1. Department of Internal Medicine, College of Medicine, The Catholic University of Korea, Seoul 06591, Korea.
2. Division of Endocrinology and Metabolism, Department of Internal Medicine, Bucheon St. Mary's Hospital, College of Medicine, The Catholic University of Korea, Kyunggi-do 14647, Korea.
3. Division of Endocrinology and Metabolism, Department of Internal Medicine, Yeouido St. Mary's Hospital, College of Medicine, The Catholic University of Korea, Seoul 06591, Korea.
4. Division of Endocrinology and Metabolism, Department of Internal Medicine, Seoul St. Mary's Hospital, College of Medicine, The Catholic University of Korea, Seoul 07345, Korea.
5. Coulter Department of Biomedical Engineering at Georgia Tech and Emory University, Atlanta, GA 30322, USA.