South Korea is about 15 times smaller than Alaska.

Alaska is approximately 1,481,348 sq km, while South Korea is approximately 99,720 sq km, making South Korea 6.73% the size of Alaska. Meanwhile, the population of Alaska is ~710,231 people (51.1 million more people live in South Korea).
Tip: This to-scale comparison of Alaska vs. South Korea uses the Mercator projection, which distorts the size of regions near the poles.