1. Department of Internal Medicine, Ulsan University Hospital, University of Ulsan College of Medicine, Ulsan, Korea.
2. Department of General Surgery, Ulsan University Hospital, University of Ulsan College of Medicine, Ulsan, Korea.
3. Department of Otolaryngology, Ulsan University Hospital, University of Ulsan College of Medicine, Ulsan, Korea.
4. Biomedical Research Center, Ulsan University Hospital, University of Ulsan College of Medicine, Ulsan, Korea.