A typical Korean name is a three syllable name. Though not quite uncommon, there are those with two syllable names. Also, there are some people with four or more syllables in there name, but these are more of a rarity. The structure of the Korean name: family name (1st syllable), generation marker (2nd syllable), and personal identifier (3rd syllable). This name structure was borrowed from the Chinese as they had a large influence on Korea for many generations.
As for family names, there are approximately two hundred fifty (250) different family names in use today. However the three most common names of Kim, Lee, and Park covers half the Korean population, both North and South.
The second syllable, as mentioned above is a generational marker. In an earlier time, extended family members would share the same name (2nd syllable) marking their generation. For instance, everybody of the same clan and family born between 1900 and 1910 would have the same second syllable. Today this is not so common, although siblings may still share this generation marker (name). An example would be Girl’s Generation member Choi Soo Young and sister Choi Soo Jin. Sometimes, but not as common, the generation name could be the third syllable as with Choi Soo Young’s fellow SNSD member Lee Soon Kyu Sunny) whose older sisters are Lee Eun Kyu and Lee Jin Kyu.
The third syllable in a Korean name is commonly the personal identifier, the actual given name. As just mention, there are times when the meaning of the second and third syllable are switched. Note that it is not uncommon for Koreans not to have a generation marker/name. In this case the second syllable is the personal name. An example of that would be Park Bom, main vocalist of the popular girl group 2NE1.
As noted before, though it is rare, some people have more than three syllables in their name. Often with those people with four or more syllables in their names, the family or the personal name that contains two or more syllables. Using another member of the South Korean girl group 2NE1, Park San Da Ra (separated by syllables). As explained by Dara (as she is commonly known), her personal name is actually the full name of the famous general from Silla (Three Kingdoms period in Korea), Kim Yushin, as he was called by his parents when he was young. Therefore, Park Sandara does not have a generational marker/name and the two extra syllables are a part of her personal/given name.
Note: It is common for Korean celebrities and those doing business abroad, Korean emigrates, and children born abroad to have a Western name (commonly English) in front of their Korean names. Using Krystal from the South Korean girl group, f(x), whose full name is Krystal Jung Soo Jung. As a celebrity she is commonly known simply as Krystal. As an American she is known as Krystal Jung and in Korea she is known as Jung Soo Jung. Only in biographical writings is the complete name used.