1. Department of Public Health Science, Graduate School, Korea University, Seoul 02841, Korea.
2. Division of Health Policy and Management, College of Health Science, Korea University, Seoul 02841, Korea.
3. Friedman School of Nutrition Science and Policy, Tufts University, Boston, MA 02111, USA.
4. School of Biosystems and Biomedical Sciences, College of Health Science, Korea University, Seoul 02841, Korea.