1Department of Social and Preventive Medicine, Hallym University College of Medicine, Chucheon, Korea
2Health Services Research Center, Hallym University, Chucheon, Korea
3Research Institute of Clinical Epidemiology, Hallym University, Chucheon, Korea
Copyright © 2017 The Korean Society for Preventive Medicine
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CONFLICT OF INTEREST
The authors have no conflicts of interest associated with the material presented in this paper.