1. Department of Otorhinolaryngology-Head and Neck Surgery, Dongguk University Gyeongju Hospital, Dongguk University College of Medicine, Gyeongju, Korea.
2. Department of Otorhinolaryngology-Head and Neck Surgery, Seoul National University Hospital, Seoul National University College of Medicine, Seoul, Korea.
3. Department of Otorhinolaryngology-Head and Neck Surgery, Kangnam Sacred Heart Hospital, Hallym University College of Medicine, Seoul, Korea.