Evaluation of seismic performance and effectiveness of multiple slim-type damper system for seismic response control of building structures.

This paper presents the evaluation of seismic performance and cost-effectiveness of a multiple slim-type damper system developed for the vibration control of earthquake excited buildings. The multiple slim-type damper (MSD) that consists of several small slim-type dampers and linkage units can control damping capacity easily by changing the number of small dampers. To evaluate the performance of the MSD, dynamic loading tests are performed with three slim-type dampers manufactured at a real scale. Numerical simulations are also carried out by nonlinear time history analysis with a ten-story earthquake excited building structure. The seismic performance and cost-effectiveness of the MSD system are investigated according to the various installation configurations of the MSD system. From the results of numerical simulation and cost-effectiveness evaluation, it is shown that combinations of the MSD systems can effectively improve the seismic performance of earthquake excited building structures.

Studies on phyto-and-zooplankton composition and its relation to fish productivity in a west coast fish pond ecosystem.

A fish pond ecosystem on the west coast of Korea was studied for biotic and abiotic factors. The occurrence rate of phytoplankton at the embanked fish farm was 84 times higher to that of shore waters. Phytoplankton species which occurred during the study period were categorized into Cyanophyta, Dinophyta and Bacillariophyta with a total of 26 subgeneric taxa (22 species of Dinophyta, 2 species of Bacillariophyta and 2 species of Cyanophyta). The total cell density during the study period ranged from16 x 103 to 13.59 x 10(5) cells l(-1). As for the zooplankton, the monthly density ranged from 26 - 8.684 x 10(3) cells m(-3) with an average of 126.0 x 10(3) cells m(-3) for April. In the case of May, it ranged from 41 - 3.331 x 10(3) cells m(-3) and its average of 50.3 x 10(3) cells m(-3) which was comparatively less. The varying environmental factors in Seosan embankment A, B and Chonsu Bay waters could have affected the fish farm. According to the results, the concentration of inorganic nitrogen was 0.067-0.106 (average: 0.083) mg l(-1) and the concentration of organic nitrogen was 0.008-0.022 (average: 0.014) mgl(-1). Also due to the release of brackish water at Seosan embankment A and B, the inorganic nitrogen showed an increasing trend. The survival rate of Sabastes schlegeli, and Acanthopagrus schlegeli was high in stations 2H and I (20.87%, 33%) and relatively low in stations 2B to 2F.