Even one more tangent.
Since calendars were mentioned in an earlier post today, here's a Wikipedia article on Korean calendar (as well as traditional holidays), which has traditionally been lunar. In fact, my flight to Seoul will take place on August 15th (AKA Chuseok, or Lunar Harvest Festival) on lunar calendar - which means my nighttime flight will enjoy plenty of moonshine, and my bus ride into Seoul will benefit from lighter-than-usual traffic due to the holiday weekend. To help out with farming, however, 24 solar terms (an example would be the summer solstice), tied to the solar calendar and its seasons, were also used. The names of the terms are largely shared with their Chinese, Japanese, and Vietnamese counterparts.
The days of the week are also an interesting topic. All days of the week get the 曜日 (yoil) suffix. The seven days of the week are 日, 月, 火, 水, 木, 金, and 土 (pronounced il, wol, hwa, su, mok, geum, and to), from Sunday to Saturday. Like the days of the week in Germanic languages, they use the sun, the moon, and the planets as their names, in the order of Sun, Moon, Mars (fire), Mercury (water), Jupiter (wood), Venus (gold), and Saturn (soil). The Japanese also use the exact same labels, though with Japanized pronunciations. This is different from the Chinese system, which sequentially number Monday through Saturday as 1 through 6; the average Chinese won't be able to understand the Korean/Japanese days of the week.
Latin languages also use the moon and the planets, but instead of Sunday, they have "Lord's Day" - dimanche in French, domingo in Spanish. In South Korea, the Christians follow the same practice, preferring to use 主日 (juil, "Master's Day" or "Lord's Day") instead of 日曜日 that everyone else uses. In the US, where virtually all Korean speakers are fundamentalist Christians, 主日 is used far more frequently.
When I arrive in Seoul, I can expect to see calendars showing Gregorian solar calendar and Christian AD/CE year, though lunar dates and solar terms (sometimes in Korean, sometimes in Chinese) will also be noted in smaller font. The days of the week will follow the secular convention, either in Korean or in Chinese characters (NOT Chinese names) - or they will be in 3-letter abbreviated English names.
And last, but not the least, in addition to the traditional holidays listed above, South Korea observes these holidays, which include modern-day nationalistic memorials as well as Christmas; some are days off, some are mere memorials, some will require flag display. And speaking of Christmas, again the Christian and the non-Christian terminology differ. Popular terminology follows the Christian preference, 聖誕節 (seongtanjeol, or Holy Birth Celebration Day), because, obviously, it was the Christians who popularized it and turned it into a national holiday. The legal name for Christmas is 基督誕辰日 (gidoktanshinil, or Christian Birthday), the preferred non-Christian terminology. It's also acceptable to simply call it Christmas (크리스마스), or in written form, X-mas (X-마스).
For comparison, check out North Korean holidays, which, by contrast, tend to celebrate Kim Il-sung, Kim Jong-il, and their milestones. In particular, July 27th is called Victory Day, which, in North Korean revisionist history, means the triumph of the great Korean people over the American imperialist aggression (North Korea still insists that the war was started by the US and South Korea); in real history, it marks the Korean War armistice signed in 1953.
