In Western languages, nomenclature for Korea is simple enough - some variant of "Korea," spelled with either a K or a C depending on the language. But in East Asian languages, it gets a wee bit more complicated - so much so, that even the Koreans themselves can't agree on what to call their own country. I threw a few of those names around in the post about the country's creation legend, and I want to expand on this. In fact, using the wrong nomenclature may land me in a gulag, depending on where I am.
Relevant Wikipedia article
One well-known historical name of Korea is Goryeo (Koryo), written as 高麗 and used from the 10th Century until 1392. The word "Korea" is itself a corrupted version of Goryeo, and even today, North Korea's state-owned airline calls itself Air Koryo. Another example: a prestigious private university in Seoul, named Korea University, also uses the Goryeo name (高麗大學校, Goryeo Daehakgyo). Another well-known historical name is Joseon (Choson), written as 朝鮮, which may refer to either the very first Korean kingdom founded in 2333 BC, or the Confucian fundamentalist state that lasted from 1392 until the Japanese annexation in 1910. The Japanese kept the Joseon name, though their pronunciation was Chosen. When the Japanese lost World War II, Soviets and Americans marched in, divided Korea at the 38th Parallel, then complicated things.
Joseon, in its dying years, had actually changed its name to the Korean Empire, written as 大韓帝國 (Daehan Jeguk, "Great Han People's Empire"), to indicate that it no longer owed a Confucian allegiance to the Chinese Emperor (even though this was largely a Japanese ploy to extend its influence over Korea). Noteworthy was the use of 韓 (han), a nationalistic character describing the Korean people; it is not to be confused with 漢, also pronounced "han" and normally referring to the Chinese people. After the Japanese annexation, some pro-independence activists gathered in Shanghai, China, to form a group, using a different version of the name, called 大韓民國臨時政府 (Daehan Minguk Imshi Jeongbu, "Great Han People's Republic Temporary Government"), or Provisional Government of the Republic of Korea. After the end of the Japanese rule, elections were to be held nationwide under UN monitoring, though in reality only the southern half could participate due to Soviet interference in the north. The government thus elected took over the 大韓民國 (Daehan Minguk, Republic of Korea) name, dropping the "Provisional Government" portion, and became South Korea. Current South Korean terminology uses 韓國 (Hanguk) as the short form for all of Korea, 南韓 (Namhan, "South Han") specifically for South Korea, and 北韓 (Bukhan, "North Han") for North Korea. The use of 韓 (Han)/大韓 (Great Han) also extends to company names; for example, Korean Air's official name is 大韓航空 (Daehan Hanggong), and while Asiana Airlines carries the "Asiana" name right into its official Korean name (아시아나 항공), it uses the name 韓亞航空 (Korea Asia Airlines) in China.
North Korea chose to return to the Joseon (Choson) name, harking back to Korea's very first nation-state. The full official name is 朝鮮民主主義人民共和國 (Choson Democratic People's Republic), officially translated as Democratic People's Republic of Korea. North Korean terminology refers to all of Korea as 朝鮮 (Choson), North Korea as 北朝鮮 (Pukjoson, "North Choson"), and South Korea as 南朝鮮 (Namjoson, "South Choson").
Using North Korean terminology in South Korea will normally get you strange, disapproving glances, but is fine in some limited contexts when quoting North Korean sources. However, the name 朝鮮 continues to be used in South Korea in historical and proper name context, one notable example being 朝鮮日報 (Chosun Ilbo), South Korea's most popular newspaper and a mouthpiece of the Lee Myung-bak regime. On the other hand, using South Korean terminology in North Korea, basically anything involving the character 韓, will result in a lengthy stint in the gulag (so horrible, the most common way out is death).
Because the two Koreas are unable to agree on a common label for themselves, various terminology have diverged. The Korean alphabet, for example, is called Hangul in South Korea, and Chosongul in North Korea. Traditional Korean dresses are known as Hanbok in South Korea, and Choson-ot in North Korea.
In neighboring countries, the prevailing terminology tended to follow the ideological allegiance of the national government. For example, China and Vietnam would use 朝鮮, 北朝鮮, and 南朝鮮, while Taiwan, Hong Kong, and the former South Vietnam would use 韓國, 北韓, and 南韓. Japan took the neutral route, continuing to refer to all of Korea as 朝鮮 (Chosen) and calling North Korea 北朝鮮 (Kita-chosen), but calling South Korea by its preferred name 韓國 (Kankoku). With the end of the Cold War, however, the neutral practice of using 北朝鮮 and 南韓, for North and South Korea respectively, took hold everywhere, though Taiwan still uses South Korean terminology throughout.
Elsewhere, while Mongolians use their own label "Solongos" for Korea, just about everyone else uses some transliterated form of "Korea." Among Korean speakers in the United States, the vast majority of whom arrived from South Korea after its founding, South Korean terminology is pretty much exclusively used, except for the very few with ties to modern-day North Korean government, who insist on neutral terminology (though given the strong McCarthyist streak of Korean-Americans, I don't even know how they survive).
As for Seoul, since its 1392 founding as a capital, several names have been used. Pre-capital names included 慰禮城 (Wiryeseong) and 南京 (Namgyeong), and as capital, it was known for a long time as 漢城 (Hanseong) or 漢陽 (Hanyang). During the Japanese era, the name became 京城 (Keijo in Japanese, Gyeongseong in Korean). After the defeat of the Japanese, rising Korean nationalism dictated that a purely Korean word, 서울 (Seoul), be used, with no corresponding Chinese characters.
Wikipedia article
For almost everyone, this change worked out fine. But for the Chinese speakers, it was a problem. They continued to use Seoul's old name, 漢城, pronounced "Hancheng" in Mandarin. It was a headache for the Koreans, partly because 漢城 could be construed as "Chinese Fortress," not exactly a flattering name for Korean nationalists. In 2005, Seoul took the matter into its own hands by choosing a new name, 首爾 ("Shou Er" in Mandarin), as its Chinese phonetic name. Not only did it force the Chinese to say something resembling "Seoul," but the first character, meaning "head," enhanced the stature of Seoul as a capital. After some opposition, both China and Taiwan officially accepted the new name, though popular terminology still uses 漢城. I remember seeing Seoul subway billboards in 2005, which wanted to indeed promote to everyone that Seoul is to be written as 首爾, and not 漢城, in Chinese.
首爾 is written as 首尔 in simplified Chinese. For the Koreans themselves though, this is a useless name, as it would be pronounced "수이" (Su i) in Korean, bearing no resemblance to Seoul. Nevertheless, given that in proper names, Seoul and 漢城 (Hanseong) could point to completely different entities, the Chinese did need a way to disambiguate the two. For example, Asiana Airlines' original planned name was Seoul Airlines; had it gone ahead, its Chinese name would've been 漢城航空. Problem is, there now is a different 漢城航空 (Hansung Airlines) in existence in South Korea, as a domestic low-cost carrier, unaffiliated with Asiana, and the Chinese speaker would have had no way to differentiate the two.
