Funding for this research was provided by:
National Research Foundation of Korea (NRF-2018R1A5A1025077)
Ministry of Science and ICT (2017R1A2B4004447)
Text and Data Mining valid from 2019-10-24
Received: 23 August 2019
Revised: 3 October 2019
Accepted: 8 October 2019
First Online: 24 October 2019
Compliance with ethical standards
: The authors declare that they no conflict of interest.
: This work did not involve the direct study of humans or animals.