1. Department of Otorhinolaryngology–Head and Neck SurgeryKonkuk University College of Medicine Seoul Republic of Korea
2. Department of Head and Neck SurgeryUCLA School of Medicine Los Angeles California U.S.A.
3. Department of Biostatistics, Biomedicine & Health SciencesCatholic University College of Medicine Seoul Republic of Korea
4. Department of Otorhinolaryngology–Head and Neck SurgeryGuro Hospital, Korea University College of Medicine Seoul Republic of Korea