diff --git a/ITC81DB_0H/Controls/CenterInformation/ControlCenterInforSystem.cs b/ITC81DB_0H/Controls/CenterInformation/ControlCenterInforSystem.cs
index 1b31c83..86c98e7 100644
--- a/ITC81DB_0H/Controls/CenterInformation/ControlCenterInforSystem.cs
+++ b/ITC81DB_0H/Controls/CenterInformation/ControlCenterInforSystem.cs
@@ -66,7 +66,7 @@ namespace ITC81DB_0H.Controls
         private void DefaultSetting()
         {
             this.labelSerialNo.Text = this.ParentForm.ParentForm.SystemConfig1.SerialNumber;
-            this.labelDisplayVer.Text = "2.1.0";
+            this.labelDisplayVer.Text = "2.1.2";
         }
 
         public void UpdateMainBoardVersionDisplay(string version)
diff --git a/ITC81DB_0H/Forms/FormMainDisplay.cs b/ITC81DB_0H/Forms/FormMainDisplay.cs
index b9eda8d..32015b1 100644
--- a/ITC81DB_0H/Forms/FormMainDisplay.cs
+++ b/ITC81DB_0H/Forms/FormMainDisplay.cs
@@ -1059,9 +1059,47 @@ namespace ITC81DB_0H.Forms
         }
         private void timerClientConnectCheck_Tick(object sender, EventArgs e)
         {
-            this.ThreadClientConnected = new Thread(this.ThreadDelegate);
-            this.ThreadClientConnected.Priority = ThreadPriority.Highest;
-            this.ThreadClientConnected.Start();
+            //this.ThreadClientConnected = new Thread(this.ThreadDelegate);
+            //this.ThreadClientConnected.Priority = ThreadPriority.Highest;
+            //this.ThreadClientConnected.Start();
+
+            try
+            {
+               if (this.ParentForm.smartTCPMultiServer.IsStart == true)
+                {
+                    if (this.ParentForm.smartTCPMultiServer.ClientInfoList == null)
+                    {
+                        this.ParentForm.DelegateUISeverStatus(false);
+
+                        // 로그
+                        if (this.ParentForm.IsCommunicationLogOpen == true)
+                            this.ParentForm.smartFileCommunicationLog.WriteString(string.Format("ClientConnectCheck ({0:yyyy-MM-dd HH:mm:ss}): false", DateTime.Now));
+                    }
+                    else
+                    {
+                        this.ParentForm.DelegateUISeverStatus(true);
+
+                        // 로그
+                        if (this.ParentForm.IsCommunicationLogOpen == true)
+                            this.ParentForm.smartFileCommunicationLog.WriteString(string.Format("ClientConnectCheck ({0:yyyy-MM-dd HH:mm:ss}): true", DateTime.Now));
+                    }
+
+                    //this.ThreadClientConnected.Join();
+
+                    //if (this.GCCount > 1800)
+                    //{
+                    //    System.GC.Collect();
+                    //    System.GC.WaitForPendingFinalizers();
+                    //    this.GCCount = 0;
+                    //}
+                    //else
+                    //    this.GCCount++;
+                }
+            }
+            catch (Exception ex)
+            {
+                FormMain.Exception(ex);
+            }
         }
 
         private void pictureBoxIconAlarm_Click(object sender, EventArgs e)
diff --git a/ITC81DB_0H/Version.txt b/ITC81DB_0H/Version.txt
index c5399c1..8b98488 100644
--- a/ITC81DB_0H/Version.txt
+++ b/ITC81DB_0H/Version.txt
@@ -12,6 +12,19 @@
 	±âº»Çü ÄÁº£¾î °íÁ¤¹Ð¼¾¼­ °è·®±â
 */
 
+@ Ver 2.1.2 by CJY
+	- 2023.03.03
+	- Ver 2.1.1 Modify	
+	- FormMainDisplay
+	  1. Ethernet Åë½Å ¾ÆÀÌÄÜ(Connect/Disconnect) Ç¥½Ã¸¦ À§ÇÏ¿© »ç¿ëÇÏ´Â ¾²·¹µå »èÁ¦
+	     -> timer·Î Á¦¾î
+
+@ Ver 2.1.1 by CJY
+	- 2023.03.03
+	- Ver 2.1.0 Modify
+	- °¡ºñÁö Ä÷º¼Ç »ç¿ë
+	  ¾²·¹µå »ç¿ë 30ºÐ¸¶´Ù °¡ºñÁö Ä÷º¼ÇÀ» »ç¿ëÇÏ¿© °´Ã¼ ÇØÁ¦½ÃÅ´
+
 @ Ver 2.1.0 by CJY
 	- 2023.02.21
 	- Ver 2.0.0 Modify
diff --git a/ITC81DB_0H/bin/Release/ITC81DB_2H.exe b/ITC81DB_0H/bin/Release/ITC81DB_2H.exe
index 9ced10f..d9e204e 100644
Binary files a/ITC81DB_0H/bin/Release/ITC81DB_2H.exe and b/ITC81DB_0H/bin/Release/ITC81DB_2H.exe differ
diff --git a/ITC81DB_0H/obj/Release/ITC81DB_2H.exe b/ITC81DB_0H/obj/Release/ITC81DB_2H.exe
index 9ced10f..d9e204e 100644
Binary files a/ITC81DB_0H/obj/Release/ITC81DB_2H.exe and b/ITC81DB_0H/obj/Release/ITC81DB_2H.exe differ