In my own experiences of culture shock I found that it came upon me in ways I simply did not anticipate. When I went to Japan, people warned us that the food and overall customs would take us by surprise but that was the least shocking simply because with the internet, books, etc it is easy to prepare for concrete cultural differences which can be seen and quantified.
It was the subtle aspects of the culture that threw me into a whirlwind, and honestly had me rather discouraged and reevaluate why I was learning the language to begin with. For example, realizing that developing relationships required a kind of inherent deception, at least from my standpoint it was deceptive, on both sides was bewildering to say the least. Being straight forward was not polite in practically any circumstance (I soon learned many Japanese students complained this was the problem with Americans in general). So because you had to go a roundabout way to communicate and express what you're thinking, (hard enough with a language barrier) notions of friendship were opaque and vague. It was like speaking in a coded language. Then there were many who simply viewed foreigners as accessories to show off to their friends and go out with, which is harmless but ineffective in what I hoped to accomplish, that is understanding one person at a time, not generic exchanges of information.
It takes skill to maneuver in the darkness that is intercultural communication where there are only unspoken rules and those a part of the culture may not necessarily see them as rules but instead just a way of being, the right way particularily. Korea and Japan are not the same but I suspect one would encounter similar situations, regardless.