Complex sentence: The issues of speed and energy associated with the T-15 were addressed by Professor Boris M. Malinin, the dean of Soviet Submarine Designers in 1947 when he claimed that the resulting inefficiencies of the weapon defeated the purpose of a submarine.
Split into simpler sentences: The issues of submarine speed and energy needs associated with the T-15 were addressed by Professor Boris M. Malinin, the dean of Soviet Submarine Designers in 1947. He claimed that the resulting inefficiencies of the weapon defeated the purpose of a submarine.