1. Department of Mathematics and Statistics, Chonnam National University, Gwangju 61186, Korea
2. Interdisciplinary Program in IT-Bio Convergence System, Chonnam National University, Gwangju 61186, Korea
3. Asian Pear Research Institute, Chonnam National University, Gwangju 61186, Korea
4. Department of Statistics, Chonnam National University, Gwangju 61186, Korea