SEOUL — For the first time in 23 years, a new auto plant has begun operating in South Korea. The facility will be operated by Gwangju Global Motors (GGM), a newly established company led by the city government of Gwangju in the southwest. It was created with capital from Hyundai Motor and others, and will specialize in the contract manufacturing of small cars. Gwangju wants to attract industry and create jobs, and Hyundai was looking for a plant to which it could outsource production at low cost.