Funding for this research was provided by:
Chosun University (2015-206644-02)
Received: 3 July 2017
Accepted: 2 February 2018
First Online: 14 February 2018
Ethics approval and consent to participate
: This study was approved by the institutional review board of the Chosun University. Informed consent in written form was obtained from all participants. Data were collected anonymously.
: Not applicable
: The authors declare that they have no competing interests.
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