var setSameHeight = {

	main : function(){
		var targetElem = document.getElementById("main");
		if(targetElem){
			var setElem = document.getElementById("side");
			if(setElem){
				var maxHeight = targetElem.offsetHeight;
				setElem.style.height = maxHeight + "px";
			}
		}
	},

	addEvent : function(){
		try {
			window.addEventListener('load', this.main, false);
		} catch (e) {
			window.attachEvent('onload', this.main);
		}
	}
}

setSameHeight.addEvent();