$(function(){
    var len = 2;
    var arr = new Array(
        "common/img/home/bnr_top_01.jpg", 
        "common/img/home/bnr_top_01.jpg"
        );
    var rand = Math.floor( Math.random() * len);
    $("p#directorBnr img").attr("src",arr[rand]);
});