diff --git a/hwe/c_double.php b/hwe/c_double.php
index dec5ac2f..a6e4c385 100644
--- a/hwe/c_double.php
+++ b/hwe/c_double.php
@@ -44,11 +44,7 @@ $comStr = EncodeCommand($fourth, $third, $double, $command);
 
 // 건국
 if($command == 46) {
-    $name = htmlspecialchars($name);
-    $name = StringUtil::removeSpecialCharacter($name);
-    $name = StringUtil::subStringForWidth($name, 0, 18);
-    $name = WebUtil::htmlPurify($name);
-    $name = StringUtil::textStrip($name);
+    $name = StringUtil::neutralize($name);
     if($name == "") { $name = "무명"; }
 
     $db->update('general', [
@@ -72,11 +68,7 @@ if($command == 53) {
     $me = MYDB_fetch_array($result);
 
     if($me['level'] >= 5) {
-        $nationname = htmlspecialchars($nationname);
-        $nationname = StringUtil::removeSpecialCharacter($nationname);
-        $nationname = StringUtil::subStringForWidth($nationname, 0, 18);
-        $nationname = WebUtil::htmlPurify($nationname);
-        $nationname = StringUtil::textStrip($nationname);
+        $nationname = StringUtil::neutralize($nationname, 18);
         if($nationname == "") { $nationname = "무명"; }
         
         $db->update('general', [
@@ -102,11 +94,7 @@ if($command == 61) {
     $me = MYDB_fetch_array($result);
 
     if($me['level'] >= 5) {
-        $note = htmlspecialchars($note);
-        $note = StringUtil::removeSpecialCharacter($note);
-        $note = StringUtil::subStringForWidth($note, 0, 90);
-        $note = WebUtil::htmlPurify($note);
-        $note = StringUtil::textStrip($note);
+        $note = StringUtil::neutralize($note, 90);
 
         $query = "update diplomacy set reserved='{$note}' where me='{$me['nation']}' and you='$double'";
         MYDB_query($query, $connect) or Error(__LINE__.MYDB_error($connect),"");
diff --git a/src/sammo/StringUtil.php b/src/sammo/StringUtil.php
index 31f2f3a8..dfb6c363 100644
--- a/src/sammo/StringUtil.php
+++ b/src/sammo/StringUtil.php
@@ -143,13 +143,30 @@ class StringUtil
         return static::padString($str, $maxsize, $ch, 0);
     }
 
-    public static function escapeTag($str)
+    public static function escapeTag(?string $str):string
     {
+        if(!$str){
+            return '';
+        }
         $str = htmlspecialchars($str);
         $str = str_replace(["\r\n", "\r", "\n"], '<br>', $str);
         return $str;
     }
 
+    public static function neutralize(?string $str, ?int $maxLen = null){
+        if(!$str){
+            return '';
+        }
+        if($maxLen && $maxLen > 0){
+            $str = StringUtil::subStringForWidth($str, 0, $maxLen);
+        }
+        $str = htmlspecialchars($str);
+        $str = StringUtil::removeSpecialCharacter($str);
+        $str = WebUtil::htmlPurify($str);
+        $str = StringUtil::textStrip($str);
+        return $str;
+    }
+
     public static function textStrip(?string $str):string{
         if(!$str){
             return '';