〔1〕Department of Mathematics, National Taiwan Normal University, Taipei, Taiwan, R.O.C.
〔2〕Research Center for Applied Sciences, Academia Sinica, Taipei, Taiwan, R.O.C.
〔3〕Department of Civil Engineering, National Taiwan University, Taipei, Taiwan, R.O.C.
〔4〕Department of Materials and Mineral Resources Engineering, National Taipei University of Technology, Taipei, Taiwan, R.O.C.
* Corresponding Author. E-mail :
cykuo06@gate.sinica.edu.tw