Received: 20 December 2017
Accepted: 20 April 2018
First Online: 9 May 2018
Ethics approval and consent to participate
: All procedures in our study involving human participants were performed in accordance with the ethical standards of the institutional and/or national research committee, and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards. For this type of study, formal consent is not required. Data were collected after approval from the Institutional Review Board at Yonsei University College of Medicine (No. 4–2017-0492).
: There are no competing interests in conducting the current research.
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