Funding for this research was provided by:
Hanyang University (HY-2017)
Received: 27 March 2019
Accepted: 26 August 2019
First Online: 3 September 2019
Ethics approval and consent to participate
: This research was approved by the Institutional Review Board at Hanyang University (HYI-17-231-2). Data used in this paper are public and anonymous.
: Not applicable
: The authors declare that they have no competing interests.