Effects of Wind Fences on the Wind Environment around Jang Bogo Antarctic Research Station

This study investigated the flow characteristics altered by Jang Bogo Antarctic Research Station using computational fluid dynamics(CFD) modeling. The topography and buildings around Jang Bogo Station were constructed with computeraided-design data in the CFD model domain. We simulated 16 cases with different inflow directions, and compared the flow characteristics with and without Jang Bogo Station for each inflow direction. The wind data recorded by the site’s automatic weather station(AWS) were used for comparison. Wind rose analysis showed that the wind speed and direction after the construction of Jang Bogo Station were quite different from those before construction. We also investigated how virtual wind fences would modify the flow patterns, changing the distance of the fence from the station as well as the porosity of the fence. For westerly inflows, when the AWS was downwind of Jang Bogo Station, the decrease in wind speed was maximized(-81% for west-northwesterly). The wind speed reduction was also greater as the distance of the fence was closer to Jang Bogo Station. With the same distance, the fence with medium porosity(25%–33%) maximized the wind speed reduction.These results suggest that the location and material of the wind fence should be selected carefully, or AWS data should be interpreted cautiously, for particular prevailing wind directions.

试析唐朝中后期的新罗奴婢问题

"安史之乱"后,唐朝国力转向衰落,与此同时,新罗也进入后期并出现了严重的社会危机。这种形势带来的变化之一便是唐朝与新罗间官方朝贡贸易的衰落和民间走私贸易的兴起,新罗奴婢问题便是民间走私贸易发展过程中的副产品之一。唐朝中后期社会出现的大量使用新罗人为奴婢的现象一度引起了新罗的不安,唐朝也数度下诏解决该问题,两国围绕此问题进行了长达十余年的交涉,其中,薛平和张保皋二人对于新罗奴婢问题的解决发挥了重要作用。