Korean firms earned a mere 4.7-7 percent of profits from sales of Apple's iPhones and iPads, according to a survey, even though they make a significant portion of the components.

Forbes magazine reported on a thesis published jointly by the University of California Irvine, UC Berkeley and Syracuse University on Sunday that found Apple took 58.5 percent of profits from sales of iPhones for its product design and software development last year. The rest went to the cost of components (21.9 percent), Korean firms' profits (4.7 percent), the cost of non-Chinese labor (3.5 percent), non-Apple U.S. firms' profits (2.4 percent), and Chinese labor (1.8 percent).

From iPads, Korean companies earned 7 percent of profits. Major suppliers of memory chips and displays for Apple include Samsung Electronics and LG Display. There are large iPhone and iPad assembly plants in China, and the study put the cost of Chinese labor for the iPad at 2 percent.