PURPOSES : The objective of this study is to investigate the capability of the combined model of traffic simulation, emission and air dispersion models on the impact analysis of air quality of mobile sources such as vehicles. METHODS : The improvement of the quality of life brings about the increasing interest of the public environment. Many endeavors including the travel demand management, the application of the state-of-the-art ITS technologies, the promotion of eco-friendly vehicles have been tried in transportation area to reduce the modal emissions. Especially, it is expected that the increasing number of eco-friendly vehicles in the road network would be able to reduce the pipe-tail emissions tremendously. From this perspective, we have performed a study on the impact analysis of the popularization of the eco-friendly vehicle in the place of the fossil fuel energy powered vehicles on the surrounding air quality using the combined framework of microscopic traffic simulation, emission and air dispersion model. RESULTS : The combined model successfully captured the effect of moving to the eco-friendly vehicles on the air quality, and the results showed that the increasing usage of eco-friendly vehicles can improve the surrounding air quality tremendously and that the air dispersion model plays a crucial role in the investigation of the air quality change around the main corridor. CONCLUSIONS : This study demonstrated the capability of the combined model showing the spatio-tempral change of emission concentration.

The purpose of this study was to evaluate the effects of different Hydraulic Retention Times (HRTs) on the contaminant removal efficiency using Aerobic Granular Sludge (AGS). A laboratory-scale experiment was performed using a sequencing batch reactor, and the Chemical Oxygen Demand (COD), nitrogen, orthophosphate removal efficiency, AGS/MLSS ratio, and precipitability in accordance with the HRT were evaluated. As a result, the COD removal efficiency was not significantly different with the reduction in HRT, and at a HRT of 6 h, the removal rate was slightly increased owing to the increase in organic loading rate. The nitrogen removal efficiency was improved by injection of influent division at a HRT of 6 h. As the HRT decreased, the MLSS and AGS tended to increase, and the sludge volume index finally decreased to 50 mL/g. In addition, the size of the AGS gradually increased to about 1.0 mm. Therefore, the control of HRT provides favorable conditions for the stable formation of AGS, and is expected to improve the contaminant removal efficiency with the selection of a proper operation strategy.

For areas with the diverse contamination sources, the change of 4-nitrophenol contamination and impact of potential contamination sources have been evaluated using monitoring data and a numerical model (HydroGeoSphere). The model considered several parameters including land cover, precipitation, and flow rate. And, the model has been performed to investigate the effect of decay rate of 4-nitrophenol. The results of the simulations showed that the influence on 4-nitrophenol in downstream was mainly greater than that in upstream, and the tributaries did not significantly affect the mainstream because of their low flow rates. In addition, the effect of contamination sources was simulated for each section, then the measured data were higher than the corresponding simulated data in most sections of the Geumho river. In particular, the impact of the potential contamination sources in the upstream area was much higher than that in the other area, thus more monitoring data for the upstream area is required.

비소의 농도에 따른 봉의꼬리의 생육 반응 및 비소 축적능을 분석하기 위해 As(III)와 As(V)의 농도를 달리하여 봉의꼬리를 12주간 재배하였다. 연구의 결과 비소의 종류에 관계없이 50, 500mg·kg-1 처리구는 비소 무처리구와 생육이 비슷하였으나, 비소의 농도가 증가할수록 초장이 감소되는 경향을 보였다. 비소의 농도를 50, 500mg·kg-1 처리하여 재배한 봉의꼬리 지상부의 비소 축적능은 As(III) 처리구가 각 802.7, 2,956.0mg·kg-1 DW로, As(V) 처리구(622.6, 2,841mg·kg-1 DW)에 비해 높았다. 그러나 고농도 처리구인 1,000과 2,000mg·kg-1에서는 As(V) 처리구(3,883.3, 5,250.6mg·kg-1 DW)에서 As(III) 처리구(3,347.8, 4,272.7 mg·kg-1 DW)에 비해 비소 축적능이 더 우수하였다. 지하부의 축적능은 2,000mg·kg-1 농도 처리구를 제외한 모든 농도에서 sodium arsenate 처리구가 sodium arsenite 처리구에 비해 높았다.

The influence of the point source inflow on the water quality variation in the downstream of Hyeongsan River was investigated. As the results of seasonal variation, the pollutant concentrations of dry season were 1.5~4 times higher than those of wet season. The increase rate of BOD5, CODMn, T-N, T-P due to point source were ranged to 8.1~42.6%, 7.3~41.9% and 17.1~207% as the inflow of P1, P2 and P3, respectively. After P1, P2 and P3 inflow, the accumulated increase rate were 64.3%, 32.6%, 93.1% and 258.9% in BOD5, CODMn, T-N, T-P, respectively. It was found that the influence of point source inflow on the water quality in the downstream of Hyeongsan River is severe.