function slide(Id, interval, to){
	
	sliding(Id, interval, to);
	chg_bg(Id);
	
}



function sliding(Id, interval, to) {
	
		var obj = document.getElementById(Id);
		var H,step = 30;

		if (obj == null) return;
		if (to == undefined) { // user clicking
			if (obj._slideStart == true) return;
			if (obj._expand == true) {
				to = 0;
				obj.style.overflow = "hidden";
			} else {
				slide.addId(Id);
				for(var i=0; i < slide.objects.length; i++) {
					if (slide.objects[i].id != Id && slide.objects[i]._expand == true) {
						slide(slide.objects[i].id);
					}
				}

				obj.style.height = "";
				obj.style.overflow = "";
				obj.style.display = "block";
				to = obj.offsetHeight; // 이거이거
				obj.style.overflow = "hidden";
				obj.style.height = "1px";
			}
			obj._slideStart = true;
		}

		step             = ((to > 0) ? 1:-1) * step;
		interval         = ((interval==undefined)?1:interval);

		obj.style.height = (H=((H=(isNaN(H=parseInt(obj.style.height))?0:H))+step<0)?0:H+step)+"px";


		if (H <= 0) {
			obj.style.display = "none";
			obj.style.overflow = "hidden";
			obj._expand = false;
			obj._slideStart = false;
		} else if (to > 0 && H >= to) {
			obj.style.display = "block";
			obj.style.overflow = "visible";
			obj.style.height = H + "px";
			obj._expand = true;
			obj._slideStart = false;
		} else {
			setTimeout("sliding('"+Id+"' , "+interval+", "+to+");", interval);
		}
	}
	
	
	slide.objects = new Array();
	slide.addId = function(Id)
	{
		for (var i=0; i < slide.objects.length; i++) {
			if (slide.objects[i].id == Id) return true;
		}
		slide.objects[slide.objects.length] = document.getElementById(Id);
	}
	
	
	
chg_bg=function(Id)
{
	var main_slide_1=document.getElementById('main_slide_1');
	var main_slide_2=document.getElementById('main_slide_2');
	var main_slide_3=document.getElementById('main_slide_3');
	
	
	if(Id=='sub1'){
		main_slide_1.style.background='url(image/ban_car_on.gif)';
		main_slide_2.style.background='url(image/ban_group_off.jpg)';
		main_slide_3.style.background='url(image/ban_world_off.jpg)';
	}else if(Id=='sub2'){
		main_slide_1.style.background='url(image/ban_car_off.gif)';
		main_slide_2.style.background='url(image/ban_group_on.jpg)';
		main_slide_3.style.background='url(image/ban_world_off.jpg)';
	}else if(Id=='sub3'){
		main_slide_1.style.background='url(image/ban_car_off.gif)';
		main_slide_2.style.background='url(image/ban_group_off.jpg)';
		main_slide_3.style.background='url(image/ban_world_on.jpg)';	
	}
	
}