diff --git a/f_install/j_create_admin.php b/f_install/j_create_admin.php
index 1a08cd9f..43e268d2 100644
--- a/f_install/j_create_admin.php
+++ b/f_install/j_create_admin.php
@@ -65,12 +65,12 @@ $rootDB->insert('member_log', [
     'member_no'=>$userID,
     'date'=>$nowDate,
     'action_type'=>'reg',
-    'action'=>json_encode([
+    'action'=>Json::encode([
         'type'=>'none',
         'aux'=>'admin',
         'id'=>$username,
         'name'=>$nickname
-    ], JSON_UNESCAPED_UNICODE)
+    ])
 ]);
 
 Json::die([
diff --git a/hwe/func_history.php b/hwe/func_history.php
index 19443710..9609bb76 100644
--- a/hwe/func_history.php
+++ b/hwe/func_history.php
@@ -175,7 +175,7 @@ function getGeneralPublicRecordRecent($count) {
     return join('<br>', $texts);
 }
 
-function getGeneralPublicRecordWithDate($count, $year, $month, $isFirst=0) {
+function getGeneralPublicRecordWithDate($year, $month) {
     $db = DB::db();
 
     $texts = [];
@@ -225,10 +225,10 @@ function LogHistory($isFirst=0) {
     $year = $map['year'];
     $month = $map['month'];
 
-    $map_json = json_encode($map, JSON_UNESCAPED_UNICODE);
+    $map_json = Json::encode($map);
     
     $log = getWorldHistoryWithDate($year, $month);
-    $genlog = getGeneralPublicRecordWithDate(50, $year, $month, $isFirst);
+    $genlog = getGeneralPublicRecordWithDate($year, $month);
 
     $nationStr = "";
     $powerStr = "";
diff --git a/hwe/func_map.php b/hwe/func_map.php
index ff96dcee..575014c9 100644
--- a/hwe/func_map.php
+++ b/hwe/func_map.php
@@ -34,7 +34,7 @@ function getHistoryMap($year, $month){
         return ['result'=>false, 'reason'=>'연감이 저장되지 않음'];
     }
 
-    return json_decode($map, true);//까짓거 json_decode, json_encode 두번하지 뭐.
+    return Json::decode($map);//까짓거 json_decode, json_encode 두번하지 뭐.
 }
 
 /**
diff --git a/hwe/func_message.php b/hwe/func_message.php
index 68d72367..24244c33 100644
--- a/hwe/func_message.php
+++ b/hwe/func_message.php
@@ -130,7 +130,7 @@ function sendRawMessage($msgType, $isSender, $mailbox, $src, $dest, $msg, $date,
         unset($msgOption['alert']);
     }
 
-    DB::db()->insert('message', array(
+    DB::db()->insert('message', [
         'address' => $dest,
         'type' => $msgType,
         'is_sender' => $isSender,
@@ -138,13 +138,13 @@ function sendRawMessage($msgType, $isSender, $mailbox, $src, $dest, $msg, $date,
         'dest' => $dest['id'],
         'time' => $date,
         'valid_until' => $validUntil,
-        'message' => json_encode(Util::eraseNullValue([
+        'message' => Json::encode([
             'src' => $src,
             'dest' =>$dest,
             'text' => $msg,
             'option' => $msgOption
-        ]))
-    ));
+        ], Json::DELETE_NULL)
+    ]);
 }
 
 function sendMessage($msgType, $src, $dest, $msg, $date = null, $validUntil = null, $msgOption = null){
diff --git a/hwe/j_msg_decide_opt.php b/hwe/j_msg_decide_opt.php
index c28eb61a..25b3d18e 100644
--- a/hwe/j_msg_decide_opt.php
+++ b/hwe/j_msg_decide_opt.php
@@ -62,13 +62,13 @@ if ($validUntil < $date) {
     ]);
 }
 
-$msgOption = json_decode(Util::array_get($messageInfo['option'], '{}'));
+$msgOption = Json::decode(Util::array_get($messageInfo['option'], '{}'));
 $msgAction = Util::array_get($msgOption['action'], null);
 $messageInfo['option'] = $msgOption;
 
-$msgSrc = json_decode($messageInfo['src']);
+$msgSrc = Json::decode($messageInfo['src']);
 $messageInfo['src'] = $msgSrc;
-$msgDest = json_decode($messageInfo['dest']);
+$msgDest = Json::decode($messageInfo['dest']);
 $messageInfo['dest'] = $msgDest;
 
 if (!$msgAction) {
diff --git a/i_entrance/j_change_password.php b/i_entrance/j_change_password.php
index dd02cc7f..bcfd7029 100644
--- a/i_entrance/j_change_password.php
+++ b/i_entrance/j_change_password.php
@@ -32,7 +32,7 @@ if(!$db->affectedRows()){
     $db->insert('member_log', [
         'member_no'=>$session->userID,
         'action_type'=>'change_pw',
-        'action'=>json_encode([
+        'action'=>Json::encode([
             'type'=>'plain',
             'result'=>false
         ])
@@ -47,7 +47,7 @@ if(!$db->affectedRows()){
 $db->insert('member_log', [
     'member_no'=>$session->userID,
     'action_type'=>'change_pw',
-    'action'=>json_encode([
+    'action'=>Json::encode([
         'type'=>'plain',
         'result'=>true
     ])
diff --git a/i_entrance/j_server_change_status.php b/i_entrance/j_server_change_status.php
index 18356c7c..ac0a3e17 100644
--- a/i_entrance/j_server_change_status.php
+++ b/i_entrance/j_server_change_status.php
@@ -93,4 +93,4 @@ function doAdminPost($action, $notice, $server){
 
 $response = doAdminPost($action, $notice, $server);
 
-echo json_encode($response);
+Json::die($response);
diff --git a/oauth_kakao/j_change_pw.php b/oauth_kakao/j_change_pw.php
index e0ad9076..bbc08b93 100644
--- a/oauth_kakao/j_change_pw.php
+++ b/oauth_kakao/j_change_pw.php
@@ -100,11 +100,11 @@ RootDB::db()->insert('member_log', [
     'member_no'=>$userID,
     'date'=>$nowDate,
     'action_type'=>'change_pw',
-    'action'=>json_encode([
+    'action'=>Json::encode([
         'type'=>'kakao',
         'no'=>$userID,
         'token'=>$access_token
-    ], JSON_UNESCAPED_UNICODE)
+    ])
 ]);
 
 RootDB::db()->query("unlock tables");
diff --git a/oauth_kakao/j_join_process.php b/oauth_kakao/j_join_process.php
index 69f1ab4b..7716e2c3 100644
--- a/oauth_kakao/j_join_process.php
+++ b/oauth_kakao/j_join_process.php
@@ -108,7 +108,7 @@ $kakaoID = Util::array_get($signupResult['id']);
 if(!$kakaoID && Util::array_get($signupResult['msg'])!='already registered'){
     Json::die([
         'result'=>false,
-        'reason'=>'카카오 로그인 과정 중 앱 연결 절차를 실패했습니다'.json_encode($signupResult)
+        'reason'=>'카카오 로그인 과정 중 앱 연결 절차를 실패했습니다'.Json::encode($signupResult)
     ]);
 }
 
@@ -158,11 +158,11 @@ RootDB::db()->insert('member_log', [
     'member_no'=>$userID,
     'date'=>$nowDate,
     'action_type'=>'reg',
-    'action'=>json_encode([
+    'action'=>Json::encode([
         'type'=>'kakao',
         'id'=>$kakaoID,
         'email'=>$email, 'name'=>$nickname
-    ], JSON_UNESCAPED_UNICODE)
+    ])
 ]);
 
 Json::die([
diff --git a/oauth_kakao/oauth.php b/oauth_kakao/oauth.php
index a01c49a5..754d2ddc 100644
--- a/oauth_kakao/oauth.php
+++ b/oauth_kakao/oauth.php
@@ -37,7 +37,7 @@ else{
     die('알 수 없는 에러:'.$me['msg']);
 }
 
-$_SESSION['tmpx'] = json_encode($result,JSON_UNESCAPED_UNICODE);
+$_SESSION['tmpx'] = Json::encode($result);
 
 //echo "<br>\n";
 $me = $restAPI->meWithEmail();
diff --git a/src/sammo/Json.php b/src/sammo/Json.php
index 703357ae..6e7df823 100644
--- a/src/sammo/Json.php
+++ b/src/sammo/Json.php
@@ -2,29 +2,38 @@
 namespace sammo;
 
 class Json{
-    public static function encode($value, $pretty = false){
-        if($pretty){
-            $flag = JSON_UNESCAPED_UNICODE | JSON_PRETTY_PRINT;
+    const PRETTY = 1;
+    const DELETE_NULL = 2;
+    const NO_CACHE = 4;
+
+    public static function encode($value, $flag = 0){
+        $rawFlag = JSON_UNESCAPED_UNICODE;
+        if($flag & static::PRETTY){
+            $rawFlag |= JSON_PRETTY_PRINT;
         }
-        else{
-            $flag = JSON_UNESCAPED_UNICODE;
+        if($flag & static::DELETE_NULL){
+            $value = Util::eraseNullValue($value);
         }
-        return json_encode($value, $flag); 
+        return json_encode($value, $rawFlag); 
+    }
+
+    public static function encodePack($value, $pretty = false){
+
     }
 
     public static function decode($value){
         return json_decode($value, true);
     }
 
-    public static function die($value, $noCache = true, $pretty = false, $die = true){
+    public static function die($value, $flag = NO_CACHE){
         //NOTE: REST 형식에 맞게, ok(), fail()로 쪼개는게 낫지 않을까 생각해봄.
-        if($noCache){
+        if($flag & static::NO_CACHE){
             WebUtil::setHeaderNoCache();
         }
         
         header('Content-Type: application/json');
     
-        echo Json::encode($value, $pretty); 
+        echo Json::encode($value, $flag); 
         if($die){
             die();
         }
diff --git a/src/sammo/WebUtil.php b/src/sammo/WebUtil.php
index 8253fd29..7f18c7d3 100644
--- a/src/sammo/WebUtil.php
+++ b/src/sammo/WebUtil.php
@@ -28,7 +28,7 @@ class WebUtil{
         $content = trim(file_get_contents("php://input"));
         
         //Attempt to decode the incoming RAW post data from JSON.
-        $decoded = json_decode($content, true);
+        $decoded = Json::decode($content);
         
         
         $jsonError = json_last_error();
diff --git a/tmp_msg/add_msg_dummy.php b/tmp_msg/add_msg_dummy.php
index 253ab4fe..7315a93a 100644
--- a/tmp_msg/add_msg_dummy.php
+++ b/tmp_msg/add_msg_dummy.php
@@ -4,8 +4,8 @@ require('../twe/lib.php');
 
 $jsonPost = WebUtil::parseJsonPost();
 
-echo json_encode([
+Json::die([
     'result'=>true,
     'reason'=>'success',
     'msgID'=>1997
-], JSON_UNESCAPED_UNICODE);
\ No newline at end of file
+]);
\ No newline at end of file
diff --git a/tmp_msg/json_result.php b/tmp_msg/json_result.php
index 60016ba8..0d99d5d3 100644
--- a/tmp_msg/json_result.php
+++ b/tmp_msg/json_result.php
@@ -18,8 +18,8 @@ function relayJson($filepath, $noCache = true, $die = true){
         header('Pragma: no-cache');
     }
 
-    $json = json_decode(file_get_contents($filepath));
-    echo json_encode($json,JSON_UNESCAPED_UNICODE);
+    $json = Json::decode(file_get_contents($filepath));
+    echo Json::encode($json);
 
     if($die){
         die();
diff --git a/tmp_msg/prompt_dummy.php b/tmp_msg/prompt_dummy.php
index 6a0ebcdc..3718dff8 100644
--- a/tmp_msg/prompt_dummy.php
+++ b/tmp_msg/prompt_dummy.php
@@ -4,7 +4,7 @@ require('../twe/lib.php');
 
 $jsonPost = WebUtil::parseJsonPost();
 
-echo json_encode([
+Json::die([
     'result'=>true,
     'reason'=>'success'
-], JSON_UNESCAPED_UNICODE);
\ No newline at end of file
+]);
\ No newline at end of file