The Comparative Study Of Knowledge Flow Based On Patent Citations

The rate at which knowledge diffuses outward from the institutional setting andgeographic location in which it is created has important implications for the modeling oftechnological change and economic growth, and for science and technology policy. Koreaand Taiwan are two newly industrializing economies that have achieved tremendoustechnological progress. Both have graduated from imitation to innovation with a singlegeneration. In contrast, china is still a country whose advantage is its labor. Knowledgeflow from JP and US have played an important role in these two economies’ transition. Sothe comparison among KR、TW and China can give a direction to China. Technology frommore advanced economies benefits these countries in two distinct ways. Imported capitalgoods embodying new technology directly increase the productivity of the using industriesin the importing country. In addition, researchers and inventors in these less-developedcountries can utilize the "imported” knowledge to R&D to increase the productivity.We have examined citation frequency at the country level. On the one hand,knowledge becomes obsolete and therefore is less likely to be cited as time elapses. On theother hand, due to language, geographical, trade, and other barriers, the accessibility tonew knowledge grows with time. The two effects are offsetting each other. After a simpledescription analysis, we find that the probability of patent citation over time after a patentis granted fits well to a double-exponential function that can be interpreted as the mixtureof diffusion and obsolescence functions. We take full use of the patent citation data fromUS patent and trademark office from1976-2006and take China、 Taiwan、Korea、Japanand US as objects to explore the process by which citations to a given patent arrive overtime. What’s more, we explicitly model the role of technology proximity in this citesprocess. What we have found is as follows:(1) the citation frequency from China Taiwanand Korea to Japan and US gets its maximum when the time lag is3or4;(2)the localeffects of knowledge flow has been reduced and the areal effects becomes stronger;(3) apatent is much more likely to cite a patent from its own technology field than another fieldfor China, but not other countries.