function showsub_a(id)
	{
		for (i = 0;i<2;i++)
		{
			document.getElementById("tab_a"+i).className = "yk_menu_bj_02";
			document.getElementById("sub_a"+i).style.display = "none";
		}
			document.getElementById("tab_a"+id).className = "yk_menu_bj_01";
			document.getElementById("sub_a"+id).style.display = "";
	}