1. Department of Oral Physiology, School of Dentistry, Kyungpook National University, Daegu 700-412, Republic of Korea
2. Department of Quality Control, Koatech, Pyeongtaek, Gyeonggi-do 451-864, Republic of Korea
3. Department of Physiology, College of Korean Medicine, Daegu Haany University, Daegu 706-060, Republic of Korea