[1] Konkuk Univ, Coll Med, Dept Otorhinolaryngol Head & Neck Surg, Seoul, South Korea
[2] Yonsei Univ, Coll Med, Dept Anat, Seoul 120752, South Korea
[3] Yonsei Univ, Coll Med, Dept Otorhinolaryngol, Seoul 120752, South Korea
[4] Yonsei Univ, Coll Med, Airway Mucus Inst, Seoul 120752, South Korea
[5] Yonsei Univ, Coll Med, Project Med Sci BK21, Seoul 120752, South Korea