1. Department of Electrical Engineering, National Dong Hwa University, Hualien 97401, Taiwan
2. Department of Education and Human Potentials Development, National Dong Hwa University, Hualien 97401, Taiwan
3. Department of Special Education, National Dong Hwa University, Hualien 97401, Taiwan
4. Department of Electrical Engineering, National Taiwan Normal University, Taipei 10610, Taiwan
5. Department of Electrical Engineering, National Sun Yat-sen University, Kaohsiung 80424, Taiwan