1. 1The Team for Radiation Food Science and Biotechnology, Korea Atomic Energy Research Institute, P.O. Box 105, Yusong, Taejon, 305-600, Korea
2. 2Department of Home Economics, Hankyung National University, Ansung, Kyonggi-do, 456-749, Korea
3. 3Department of Pediatrics, School of Medicine, Ajou University, Suwon, Kyonggi-do, 442-749, Korea
4. 4Graduate School of Biotechnology, Korea University, Sungbuk-ku, Seoul 136-701, Korea