Funding for this research was provided by:
National Research Foundation of Korea (2017R1C1B5076003)
Text and Data Mining valid from 2019-07-29
Received: 16 January 2019
Accepted: 9 July 2019
First Online: 29 July 2019
Ethics approval and consent to participate
: Not applicable as secondary data was used in this study.
: Not applicable.
: The author declares that she has no competing interests.