1. Department of Otorhinolaryngology–Head and Neck Surgery, Seoul National University Boramae Medical Center, Seoul National University College of Medicine, Seoul, South Korea
2. Department of Otorhinolaryngology–Head and Neck Surgery, Konkuk University Medical Center, Seoul, South Korea
3. Medical Research Collaborating Center, Seoul National University Boramae Medical Center, Seoul National University College of Medicine, Seoul, South Korea