1. Department of Otorhinolaryngology–Head and Neck Surgery, College of Medicine, Soonchunhyang University, Bucheon Hospital, Bucheon, Korea
2. Department of Otorhinolaryngology–Head and Neck Surgery, College of Medicine, Hanyang University, Seoul, Korea
3. Department of Obstetrics and Gynecology, College of Medicine, Konkuk University, Seoul, Korea
4. Department of Head and Neck Surgery, UCLA School of Medicine, Los Angeles, California, USA
5. Department of Otorhinolaryngology–Head and Neck Surgery, College of Medicine, Konkuk University, Seoul, Korea