Complex sentence: He co-founded "Dance Music Report" magazine, which ran from 1978 to 1992, and he co-founded the Dance Music Hall of Fame, which existed from 2003 to 2005.
Split into simpler sentences: He co-founded "Dance Music Report" magazine, which ran from 1978 to 1992. Tom co-founded the Dance Music Hall of Fame, which existed from 2003 to 2005.