Hello all! I did some air testing with my Fisher F22 and now have a laminated cheat sheet attached to my machine. Below is the cheat sheet of each Korean coin and the number it displays on the F22.
500 Won: 37-38
100 Won: 35
50 Won : 37-38 (1st and 2nd editions ring up the same)
10 Won (1966-1969 and red 1970): 61-63
10 Won (1970-1982): 51-52
10 Won (1983-2006): 55-56
10 Won (2006-Present): 66-67(if flat), 68-72(if on its side)
5 Won (1966-1969): 61-63
5 Won 1970 (red): 60-61
5 Won (1970-1982): 47-48
5 Won (1983-Present): 49-50
1 Won (1966-1967): 44-45
1 Won (1968-Present): 64-66
10 Hwan (1959-1961): 61-62
50 Hwan (1959-1961): 57-59
100 Hwan (1959-1961): 36-37
Soju caps: ~54 (in same range as a large number of 10 won coins)
For reference, Joseon dynasty Sangpyeong Tongbo coins ring in a very large range from 20-53+ and differ per mint. That will require a completely differnt post if anyone is interested. Also the very common 1/4 Yang from the late 1890s to the very early 1900s comes in at a sweet 34.
Let me know if this helps any of you detecting in Korea.