  We study the transport properties of one-dimensional (1D) interacting
Fermions through a barrier by numerically calculating the Kohn charge stiffness
constant and the relative Drude weight. We find that the transport properties
of the 1D Hubbard model are quite different from those of the 1D spinless
Fermion model. For example, the presence of the attractive interaction between
electrons in the 1D Hubbard model actually {\em suppresses} the DC conductance,
while a small repulsive interaction {\em enhances} the DC conductance. These
results show that the spin degree of freedom plays an important role in the
transport properties of the 1D interacting Fermion systems.
