How would the US have been referred to in everyday conversation? Surely Koreans have their own way of referring to the US other than the phonetics for "US" or "America."
Indeed Koreans do have their own way of referring to the United States. It's 미국 (pronounced "mee-gook".) It is Korean pronunciation for the Chinese characters 美國 - the "beautiful country."
God bless 미국!
But this is where it gets interesting -- why "beautiful country"? And why Chinese? Does this apply to all countries?
The basic rule of referring to a country's name is the same rule that applies to all foreign words -- 외래어 표기법 (Transliteration Rules for Foreign Words) established by National Institute of Korean Language (국립 국어원.) In fact, the Korean already explained this once, about why Koreans call "Haiti" like "IT":
(By the way, did you notice Dominique Strauss-Kahn in that post? What a year he has had!)What comes into play here is Rule of Foreign Words Transliteration established by the National Institute of the Korean Language (국립국어원). Just like L'Academie francaise, NIKL governs all things related to Korean language, including how words that did not originate from Korea are supposed to be written. The overarching principle of the rule is to transliterate the words as they are pronounced in their language. Specifically, the Rule of Transliteration provides a chart that matches up the International Phonetic Alphabet to Korean characters, with more detailed rules in different languages such as English, Spanish, Japanese, French, etc.
The Korean likes this rule because it shows respect. Although Korean language sometimes has a separate name for a famous city in a foreign country -- for example, Sang-Hae (상해) for Shanghai (상하이) or Dong-Kyeong (동경) for Tokyo (도쿄) -- under this rule, Koreans are supposed to write them as 상하이 and 도쿄, not as 상해 or 동경. (In contrast, English-speakers have no qualms for calling München as "Munich" or Praha as "Prague".) Calling a different country/culture with the name that they gave to themselves shows a lot more respect than calling with the name that we came up for them.
So the default rule for a country name in Korean is to pronounce it as closely as the countrymen would pronounce. Then why 미국? Why not 아메리카 ("America")? That's because Rule 5 of the Transliteration Rules -- "For foreign words that have been already solidified in use, respect the common usage." Rule 5 sometimes feels like an exception that swallows the whole default rule, because the "solidified" foreign words are usually the most commonly used ones. In other words, the exceptions are so prominent that it becomes easy to forget the rule.
At any rate, it is no surprise that the names of the countries that interact the most with Korea fall under Rule 5. Most of these names originate from the 19th century, when Koreans finally realized that the world had more countries that their own, China and Japan. For the newly discovered countries (from Korea's perspective,) Korea borrowed the Chinese transliteration convention -- that is, take the prominent sounds of a name, pick the Chinese characters with good meanings that match the sound, and add the character 國 to signify that it is a country. The Chinese called America 美國 -- pronounced "mei-guo", taking "mei" from "aMErica". (Yes, it is quite arbitrary.) Koreans borrowed the word 美國, and simply pronounced it their own way -- thus, Koreans refer to America as 미국.
Other countries who fall under Rule 5? At this point, China (중국 -- "joong-gook", not "zhong-guo"), Japan (일본 -- "il-bon", not "nippon") and Germany (독일 -- "dok-il", not "deutschland") are pretty much it. (-EDIT 8/6/2011- There are also Australia (호주 -- "ho-ju"), England (영국 -- "yeong-gook") and Thailand (태국 -- "tae-gook"). Clearly the Korean should have given this post another day and thought about it harder.) In older Korean books and among older Koreans, one can catch glimpses of the words like 불란서 (佛蘭西) instead of 프랑스 (France) or 구라파 (歐羅巴) instead of 유럽 (Europe). But those uses are rapidly fading away.
Got a question or a comment for the Korean? Email away at firstname.lastname@example.org.