var load = 0;
var BtName = new Array("intro1","const","intro2","intro3","member","change","news","journal","igcc");
var BtOn   = new Array();
var BtOff  = new Array();

for(i in BtName){
   var im = BtName[i];
   BtOn[im]  = new Image();
   BtOff[im] = new Image();
   BtOn[im].src  = './shared/left_' + im + '_over.gif';
   BtOff[im].src = './shared/left_' + im + '_off.gif';
}

function ChBt(name,flag){
   if(load){
      document.images[name].src = ( flag ) ? BtOn[name].src : BtOff[name].src;
   }
}