I love the Korean target face. I think it adds to the flamboyance and style that makes our sport so different from standing 70m from a target and shooting endless identical arrows at a boring circular target.
Unfortunately, much of the world is not set up for the Korean target. We were very lucky that WHAF, in their ongoing kindness and support, sent us some beautiful targets ready for our national championships last year. We had bosses of the correct size and everything went well. Many people do not have ready access to big square target bosses, even if WHAF were to send faces to everybody who wanted them. In particular, we were informed by our American friends that almost all bosses over there are circular and either 80cm or 120cm (the two most common sizes for FITA archery targets). Pythagoras told us many centuries ago that the corner of a 90cm Korean target face is some 63.6cm from the centre, whereas the edge of a 120cm boss is only 60cm from the centre.
This caused us some difficulty when establishing a grading system. Clearly for a system to have any meaning you had to be comparing like with like. If one person has a bigger target than another then how do you compare their scores? We needed to have either everybody using the same scores or a way of comparing scores on different targets accurately and fairly.
The general feeling was that in America, and possibly many other places, use of the Korean target face would restrict the number of people able to use the system we were trying to establish. We had to allow people to use the ubiquitous FITA target faces.
My feeling was that this was not a major problem. It should not be beyond the wit of man to devise a system of converting zones 1-5 in a square of known edge length to zones 1-5 in a circle of known diameter. It should simply be a matter of working out how much bigger the square is than the circle. Each zone should decrease proportionately since they are marked by a given fraction of the edge/diameter.
As it turns out, this cannot be done after all. The Korean target faces do not have zones of equal edge length. Measuring from the centre towards one edge, the 5 zone is 12cm, 4 and 3 are 7cm each and 2 and 1 are 9cm each. A direct comparison is beyond my abilities.
I am still pondering ways to get around this problem nothing in the whole system has caused me more mental turmoil than abandoning the Korean target face. If anyone can think of a mathematical model that will allow a direct comparison then please get in touch. In the alternative I intend to keep a close eye on scores shot under each system in the hope of working out a rough (but as accurate as possible) conversion based on a mixture of geometry and statistics. I will not give up those wonderful targets without a fight!