1. Department of Medical Engineering, Yonsei University College of Medicine, 50-1 Yonsei-ro, Seodaemun-gu, Seoul 120-752, Republic of Korea
2. Brain Korea 21 PLUS Project for Medical Science, Yonsei University, Republic of Korea
3. Department of Medicine, Yonsei University College of Medicine, Republic of Korea
4. Graduate Program in Biomedical Engineering, Yonsei University, Seoul, Republic of Korea
5. Department of Internal Medicine, Yonsei University Health System, Republic of Korea