These are a dangerous nonmemory resident parasitic viruses. It seems that they were created by using some buggy virus-creation kit.
They search for .COM or EXE files, then write themselves to the end of the file. They have lot of bugs and often halt the computer. "Yukom.402" infects EXE files as COM, and these files halt the computer being executed. Depending on the system date they manifest themselves by some sound effect (noise?). They contain the text string:
"Yukom.389": My Name is Yukom Pete and I am a Virus
"Yukom.392": My Name is Yukom Pete and I am your Virus
"Yukom.402": My Name is Yukom Pete and I am your unfriendly Virus
