Molecular dynamics simulations show that electrophoresis of DNA segments through a nanoscale electrode gap can be controlled by applying appropriate biased voltages in the transmembrane direction. The translocation velocities are dependent on both the DNA molecular weight and nucleotide structure. Application of alternating driving fields results in oscillatory motion of DNA inside the gap. Interruption of the driving field can effectively pause the translocation of DNA segments. Results from this work are useful for designing novel sequencing devices.