1. Department of Family Medicine, Korea University College of Medicine, Seoul, Korea
2. Department of Statistics and Actuarial Science, Soongsil University, Seoul, Korea
3. Department of Biostatistics, College of Medicine, The Catholic University of Korea, Seoul, Korea
4. Division of Endocrinology and Metabolism, Department of Internal Medicine, Kangbuk Samsung Hospital, Sungkyunkwan University School of Medicine, Seoul, Korea