1. Department of Ceramic Engineering, School of Advanced Materials Engineering, Yonsei University134 Shinchon-dong, Seodaemun-gu, Seoul 120-749Korea
2. Department of Material Chemistry, Graduate School of Engineering, Kyoto UniversityKatsura, Nishikyo-ku, Kyoto 615-8510Japan
3. Research Institute of Science and Technology, Chubu University1200 Matsumoto-cho, Kasugai-shi, Aichi 487-8501Japan
4. Department of Orthopaedic Surgery, Graduate School of Medicine, Kyoto UniversityShogoin, Sakyo-ku, Kyoto 606-8507Japan