diff --git a/waypoint_manager/scripts/manager_GUI.py b/waypoint_manager/scripts/manager_GUI.py
index b2ea0a9..802bca5 100755
--- a/waypoint_manager/scripts/manager_GUI.py
+++ b/waypoint_manager/scripts/manager_GUI.py
@@ -2,6 +2,7 @@
 import tkinter.filedialog
 import math
 import ruamel.yaml
+import gc
 from pathlib import Path
 from tkinter import messagebox
 from lib.mymaplib import MyMap
@@ -132,6 +133,7 @@
             messagebox.showerror(title="Format error", message="Selected map file is unexpected format.")
             return
         try:
+            del self.mymap
             self.mymap = MyMap(Path(map_path), map_yaml)
         except FileNotFoundError:
             messagebox.showerror(title="Image file is not found", message="\""+map_yaml["image"]+"\"  is not found.")
@@ -166,6 +168,7 @@
             self.menu_open_waypoints()
         else:
             self.plot_waypoints()
+        gc.collect()
         return
     
 
@@ -198,6 +201,7 @@
         if (not "waypoints" in wp_yaml.keys()) or (not "finish_pose" in wp_yaml.keys()):
             messagebox.showerror(title="Format error", message="Selected waypoints file is unexpected format.")
             return
+        del self.waypoints
         self.waypoints = WaypointList(wp_yaml)
         self.finish_pose = FinishPose(wp_yaml)
         self.waypoints_filepath = Path(filepath)
@@ -207,6 +211,7 @@
         self.file_menu.entryconfigure("Save", state=tk.NORMAL)
         self.file_menu.entryconfigure("Save As", state=tk.NORMAL)
         self.popup_menu.entryconfigure("Add waypoint here", state=tk.NORMAL)
+        gc.collect()
         return
     
 
@@ -630,6 +635,7 @@
             self.wp_info_win.destroy()
             self.disp_waypoint_info(self.editing_waypoint_id)
             self.update_title()
+            gc.collect()
             return
         add_btn = tk.Button(sub_win, text="Add", width=5, height=1, font=font, anchor=tk.CENTER, bg="#AFA")
         add_btn["command"] = add_param
@@ -667,6 +673,7 @@
         self.editing_waypoint_id = None
         self.moving_waypoint = False
         self.wp_info_win.destroy()
+        gc.collect()
         return
 
 
diff --git a/waypoint_nav/launch/waypoint_nav.launch b/waypoint_nav/launch/waypoint_nav.launch
index a19d48e..654e341 100755
--- a/waypoint_nav/launch/waypoint_nav.launch
+++ b/waypoint_nav/launch/waypoint_nav.launch
@@ -1,7 +1,7 @@
 <?xml version="1.0"?>
 
 <launch>
-    <arg name="waypoints_file"     default="$(find waypoint_nav)/waypoints_cfg/waypoints.yaml"/>
+    <arg name="waypoints_file"     default="waypoints.yaml"/>
     <arg name="StartFromTheMiddle" default="false"/>
     <arg name="cmd_vel_topic_in"   default="/move_base/cmd_vel"/>
     <arg name="cmd_vel_topic_out"  default="/wp_nav/cmd_vel"/>
diff --git a/waypoint_nav/scripts/tandem_run_manager.py b/waypoint_nav/scripts/tandem_run_manager.py
index 0dc16cd..7182457 100755
--- a/waypoint_nav/scripts/tandem_run_manager.py
+++ b/waypoint_nav/scripts/tandem_run_manager.py
@@ -72,13 +72,14 @@
         try:
             if self.front_range is None:
                 front = round(-msg.angle_min / msg.angle_increment)
-                ran = int(round(np.deg2rad(5) / msg.angle_increment))
+                ran = int(round(np.deg2rad(10) / msg.angle_increment))
                 self.front_range = [front-ran, front+ran]
                 return
             
             if not self.in_tandem_area: return
             
-            min_range = np.min(msg.ranges[self.front_range[0]:self.front_range[1]])
+            sort_ranges = np.sort(msg.ranges[self.front_range[0]:self.front_range[1]])
+            min_range = np.mean(sort_ranges[:5])
             if (not self.stop) and (min_range < self.danger_dist):
                 self.stop_nav()
                 self.stop = True