North Korea did request and accept aid from the UN in 1995. It wasn't a food shortage that killed all those people, it was what happened to the food when it arrived. Apparently some of the food went to the military and the government but the rest was sold to other countries for a profit. 5 or 6 humanitarian groups tried to monitor the food distribution but the malnutrition issues never improved.
I found this in a Harvard Law School paper:
THE NORTH KOREAN FAMINE AND FOOD SHORTAGE:

@ Eric: Have you ever lived in North Korea or do you know anyone who has? I still don't know much about what life is like there but apparently not many people do - except the people that still live there and people who escaped. It would be a lot easier to learn more about North Korea if they didn't have closed borders.

@ Hanna: Thanks for the read about Korea in 1990's. Everything helps.