Take public transportation.
According to the search on Baidu Map, you can find Gate 7 on the third floor of Terminal 1 of Incheon International Airport. There is a bus stop in front of Gate 7. From here, you can take bus No. 111 to Eulwangri Beach.
Incheon Airport is located on Yeongjong Island, Jung-gu, Incheon Metropolitan City, the Republic of Korea. It is 23.5 kilometers east of the Incheon Metropolitan City Center and 49 kilometers northeast of the Seoul Special City Center. It is a 4F-level international airport.