Complex sentence: Ulsan is currently the home of the world's largest automobile assembly plant operated by Hyundai Motor; the world's largest shipyard, operated by Hyundai Heavy Industries; and the world's second largest oil refinery, owned by SK Energy.
Split into simpler sentences: Ulsan is currently the home of the world's largest automobile assembly plant, operated by Hyundai Motor. The city also has the world's largest shipyard, operated by Hyundai Heavy Industries; and the world's second largest oil refinery, owned by SK Energy.