Fix: history board monthday

src/game/lib/string_util.js

@@ -2,7 +2,11 @@ function StringUtil() {
 }
 
 StringUtil.printMonthDay = function(date) {
+	console.log(date);
 	let dateTime = new Date(date);
+	console.log(dateTime);
+	console.log("month : " + dateTime.getMonth());
+	console.log("date : " + dateTime.getDate());
 	return (dateTime.getMonth() + 1) + "월 " + dateTime.getDate() + "일";
 }