1. School of Biomedical Engineering; Korea University; Seoul 136-701 Korea
2. Department of Bio-convergence Engineering; Korea University; Seoul 136-701 Korea
3. Department of Materials Science and Engineering; Seoul National University; Seoul 151-742 Korea
4. Biomedical Implant Convergence Research Center; Advanced Institutes of Convergence Technology; Suwon-si Gyeonggi-do 443-270 Korea