diff --git a/hwe/_admin7.php b/hwe/_admin7.php
index e44f1ec7..8623f9c2 100644
--- a/hwe/_admin7.php
+++ b/hwe/_admin7.php
@@ -31,7 +31,7 @@ $queryMap = [
 ];
 
 if ($reqQueryType === null || !key_exists($reqQueryType, $queryMap)) {
-    $reqQueryType = Util::array_first_key($queryMap);
+    $reqQueryType = array_key_first($queryMap);
 }
 
 //로그인 검사
diff --git a/hwe/func_gamerule.php b/hwe/func_gamerule.php
index 6bb0b224..56883c7f 100644
--- a/hwe/func_gamerule.php
+++ b/hwe/func_gamerule.php
@@ -559,7 +559,7 @@ function checkStatistic()
 
     $nationHist = '';
     foreach (GameConst::$availableNationType as $nationType) {
-        if (!Util::array_get($nationHists[$nationType])) {
+        if (!($nationHists[$nationType] ?? null)) {
             $nationHists[$nationType] = '-';
         }
         $nationHist .= getNationType($nationType) . "({$nationHists[$nationType]}), ";
diff --git a/hwe/func_legacy.php b/hwe/func_legacy.php
index ffe23de9..deaf55c3 100644
--- a/hwe/func_legacy.php
+++ b/hwe/func_legacy.php
@@ -138,7 +138,7 @@ function JSCitiesBasedOnDistance(int $cityNo, int $maxDistance = 1): array{
     $distanceList = searchDistance($cityNo, $maxDistance, true);
     $result = [];
     for ($dist = 1; $dist <= $maxDistance; $dist++) {
-        $result[$dist] = Util::array_get($distanceList[$dist], []);
+        $result[$dist] = $distanceList[$dist] ?? [];
     }
     return $result;
 }
@@ -152,7 +152,7 @@ function printCitiesBasedOnDistance(int $cityNo, int $maxDistance = 1): string
     for ($dist = 1; $dist <= $maxDistance; $dist++) {
         $cityList = array_map(function ($cityID) {
             return CityConst::byID($cityID)->name;
-        }, Util::array_get($distanceList[$dist], []));
+        }, $distanceList[$dist] ?? []);
 
         $cityStr = join(', ', $cityList);
 
diff --git a/hwe/process_war.php b/hwe/process_war.php
index 1c8f7f01..c7c84701 100644
--- a/hwe/process_war.php
+++ b/hwe/process_war.php
@@ -526,7 +526,7 @@ function DeleteConflict($nation)
 function getConquerNation($city): int
 {
     $conflict = Json::decode($city['conflict']);
-    return Util::array_first_key($conflict);
+    return array_key_first($conflict);
 }
 
 function ConquerCity(array $admin, General $general, array $city, array $defenderCityGeneralList)
diff --git a/hwe/sammo/ActionItem/event_전투특기_공성.php b/hwe/sammo/ActionItem/event_전투특기_공성.php
index a26a47e2..ad9cc8f9 100644
--- a/hwe/sammo/ActionItem/event_전투특기_공성.php
+++ b/hwe/sammo/ActionItem/event_전투특기_공성.php
@@ -33,7 +33,7 @@ class event_전투특기_공성 extends \sammo\BaseItem{
     }
 
     public function onCalcStat(General $general, string $statName, $value, $aux=null){
-        if(\sammo\Util::starts_with($statName, 'dex')){
+        if(str_starts_with($statName, 'dex')){
             $myArmType = 'dex'.GameUnitConst::T_SIEGE;
             $opposeArmType = 'dex'.$aux['opposeType']->armType;;
             if($aux['isAttacker'] && $opposeArmType === $statName){
diff --git a/hwe/sammo/ActionItem/event_전투특기_궁병.php b/hwe/sammo/ActionItem/event_전투특기_궁병.php
index 81381a69..62dacf2c 100644
--- a/hwe/sammo/ActionItem/event_전투특기_궁병.php
+++ b/hwe/sammo/ActionItem/event_전투특기_궁병.php
@@ -28,7 +28,7 @@ class event_전투특기_궁병 extends \sammo\BaseItem{
         if($statName === 'warAvoidRatio'){
             return $value + 0.2;
         }
-        if(\sammo\Util::starts_with($statName, 'dex')){
+        if(str_starts_with($statName, 'dex')){
             $myArmType = 'dex'.GameUnitConst::T_ARCHER;
             $opposeArmType = 'dex'.$aux['opposeType']->armType;;
             if($aux['isAttacker'] && $opposeArmType === $statName){
diff --git a/hwe/sammo/ActionItem/event_전투특기_귀병.php b/hwe/sammo/ActionItem/event_전투특기_귀병.php
index e11ea251..ca181504 100644
--- a/hwe/sammo/ActionItem/event_전투특기_귀병.php
+++ b/hwe/sammo/ActionItem/event_전투특기_귀병.php
@@ -28,7 +28,7 @@ class event_전투특기_귀병 extends \sammo\BaseItem{
         if($statName === 'warMagicSuccessProb'){
             return $value + 0.2;
         }
-        if(\sammo\Util::starts_with($statName, 'dex')){
+        if(str_starts_with($statName, 'dex')){
             $myArmType = 'dex'.GameUnitConst::T_WIZARD;
             $opposeArmType = 'dex'.$aux['opposeType']->armType;;
             if($aux['isAttacker'] && $opposeArmType === $statName){
diff --git a/hwe/sammo/ActionItem/event_전투특기_기병.php b/hwe/sammo/ActionItem/event_전투특기_기병.php
index e19ad59b..ba4457b4 100644
--- a/hwe/sammo/ActionItem/event_전투특기_기병.php
+++ b/hwe/sammo/ActionItem/event_전투특기_기병.php
@@ -32,7 +32,7 @@ class event_전투특기_기병 extends \sammo\BaseItem{
     }
 
     public function onCalcStat(General $general, string $statName, $value, $aux=null){
-        if(\sammo\Util::starts_with($statName, 'dex')){
+        if(str_starts_with($statName, 'dex')){
             $myArmType = 'dex'.GameUnitConst::T_CAVALRY;
             $opposeArmType = 'dex'.$aux['opposeType']->armType;;
             if($aux['isAttacker'] && $opposeArmType === $statName){
diff --git a/hwe/sammo/ActionItem/event_전투특기_보병.php b/hwe/sammo/ActionItem/event_전투특기_보병.php
index 36af41ad..b9f0ebaa 100644
--- a/hwe/sammo/ActionItem/event_전투특기_보병.php
+++ b/hwe/sammo/ActionItem/event_전투특기_보병.php
@@ -33,7 +33,7 @@ class event_전투특기_보병 extends \sammo\BaseItem{
     }
 
     public function onCalcStat(General $general, string $statName, $value, $aux=null){
-        if(\sammo\Util::starts_with($statName, 'dex')){
+        if(str_starts_with($statName, 'dex')){
             $myArmType = 'dex'.GameUnitConst::T_FOOTMAN;
             $opposeArmType = 'dex'.$aux['opposeType']->armType;;
             if($aux['isAttacker'] && $opposeArmType === $statName){
diff --git a/hwe/sammo/ActionSpecialDomestic/che_event_공성.php b/hwe/sammo/ActionSpecialDomestic/che_event_공성.php
index 52da3cd4..23f62508 100644
--- a/hwe/sammo/ActionSpecialDomestic/che_event_공성.php
+++ b/hwe/sammo/ActionSpecialDomestic/che_event_공성.php
@@ -35,7 +35,7 @@ class che_event_공성 extends \sammo\BaseSpecial{
     }
 
     public function onCalcStat(General $general, string $statName, $value, $aux=null){
-        if(\sammo\Util::starts_with($statName, 'dex')){
+        if(str_starts_with($statName, 'dex')){
             $myArmType = 'dex'.GameUnitConst::T_SIEGE;
             $opposeArmType = 'dex'.$aux['opposeType']->armType;;
             if($aux['isAttacker'] && $opposeArmType === $statName){
diff --git a/hwe/sammo/ActionSpecialDomestic/che_event_궁병.php b/hwe/sammo/ActionSpecialDomestic/che_event_궁병.php
index 43862278..ee243c6d 100644
--- a/hwe/sammo/ActionSpecialDomestic/che_event_궁병.php
+++ b/hwe/sammo/ActionSpecialDomestic/che_event_궁병.php
@@ -31,7 +31,7 @@ class che_event_궁병 extends \sammo\BaseSpecial{
         if($statName === 'warAvoidRatio'){
             return $value + 0.2;
         }
-        if(\sammo\Util::starts_with($statName, 'dex')){
+        if(str_starts_with($statName, 'dex')){
             $myArmType = 'dex'.GameUnitConst::T_ARCHER;
             $opposeArmType = 'dex'.$aux['opposeType']->armType;;
             if($aux['isAttacker'] && $opposeArmType === $statName){
diff --git a/hwe/sammo/ActionSpecialDomestic/che_event_귀병.php b/hwe/sammo/ActionSpecialDomestic/che_event_귀병.php
index ba9863f4..6267e8d8 100644
--- a/hwe/sammo/ActionSpecialDomestic/che_event_귀병.php
+++ b/hwe/sammo/ActionSpecialDomestic/che_event_귀병.php
@@ -30,7 +30,7 @@ class che_event_귀병 extends \sammo\BaseSpecial{
         if($statName === 'warMagicSuccessProb'){
             return $value + 0.2;
         }
-        if(\sammo\Util::starts_with($statName, 'dex')){
+        if(str_starts_with($statName, 'dex')){
             $myArmType = 'dex'.GameUnitConst::T_WIZARD;
             $opposeArmType = 'dex'.$aux['opposeType']->armType;;
             if($aux['isAttacker'] && $opposeArmType === $statName){
diff --git a/hwe/sammo/ActionSpecialDomestic/che_event_기병.php b/hwe/sammo/ActionSpecialDomestic/che_event_기병.php
index 6a5e92f4..b40ce270 100644
--- a/hwe/sammo/ActionSpecialDomestic/che_event_기병.php
+++ b/hwe/sammo/ActionSpecialDomestic/che_event_기병.php
@@ -35,7 +35,7 @@ class che_event_기병 extends \sammo\BaseSpecial{
     }
 
     public function onCalcStat(General $general, string $statName, $value, $aux=null){
-        if(\sammo\Util::starts_with($statName, 'dex')){
+        if(str_starts_with($statName, 'dex')){
             $myArmType = 'dex'.GameUnitConst::T_CAVALRY;
             $opposeArmType = 'dex'.$aux['opposeType']->armType;;
             if($aux['isAttacker'] && $opposeArmType === $statName){
diff --git a/hwe/sammo/ActionSpecialDomestic/che_event_보병.php b/hwe/sammo/ActionSpecialDomestic/che_event_보병.php
index 1e99d048..08bc934f 100644
--- a/hwe/sammo/ActionSpecialDomestic/che_event_보병.php
+++ b/hwe/sammo/ActionSpecialDomestic/che_event_보병.php
@@ -35,7 +35,7 @@ class che_event_보병 extends \sammo\BaseSpecial{
     }
 
     public function onCalcStat(General $general, string $statName, $value, $aux=null){
-        if(\sammo\Util::starts_with($statName, 'dex')){
+        if(str_starts_with($statName, 'dex')){
             $myArmType = 'dex'.GameUnitConst::T_FOOTMAN;
             $opposeArmType = 'dex'.$aux['opposeType']->armType;;
             if($aux['isAttacker'] && $opposeArmType === $statName){
diff --git a/hwe/sammo/ActionSpecialWar/che_공성.php b/hwe/sammo/ActionSpecialWar/che_공성.php
index ca866324..6df70402 100644
--- a/hwe/sammo/ActionSpecialWar/che_공성.php
+++ b/hwe/sammo/ActionSpecialWar/che_공성.php
@@ -35,7 +35,7 @@ class che_공성 extends \sammo\BaseSpecial{
     }
 
     public function onCalcStat(General $general, string $statName, $value, $aux=null){
-        if(\sammo\Util::starts_with($statName, 'dex')){
+        if(str_starts_with($statName, 'dex')){
             $myArmType = 'dex'.GameUnitConst::T_SIEGE;
             $opposeArmType = 'dex'.$aux['opposeType']->armType;;
             if($aux['isAttacker'] && $opposeArmType === $statName){
diff --git a/hwe/sammo/ActionSpecialWar/che_궁병.php b/hwe/sammo/ActionSpecialWar/che_궁병.php
index c64b0645..47813188 100644
--- a/hwe/sammo/ActionSpecialWar/che_궁병.php
+++ b/hwe/sammo/ActionSpecialWar/che_궁병.php
@@ -31,7 +31,7 @@ class che_궁병 extends \sammo\BaseSpecial{
         if($statName === 'warAvoidRatio'){
             return $value + 0.2;
         }
-        if(\sammo\Util::starts_with($statName, 'dex')){
+        if(str_starts_with($statName, 'dex')){
             $myArmType = 'dex'.GameUnitConst::T_ARCHER;
             $opposeArmType = 'dex'.$aux['opposeType']->armType;;
             if($aux['isAttacker'] && $opposeArmType === $statName){
diff --git a/hwe/sammo/ActionSpecialWar/che_귀병.php b/hwe/sammo/ActionSpecialWar/che_귀병.php
index aa99c869..83160ebf 100644
--- a/hwe/sammo/ActionSpecialWar/che_귀병.php
+++ b/hwe/sammo/ActionSpecialWar/che_귀병.php
@@ -30,7 +30,7 @@ class che_귀병 extends \sammo\BaseSpecial{
         if($statName === 'warMagicSuccessProb'){
             return $value + 0.2;
         }
-        if(\sammo\Util::starts_with($statName, 'dex')){
+        if(str_starts_with($statName, 'dex')){
             $myArmType = 'dex'.GameUnitConst::T_WIZARD;
             $opposeArmType = 'dex'.$aux['opposeType']->armType;;
             if($aux['isAttacker'] && $opposeArmType === $statName){
diff --git a/hwe/sammo/ActionSpecialWar/che_기병.php b/hwe/sammo/ActionSpecialWar/che_기병.php
index 683db233..3ab31d7e 100644
--- a/hwe/sammo/ActionSpecialWar/che_기병.php
+++ b/hwe/sammo/ActionSpecialWar/che_기병.php
@@ -35,7 +35,7 @@ class che_기병 extends \sammo\BaseSpecial{
     }
 
     public function onCalcStat(General $general, string $statName, $value, $aux=null){
-        if(\sammo\Util::starts_with($statName, 'dex')){
+        if(str_starts_with($statName, 'dex')){
             $myArmType = 'dex'.GameUnitConst::T_CAVALRY;
             $opposeArmType = 'dex'.$aux['opposeType']->armType;;
             if($aux['isAttacker'] && $opposeArmType === $statName){
diff --git a/hwe/sammo/ActionSpecialWar/che_보병.php b/hwe/sammo/ActionSpecialWar/che_보병.php
index 4bedeb93..1a89d48f 100644
--- a/hwe/sammo/ActionSpecialWar/che_보병.php
+++ b/hwe/sammo/ActionSpecialWar/che_보병.php
@@ -35,7 +35,7 @@ class che_보병 extends \sammo\BaseSpecial{
     }
 
     public function onCalcStat(General $general, string $statName, $value, $aux=null){
-        if(\sammo\Util::starts_with($statName, 'dex')){
+        if(str_starts_with($statName, 'dex')){
             $myArmType = 'dex'.GameUnitConst::T_FOOTMAN;
             $opposeArmType = 'dex'.$aux['opposeType']->armType;;
             if($aux['isAttacker'] && $opposeArmType === $statName){
diff --git a/hwe/sammo/Command/General/che_랜덤임관.php b/hwe/sammo/Command/General/che_랜덤임관.php
index be17946c..715dfa43 100644
--- a/hwe/sammo/Command/General/che_랜덤임관.php
+++ b/hwe/sammo/Command/General/che_랜덤임관.php
@@ -208,7 +208,7 @@ class che_랜덤임관 extends Command\GeneralCommand
             foreach ($rawGeneralsCnt as $nation) {
                 $calcCnt = $nation['warpower'] + $nation['develpower'];
 
-                if ($general->getNPCType() < 2 && Util::starts_with($nation['name'], 'ⓤ')) {
+                if ($general->getNPCType() < 2 && str_starts_with($nation['name'], 'ⓤ')) {
                     $calcCnt *= 100;
                 }
 
diff --git a/hwe/sammo/Command/General/che_출병.php b/hwe/sammo/Command/General/che_출병.php
index da28b875..7477937d 100644
--- a/hwe/sammo/Command/General/che_출병.php
+++ b/hwe/sammo/Command/General/che_출병.php
@@ -164,7 +164,7 @@ class che_출병 extends Command\GeneralCommand
 
         $currDist = 999;
 
-        $minDist = Util::array_first_key($distanceList);
+        $minDist = array_key_first($distanceList);
         do {
             //1: 최단 거리 도시 중 공격 대상이 있는가 확인
             //2: 최단 거리 + 1 도시 중 공격 대상이 있는가 확인
diff --git a/hwe/sammo/Event/Action/ChangeCity.php b/hwe/sammo/Event/Action/ChangeCity.php
index b9ef9475..c4a05507 100644
--- a/hwe/sammo/Event/Action/ChangeCity.php
+++ b/hwe/sammo/Event/Action/ChangeCity.php
@@ -127,7 +127,7 @@ class ChangeCity extends \sammo\Event\Action{
             return DB::db()->sqleval('ROUND(%b * %d, 0)', $keyMax, $value/100);
         }
 
-        if(Util::ends_with($key, '_max') && preg_match(self::REGEXP_MATH, $value, $matches)){
+        if(str_ends_with($key, '_max') && preg_match(self::REGEXP_MATH, $value, $matches)){
             //key가 아예 최대치에 대한 값이면 연산은 결과값이 0보다만 높게.
             $op = $matches[1];
             $value = $matches[2];
diff --git a/hwe/sammo/GeneralAI.php b/hwe/sammo/GeneralAI.php
index 1c7458f1..5b89f246 100644
--- a/hwe/sammo/GeneralAI.php
+++ b/hwe/sammo/GeneralAI.php
@@ -2084,7 +2084,7 @@ class GeneralAI
             }
         }
 
-        $finalCityID = Util::array_first_key($cityScoreList);
+        $finalCityID = array_key_first($cityScoreList);
         $dist = $distanceList[$capital][$finalCityID];
         $targetCityID = $finalCityID;
         if ($dist > 1) {
diff --git a/hwe/sammo/TriggerCaller.php b/hwe/sammo/TriggerCaller.php
index 0f3d36b3..31378a79 100644
--- a/hwe/sammo/TriggerCaller.php
+++ b/hwe/sammo/TriggerCaller.php
@@ -62,7 +62,7 @@ abstract class TriggerCaller{
             return $this;
         }
 
-        $lastKey = Util::array_last_key($this->triggerListByPriority);
+        $lastKey = array_key_last($this->triggerListByPriority);
         if($lastKey < $priority){
             $this->triggerListByPriority[$priority] = [$uniqueID=>$trigger];
             return $this;
diff --git a/j_updateServer.php b/j_updateServer.php
index 3d0ad1c6..7e8abf4b 100644
--- a/j_updateServer.php
+++ b/j_updateServer.php
@@ -174,7 +174,7 @@ function tryNpmInstall()
 
 tryComposerInstall();
 if (tryNpmInstall()) {
-    genJS(Util::array_last_key(ServConfig::getServerList()));
+    genJS(array_key_last(ServConfig::getServerList()));
 }
 $session = Session::requireLogin(null)->setReadOnly();
 
@@ -227,7 +227,7 @@ if (!$allowFullUpdate || !$target) {
     $target = $request['target'];
 }
 
-$baseServerName = Util::array_last_key(ServConfig::getServerList());
+$baseServerName = array_key_last(ServConfig::getServerList());
 
 if (!$target && $server != $baseServerName) {
     Json::die([
diff --git a/oauth_kakao/j_join_process.php b/oauth_kakao/j_join_process.php
index d902c3cf..087ca8bd 100644
--- a/oauth_kakao/j_join_process.php
+++ b/oauth_kakao/j_join_process.php
@@ -109,16 +109,16 @@ if($expires < $nowDate){
     $access_token = $result['access_token'];
     $expires = TimeUtil::nowAddSeconds($result['expires_in']);
     if(isset($result['refresh_token'])){
-        $refresh_token = Util::array_get($result['refresh_token']);
+        $refresh_token = $result['refresh_token'] ?? null;
         $refresh_token_expires = TimeUtil::nowAddSeconds($result['refresh_token_expires_in']);
     }
 }
 
 
 $signupResult = $restAPI->signup();
-$kakaoID = Util::array_get($signupResult['id']);
+$kakaoID = $signupResult['id'] ?? null;
 
-if(!$kakaoID && Util::array_get($signupResult['msg'])!='already registered'){
+if(!$kakaoID && ($signupResult['msg'] ?? null) !='already registered'){
     Json::die([
         'result'=>false,
         'reason'=>'카카오 로그인 과정 중 앱 연결 절차를 실패했습니다'.Json::encode($signupResult)
@@ -126,7 +126,7 @@ if(!$kakaoID && Util::array_get($signupResult['msg'])!='already registered'){
 }
 
 $me = $restAPI->meWithEmail();
-$me['code'] = Util::array_get($me['code'], 0);
+$me['code'] = $me['code'] ?? 0;
 $kakao_account = $me['kakao_account']??[];
 if ($me['code']< 0) {
     $restAPI->unlink();
diff --git a/src/sammo/Setting.php b/src/sammo/Setting.php
index af9d29ae..c24dc2b5 100644
--- a/src/sammo/Setting.php
+++ b/src/sammo/Setting.php
@@ -88,9 +88,9 @@ class Setting
         $tail = new FileTail($this->versionFile);
         $version = 'noVersionJson';
         foreach ($tail->smart(5, 100, true) as $line) {
-            if (Util::starts_with($line, '//{')) {
+            if (str_starts_with($line, '//{')) {
                 $version = Json::decode(substr($line, 2));
-                $version = Util::array_get($version['version'], 'noVersionValue');
+                $version = $version['version'] ?? 'noVersionValue';
                 break;
             }
         }
@@ -106,8 +106,8 @@ class Setting
         $templates = new \League\Plates\Engine(__DIR__.'/templates');
         //TODO: .htaccess가 서버 오픈에도 사용될 수 있으니 별도의 방법이 필요함
         $allow_ip = Util::get_client_ip(false);
-        if (Util::starts_with($allow_ip, '192.168.') ||
-            Util::starts_with($allow_ip, '10.')) {
+        if (str_starts_with($allow_ip, '192.168.') ||
+            str_starts_with($allow_ip, '10.')) {
             //172.16~172.31은 코딩하기 귀찮으니까 안할거다
             $allow_ip = Util::get_client_ip(true);
         }
diff --git a/src/sammo/Util.php b/src/sammo/Util.php
index c618b6af..dd9227f6 100644
--- a/src/sammo/Util.php
+++ b/src/sammo/Util.php
@@ -3,7 +3,7 @@ namespace sammo;
 
 use Iterator;
 
-class Util extends \utilphp\util
+class Util
 {
 
     /**
@@ -889,4 +889,110 @@ class Util extends \utilphp\util
         }
         return join('|', $result);
     }
+
+
+/** 
+ * http://github.com/brandonwamboldt/utilphp/ 의 구버전 코드에서 이식함
+ * 일부 코드는 수정
+ * 해당 라이선스: MIT
+ */
+
+    /**
+     * Returns the first element in an array.
+     * PHP 8.5부터 array_first 사용 가능
+     *
+     * @param  array $array
+     * @return mixed
+     */
+    public static function array_first(array $array)
+    {
+        return $array[array_key_first($array)];
+    }
+
+    /**
+     * Returns the last element in an array.
+     * PHP 8.5부터 array_last 사용 가능
+     *
+     * @param  array $array
+     * @return mixed
+     */
+    public static function array_last(array $array)
+    {
+        return $array[array_key_last($array)];
+    }
+
+    /**
+     * Flatten a multi-dimensional array into a one dimensional array.
+     *
+     * Contributed by Theodore R. Smith of PHP Experts, Inc. <http://www.phpexperts.pro/>
+     *
+     * @param  array   $array         The array to flatten
+     * @param  boolean $preserve_keys Whether or not to preserve array keys.
+     *                                Keys from deeply nested arrays will
+     *                                overwrite keys from shallowy nested arrays
+     * @return array
+     */
+    public static function array_flatten(array $array, $preserve_keys = true)
+    {
+        $flattened = array();
+
+        array_walk_recursive($array, function($value, $key) use (&$flattened, $preserve_keys) {
+            if ($preserve_keys && !is_int($key)) {
+                $flattened[$key] = $value;
+            } else {
+                $flattened[] = $value;
+            }
+        });
+
+        return $flattened;
+    }
+
+    /**
+     * Returns the IP address of the client.
+     *
+     * @param   boolean $trust_proxy_headers Whether or not to trust the
+     *                                       proxy headers HTTP_CLIENT_IP
+     *                                       and HTTP_X_FORWARDED_FOR. ONLY
+     *                                       use if your server is behind a
+     *                                       proxy that sets these values
+     * @return  string
+     */
+    public static function get_client_ip($trust_proxy_headers = false)
+    {
+        if (!$trust_proxy_headers) {
+            return $_SERVER['REMOTE_ADDR'];
+        }
+
+        if (!empty($_SERVER['HTTP_CLIENT_IP'])) {
+            $ip = $_SERVER['HTTP_CLIENT_IP'];
+        } elseif (!empty($_SERVER['HTTP_X_FORWARDED_FOR'])) {
+            $ip = $_SERVER['HTTP_X_FORWARDED_FOR'];
+        } else {
+            $ip = $_SERVER['REMOTE_ADDR'];
+        }
+
+        return $ip;
+    }
+
+    /**
+     * Access an array index, retrieving the value stored there if it
+     * exists or a default if it does not. This function allows you to
+     * concisely access an index which may or may not exist without
+     * raising a warning.
+     * 
+     * @deprecated PHP 7.0 이상에서는 null 병합 연산자 사용을 권장
+     *
+     * @param  array  $var     Array value to access
+     * @param  mixed  $default Default value to return if the key is not
+     *                         present in the array
+     * @return mixed
+     */
+    public static function array_get(&$var, $default = null)
+    {
+        if (isset($var)) {
+            return $var;
+        }
+
+        return $default;
+    }
 };