Three-dimensional integrated systems that combine large-capacity dynamic random access memory (DRAM) with high-performance processors represent a promising solution to implementing high-performance computing. However, in such configurations stacked DRAM cells will inevitably be exposed to high temperatures generated by the processor, thereby necessitating DRAMs with high refresh rates driven by embedded temperature sensors. In this Letter, a thermally aware refresh-control method that accounts for abrupt changes in temperature and thermal distribution using low-power techniques such as dynamic voltage frequency scaling is proposed. Comparisons with previous systems via single-and eight-core simulations reveal that the proposed method improves efficiency with no additional overhead.