aDivision of Pulmonology, Department of Internal Medicine, Chungnam National University, Daejeon, Korea
bDepartment of Pathology, Chungnam National University School of Medicine, Daejeon, Korea
cDepartment of Thoracic and Cardiovascular Surgery, School of Medicine, Chungnam National University, Daejeon, Korea
Copyright © 2016 Korea Centers for Disease Control and Prevention. Published by Elsevier Korea LLC.
This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).