1. Departments of Internal Medicine; Asan Medical Center; University of Ulsan College of Medicine; Seoul Korea
2. Division of Endocrinology & Metabolism; Department of Medicine, Thyroid Center; Samsung Medical Center, Sungkyunkwan University School of Medicine; Seoul Korea
3. Biostatistics and Clinical Epidemiology Center; Samsung Medical Center; Seoul Korea
4. Department of Biostatistics and Bioinformatics; Duke University; Durham NC USA