1. Department of Otolaryngology–Head and Neck Surgery, Kyung Hee University School of Medicine, Seoul, Korea
2. Department of Otolaryngology–Head and Neck Surgery, Kyung Hee University Hospital at Gangdong, Seoul, Korea
3. Department of Otorhinolaryngology–Head and Neck Surgery, Kangdong Sacred Heart Hospital, Hallym University School of Medicine, Seoul, Korea