Funding for this research was provided by:
National Research Foundation (NRF-2018R1A5A2024418, NRF-2016R1A2B3006584)
Text and Data Mining valid from 2019-03-12
Received: 1 November 2018
Accepted: 8 March 2019
First Online: 12 March 2019
Compliance with ethical standards
: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be constructed as a potential conflict of interest.