KIM Ki-hoon earns $4 million a year in South Korea, where he is known as a rock-star teachera combination of words not typically heard in the rest of the world. Mr. Kim has been teaching for over 20 years, all of them in the country's private, after-school tutoring academies, known as hagwons. Unlike most teachers across the globe, he is paid according to the demand for his skillsand he is in high demand.