Need to frequently visit china from south Korea : how to get a 6 month visa ?

Hello, I'm a french citizen working in South Korea (permanent resident). The Company I work for is starting a project in China and want me to be involved. Therefore, I will have to frequently travel from Korea to China in the coming 6 months. How can I get a 6 month one for business purpose ? For your information, my company is a multinational and already has several legal entities in China which can support me to get invitation letters if needed).