1. College of Computer Science and Technology, Qingdao University, Qingdao, China
2. Department of Geriatrics, The Affiliated Hospital of Qingdao University, Qingdao, China
3. Dawning International Information Industry Company Ltd., Qingdao, China
4. Faculty of Biomedical and Rehabilitation Engineering, University of Health and Rehabilitation Sciences, Qingdao, China