1. Supercomputing Center, Korea Institute of Science and Technology Information, Daejon 305-806, Korea.
2. Laboratory of Computational Biology and Bioinformatics, Institute of Health and Environment, Graduate School of Public Health, Seoul National University, Seoul 110-799, Korea.
3. Interdisciplinary Graduate Program in Bioinformatics, College of Natural Science, Seoul National University, Seoul 151-742, Korea.