Many PDF versions include blank review quizzes at the end of each section. Photocopy these (or screenshot them) and retake them after 3 days, 1 week, and 2 weeks. This spaced repetition system (SRS) is built-in—you just need to schedule it.
If your PDF doesn’t have audio (many scraped versions don’t), use a Text-to-Speech (TTS) tool like Naver Papago’s voice. Listen to the word, pause, say it out loud, then check the PDF spelling. Power Up Korean Vocabulary Pdf