Funding for this research was provided by:
National Research Foundation of Korea (NRF-2016H1D5A1910159, NRF-2016R1D1A3B03932709)
Text and Data Mining valid from 2018-02-05
Received: 24 September 2017
Accepted: 27 December 2017
First Online: 5 February 2018
: The authors declare that they have no competing interests.
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