diff --git a/app/src/main/AndroidManifest.xml b/app/src/main/AndroidManifest.xml
index dd56a68421bcff7cb08947d55fd4fe212ad498da..ad1d892b9a89a951a84dd87d83fbc3209ed03870 100644
--- a/app/src/main/AndroidManifest.xml
+++ b/app/src/main/AndroidManifest.xml
@@ -24,7 +24,12 @@
         android:label="@string/app_launcher_name"
         android:roundIcon="@mipmap/ic_launcher"
         android:theme="@style/AppTheme">
+        
+        <activity android:name=".activities.Dday">
 
+        </activity>
+
+        
         <activity
             android:name=".activities.SplashActivity"
             android:launchMode="singleTask"
diff --git a/app/src/main/kotlin/com/simplemobiletools/calendar/activities/Dday.kt b/app/src/main/kotlin/com/simplemobiletools/calendar/activities/Dday.kt
new file mode 100644
index 0000000000000000000000000000000000000000..5ec7b94c949e68c8d89cb483f1aceeb3c247d5d9
--- /dev/null
+++ b/app/src/main/kotlin/com/simplemobiletools/calendar/activities/Dday.kt
@@ -0,0 +1,79 @@
+package com.simplemobiletools.calendar.activities
+
+import android.os.Bundle
+import android.support.v7.app.AppCompatActivity
+import android.content.Intent
+import android.view.View
+import android.widget.EditText
+import android.widget.Toast
+import com.simplemobiletools.calendar.R
+import com.simplemobiletools.commons.extensions.toast
+import  kotlinx.android.synthetic.main.activity_dday.*
+import java.time.Year
+import java.util.*
+
+//class GregorianCalendar()
+//{
+//
+//}
+class Dday : SimpleActivity() {
+
+    override fun onCreate(savedInstanceState: Bundle?) {
+        super.onCreate(savedInstanceState)
+        setContentView(R.layout.activity_dday)
+
+        var CalculDate : String
+        var tz = TimeZone.getTimeZone("Asia/Seoul")
+        var gc = Calendar.getInstance(tz)
+        var t_year = gc.get(Calendar.YEAR).toString()
+        var t_year2 = gc.get(Calendar.YEAR).toInt()
+        var t_month = gc.get(Calendar.MONTH).toString()
+        var t_month2 = gc.get(Calendar.MONTH).toInt()
+        var t_day = gc.get(Calendar.DATE).toString()
+        var t_day2 = gc.get(Calendar.DATE).toInt()
+
+        var gc2 = Calendar.getInstance(tz)
+        var t_mil = gc.timeInMillis
+        var d_mil : Long = 0
+//        CalculDate = year + "," + month + "," + day
+        //toast(CalculDate)
+        //var chooseDate = editText3.selectAll().toString()
+        button3.setOnClickListener {
+            var chooseDate = findViewById<View>(R.id.editText3) as EditText
+            var chooseDate2 = chooseDate.text.toString()
+            //Toast.makeText(this,chooseDate.text, Toast.LENGTH_SHORT).show()
+            //toast(chooseDate2)
+            var tmp = chooseDate2.split("/")
+            var tmp_year = tmp[0].toInt()
+            var tmp_month = tmp[1].toInt()
+            var tmp_day = tmp[2].toInt()
+            gc2.set(tmp_year, (tmp_month-1), tmp_day)
+            //toast(tmp_year.toString())
+            d_mil = gc2.timeInMillis
+            //toast(t_mil.toString())
+            var dif_time = (d_mil-t_mil)/(24*60*60*1000)
+            var asd = dif_time.toInt()
+            //toast(tmp_month.toString())
+
+            toast("D-day: " + asd.toString())
+        }
+        //var d_mil = gc2.timeInMillis
+        var dif_time = (d_mil-t_mil)/(24*60*60*1000)
+        var asd = dif_time.toInt()
+
+
+
+//        var tmp = arrayOf(chooseDate.split("/"))
+
+//        toast(chooseDate)
+
+//        calendarView.setOnDateChangeListener { calendarView, i, j, k ->  }
+
+
+
+
+    }
+
+
+
+}
diff --git a/app/src/main/kotlin/com/simplemobiletools/calendar/activities/MainActivity.kt b/app/src/main/kotlin/com/simplemobiletools/calendar/activities/MainActivity.kt
index 73c39c739b42ca90759fec529c6dc0d3ce5131ed..825de8c3a2281058b85c8fed77dc2aa1e588ef82 100644
--- a/app/src/main/kotlin/com/simplemobiletools/calendar/activities/MainActivity.kt
+++ b/app/src/main/kotlin/com/simplemobiletools/calendar/activities/MainActivity.kt
@@ -67,7 +67,6 @@ import android.util.Log
 import java.io.IOException
 
 class MainActivity : SimpleActivity(), RefreshRecyclerViewListener , com.google.android.gms.location.LocationListener{
-
     //for gps module
     private var REQUEST_LOCATION_CODE = 101
     private var mGoogleApiClient: GoogleApiClient? = null
@@ -101,7 +100,12 @@ class MainActivity : SimpleActivity(), RefreshRecyclerViewListener , com.google.
         // You can now create a LatLng Object for use with maps
         // val latLng = LatLng(location.latitude, location.longitude)
     }
-
+//    init {
+//        button_Dday.setOnClickListener {
+//            val intent_dday = Intent(button_Dday.context, Dday::class.java)
+//            button_Dday.context.startActivity(intent_dday)
+//        }
+//    }
     @SuppressLint("MissingPermission")
     private fun getLocation() {
         mLocation = LocationServices.FusedLocationApi.getLastLocation(mGoogleApiClient);
@@ -145,6 +149,14 @@ class MainActivity : SimpleActivity(), RefreshRecyclerViewListener , com.google.
             launchNewEventIntent(currentFragments.last().getNewEventDayCode())
         }
 
+
+        button_Dday.setOnClickListener {
+
+            toast("click!!!!!")
+            val intent_dday = Intent(this, Dday::class.java)
+            startActivity(intent_dday)
+        }
+
         storeStateVariables()
         if (resources.getBoolean(R.bool.portrait_only)) {
             requestedOrientation = ActivityInfo.SCREEN_ORIENTATION_PORTRAIT
@@ -165,6 +177,8 @@ class MainActivity : SimpleActivity(), RefreshRecyclerViewListener , com.google.
         if (config.caldavSync) {
             refreshCalDAVCalendars(false)
         }
+
+
     }
     @Synchronized
     private fun buildGoogleApiClient() {
@@ -347,6 +361,7 @@ class MainActivity : SimpleActivity(), RefreshRecyclerViewListener , com.google.
             R.id.export_events -> tryExportEvents()
             R.id.settings -> launchSettings()
             R.id.about -> launchAbout()
+//            R.id.button_Dday ->
             android.R.id.home -> onBackPressed()
             else -> return super.onOptionsItemSelected(item)
         }
diff --git a/app/src/main/res/layout/activity_dday.xml b/app/src/main/res/layout/activity_dday.xml
new file mode 100644
index 0000000000000000000000000000000000000000..8b9a74b7f6323469a164b14dbe935a8b2074a3e3
--- /dev/null
+++ b/app/src/main/res/layout/activity_dday.xml
@@ -0,0 +1,46 @@
+<?xml version="1.0" encoding="utf-8"?>
+<android.support.constraint.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
+    xmlns:app="http://schemas.android.com/apk/res-auto"
+    xmlns:tools="http://schemas.android.com/tools"
+    android:layout_width="match_parent"
+    android:layout_height="match_parent"
+    tools:context=".activities.Dday">
+    <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
+        xmlns:app="http://schemas.android.com/apk/res-auto"
+        xmlns:tools="http://schemas.android.com/tools"
+        android:layout_width="match_parent"
+        android:layout_height="match_parent"
+        android:orientation="vertical"
+        tools:context="com.kotlin_test.Activity.FunctionActivity">
+        <LinearLayout
+            android:layout_width="match_parent"
+            android:layout_height="50dp"
+            android:orientation="horizontal"
+            android:weightSum="4">
+
+            <EditText
+                android:id="@+id/editText3"
+                android:layout_width="wrap_content"
+                android:layout_height="wrap_content"
+                android:layout_weight="1"
+                android:ems="10"
+                android:inputType="date"
+                android:text="입력: 예) 1994/09/16" />
+
+            <Button
+                android:id="@+id/button3"
+                android:layout_width="wrap_content"
+                android:layout_height="wrap_content"
+                android:layout_weight="1"
+                android:background="#aad3e5"
+                android:text="입력" />
+        </LinearLayout>
+
+        <CalendarView
+            android:id="@+id/calendarView"
+            android:layout_width="match_parent"
+            android:layout_height="wrap_content" />
+
+    </LinearLayout>
+
+</android.support.constraint.ConstraintLayout>
diff --git a/app/src/main/res/layout/activity_main.xml b/app/src/main/res/layout/activity_main.xml
index b8790ad08e00cf639a0596fb62985cfaf6fce2d0..af65bed0ba173b768bc05d4bbb6cdc6d0d57a594 100644
--- a/app/src/main/res/layout/activity_main.xml
+++ b/app/src/main/res/layout/activity_main.xml
@@ -8,7 +8,17 @@
     <FrameLayout
         android:id="@+id/fragments_holder"
         android:layout_width="match_parent"
-        android:layout_height="match_parent" />
+        android:layout_height="match_parent" >
+
+        <Button
+            android:id="@+id/button_Dday"
+            android:layout_width="wrap_content"
+            android:layout_height="wrap_content"
+            android:layout_marginLeft="20dp"
+            android:layout_marginTop="455dp"
+            android:background="#97f500"
+            android:text="DDAY" />
+    </FrameLayout>
 
     <com.simplemobiletools.commons.views.MyFloatingActionButton
         android:id="@+id/calendar_fab"