Welcome to the forums. The serial number format is consistent with that of Japanese manufacturer Miki. It was manufactured during a calendar year ending in '9' and based on the frame characteristics, 1979 would be most appropriate. There is some disagreement over whether the 3rd character represents a fortnight on month, making it either mid-calendar year or end of calendar year manufacture. In the latter case, it would be a 1980 model, as opposed to 1979.

Miki is best known in the USA for manufacturing some of the mid and high end Centurion and Sekai models during the late 970s to early 1980s. While they typically didn't build entry level models, your bicycle is reminiscent of a Centurion Le Mans of the era. I don't know what brands they might have manufactured for the Ukrainian market. I'd appreciate a photo of the head badge, as I'm not sure if this is the same Union brand that we saw in the USA. Thxs for posting. Photo assist...