1. Department of Otolaryngology-Head and Neck Surgery, Korea Cancer Center Hospital, Seoul, Korea.
2. Department of Otolaryngology-Head and Neck Surgery, Dongin Medical Center, Gangneung, Korea.
3. Department of Otolaryngology-Head and Neck Surgery, Konkuk University School of Medicine, Seoul, Korea.
4. Department of Otolaryngology-Head and Neck Surgery, Seoul Paik Hospital, Inje University College of Medicine, Seoul, Korea.