1. College of Electrical Engineering and Computer Science, National Tsing Hua University, Hsinchu, Taiwan
2. Department of Computer Science, National Tsing Hua University, Hsinchu, Taiwan
3. Department of Computer, Control, and Management Engineering, Sapienza University of Rome, Rome, Italy
4. Department of Computer Science and the Center of Innovative Incubator, National Tsing Hua University, Hsinchu, Taiwan