function set_img(place) {
	dtToday = new Date();
	intToday = dtToday.getMonth()+1;
	strUrl = "img/backicon/";
	if ( intToday < 4 ) {
		strUrl = strUrl + "3/";
	} else if ( intToday < 9 ) {
		strUrl = strUrl + "1/";
	} else {
		strUrl = strUrl + "2/";
	}
	switch ( place ) {
	case "left":
		document.body.background = strUrl + "left.jpg";
		document.body.style.backgroundRepeat = "repeat-y";
		document.body.style.backgroundPosition = "100% 0%";
		break;
	case "right":
		document.body.background = strUrl + "right.jpg";
		document.body.style.backgroundRepeat = "repeat-y";
		document.body.style.backgroundPosition = "0% 0%";
		break;
	case "head":
		document.body.background = strUrl + "head.jpg";
		document.body.style.backgroundRepeat = "no-repeat";
		break;
	}
}
function set_icon() {
	dtToday = new Date();
	intToday = dtToday.getMonth()+1;
	strUrl = "http://kyouwa.ashi-s.ed.jp/img/backicon/";
	for( i= 0 ; i < document.images.length; i++ ) {
		if ( document.images[i].name == "btn" ) {
			if ( intToday < 4 ) {
				document.images[i].src = strUrl + "3/btn.gif";
			} else if ( intToday < 9 ) {
				document.images[i].src = strUrl + "1/btn.gif";
			} else {
				document.images[i].src = strUrl + "2/btn.gif";
			}
		}
	}
}