Funding for this research was provided by:
This research was supported by the 2017 scientific promotion program funded by Jeju National University
Text and Data Mining valid from 2018-07-09
Received: 29 December 2017
Accepted: 6 April 2018
First Online: 9 July 2018
Ethics approval and consent to participate
: Not applicable.
: The authors declare that they have no competing interests.
: Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.