I spotted this on an archived Delcampe sold file of a highly-questionable Dealer located in France. In my fifty-five-plus years collecting, researching and specializing in Empire Korea material I have never seen, or heard, of this item. This sold for 300 Euros. Apparently, it is the same item that was discussed in this article on the Korea Stamp Society’s webpage.
I would note that many of the items this French Dealer is currently offering under U.S. Postal History are fake philatelic material; not marked fake, with a starting auction price of 1 Euro — which speaks for itself. As an example: a early print, deep, rich-black, bi-sected US Scott #2, on a pristine 1850 folded cover, tied by a single grid cancel (likely a Fournier fake), starting at 1 Euro!