The dynamic asset allocation problem has its origin in the pioneering work of Merton (1969, 1971) using stochastic control framework and Hamilton-Jacobi-Bellman (HJB) equation. However, a drawback of his approach is the assumption of a deterministic interest rate. In this presentation, I review certain researches mainly by Munk (2010) who applies interest rate models of an affine form with such problems focusing on individuals with constant relative risk aversion (CRRA) utility. This results in explicit investment strategy with hedge variations in interest rates of mixed stock and bond dynamic portfolio problems. A numerical example is also presented to demonstrate some ideas from the theory.