Clinical Trial to Assess the Efficacy and Safety of YYD601 in the Treatment of Esophageal Reflux Disease (ERD)

Inclusion Criteria: * A man or woman over 20 years old less than 70 years old. * A man or woman who has experienced symptom (heartburn and acid regurgitation) within 7 days before Visit 1, meet below 1) or 2) criteria, who has been made diagnosis as Erosive esophagitis(LA grade A\~D) measured through the endoscopy which is carried out within (-2W±D2) \* Symptom (heartburn and acid regurgitation) is confirmed by RDQ. 1. Experienced above 2 days in 1 week, Heartburn of acid regurgitation above the weakness. 2. Experienced above 1 day in 1 week, Heartburn of acid regurgitation above the middle. * A man or woman who has a full understanding of this clinical trial through the detailed explanation, agree in writing to participate in this trial. Exclusion Criteria: * Who has hyper sensitivity reaction about other drugs, ingredients, components of investigator product or compound of benzimidazole. * Who has NERD * Who get a diagnosis as a IBS within the last 3 months. * Who have taken gastric acid secretion inhibitors including PPIs within 2 weeks before the endoscopy. * Who have taken drugs about reflux esophagitis (H₂-receptor inhibitor (H2RA) Prostaglandin(PG), Antacid, Prokinetic acid etc.) above 2 times as an usual dose. (\* refer to the Concomitant medication in text.) * Who has been experienced the disease affecting the esophagus(Eosinophilic esophagitis, esophageal varices, cirrhosis, Virus or Fungal infection, Esophageal stricture, primary esophageal motility disorder and gastrointestinal bleeding). Or who has a history of radio therapeutics, freeze treatment about the esophagus. * Who has clinically significant abnormal result of ECG. * Abnormal result of Major arrhythmia, Multifocal PVS, 2 AV-blcok etc. * Who has the Schatzki near the LES(lower esophageal sphincter) except the Barret's esophagus.