Funding for this research was provided by:
National Research Foundation of Korea (NRF-2018R1D1A1A02050292, NRF-2017R1D1A1B03034137)
Text and Data Mining valid from 2019-02-28
First Online: 28 February 2019
Compliance with ethical standards
: The authors declare that they have no conflict of interest. The research grant is the grant supported by the university.
: 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.