Funding for this research was provided by:
the National Rsearch Foundation of Korea Grant funded by the Korean Government (NRF-2017S1A5B8066096)
Text and Data Mining valid from 2018-02-09
Received: 18 December 2017
Accepted: 20 January 2018
First Online: 9 February 2018
Compliance with ethical standards
: This work was supported by the National Rsearch Foundation of Korea Grant funded by the Korean Government (NRF-2017S1A5B8066096).
: 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.