, South Korea
4. Department of Otorhinolaryngology–Head and Neck Surgery, Pusan National University School of Medicine, Pusan National University Hospital, Busan, South Korea
5. Department of Otorhinolaryngology–Head and Neck Surgery, Pusan National University School of Medicine, Pusan National University Yangsan Hospital, Yangsan, South Korea
6. Department of Otorhinolaryngology–Head and Neck Surgery, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, South Korea
7. Department of Otorhinolaryngology, Gyeongsang National University Changwon Hospital, College of medicine, Gyeongsang National University, Changwon, South Korea
8. Department of Otorhinolaryngology, Yonsei University College of Medicine, Seoul, South Korea
9. Department of Otolaryngology–Head and Neck Surgery, Chonnam National University Medical School, Gwangju, South Korea