1. Department of Otolaryngology, Head and Neck Surgery, Seoul St. Mary’s Hospital, College of Medicine, The Catholic University of Korea, Seoul, Korea
2. Department of Otolaryngology, Head and Neck Surgery, Uijeongbu St. Mary’s Hospital, College of Medicine, The Catholic University of Korea, Seoul, Korea
3. Department of Otorhinolaryngology, Head and Neck Surgery, St. Vincent’s Hospital, College of Medicine, The Catholic University of Korea, Seoul, Korea
4. Department of Otolaryngology, Head and Neck Surgery, Bucheon St. Mary’s Hospital, College of Medicine, The Catholic University of Korea, Seoul, Korea