This looks different from the usual cash coins I find. I think I see the number 2 on the side that usually has the mint location. What do I have here?
I'd have to look up the exact variety, but if looks like a Korea 2 Mun to me. There were many different issuers authorized for Korean cast coins! I think it was essentially a money-making privilege doled out by the government without much care for the money supply. Maybe that's why late-Dynastic Korea had so much inflation... Here's some of mine, but I inexplicably didn't photograph the reverse. "Korea 2 Mun 1695-1742"
OK, I looked around a bit more. I think the reverse reads 捻 (Chong) and means it was issued under the "General Military Office". The number at the bottom seems to be the series number, not the denomination. So it's probably a 1 mun, 1757. Here's a link showing the crescent-shaped mark on the left. If you scroll down you can see it was issued in series 1-10 with different Chinese numerals at the bottom for each. Here's your original coin in standard orientation for comparison.
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I agree with Eidolon that it's a "총융청" (Chongyungcheong) General Military Office. I'm using the Op den Velde and Hartill book (2013), and I cannot see a 1-Mun coin with a crescent on the left. However, using my 2022 Daegwangsa catalog, I think I found this coin on page 52. The DK (Daegwangsa catalog) number is 8.6-42, same mintmark (Chong) and dated (approx.?) 1836.
