If you're struggling to pass the Korean history exam in the public service sector, 브레인 한국사 - 공무원기출문제 OX퀴즈 might be the app for you. Developed by SweetSeven, this free Android app provides detailed explanations for each question, randomizes questions and answer options, and offers mock exams based on national, local, and Seoul city-level questions. The app also allows you to track your progress through the use of graphs displaying your correct and incorrect answers. In addition, there are OX quizzes, chronological order puzzles, and open-ended questions to supplement your learning. The app even includes a feature to report errors and suggest improvements. The app does contain optional full-screen ads, but they do not interfere with the learning experience.