function slideBtn()
{
	var beforePosi, afterPosi, moveCount, interval;
	
	beforePosi = parseInt (sideBtn.style.top, 10) - 150; //óÀ½ ½ÃÀÛ À§Ä¡

	afterPosi = document.body.scrollTop;

	interval = 100; // À̵¿ üũ ½Ã°£

	if (beforePosi != afterPosi)
	{
  	  moveCount = Math.ceil(Math.abs(afterPosi - beforePosi) / 10); // À̵¿ °£°Ý
	  if (afterPosi < beforePosi) moveCount = -moveCount;

	  sideBtn.style.top = parseInt (sideBtn.style.top, 10) + moveCount;
	  
	  interval = 1 + moveCount/10;
	}

	setTimeout("slideBtn()", interval);
}