Samsung Electronics and SK Hynix have rejected Korea Electric Power Corp.'s proposal to prepay five years of electricity fees, ending a plan intended to help finance power-grid construction for advanced semiconductor industrial complexes. The companies cited the burden of paying a large sum upfront and uncertainty over whether the semiconductor boom would last five years. The proposed prepayment totaled 25 trillion won, comprising about 20 trillion won from Samsung Electronics and 5 trillion won from SK hynix, with payments spread over one year and interest provided by KEPCO. The state-run utility, which carries more than 200 trillion won in debt and estimates roughly 100 trillion won in grid investment needs, said no other companies received the additional prepayment proposal.