- Correspondence to Professor Eun-Cheol Park, Department of Preventive Medicine, College of Medicine, and Institute of Health Services Research, Yonsei University, 50-1 Yonsei-ro, Seodaemun-gu, Seoul 120-752, Republic of Korea;
- Received 18 January 2016
- Revision received 17 June 2016
- Accepted 7 August 2016
- Published online 22 September 2016.
If you wish to reuse any or all of this article please use the link below which will take you to the Copyright Clearance Center’s RightsLink service. You will be able to get a quick price and instant permission to reuse the content in many different ways.