The largest movable mold EMS developed by POSCO in collaboration with Daineli-Rotelec for improving internal quality of a large CC bloom is being used at a large size bloom caster of POSCO since 2011.Internal quality of carbon steel CC bloom of 700×700 mm~2 section size with the mold EMS was much improved compared with without the mold EMS.Equiaxed zone ratio increased from 50%to 100%and the grain of equiaxed structure became globular and fine.Top shrinkage was also much reduced by applying the movable mold EMS. The largest movable mold EMS developed by POSCO in collaboration with Daineli-Rotelec for improving internal quality of a large CC bloom is being used at a large size bloom caster of POSCO since 2011. Internal quality of carbon steel CC bloom of 700 × 700 mm ~ 2 section size with the mold EMS was much improved compared with without the mold EMS.Equiaxed zone ratio increased from 50% to 100% and the grain of equiaxed structure has globular and fine.Top shrinkage was also much reduced by applying the movable mold EMS .