  In this study, the minimum amount of work needed to drive a thermodynamic
system from one initial distribution to another in a given time duration is
discussed. Equivalently, for given amount of work, the minimum time duration
required to complete such a transition is obtained. Results show that the
minimum amount of work is used to achieve the following three objectives, to
increase the internal energy of the system, to decrease the system entropy, to
change the mean position of the system, and with other nonzero part dissipated
into environment. To illustrate the results, an example with explicit solutions
is presented.
