if (document.images) {
	idx1on = new Image();
	idx1on.src = "parts/btn_profile.jpg";
	idx1off = new Image();
	idx1off.src = "parts/btn_profile.jpg";
	idx2on = new Image();
	idx2on.src = "parts/btn_lesson.jpg";
	idx2off = new Image();
	idx2off.src = "parts/btn_lesson.jpg";
	idx3on = new Image();
	idx3on.src = "parts/btn_party.jpg";
	idx3off = new Image();
	idx3off.src = "parts/btn_party.jpg";
	idx4on = new Image();
	idx4on.src = "parts/btn_medatest.jpg";
	idx4off = new Image();
	idx4off.src = "parts/btn_medatest.jpg";
	idx5on = new Image();
	idx5on.src = "parts/btn_studiomap.jpg";
	idx5off = new Image();
	idx5off.src = "parts/btn_studiomap.jpg";
	idx6on = new Image();
	idx6on.src = "parts/btn_bbs.jpg";
	idx6off = new Image();
	idx6off.src = "parts/btn_bbs.jpg";
}
function imgOn(imgName) {
	if (document.images) {
		document[imgName].src=eval(imgName+"on.src");
	}
}
function imgOff(imgName) {
	if (document.images) {
		document[imgName].src=eval(imgName+"off.src");
	}
}