1. Institute of Applied Mechanics, National Taiwan University, 1, Sec. 4, Roosevelt Road, Taipei 106, Taiwan
2. Department of Mechanical Engineering, Chang Gung University, 259 Wen-Hwa first Road, Kwei-Shan, Taoyuan 333, Taiwan
3. Department of Mechanical Engineering, Ming Chi University of Technology, New Taipei City 243303, Taiwan
4. Proton and Radiation Therapy Center, Linkou Chang Gung Memorial Hospital, Taoyuan City 33305, Taiwan