1. School of Life Sciences and Biotechnology, Korea University, Seoul 136-713, Korea
2. Department of Statistics, Korea University, Seoul 136-701, Korea
3. Department of Herbal Crop Research, National Institute of Horticultural and Herbal Science, Rural Development Administration, Eumseong 369-873, Korea
4. College of Pharmacy, Chung-Ang University, Seoul 156-756, Korea
5. College of Pharmacy, Chungbuk National University, Cheongju 361-763, Korea