Myung Hoon Yoo1, Jun Woo Park2, Hwan Seo Lee2, Chan Joo Yang2, Hong Ju Park2. 1. Department of Otorhinolaryngology-Head & Neck Surgery, Ansan Hospital, Korea University Medical Center, Ansan, Republic of Korea. 2. Department of Otolaryngology, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Republic of Korea.