• Journal of Environmental Health Sciences
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• v.27 no.4
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• pp.15-24
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• 2001

The objective of this study it to evaluate the microbial safety in rapid sand filters adapted in most drinking water treatment plants. The potential pathogens to cause water quality problems Are presumed to be Giardia and Gryptosporidium. They look like particles in view of their size. It has been reported that if the number of particles (larger than 2 ${\mu}{\textrm}{m}$ in water) is less than 100 per mL and its turbidity is below 0.1 NTU, it is considered as a safe water in terms of pathogens. In order to achieve such a good water quality. filter-aids (chemicals) were added to the inlet-channel of filter and their effectiveness was evaluated on the basis of water quality factors such as turbidity and particle counting. This study was conducted in she three steps of experiment: jar test. pilot plant test and real water treatment plant test (P plant in seoul). The experiment reult of the P water treatment showed that cationic polyamine was the most effective in the removal of particles and turbidity at the does of 0.25 mg/L. The turbidity without filer-aids showed in the range of 0.12 ~0.17 NTU during filtration and 0.14 NTU on the average. However. with addition of polyamine, the turbidity represented below(or less than) 0.1 NTU after 20 min in the start of filtration and kept 0.08 NTU on the average. On the other hand, as for number of particles, while no filter-aids led to the range of 111 ~270 per mL and 190 on the average, addition of polydmine led to 113 per mL on talc average, and kept below100 per mL after 20 min in the start of filtration.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.14 no.5
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• pp.506-512
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• 2003

An output multiplexer of manifold type is widely used in a recent satellite transponder f3r its mass and volume reduction. For correct operation, the filter of such a multiplexer must be singly terminated. In this paper, a simple synthesis method of a 6-pole dual-mode singly terminated filter is described. From the transfer function of the filter, network parameters such as in/output terminations and coupling matrix are obtained with the aid of orthogonal projection and plane rotation. The rotation order, pivot, and rotation angle of the plane rotation process are given for easy filter synthesis. Two different-structure filters are taken into consideration and the network parameters of each filter have been obtained from the same transfer function. The method described in this paper can be applied to the other degree singly terminated filter.