Acknowledgements
The authors thank the following professors for assistance with data collection: So Hyang Chung, College of Medicine, The Catholic University of Korea, Republic of Korea; Chul Young Choi, Sungkyunkwan University School of Medicine, Republic of Korea; Byung Yi Ko, Konyang University College of Medicine, Republic of Korea; Hong Kyun Kim, School of Medicine, Kyungpook National University, Republic of Korea; Jong Suk Song, Korea University College of Medicine, Republic of Korea; Youngsub Eom, Korea University College of Medicine, Republic of Korea; Hyo Myung Kim, Korea University College of Medicine, Republic of Korea; Jong Soo Lee, Pusan National University College of Medicine, Republic of Korea; Joon Young Hyon, Seoul National University College of Medicine, Republic of Korea; Tae-Young Chung, Sungkyunkwan University School of Medicine, Republic of Korea; Mee Kum Kim, Seoul National University College of Medicine, Republic of Korea; Jae Yong Kim, University of Ulsan College of Medicine, Republic of Korea; Hyung Keun Lee, Yonsei University College of Medicine, Republic of Korea; Kyoung Yul Seo, Yonsei University College of Medicine, Republic of Korea; and Kyung Chul Yoon, Chonnam National University Medical School, Republic of Korea.