/**
* Floater.js
* »ç¿ë¹ý
window.setInterval("heartBeat()", 500);
#floater {
	position:absolute; 
	left:875px; 
	top:400px; 
	width:40px; 
	height:260px; 
}
<div id="floater" _top="400"></div>
*/
var _floater_lastScrollY = 0;
var _floater_diffY = 0;
var _floater_otop = false;
var _floater_id = 'floater';
function heartBeat()
{
	if (!_floater_otop) _floater_otop = parseInt(window.document.getElementById(_floater_id).getAttribute("_top"));

	if(document.all)	_floater_diffY = document.body.scrollTop;
	else				_floater_diffY = window.pageYOffset;

	if(_floater_diffY != _floater_lastScrollY && (_floater_diffY > _floater_otop || _floater_lastScrollY > _floater_otop))
	{
		var percent = 0.15 * (_floater_diffY - _floater_lastScrollY);

		if (percent > 0)	percent = Math.ceil(percent);
		else				percent = Math.floor(percent);

		if(document.all)	
		{
			var look = document.all.floater.style.pixelTop + percent;
			if (look < _floater_otop) look = _floater_otop;
			document.all.floater.style.pixelTop = look;
			_floater_lastScrollY = look;
		}
		else
		{
			var tmp = window.document.getElementById(_floater_id).style.top;
			var top_value = parseInt(tmp.substr(0, tmp.length -2));
			top_value = top_value + percent;
			window.document.getElementById(_floater_id).style.top = top_value;
			_floater_lastScrollY = top_value;
		}
	}
}