function z_index(num)
{
 var tg_01 = document.getElementById("div_01");
 var tg_02 = document.getElementById("div_02");
 if(tg_01 && tg_02){
  if(num == 1){
   tg_01.style.zIndex = "100";
   tg_02.style.zIndex = "10";
  }else{
   tg_01.style.zIndex = "10";
   tg_02.style.zIndex = "100";
  }
 }
}