Research Professor.Biomedical Device Usability Testing Center & Department of Oral and Maxillofacial Surgery Chosun UniversityDental College. Address: Dental College 3F, No.3105, 309, Pilmun-daero, Dong-gu, Gwangju,Republic of KoreaTel: 82-62-230-6883 Fax: 82-62-608-5407Mobile: 010-8885-1412 E-mail : cream4251@hanmail.net