The article North Korea 'executes three people found guilty of cannibalism' reports:
Some of the 230 defectors interviewed by the Korean Institute for National Unification told of witnessing executions of people who had either eaten or sold human flesh.
and describes three specific executions.
Also, at the at the 2004 5th International Conference on North Korean Human Rights & Refugees in Poland, one of the 5 defectors to testify was Kim Hyeok and, as reported in Defectors Tell of Cannibalism, Torture, Lost Families>
22-year-old Kim Hyeok, who was born in Cheongjin, North Hamgyeong Province, lost his parents at an early age and was raised in an orphanage. When he was teenager, he began crossing back and forth across the Chinese border in order to make a living. At the age of 16, he was caught and forced to spend time in prison. While he was in prison, he saw an engineer -- a university graduate -- brought in on charges of eating children. "At first, I thought, 'How can a person eat other people?' But as I starved, I began to experience hallucinations in which people appeared as beasts, too. I became extremely frightened of myself."
Also, as reported by the International Business Times, the Caleb mission obtained a copy of a 791 page North Korean law enforcement manual that goes through 721 crimes/situations. 5 of the 721 involve cannibalism, for example:
One case involved a guard named Lee Man-sung, who killed his roommate with an axe when he was sleeping, ate part of the corpse and then sold the rest on the market describing it as lamb meat.
Also, form the LA Times 12/25/2000 article Mr. President, Don't Shake Hands With Kim Jong Il
Clinton should know about Jang Gil-Su, a 15-year-old who risked being shot as he escaped to China. He and 14 members of his family are in hiding there, desperate to avoid the Chinese police who return North Korean refugees to face punishment, even death.
Jang's is a chilling case. Over the last three years, he has drawn and annotated 120 pictures of everyday life in his country. The Center for Saving Gil-Su's Family, headed by Prof. Dongkyu Kim of Korea University, gave these drawings to me, and they have been published in Seoul in book form. They show families eating anything to survive: pine bark, snakes, rats. A man at a market stall--"Man selling human flesh at a farmers market in Hoeroung city," writes Jang.
Human flesh? "Saram hoki" (cannibalism), other refugees tell us. All of the North Koreans we interviewed knew about it. Gil-Su's picture of a dismembered child in a cooking pot says more than any of the numbing statistics. "There are many cases of killing people and eating the flesh," a refugee told us. "You eat it, without knowing it's human flesh," a teenage orphan added. "You're so hungry, you just eat it."