"그녀는 확고한 자신의 예술세계를 가진다."
She has her own firm theory of art. //Is this right?^^;
Does it mean art and the people who make it?
The "예술세계" means 예술사상, 예술이론 or 예술개념.
theory, concept, idea - theory of art, ...
Can it refer to one segment of the people who make art?
Artists have their theory of art.
Can it refer to the works of an individual artist?
It's a kind of an idea about art.