I had to do some research - the history of Korean coinage is just confusing and sad in many sense. The reference that I just used is from "The History of Korean Money - The Bank of Korea (1969?)"
With the early cash coins, people had a general distrust with their own coinage as they have known that Korean mints have melted down good quality 'copper' coins and debased them with cheaper brass coins. Some were even debased with iron. At its worst, it is estimated that one old coin was melted down to make THREE coins. Of course, the general public was not impressed with this.
To solve this issue of 'bad' money, the King attempted to circulate silver coins by importing Chinese sycee to stabilize the currency issue. This did not work as traders hoarded all these coins and sold them overseas as the price of silver increased. Of course, this meant that silver hoarders literally killed their circulation.
In 1884, the Korean government appointed a German - Mollendorf to oversee the mint operation. More can be read here.
https://coinweek.com/dealers-compan...ern-coinage/Some attempts were made to circulate machine struck coins in 1888 (5 mun, 10 mun and 1 hwan struck in Seoul) but this proved to be unpopular and was discontinued. In 1892, minting machines, planchets and even technicians were imported from Japan. While these coins were supposed to be of reasonable success - international politics had to come in play. This will not be the first and last of it.
At that time, Chinese Emperor Yuan Shi Kai strongly objected to the wording "Great Chosen" as he feared the Japanese influence. He had good reason to be. The First Sino Japanese war in 1894 - 1895 ended up to be in China's loss. Hence you can see why in between the coins struck in 1892 to 1896, it just seemed Incheon Mint could not decide whether to go with "Chosen" or "Great Chosen". Or it might be the Japanese mint officers snubbing China.
In between 1893 and 1897, as no silver coins were struck and large amount of nickel copper coins were issued. A large amount of silver and Mexican dollar flowed into the country. The general public had good reasons to be worried as they feared a repeat of being defrauded with 'cheap base metals'. In 1897, the matter was made worse as Japan adopted the gold standard and the silver Japanese yen was no longer legal tender. To avoid major panic, silver yang was issued in 1898 and countermarked yen coins (now no longer legal tender in Japan) became the choice for circulation.
As described by Lembafc, the Russo-Korean bank was setup in Korea for a good reason. Russia was started to be concerned with the Japanese influence as Japan started to make a big headway in China. Now the real question is this - where were these coins struck? St. Petersburg? I cannot see how these coins were struck in Korea as Japanese mint officers were in charge of operation. I personally believe they were struck in St. Petersburg in 1899. Sensing the negative intentions of the Russians, the Japanese paired up with the British (it's ally back then) had a military demonstration in Incheon Habour. Three months after the establishment of the Russo-Korean Bank, Alexeyev got recalled.
Now this is where things get MORE complicated than it needs be. Just when you think everything is all good and sorted - no it does not end there. I did not know this either until right now. In 1901, a pro Russian figure was appointed as the Minister of Treasury, Yi Yong-ik. With Russian support, he planned to get rid of the Japanese silver yen and issue pro Russian coinage of 7 different denominations: 20 hwan, 10 hwan, 5 hwan in gold, half hwan, 20 chon in silver, 5 chon in nickel copper and 1 chon in copper. (WOW) These were actually struck in Korea. A small batch did get produced but needless to say, was confiscated and melted down by the Japanese Army. Not all denominations have survived.
In 1904, the Japanese decided to shut down mint operations in Korea. Lack of funds is the most likely reason but perhaps the Japanese didn't find the 1901 issue to be entertaining and was determined not to allow Korea to strike coins ever again.
I'll leave it for now. This is a lot more intense than I expected!