1. Department of Biosystems & Biomaterials Science and Engineering, Seoul National University, Seoul 151-921, Republic of Korea
2. Department of Oral and Maxillofacial Surgery and Dental Research Institute, School of Dentistry, Seoul National University, Seoul 110-744, Republic of Korea
3. Tooth Bioengineering National Research Laboratory of Post BK21, School of Dentistry, Seoul National University, Seoul 110-744, Republic of Korea
4. Research Institute for Agriculture and Life Sciences, Seoul National University, Seoul 151-921, Republic of Korea