The cast-iron factory was considered the most difficult place to work in the entire prison. Christians were usually sent there to work. One Christian working at the cast-iron factory was killed by hanging in a public execution in December 1988 for hiding a friend at his house before he was arrested.

In the spring of 1990, I was carrying a work order to the cast-iron factory in the male prison. Five or six elderly Christians were lined up and forced to deny their Christianity and accept the Juche Ideology of the State. The selected prisoners all remained silent at the repeated command for conversion. The security officers became furious by this and killed them by pouring molten iron on them one by one.