The purpose of this study is to evaluate the efficacy and safety by comparing prevention of recurrent peptic ulcer in low-dose aspirin users between PMK-S005 and Placebo.

Inclusion Criteria:

• Male or female over 19 years of age
• Accompanied by hypertension, diabetes, ischemic heart disease, arrhythmia, dyslipidemia patients who are required to continuous administration of low-dose aspirin(100mg)
• Patients who get Modified Lanza Score (MLS) 0 in screening period according to endoscopic findings
• Patients who have stomach or duodenal ulcer scar in screening period according to endoscopic findings. But, the cases that scars caused by other disorders or endoscopic treatment are excluded
• Patients who have no digestive symptoms(except for mild physconia, abdominal pain, diarrhea and vomit, nausea-vomiting) in screening period
• Signature of the written informed consent

Exclusion Criteria:

• Within 4 weeks prior to screening period, patients who continuously take aspirin or NSAIDs
• Patient who has hypersensitivity to PMK-S005 and aspirin components or is banned to use them
• Patients who had a abdominal surgery that affect gastrointestinal motility (Except appendectomy and hysterectomy), But, patients who had enterectomy is excluded regardless of the time period
• Patients who are judged by investigator that they have other upper gastroesophageal disease, active/healing-stage peptic ulcer, digestive malignant tumor or Barrett's esophagus
• Patients with Irritable Bowel Syndrome (IBS), Inflammatory Bowel Disease (IBD), Ulcerative Colitis, Crohn's disease, Zolinger-Ellison syndrome
• History of esophagus, liver, pancreas, stomach, colorectal cancer or malignant tumors within 5 years
• History of malabsorption within 3 months prior to screening period
• Patients who have been taken drug that affect the validity within 2 weeks before beginning of the clinical test
• Patient who is needed continuously to take antithrombotic agents , anti- coagulant , anti- choline agents, prostaglandins , mucosal protective agents , methotrexate, antidepressants , iron treat agents during clinical test.
• Patients with clinical meaningful laboratory test results
• Known alcohol and/or any other drug abuse or dependence
• Pregnant or lactating women
• Women planning to become pregnant
• Within 1 month, patients who have been taken other clinical test drug
• Patients who are judged by investigator that participation of the study is difficult