function random_mainImg() {
	mainImg = new Array();
	/*
	mainImg[0]="img/changeImg/mainImg_newyear.jpg";
	
	mainImg[0]="img/changeImg/mainImg_summer01.jpg";
	mainImg[1]="img/changeImg/mainImg_summer02.jpg";
	mainImg[2]="img/changeImg/mainImg_summer03.jpg";
	mainImg[3]="img/changeImg/mainImg_summer04.jpg";
	
	*/
	mainImg[0]="img/changeImg/mainImg_101223a.jpg";
	mainImg[1]="img/changeImg/mainImg_101223b.jpg";

	
	rand = Math.floor(Math.random()*mainImg.length);
	document.write("<p id='randomImageCon'><img src="+mainImg[rand]+" alt='' width='433' height='308'></p>");
	setFade();
	function setFade() {
		$("#randomImageCon").fadeOut("fast",function() {
				$("#randomImageCon").fadeIn(2400);
			}
		);
	}

}