1. Department of Otorhinolaryngology, Yonsei University College of Medicine, Seoul, Korea.
2. Department of Otorhinolaryngology-Head and Neck Surgery, College of Medicine, Konkuk University, Seoul, Korea.
3. Department of Otolaryngology, Ajou University School of Medicine, Suwon, Korea.
4. Department of Otorhinolaryngology-Head and Neck Surgery, The Catholic University of Korea, Seoul, Korea.
5. Department of Otorhinolaryngology-Head and Neck Surgery, College of Medicine, Kyungpook National University, Daegu, Korea.
6. Department of Otorhinolaryngology-Head and Neck Surgery, College of Medicine, Yeungnam University, Daegu, Korea.
7. Department of Otorhinolaryngology-Head and Neck Surgery, Korea University College of Medicine, Seoul, Korea.
8. Department of Otorhinolaryngology-Head and Neck Surgery, School of Medicine, Kyunghee University, Seoul, Korea.
9. Department of Otorhinolaryngology, Pusan National University School of Medicine, Busan, Korea.
10. Department of Otorhinolaryngology, Seoul National University College of Medicine, Seoul, Korea.
11. Department of Otorhinolaryngology-Head and Neck Surgery, Sungkyunkwan University School of Medicine, Seoul, Korea.
12. Department of Otolaryngology, Chungnam National University School of Medicine, Daejeon, Korea.