winow.open할때 새창으로 폼 값 submit

<script language='javascript'>
     function paycheck(){
      var win = window.open('about:blank','page_name','width=500,height=500');
      var frm =document.frm;
      frm.action = '/payment/payreq.php';
      frm.target ="page_name";
      frm.method ="post";
      frm.submit();
     }
</script>