Funding for this research was provided by:
National Research Foundation of Korea (NRF-2015M3C7A1031969)
Text and Data Mining valid from 2019-08-14
First Online: 14 August 2019
Compliance with ethical standards
: The authors declare that they have no conflict of interest.
: All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards.
: Informed consent was obtained from all individual participants included in the study.