The African team will face either Italy or Hungary in Cairo.
Ghana took the lead on eight minutes when Samuel Inkoom played the pictured Adiyiah through to stab the ball past Kim Seung-Guy.
Ransford Osei made it 2-0 by the half-hour mark with an incisive left-foot finish.
The Koreans enjoyed their share of possession and pulled one back when Park Hee-Seong netted a looping header after 31 minutes.
Adiyiah rounded off a fine performance with his second on 78 minutes, casually passing the ball home to seal the win.
Kim Dong-Sub hit a consolation header eight minutes from time.