Funding for this research was provided by:
Dankook University (2016)
Text and Data Mining valid from 2018-04-04
Received: 5 July 2017
Accepted: 26 March 2018
First Online: 4 April 2018
Ethics approval and consent to participate
: The study was approved by the Institutional Review Board of Yonsei University Graduate School of Public Health (2–1,040,939-AB-N-01-2015-305). All participants gave written informed consent to participate.
: Not applicable.
: The authors declare that they have no competing interests.
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