function OnLoad()
{
  var y;

  // ÆäÀÌÁö ·Îµù½Ã Æ÷Áö¼Ç
		top_button.style.pixelTop=document.body.scrollTop + document.body.clientHeight - top_button.offsetHeight - 100
	   top_button.style.visibility = "visible";  

  // initializing UI update timer
  CheckUIElements();

  return true;
}

function CheckUIElements()
{
  var yMenuFrom, yMenuTo, yButtonFrom, yButtonTo, yOffset, timeoutNextCheck;

			yMenuFrom   = parseInt (top_button.style.top, 10);
			//yMenuTo     = document.body.scrollTop + 520; // À§ÂÊ À§Ä¡
			yMenuTo     = document.body.scrollTop + document.body.clientHeight - top_button.offsetHeight - 100

  timeoutNextCheck = 500;

  if ( Math.abs (yButtonFrom - (yMenuTo + 152)) < 6 && yButtonTo < yButtonFrom ) {
	   setTimeout ("CheckUIElements()", timeoutNextCheck);
  return;
  }

  if ( yButtonFrom != yButtonTo ) {
	   yOffset = Math.ceil( Math.abs( yButtonTo - yButtonFrom ) / 10 );
	   if ( yButtonTo < yButtonFrom )
			yOffset = -yOffset;
	   timeoutNextCheck = 10;
  }
  if ( yMenuFrom != yMenuTo ) {
	   yOffset = Math.ceil( Math.abs( yMenuTo - yMenuFrom ) / 20 );
	   if ( yMenuTo < yMenuFrom )
			yOffset = -yOffset;

				 top_button.style.top = parseInt (top_button.style.top, 10) + yOffset;

	   timeoutNextCheck = 10;
	   }

  setTimeout ("CheckUIElements()", timeoutNextCheck);
}
OnLoad();