Funding for this research was provided by:
Mogam Science Scholarship Foundation (None)
Text and Data Mining valid from 2019-02-28
Received: 28 September 2018
Accepted: 15 February 2019
First Online: 28 February 2019
Ethics approval and consent to participate
: The data analysed in this study does not contain personal information. The institutional review board designated by the Korean Ministry of Health and Welfare waived the requirement for ethical approval (P01–201710–21-008).
: Not applicable
: The authors declare that they have no competing interests.
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