I made multiple different trials. Major change is adding trigrams and changing codes a bit for the circles.

I realized that I was using two different references for the flag. Both are correct; one I used for my second version, it shows ratios for the measurment, using something like 1, (1/2), (1/4). The one Dr. Proctor shared with me was using bigger numbers for the measurement such as 12, 24, and 6.
When I realized that the taeguk pattern is much bigger than it should be when I draw 건(gun), I realize that my code needs to be revised to make my circles smaller.
I had to think of the usage of 'wdith' and 'unit' in the code. It took a while for me to figure things out.
I did not want to change the fuction Dr. Proctor created, so I make adjustment of my previous work.
I think of how this work would related to math learning or appying math skills. I used arc tangent to figure the angle I need to make for a turtle. I use the center of the big circle as one of a vertex of a right triangle and use the measurement of right trangle (with base 36 and height 24). That's how I got 33.69 degrees, and this was important information for me to move my turtle to the starting point of Dr. Proctor's Trigram fuction.
A strategy I used consistently is that making lots of sketchy work on the piece of paper.
I think of a couple different ways to do math using Taegukgi for elementary or middle schooler. So far just ideas, but I am hoping I can make actual lesson plans and use as an example for an culturally relevant lessons in math class. We can start with korean Flag, but I am sure there are many different flags we can try as well.
I have not been able to make any motions in this drawing project. I wonder if I can make the flag to be waved or try to make the flag looking like fluttering in the wind, but I am pretty sure it requires much more advanced skills.
I am sure I probably have many typos and mistakes here, but somehow this black screen for code makes me care less about me making typoes and errors. haha, I don't know why,  but typing here feels very different from typing on word or google doc.
This activity makes me feel much more comfortable to do 'try and see' without having a clear plan. I did many small changes and see how little changes I made worked or not worked.

drawing old.py

@@ -0,0 +1,28 @@
+# drawing.py
+# ----------
+# By Seoyeon___________
+#
+# (second trial_use fuction_center of Korean flag with two colors)
+
+from turtle import * 
+def tadpole (radius,colour):  # "I name half of yinyang shape tadpole"
+    color("black", colour)   # British spellings for colour to distinguish this from color" 
+    begin_fill()
+    circle(radius,180)  # half circle
+    circle(-radius,180)  # another half circle
+    circle(-radius*2,180)
+    end_fill() 
+
+right(15)
+left(90)
+tadpole (40, "red")
+right(90)
+penup()
+forward(160)
+pendown()
+left(90)
+tadpole (40, "blue")
+
+input()
+
+

drawing.py

@@ -2,27 +2,62 @@
 # ----------
 # By Seoyeon___________
 #
-# (second trial_use fuction_center of Korean flag with two colors)
+# (Final Version_adding trigram, adding color code)
 
 from turtle import * 
-def tadpole (radius,colour):  # "I name half of yinyang shape tadpole"
+from trigram import draw_trigram
+def tadpole (width,colour):  # "I name half of yinyang shape tadpole"
     color("black", colour)   # British spellings for colour to distinguish this from color" 
     begin_fill()
-    circle(radius,180)  # half circle
-    circle(-radius,180)  # another half circle
-    circle(-radius*2,180)
+    circle(1/2 * width,180)  # half circle
+    circle(-1/2 * width,180)  # another half circle
+    circle(-1 * width,180)
     end_fill() 
 
-right(15)
+width=100
+penup()
+forward(1/2 * width)
+right(90)
+forward(1*width)
 left(90)
-tadpole (40, "red")
+left(90)
+circle(-2 * width, 33.69)
+pendown()
+
+tadpole (width, "#CD2E3A")
 right(90)
 penup()
-forward(160)
+forward(2* width)
 pendown()
 left(90)
-tadpole (40, "blue")
+tadpole (width, "#0047A0")
 
+left(90)
+penup()
+forward(1/2 * width)
+pendown()
+
+draw_trigram ([True, True, True], width)
+
+
+right(180)
+penup()
+forward( (6+12+12+6) / 12 * width)
+draw_trigram ([False, False, False], width)
+
+left(90)
+penup()
+circle(18 /12 * width, 33.69*2)
+right(90)
+draw_trigram ([False, True, False], width)
+
+right(180)
+penup()
+forward( (6+12+12+6) / 12 * width)
+draw_trigram ([True, False, True], width)
 input()
 
 
+
+
+

drawing_old.py

@@ -0,0 +1,28 @@
+# drawing.py
+# ----------
+# By Seoyeon___________
+#
+# (second trial_use fuction_center of Korean flag with two colors)
+
+from turtle import * 
+def tadpole (radius,colour):  # "I name half of yinyang shape tadpole"
+    color("black", colour)   # British spellings for colour to distinguish this from color" 
+    begin_fill()
+    circle(radius,180)  # half circle
+    circle(-radius,180)  # another half circle
+    circle(-radius*2,180)
+    end_fill() 
+
+right(15)
+left(90)
+tadpole (40, "red")
+right(90)
+penup()
+forward(160)
+pendown()
+left(90)
+tadpole (40, "blue")
+
+input()
+
+

test_trigram.py

@@ -8,5 +8,5 @@ from trigram import (
 )
 
 left(90)
-draw_trigram(리, 200)
+draw_trigram([True,False,False], 200)
 input()