Suchergebnisse

Recent research in international trade has explored the stylized facts and causes and effects of export diversification. A simple model in this paper drawing on the work of Melitz suggests that there is an order in which a country spreads its goods to foreign countries. We estimate the order by using a methodology which takes account of the fact that most goods are not exported to several countries in our sample (unbalanced panel). We find that Korea exports its new goods first to the United States, followed by Japan, Hong Kong, and Singapore, and most recently to Bosnia‐Herzegovina. Finally we find that the countries that Korea has exported to first are those with large GDP, low tariff rates, geographic proximity, language familiarity, in‐country Korean export promotion offices, and high‐quality institutions.

The antimicrobial effects of silver (Ag) ion or salts are well known, but the effects of Ag nanoparticles on microorganisms and antimicrobial mechanism have not been revealed clearly. Stable Ag nanoparticles were prepared and their shape and size distribution characterized by particle characterizer and transmission electron microscopic study. The antimicrobial activity of Ag nanoparticles was investigated against yeast, Escherichia coli, and Staphylococcus aureus. In these tests, Muller Hinton agar plates were used and Ag nanoparticles of various concentrations were supplemented in liquid systems. As results, yeast and E. coli were inhibited at the low concentration of Ag nanoparticles, whereas the growth-inhibitory effects on S. aureus were mild. The free-radical generation effect of Ag nanoparticles on microbial growth inhibition was investigated by electron spin resonance spectroscopy. These results suggest that Ag nanoparticles can be used as effective growth inhibitors in various microorganisms, making them applicable to diverse medical devices and antimicrobial control systems. ; This work was supported by the NSI-NCRC program of KOSEF. D.H.J. was supported by BK21 program. H.J.L. was supported by the the Korean Research Foundation Grant funded by the Korea Government (MOEHRD) (R05-2004-10627-0).