if (document.images) {

var snavi_1 = new Image()
snavi_1.src = "images/about_sub01_off.jpg";
var snavi_1_2 = new Image()
snavi_1_2.src = "images/about_sub01_on.jpg";

var snavi_2 = new Image()
snavi_2.src = "images/about_sub02_off.jpg";
var snavi_2_2 = new Image()
snavi_2_2.src = "images/about_sub02_on.jpg";

var snavi_3 = new Image()
snavi_3.src = "images/about_sub03_off.jpg";
var snavi_3_2 = new Image()
snavi_3_2.src = "images/about_sub03_on.jpg";

var snavi_4 = new Image()
snavi_4.src = "images/about_sub04_off.jpg";
var snavi_4_2 = new Image()
snavi_4_2.src = "images/about_sub04_on.jpg";

}

function act(imgName) {
	if (document.images)
	document[imgName].src = eval(imgName + '_2.src')
}

function inact(imgName) {
	if (document.images)
	document[imgName].src = eval(imgName + '.src')
}