IIRC this is actually the main purpose of one of these, they run slightly warmer to keep fermentation going while still being cold enough to preserve. Traditonal kimchi was stored underground so maybe a temp close to those conditions.
[1] Example here https://www.lge.co.kr/support/product-manuals?title=manual&m..., see table on page 10, it's between -0.7°C and -1.7°C for kimchi.