1. Department of Surgery, School of Medicine, Kyungpook National University, Daegu, Republic of Korea
2. Department of Surgery, School of Medicine, Keimyung University, Daegu, Republic of Korea
3. Department of Surgery, Goo Hospital, Daegu, Republic of Korea
4. Department of Surgery, Daegu Fatima Hospital, Daegu, Republic of Korea
5. Department of Surgery, School of Medicine, Catholic University of Daegu, Daegu, Republic of Korea
6. Department of Surgery, College of Medicine, Yeungnam University, Daegu, Republic of Korea
7. Department of Otolaryngology-Head and Neck Surgery, Johns Hopkins University School of Medicine, Baltimore, MD, USA