1 Department of Internal Medicine, Chung-Ang University Hospital, Chung-Ang University College of Medicine, Dongjak-gu, Seoul 06973, South Korea.
2 Department of Internal Medicine, Chung-Ang University Hospital, Chung-Ang University College of Medicine, Dongjak-gu, Seoul 06973, South Korea. Electronic address: wykim81@cau.ac.kr.