Without 'var lightdisplay_info',   the function lightning_one works fine .

But it doesn't work together with var lightdisplay_info',

$(document).ready(function () {
 
   var int1;

  
   $('#start').click(function(){
    
      var stage_status ='initial_stage';
      var num = -1;
      start(stage_status, num);

   });//$('#start').
  
  
  
  function start(stage_status, num){
   
  
  int1 = setInterval(function() {
          //이하 영역은 계속 반복되는 영역임 
       num = num+1;
   
       lightning_one(stage_status, num);     
   
      },  
      3000
   );
 }

var lightdisplay_info = function lightning_one(stage_status, num){

         alert(num);     
   
}//function lightning_one