function link1(){
var navi = document.getElementById("p01");
var img = navi.getElementsByTagName("img");
for(var i=0; i < img.length; i++){
img[i].setAttribute("src","images/bt_01_on.gif");

}

var naviother = document.getElementById("p02");
var imgother = naviother.getElementsByTagName("img");
for(var i=0; i < imgother.length; i++){
imgother[i].setAttribute("src","images/bt_02_off.gif");
}
}

function link2(){
var navi = document.getElementById("p01");
var img = navi.getElementsByTagName("img");
for(var i=0; i < img.length; i++){
img[i].setAttribute("src","images/bt_01_off.gif");
}

var naviother = document.getElementById("p02");
var imgother = naviother.getElementsByTagName("img");
for(var i=0; i < imgother.length; i++){
imgother[i].setAttribute("src","images/bt_02_on.gif");
}
}