In this study, in order to analyze the water purification efficiency according to the influent water conditions of artificial wetlands, the purification efficiency was compared at two points where sewage treatment water flows in and one point where good effluent flows in. As a result of reviewing the results of the analysis of influent and effluent and the removal efficiency, the T-N and T-P removal efficiency was calculated at 54.7% and 77.4%, respectively, for the two points where sewage treatment water was treated, the treatment efficiency of SS 90.8%, BOD 51.1%, TOC 30.6%, T-N 38.8%, T-P 55.3% was shown. As a result, the efficiency of removing pollutants in the artificial wetland was found to be proportional to the concentration of influent water, and in order to create an efficient artificial wetland, it is judged that thorough review and management at the design stage are necessary considering that the removal efficiency of high-concentration contaminated water was high.

The purpose of this study is to find out the effect of particle size of sediment on adsorption of fluoride. Particle size is classified as sand, silt and clay. Adsorption equilibrium time, adsorption isotherms and the effect of pH were investigated through batch tests. The pHpzc of sand, silt, clay was respectively 6, 8, 4.5 and AEC (anion exchange capacity) was highest in silt, respectively 0.0095, 0.0224, 0.014 meq g-1. Adsorption of fluoride on the sediment was in equilibrium within 300 minutes from all particle size. The experimental data of isotherms at various pH were well explained by Freundlich equation. As the experimental results of the effect of pH, the adsorption efficiency of sand and silt were reduced after the pHpzc. However, the adsorption efficiency of clay was maintained after the pHpzc, and decreased rapidly higher than pH 12.

Bipolar plates require some specific properties such as electrical conductivity, mechanical strength, chemical stability, and low permeability for the fuel cell application. This study investigated the effects of carbon nanotube (CNT) contents and process conditions of hot press molding on the electrical and physical properties using CNT 3~7 wt% added graphite nano-composites in the curing temperatures range of 140~200℃ and pressure of 200~300 kg/cm2. Bulk density, hardness and flexural strength increased with increasing CNT contents, curing pressure and temperature. With the 7 wt% CNT added noncomposite, the electrical resistance improved by 30% and the flexural strength increased by 25% as compared to that without CNT at the temperature of 160℃ and pressure of 300 kg/cm2. These properties were close to the DOE reference criteria as bulk resistance of 13 mΩcm and tensile strength of 515 kg/cm2.

Denitrification activity of microbial communities in sand-gravel sediments and biofilms developing on a concrete riverbed of an urban small stream, Nogawa River, was measured monthly by laboratory incubations after the acetylene inhibition technique during une year from December 1987. The annual mean denitrification rate of the biofilm samples, 1.5 mgN m-2 h-1. was higtrer than the rate ut the sandgravel sediment samples. 0.8 mgN m-2 h-1. Contrary, ratios of the denitrified nitrogen to the total inorganic nitrogen fluxes was lower at the stretch where an attached microbial community developed un the concrete riverbed the stretch with sand-gravel riverbed. The longer residence times of water masses ut the site with a sand-gravel riverbed is responsible for the above relationship. Based on the average denitrifieation rates, if all the channel of Nogawa River were covered with concrete, the proportion of denitrified nitrogen to the input nitrogen should decrease to 1.3 %, whereas the ratio is 2.5% when the riverbed is composed of sands and gravel. The results suggest that the efficiency of nitrogen removal by benthic denitrification is strongly affected by the structure of a channel of the river.

Low temperature is a major abiotic stress that adversely affects rice production in rice cultivation regions of the world. Low temperature during the rice growing season, can inhibit growth and development at any development stage, from germination to grain filling. Among the rice growth stage, reproductive stage was known as the most sensitive to low temperature, causing sterile grain and lead yield loss. However, low temperature during the grain filling stage also, may cause delay and incomplete grain maturation. In this study QTL analysis were performed to identify the QTLs associated with percent of grain filling under low temperature condition during the grain filling stage. A 139 RIL derived from a cross between ‘Milyang23’ (Tong-il, cold susceptible) and ‘Gihobyeo’(Japonica, cold tolerance) were exposed to air and water of 17℃ at the same time for 14 days during the grain filling stage. One significant QTL associated to percent of grain filling was detected on chromosome 7. This QTL could explain 14.7% of the phenotypic variance for percent of grain filling. We have the plan to confirm the detected QTL through further study.