Sino-Korea Chongqing GIS Research Center, College of Computer Science and Technology,Chongqing University of Posts and Telecommunications, Chongqing 400065, P.R China;
Sino-Korea Chongqing GIS Research Center, College of Computer Science and Technology,Chongqing University of Posts and Telecommunications, Chongqing 400065, P.R China;
Dept. of Computer Science & Engineering, Inha University,Incheon 402-751, Korea;
Dept. of Computer Science & Engineering, Inha University,Incheon 402-751, Korea;