The purpose of this study is to contribute to the cost competitiveness of domestic power generation companies against uncertainties such as raw material price volatility. Specifically, we created and analyzed scenarios based on how fluctuations in demand changes in inventory holdings, how ship size decision affects the cost of inventory, and the variations of transportation costs influences the amount of raw material to be purchased by the region. To derive the results reflecting the reality, we based on the existing optimization model on minimizing the total cost and by using the real data of a power generation company in Korea. Technically we applied a rolling horizon technique and estimated the effects of rising temperature on the amount of raw materials to be imported.