Department of Otolaryngology-Head & Neck Surgery, College of Medicine, The Catholic University of Korea, Seoul, Korea
2.Department of Obstetrics & Gynecology, College of Medicine, The Catholic University of Korea, Seoul, Korea
3.Department of Otolaryngology-HNS, College of Medicine, The Catholic University of Korea, Seoul, Korea
4.Department of Otolaryngology-Head and Neck Surgery, College of Medicine, The Catholic University of Korea, Seoul, Korea
5.Department of Otolaryngology Head Neck Surgery, Catholic University Medical Center, Seoul, Korea