1. Division of Endocrinology and Metabolism, Department of Internal Medicine, Pusan National University Hospital, Busan, Korea.
2. Biomedical Research Institute, Pusan National University Hospital, Busan, Korea.
3. Department of Internal Medicine, Pusan National University School of Medicine, Yangsan, Korea.
4. Department of Biostatistics, Clinical Trial Center, Biomedical Research Institute, Pusan National University Hospital, Busan, Korea.
5. Department of Mathematics, Howard University, Washington, D.C., USA.