Funding for this research was provided by:
Bio & Medical Technology Development Program of the National Research Foundation (NRF) funded by the Korean government, MISP (No. 2016M3A9B694241)
National Research Foundation of Korea (NRF) grant funded by the Korea government (NRF-2017R1C1B5018142)
Article History
Received: 28 September 2018
Accepted: 16 April 2019
First Online: 2 May 2019
Ethics approval and consent to participate
: The Korea Centers for Disease Control and Prevention (KCDC) Institutional Review Board approved the survey protocol, and all participants provided written informed consent (approval nos. 2007-02CON-04-P, 2008-04EXP-01-C, and 2009-01CON-03-2C).
: Not applicable.
: The authors declare that they have no competing interests.
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