function doNotload(){

 if(    (event.ctrlKey == true && (event.keyCode == 78 || event.keyCode == 82))   || (event.keyCode == 116) )   {

  event.keyCode = 0;

  event.cancelBubble = true;

  event.returnValue = false;

 }

}

document.onkeydown = doNotload;

#f5키막기