var image_url = ['/images/wwob_blank.jpg','/images/wwob_bw.jpg','/images/wwob_bw_sp.jpg','/images/wwob_bw_ru.jpg','/images/wwob_bw_te.jpg','/images/wwob_bw_po.jpg'];
var image_object = new Array();
for(var i=0; i<=image_url.length-1; i++) {
	image_object[i] = new Image();
	image_object[i].src = image_url[i];
}
var logo = 1;
function changeLogo() {
	if (logo == image_url.length-1) {
		logo = 0;
	}
	document.getElementById('logo').src = image_url[0];
	setTimeout("document.getElementById('logo').src = image_url[logo]",1000)
	logo++;
}