. 2015 Mar 30;68(2):136–140. doi: 10.4097/kjae.2015.68.2.136
Copyright © the Korean Society of Anesthesiologists, 2015
This is an open-access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/3.0/), which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.