function format_YYYYMMDD(object) {
	
	    var num, year, month, day;
	    num=object.value;
	    
	    while (num.search("-") != -1){	
			    num = num.replace("-","");
		}
		
		if (isNaN(num)) {        
		    window.alert("Date Format Error");
		    object.focus();
		    return "";
		}

	    if( num != 0 && num.length == 8 ) {

	        year = num.substring( 0, 4 );
	        month = num.substring( 4, 6 );  
	        day = num.substring(6);
	        if(isValidDay(year,month,day)==false) {
		        num = "";
		        window.alert("Date Format Error");
	    	    object.focus();
	        	return "";
			}        		
	        num = year + "-" + month + "-" + day;
	        
	    } else {
	        num = "";
	        window.alert("Date Format Error");
	        object.focus();
	        return "";
	    }	
	    return num;
	}
	function dateCheck(obj){
		if (obj.value == "") return;
		retVal = format_YYYYMMDD(obj);
		obj.value = retVal;
	}
	function isValidDay(yyyy, mm, dd) {
	    var m = parseInt(mm,10) - 1;
	    var d = parseInt(dd,10);
	
	    var end = new Array(31,28,31,30,31,30,31,31,30,31,30,31);
	    if ((yyyy % 4 == 0 && yyyy % 100 != 0) || yyyy % 400 == 0) {
	        end[1] = 29;
	    }
	
	    return (d >= 1 && d <= end[m]);
	}