The Korea Railroad Corporation, branded as KORAIL, is South Korea's national rail operator. Together with Seoul Metro and Incheon Metro, they share the operation of most of the Seoul Metropolitan Subway system. While some lines are operated exclusively by one of these companies, certain lines are run in a shared system by two operating companies. For two of these shared lines between Korail and Seoul Metro, the vehicle manufacturer Woojin Industrial Systems delivered new vehicles. The new generation of KORAIL Series 3000 and 311000 vehicles entered passenger service on Line 1 and Line 3 (Ilsan-Line) to replace older vehicles.

Due to its characteristic and sleek frontend design, the vehicle has already found the nickname “Cube” (큐브) amongst rail enthusiastic Seoulites.