Why not using Naver map or Kakaomap?
Most Koreans use Naver Map or Kakao Map instead of Google Maps(In fact, I haven't seen any of my friends use Google maps, and it would be really weird if they did). These apps provide more up-to-date and accurate information for those living in Korea. You might not have heard of Naver before. It is the most popular search engine in Korea, with about 56% of Koreans using. It also has thousands of blogs and reviews. I use Naver myself looking up local topics. As they offer maps in English, I highly recommend using them when you explore Korea.