Evaluation of symptom relief in functional dyspepsia patients with PPI-resistant Gastroesophageal reflux disease -Acotiamide + standard-dose PPI vs double-dose PPI ; Prospective multi-center randomized study-

INTERVENTION: Acotiamide 300mg/day and Rabeprazole 10mg/day Rabeprazole 20mg/day CONDITION: Functional Dyspepsia patients with PPI‐resistant Gastroesophageal reflux disease PRIMARY OUTCOME: Comparison of responder rate defined as >=50% decrease in the Izumo Scale between groups SECONDARY OUTCOME: 1) Responder rate defined as >=50%; decrease in the total score of 3 upper abdominal symptoms (heartburn, gastralgia, and epigastric fullness of the Izumo Scale (comparison between groups); 2) Change in each symptom score (total/3 upper abdominal symptoms/heartburn/gastralgia/epigastric fullness/constipation/diarrhea) of Izumo Scale; a) Comparison of change in score between groups; b) Comparison of change in score between pre‐dose and post dose; c) Sub‐analysis of above a) and b) by patient demographics (including gender, age, H. pylori and BMI); 3) Change in revised F scale score (total score/FD score/GERD score); a) Comparison of change in score between groups; b) Comparison of change in score between pre‐dose and post dose; c) Sub‐analysis of above a) and b) by patient demographics (including gender, age, H. pylori and BMI); 4)Adverse event INCLUSION CRITERIA: 1) Patient with the following symptoms ( a) and b)) even if they take usual dose PPI* for >=8 weeks a) At least one symptom score is "slightly uncomfortable" or worsen in the 3 heartburn‐related symptoms b) At least one symptom score is "slightly uncomfortable" or worsen in the 3 epigastric fullness‐related symptoms 2) GERD Patients with >=Grade M classified by revision Los Angeles classification even if they take usual dose PPI* for >=8 weeks 3) Patients taking usual dose PPI* until just before taking experimental drugs "study treatment" 4) Patients diagnosed as FD with upper gastrointestinal endoscopy during the past year before giving written informed consent 5) Patients giving written informed consent of this study * usual dose PPI: Rabeprazole 10mg/day, Lansoprazole 30mg/day, Esomeprazole 20mg/day, Omeprazole 20mg/day