There was a clone of the Sinclair Spectrum+ in South Korea called the Samsung SPC-650 that looks identical to original British version with just an extra model number/logo. It even retains the Sinclair and Spectrum names. I believe Samsung was doing some manufacturing for Sinclair in this era, so it's probably an officially re-badged model, unlike the Russian and Eastern European Speccy clones.
But there's very little information about it online. This was in an era before Korea's tech boom and well before the Korean Wave, so there wasn't much cultural contact between Korea and the west in those days. I've even been to Korea a bunch of times in the past twenty years but did't know about these machines to try to find one.
For comparison, there was also an official Spanish version of the Spectrum sold by Investronica in this era and we know it had ROM differences including some text strings and accented characters. There was also a French localized ROM which seems to be official.
So did the Korean version also have localized ROMs, support for Hangul (the Korean writing system), or any other differences besides the extra writing on top?
I was content that the SPC-650 was probably just a Spectrum+ with a different logo, but then I watched this YouTube video which revealed more differences between the Spanish Inves and Sinclair Spectrum+ than just the accent letters and Spanish copyright message. It had a slightly different CPU speed, PAL encoding, and RAM contention between CPU and ULA than a Sinclair Speccy. This makes it seem quite possible that the SPC-650 also could easily have had such differences too even with no changes for the Korean language.
UPDATE part 2:
I just checked and apparently South Korea uses NTSC rather than PAL, so the SPC-650 would have to at least have a different RF modulator too.