Complex sentence: Krause advocated for artists' economic and working conditions, becoming a founding member of the Oregon chapter of the Artists Equity Association, and its president from 1954--1955 and 1966--1968; she was national president of Artists Equity from 1969--1970.
Split into simpler sentences: Krause advocated for artists' economic and working conditions, and became a founding member of the Oregon chapter of the Artists Equity Association. She became its president from 1954--1955 and 1966--1968; she was national president of Artists Equity from 1969--1970.