1. Department of Dentistry, Graduate School, Kyungpook National University, Daegu 700-412, Republic of Korea
2. Center for Research Facilities, Yeungnam University, Gyeongsan 712-749, Republic of Korea
3. Institute for Biomaterials Research and Development, Kyungpook National University, Daegu 700-412, Republic of Korea
4. Korea Textile Development Institute, Daegu 703-712, Republic of Korea