Study to Confirm the Safety and Efficacy of CJ-12420 in Patients With Erosive Esophagitis

CJ-12420 100mg tablets will be orally administered, once daily, for up to 8 weeks. For subjects whose erosive esophagitis is not endoscopically healed at Week 4, subjects will receive additional 4 week treatment of CJ-12420 100mg.

Esomeprazole 40mg tablets will be orally administered, once daily, for up to 8 weeks. For subjects whose erosive esophagitis is not endoscopically healed at Week 4, subjects will receive additional 4 week treatment of Esomeprazole 40mg.

CJ-12420 50mg tablets will be orally administered, once daily, for up to 8 weeks. For subjects whose erosive esophagitis is not endoscopically healed at Week 4, subjects will receive additional 4 week treatment of CJ-12420 50mg.