In the 1970s, television sets started to spread among the general population, and dramas switched from portraying dramatic historical figures to introducing national heroes like Lee Sun-shin or Sejong the Great. Contemporary series dealt with personal sufferings, such as Kim Soo-hyun's influential "Stepmother" (새엄마, Saeeomma), aired by Munhwa Broadcasting Corporation (MBC) in 1972 and 1973. As technology and funding was limited, Korean channels could not make series in resource-heavy genres like action and science fiction; American and other foreign series were imported instead.