Update flask

@@ -117,7 +117,7 @@ and is wrapped around the whole page content, except for the footer in this exam
 				이름: <input type="text" name="student_name"><br><br>
 				<input type="file" id="fileloader" name="file" onchange="loadFile(event)" autocomplete="off" accept="image/jpeg" required disabled>
 				<div>
-					<img id="imagefile" style="display:none;">
+					<img id="imagefile">
 					<canvas id="preview"></canvas>
 				</div>
 				<input id="sender" type="button" onclick="submit" value="등록" disabled>