1. a Center for Biomaterials, Medical Engineering Institute, Korea Institute of Science and Technology , 39-1 Hawolgok, Seongbuk , Seoul , 136-791 , South Korea
2. b Department of Oral Biology , School of Dentistry, Kyung Hee University , Seoul , 130-701 , South Korea
3. c Department of Plastic Surgery , College of Medicine, The Catholic University of Korea , Seoul , 137-701 , South Korea