Only get Single entry visa for entry China

I'm South Korea passport holder, i will giong Shanghai from Singapore for taking cruise to Okinawa on 10/3 and coming back to shanghai again on 16/3, but now i only have single entry, so i will no any visa while i come back from Okinawa, my flight from Shanghai to Singapore is 16/3 also, so in this case can i doing 24 Hours free Transit?