function update_frame(myoptions)
{
        destination = myoptions[myoptions.selectedIndex].value;
        if (destination == "null")
        {
                return true;
        }
        window.open(destination, '_top');
        myoptions.selectedIndex = 0;

        return true;
}
//ÀÔ·Â Æû Á¦¾î ½ºÅ©¸³Æ®---------------------------------------------------------
function field_check(field_name, field_size, message) {
	if(field_name.value.length < field_size) {
		alert(message + "¶õÀÌ ÀԷµÇÁö ¾Ê¾Ò°Å³ª À߸ø ÀԷµǾú½À´Ï´Ù.")
		field_name.focus()
		return(true)
	} else return(false)
}

function number_check(field_name, message) {
	for(i=0; i < field_name.value.length; i++){
		if(field_name.value.charCodeAt(i) < 48 || field_name.value.charCodeAt(i) > 57) {
			alert(message + "¶õÀº ¼ýÀÚ¸¸ ÀÔ·Â °¡´ÉÇÕ´Ï´Ù.")
			field_name.focus()
			return(true)
		} else return(false)
	}
}

function email_check(field_name, message) {
	if(field_name.value.indexOf("@") < 1 || field_name.value.indexOf(".") < 3) {
		alert(message + "¶õÀÇ À̸ÞÀÏÁÖ¼Ò°¡ ¿Ã¹Ù¸£Áö ¾Ê½À´Ï´Ù.");
		filed_name.focus()
		return(true)
	} else return(false)
}
function errMsg(thisfield, msg) {
	alert (msg)
	thisfield.focus()
}

// --------------------------- Á¡ÇÁ ¸Þ´º ½ÃÀÛ ------------------------------------------------

function link_site_goto(sel, targetstr){
  var index = sel.selectedIndex;

  if (sel.options[index].value != '') {
     if (targetstr == 'blank') {
       window.open(sel.options[index].value, 'win1');
     } else {
       self.location = sel.options[index].value;
     }
  }
}
//------------------------------ Á¡ÇÁ ¸Þ´º ³¡ ---------------------------------------------------



<!-- ===== ·Ñ¿À¹ö ½ºÅ©¸³Æ® ===== -->
function MM_swapImgRestore() { //v3.0
  var i,x,a=document.MM_sr; for(i=0;a&&i<a.length&&(x=a[i])&&x.oSrc;i++) x.src=x.oSrc;
}

function MM_preloadImages() { //v3.0
  var d=document; if(d.images){ if(!d.MM_p) d.MM_p=new Array();
    var i,j=d.MM_p.length,a=MM_preloadImages.arguments; for(i=0; i<a.length; i++)
    if (a[i].indexOf("#")!=0){ d.MM_p[j]=new Image; d.MM_p[j++].src=a[i];}}
}

function MM_findObj(n, d) { //v4.01
  var p,i,x;  if(!d) d=document; if((p=n.indexOf("?"))>0&&parent.frames.length) {
    d=parent.frames[n.substring(p+1)].document; n=n.substring(0,p);}
  if(!(x=d[n])&&d.all) x=d.all[n]; for (i=0;!x&&i<d.forms.length;i++) x=d.forms[i][n];
  for(i=0;!x&&d.layers&&i<d.layers.length;i++) x=MM_findObj(n,d.layers[i].document);
  if(!x && d.getElementById) x=d.getElementById(n); return x;
}

function MM_swapImage() { //v3.0
  var i,j=0,x,a=MM_swapImage.arguments; document.MM_sr=new Array; for(i=0;i<(a.length-2);i+=3)
   if ((x=MM_findObj(a[i]))!=null){document.MM_sr[j++]=x; if(!x.oSrc) x.oSrc=x.src; x.src=a[i+2];}
}
<!-- ===== ·Ñ¿À¹ö ½ºÅ©¸³Æ® ===== -->

<!-- ===== ·¹ÀÌ¾î ½ºÅ©¸³Æ® ===== -->
function MM_reloadPage(init) {  //reloads the window if Nav4 resized
  if (init==true) with (navigator) {if ((appName=="Netscape")&&(parseInt(appVersion)==4)) {
    document.MM_pgW=innerWidth; document.MM_pgH=innerHeight; onresize=MM_reloadPage; }}
  else if (innerWidth!=document.MM_pgW || innerHeight!=document.MM_pgH) location.reload();
}
MM_reloadPage(true);

function MM_showHideLayers() { //v6.0
  var i,p,v,obj,args=MM_showHideLayers.arguments;
  for (i=0; i<(args.length-2); i+=3) if ((obj=MM_findObj(args[i]))!=null) { v=args[i+2];
    if (obj.style) { obj=obj.style; v=(v=='show')?'visible':(v=='hide')?'hidden':v; }
    obj.visibility=v; }
}
<!-- ===== ·¹ÀÌ¾î ½ºÅ©¸³Æ® ===== -->