Korean immigration to Hawaii can be compared to ocean waves and there have been four waves of Korean immigrants in all. The first wave brought around 7,000 Koreans to Hawaiian shores between 1903 and 1905, the second wave brought 951 Korean picture brides between 1912 and 1924, the third wave occurred between 1947 and 1967, and the fourth followed in 1967(http://www.kamuseum.org/community/base.htm).
As word of immigration reached Korea prior to the first wave, numerous Koreans volunteered to immigrate to Hawaii. The first groups were pioneers in the truest sense. They had the courage to leave their homeland to seek out a meager living in a foreign country. Each had his or her own reasons to immigrate to Hawaii, but in choosing this risky path they all shared a common goal—to earn money and live a better life. After arriving in Hawaii, however, some 7,000 Korean immigrants soon discovered that the promised land of paradise was a place of backbreaking physical labor. On a typical 10 hour working day, they awoke at the sound of the five o’clock sugar plantation siren and worked continuously until dusk. Besides the hard work, they managed to form friendship associations and founded their own churches and schools. They lived

Patterson, Wayne. THE ILSE: First-Generation Korean Immigrants in Hawaii, 1903-1973. Honolulu: University of Hawaii Press. 2000

Another wave of immigrants started to come to the U.S. soon after the liberation of Korea from Japan. Until the Republic of Korea was established in 1948, the military was in charge of their former colony of Japan, with an American occupation army stationed in Korea. The American soldiers, while in Korea, married many Korean girls, who came to the U.S. as so called “War-Brides”. This GI marriage continued to be popular among the American soldiers. After the Korean War (1950-1953), there were not only many war refugees in Korea but also many war orphans, who were adopted and brought to the U.S. by the thousands (http://www.columbia.edu/itc/sipa/U6210/ik105/INDEX.HTM).