We decompose the patent increase over the period 1982 through 2000 using the data provided by KIPO(Korean Intellectual Property Office) and also compare our results to U.S. experiences. First, we show that the contribution of the increase in the R&D spending accounts for $71\%$ of patent increase between 1982 and 2000. Second, an overall increase in patent intensity measured by patent-R&D ratio between 1982 and 2000 is explained by $234\%$ of the changes in the patent yields in individual industries rather than by the reallocation of resources. Third, we find that there is structural change in patent intensity and patenting between 1994 and 1995. The patent yields in individual industries account for $86.4\%$ of patent increase between 1994 and 1995. Fourth, two high tech fields, electrical machinery and precision instrument, account for about $80\%$ of the patent increase.