1. Institute of Electro-Optical Engineering, Chang Gung University, Kweisan, Taoyuan 333, Taiwan R.O.C.
2. Department of Dentistry, Chang Gung Medical Center, Kweisan, Taoyuan 333, Taiwan R.O.C.
3. Department of Applied Mathematics, National Dong Hwa University, Hualien 974, Taiwan R.O.C.