1. Department of Otorhinolaryngology-Head and Neck Surgery, Sungkyunkwan University School of Medicine, Seoul, Korea.
2. Department of Otorhinolaryngology-Head and Neck Surgery, Inje University Ilsan Paik Hospital, Inje University School of Medicine, Goyang, Korea.
3. Department of Otorhinolaryngology-Head and Neck Surgery, Pusan National University Hospital, Busan, Korea.