Let me start this post with a personal story. I entered graduate school in Korea 4 years ago. It was an international school and the curriculum was in English. I had attended college in France and was accustomed to a certain way of "smart" or let's say "wise" discussion.
As I said in my previous post, in France, the more facts one knows, the smarter he is. So I was sitting there taking my first class, and the professor asks us something about democracy. I raise my hand and start blurting out the raw historical facts I knew about democracy, from Plato's criticism of Greek democracy to a democratically elected Adolf Hitler and so on. Professor stops me and redirects the discussion, and I looked like an idiot.
Anyway, knowledge of historical facts do not make look one smart in Korea and are considered useless. So how should I have answered the question?
In fact, content of the answer is not what makes look someone "smart" in South Korea. Koreans don't care about how much people know about the world, they care about how people say it.
First, diction and pronunciation are key when addressing a Korean public. President Kim Young Sam was called an "idiot" by many including the press, for the mere reason that he could not get rid of his Kyeongsan accent. His catch word was his pronunciation of the word "확실히" (certainly) which he pronounced "학실히". And I'm going to stop there with facts. The point is accent, diction and pronunciation have an enormous impact on how Koreans evaluate each other. People who use standard pronunciation, the kind of pronunciation prescribed by the National Institute of Korean Language, are viewed as "smart" people.
Another determining factor in how Korean people view each other as smart is the choice of words. Exact use of complicated words derived from English or old Chinese (hanja) are an excellent way to give a good impression at a job interview or a social gathering in which academic or economic stakes are high. This is why, by the way, when Korean people speak English they tend to prefer using all those words we only come through while studying for exams like the GRE and no one actually uses.
A third, very important factor on how Koreans consider someone "intelligent" is the proper use of grammar, honorifics in particular. The use of Korean grammar is different when talking to friends and in formal occasions. 이랑 is replaced by 과, 께서 has very precise uses, 요 and 입니다 have "should" be used alternatively and have very precise rules as to when they should be used, rules that no school actually teaches, and many other rules.
Interventions should be concise and informative at the same time, but most importantly, group harmony should be maintained, meaning that it is a taboo to mention facts people might not know during discussions. In a way, Koreans make sure that people have previous knowledge of what is being said. I noticed that when Koreans argue about a subject in particular, they use the 잖아 inflection (meaning "as you know") more than at any other time, to make sure that their "opponent" knows what they are talking about. If new facts are to be taught, they should be done conventionally: through books, lectures, television but not during discussions.
Finally, body language should be reduced to a minimum, Korean people don't value people who move and gesticulate when they are trying to make a point. Korean prefer the tone of the voice to be kept low.
During my class intervention, I committed three social blunders: I was laid back and used rather colloquial English, gesticulating, and giving out information people were not always aware of. Foreign students have a harder time when trying to discuss their thesis content or paper content with their professors: professors will often tell them to write the thesis or paper first before discussing the contents, rather than hear their students telling them things they may not know. Some consider it is a sign of lack of quality in education, but I personally argue that it is purely cultural.