Marci Jarvis, editor of Cat Mews (which is the magazine of the Cats on Stamps Study Unit) has a question with regards to the postage on this envelope. The Korean Stamp Corporation (KSC) sent it to the then editor of Topical Time, Jerry Husak, the founder of the American Topical Association. On it are a total of 260 won of non-cat stamps plus a sheet of cat stamps and cut outs from another sheet of cat stamps.
The question is: what was the actual international rate for this type of envelope at the time?
It is a good but difficult question. Currently I’m doing a research on it but do not get answer yet, Please wait patiently.
No official postal rate change announcement available at present. We can only try to compare from existed covers. International rate to Europe/America/Asia/China might be different. And rates of letter/postcard might be different too.
The registration rate of this cover is 260ch (cat stamps not included). It is reasonably to assume the letter rate is around 130ch and registration rate is 130ch. ( I myself have two 1979 covers to Europe with 130 rate).