Maybe. An October 21 report in NK Daily says so, with further speculation on this matter on blogs that cover North Korea. Supposedly Kim Jong Un agreed to this with V.V. Putin in their most recent meeting. The number supposedly to be around 800-1,000, with the NK Daily report saying that they have actually been selected. Russia, China, and North Korea somehow agreeing that having these workers work in Russian-occupied annexed portions of Ukraine would not violate sanctions.
I do not know what these workers will supposedly be doing. However, supposedly they will be going in November specifically to the Donbas area. I guess we shall see more about this, a curious development.