fadein 효과를 사용한 2번째 예제입니다.
       
     <ul id="scroll">
              <li id="main_img_img0" style="position:absolute;z-index:10;top:0px;left:0;width:100%;"><img src="images/common/visual1.jpg" title="" alt=""></li>
              <li id="main_img_img2" style="position:absolute;z-index:11;top:0px;left:0;width:100%;display:none;"><img src="images/common/visual2.jpg" title="" alt=""></li>
              <li id="main_img_img3" style="position:absolute;z-index:11;top:0px;left:0;width:100%;display:none;"><img src="images/common/visual3.jpg" title="" alt=""></li>
            </ul>

  <script type="text/javascript">
  //<![CDATA[

  var s = null;

  var j = 1;
  var times = 4000;
  function TiVis(){
     clearInterval(s);

     ButtonClear();

     if( j == 0 ){ $("#main_img_img0").css({zIndex : 13});$("#main_img_img2").hide(); $("#main_img_img_tab1").attr('src','images/common/main_img_on.gif');$("#main_img_img0").fadeIn(1000);}
     if( j == 1 ){ $("#main_img_img0").css({zIndex : 10});$("#main_img_img0").hide(); $("#main_img_img3").hide(); $("#main_img_img_tab2").attr('src','images/common/main_img_on.gif');$("#main_img_img2").fadeIn(1000);}
     if( j == 2 ){ $("#main_img_img_tab3").attr('src','images/common/main_img_on.gif'); $("#main_img_img3").fadeIn(1000); }

      j++;
      if(j==3) {
        j=0;
      }
      s = setInterval( "TiVis()", times );
    }

window.onload = function(){
  /*$("#main_img_img0").css({zIndex : 10});
  $("#main_img_img2").css({zIndex : 11});
  $("#main_img_img3").css({zIndex : 12});*/
  $("#main_img_img_tab1").css({cursor:'pointer'});
  $("#main_img_img_tab2").css({cursor:'pointer'});
  $("#main_img_img_tab3").css({cursor:'pointer'});
  s = setInterval( "TiVis()", times );
}

function ButtonClear(){
     $("#main_img_img_tab1").attr('src','images/common/main_img_off.gif');
     $("#main_img_img_tab2").attr('src','images/common/main_img_off.gif');
     $("#main_img_img_tab3").attr('src','images/common/main_img_off.gif');
}
$(document).ready(function(){
  $(".number_tab img").click(function(){
    j = Number($(this).val());

     if( j == 1 ){ $("#main_img_img0").css({zIndex : 13});$("#main_img_img2").hide();}
     if( j == 2 ){ $("#main_img_img0").css({zIndex : 10});$("#main_img_img0").hide(); $("#main_img_img3").hide();}

    ButtonClear();
    TiVis();
  });
});
  //]]>
  </script>