function Init(){
	img = new Array();
	img[0] = "img/main_img01.jpg";
	img[1] = "img/main_img02.jpg";
	img[2] = "img/main_img03.jpg";
	img[3] = "img/main_img04.jpg";
	img[4] = "img/main_img05.jpg";
	img[5] = "img/main_img06.jpg";
	n = Math.floor(Math.random()*img.length);
	
	imgName = img[n];
	mainImage = document.getElementById('main_img');
	if(mainImage != null){
		mainImage.src = imgName;
	}
}