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Article History

Received: 17 May 2019

Accepted: 21 May 2019

First Online: 1 June 2019

Compliance with Ethical Standards

:

: The authors declare that they have no conflict of interest.

: All procedures performed in this study were in accordance with the ethical standards of the institutional research committee (Korea University Institutional Review Board Approval no. 1040548-KU-IRB-16-178-A-1) and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards.

: Informed consent was obtained from all individual participants included in the study.