Kyung Jae Yoon, MD, PhD,
Department of Physical & Rehabilitation Medicine, Kangbuk Samsung Hospital
Sungkyunkwan University School of Medicine
29 Saemunan-ro, Jongro-ku, Seoul, Korea (zip 03181)  tel: +82-2-2001-1784  fax: +82-2-2001-1284, e-mail:yoon.kjae@gmail.com
ORCID ID: 0000-0002-2765-4309
Co-corresponding author :