1. Department of Otorhinolaryngology-Head and Neck Surgery, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul 06351, Republic of Korea
2. Department of Otorhinolaryngology-Head and Neck Surgery, Jeju National University Hospital, Jeju National University College of Medicine, Jeju 63243, Republic of Korea
3. Department of Otorhinolaryngology-Head and Neck Surgery, Myongi Hospital, Hanyang University College of Medicine, Ilsan 10475, Republic of Korea
4. Department of Otorhinolaryngology-Head and Neck Surgery, Kyungpook National University Chilgok Hospital, Kyungpook National University School of Medicine, Daegu 41944, Republic of Korea