Cardenas-Barron (2009) minimizes the annual total relevant cost
to find the economic production quantity with rework process at a manufacturing system and assumes that
is convex. So, the solution
satisfying the first-order-derivative condition for
will be the optimal solution. However, this paper indicates that
does not necessarily exist although
is convex. Consequently, the main purpose of this paper is two-fold:
This paper tries to develop the sufficient and necessary condition for the existence of the solution
satisfying the-first-derivative condition of
.
This paper tries to present a concrete solution procedure to find the optimal solution of
.
