Most Koreans spend many years studying English in public school, with about as much effect as high school foreign language classes in the U.S. The Korean public school system remains very "traditional" -- i.e., teacher-centered. The teacher stands at the front of the classroom and lectures (often simply droning from a book); students ask no questions and say nothing, except to occasionally repeat things by rote.
(Obviously this is a generalization, and there are innovative Korean teachers, and schools that use alternative teaching methods. But the style described above is how all of my students described their public school educations.)
Particularly in the field of language instruction, this is not an efficient way to teach. To learn a language, you have to communicate in that language; you can't absorb English by watching a teacher conjugate verbs for you.
We used the communicative method at ANU's Language Center. The program, designed by Andy Finch, was very student-centered. He started with the premise that Korean students had already "learned" English; i.e., they had been exposed to English grammar and vocabulary for years, and it was not our task to simply try to cram more of it into their heads. Instead, our task was to elicit English from them -- get them to use the English they'd been studying (but not practicing) for years.
The textbooks (written by Andy and Dr. Hyun Tae-Duck) were not English "lessons," but collections of activities intended to get the students to communicate.
While there were problems in execution, generally it was a good program. The most crucial factor in language-learning is the student; the best teacher in the world can't impart linguistic fluency to an unwilling, uninterested student, while a motivated student can learn even with a poor teacher. Accordingly, we saw dedicated students who really wanted to learn English flourish, while those who only took English because they had to (which was, frankly, the majority of them) progressed incrementally, or not at all.
Our greatest challenge was the "culture shock" students experienced coming from years of the Korean public education system. In our classrooms, they were expected to actually speak English, often for the first time! Furthermore, Andong was a rural agricultural city, not a cosmopolitan metropolis like Seoul. Foreigners were rare, and we were sometimes the first foreigners the students had ever met up close. It was very difficult for some, especially the shyer students, to open up and risk the embarrassment of making a mistake. But we did our best, and the students really responded to sincere concern for their progress. It could be frustrating, but it was also extremely rewarding.