  The significance of the recent finding of the velocity distribution function
of the steady-state Boltzmann equation under a steady heat current obtained by
  Kim and Haykawa (J. Phys. Soc. Jpn. {\bf 72}, 1904 (2003)) is discussed.
Through the stability analysis, it seems that the steady solution is stable.
One of possible applications to the nonequiliburium Knudsen effect in which one
cell at equilibrium is connected to another cell under the steady heat
conduction is discussed. This solution apparently shows that steady-state
thermodynamics proposed by Sasa and Tasaki cannot be used in a naive setup. The
preliminary result of our simulation based on molecular-dynamics for
nonequilibrium Knudsen effect is also presented to verify the theoretical
argument.
