if (document.images) {
	//bg
	btn_01_bg_on = new Image();
	btn_01_bg_on.src = "images/btn_01_bg_on.gif";
	btn_01_bg_off = new Image();
	btn_01_bg_off.src = "images/btn_01_bg_off.gif";
	btn_02_bg_on = new Image();
	btn_02_bg_on.src = "images/btn_02_bg_on.gif";
	btn_02_bg_off = new Image();
	btn_02_bg_off.src = "images/btn_02_bg_off.gif";
	btn_03_bg_on = new Image();
	btn_03_bg_on.src = "images/btn_03_bg_on.gif";
	btn_03_bg_off = new Image();
	btn_03_bg_off.src = "images/btn_03_bg_off.gif";
	btn_04_bg_on = new Image();
	btn_04_bg_on.src = "images/btn_04_bg_on.gif";
	btn_04_bg_off = new Image();
	btn_04_bg_off.src = "images/btn_04_bg_off.gif";
	btn_05_bg_on = new Image();
	btn_05_bg_on.src = "images/btn_05_bg_on.gif";
	btn_05_bg_off = new Image();
	btn_05_bg_off.src = "images/btn_05_bg_off.gif";
	// en
	btn_01_en_on = new Image();
	btn_01_en_on.src = "images/btn_01_en_on.gif";
	btn_01_en_off = new Image();
	btn_01_en_off.src = "images/btn_01_en_off.gif";
	btn_02_en_on = new Image();
	btn_02_en_on.src = "images/btn_02_en_on.gif";
	btn_02_en_off = new Image();
	btn_02_en_off.src = "images/btn_02_en_off.gif";
	btn_03_en_on = new Image();
	btn_03_en_on.src = "images/btn_03_en_on.gif";
	btn_03_en_off = new Image();
	btn_03_en_off.src = "images/btn_03_en_off.gif";
	btn_04_en_on = new Image();
	btn_04_en_on.src = "images/btn_04_en_on.gif";
	btn_04_en_off = new Image();
	btn_04_en_off.src = "images/btn_04_en_off.gif";
	btn_05_en_on = new Image();
	btn_05_en_on.src = "images/btn_05_en_on.gif";
	btn_05_en_off = new Image();
	btn_05_en_off.src = "images/btn_05_en_off.gif";
}

function turnon(imageName) {
	if (document.images) {
		document[imageName].src = eval(imageName + "_on.src");
	}
}

function turnoff(imageName) {
	if (document.images) {
		document[imageName].src = eval(imageName + "_off.src");
	}
}