http://miniwini.com/miniwinis/bbs/index.php?bid=qna&mode=read&id=11292===================================================================
새창 띄울 소스
===================================================================
<script>
function getCookie(name) {
        var nameOfCookie = name + "=";
        var x = 0;
        while (x <= document.cookie.length)
        {
                var y = (x+nameOfCookie.length);
                if (document.cookie.substring( x, y ) == nameOfCookie)
                {
                        if ((endOfCookie=document.cookie.indexOf(";",y)) == -1)
                        {
                                endOfCookie = document.cookie.length;
                        }
                        return unescape(document.cookie.substring(y,endOfCookie));
                }

                x = document.cookie.indexOf(" ",x) + 1;
                if (x == 0)
                {
                        break;
                }
        }
        return "";
}

function openWin() {
        var openedOnce = getCookie('fallout');
        if (openedOnce) {
                // return false;
                alert("뷁!");
        }
        else {
                window.open('window.html','','width=500, height=300');
        }
}

</script>

<body onload=openWin()>
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새창 띄워진 소스
===================================================================
<script>
function setCookie(name,value,expiredays) {
        var todayDate = new Date();
        todayDate.setDate(todayDate.getDate() + expiredays);
        document.cookie = name + "=" + escape(value) + "; path=/; expires=" + todayDate.toGMTString() + ";"
}
</script>

<body onload=setCookie('fallout','ABC',1) onunload=setCookie('fallout','',-1)>

Window Loaded.