1. Department of Otolaryngology-Head and Neck Surgery, Seoul St. Mary’s Hospital, College of Medicine, The Catholic University of Korea, Seoul, Republic of Korea and Department of Otorhinolaryngology-Head and Neck Surgery, Gangneung Asan Hospital, College of Medicine University of Ulsan, Gangneung, Republic of Korea;
2. Department of Otolaryngology-Head and Neck Surgery, Busan Paik Hospital, College of Medicine, Inje University, Busan, Republic of Korea;
3. Department of Otolaryngology-Head and Neck Surgery, Yeouido St. Mary’s Hospital, College of Medicine, The Catholic University of Korea, Seoul, Republic of Korea