The objective of this study is to develop the innovative application methodology of Geofoam for sustainable design of eco-bridges under deep soil cover. Traditionally, the soft maerial zone has been located on the top or above the buried conduit to reduce the earth pressures, which is called imperfect trench installation (ITI). There, however have been no previous studies for the application of ITI on buried arch structures. This study investigated the structural effects of Geofoam surrouding buried arch bridges, which was named as embedded trench installation (ETI). Various shapes and locations of Geofoam have been investigated for both ETI and ITI. The findings from this study showed that ETI could effectively increase the stability and sustainability of deeply buried eco-bridges.
In this study, the effect of chemically enhanced backwash(CEB) coping with algal(Heterosigma Akashiwo) inflow was evaluated in the seawater desalination pretreatment process using ceramic membrane. In order to confirm the possibility of long-term filtration operation, the recovery rate of transmembrane pressure(TMP) due to the CEB using NaOCl was examined. When the membrane flow rate was 83.3 LMH, the TMP was maintained within 200 kPa for 84 hours in seawater influent. As the algal counts of 30,000 cell/mL were injected into the influent of seawater, however, the TMP rapidly increased and exceed maximum value. Membrane fouling caused by the algae was very poorly recovered by usual physical backwash. The CEB was performed for 30 min(3 min circulation / 27 min immersion) with 300 mg/L of NaOCl. As a result of the CEB application, it was possible to maintain a stable operating of filtration during 10 days and the average recovery rate of TMP by the CEB was 98.1%. It has been confirmed that the CEB using NaOCl is very effective in removal of membrane fouling by algae, resulted in stable membrane filtration for the long-term operation.
In this study, the effects of operating conditions on the formation of reversible and irreversible fouling were investigated in the filtration using ceramic membrane for water treatment process. The effect of coagulation pretreatment on fouling formation was also evaluated by comparing the performance of membrane filtration both with and without addition of coagulant. A resistance-in-series-model was applied for the analysis of membrane fouling. Total resistance (RT) and internal fouling resistance (Rf) increased in the membrane filtration process without coagulation as membrane flux and feed water concentrations increased. Internal fouling resistance, which was not recovered by physical cleaning, was more than 70% of the total resistance at the range of the membrane flux more than 5 m3/m2･day. In the combined process with coagulation, the cake layer resistance (Rc) increased to about 30-80% of total resistance. As the cake layer formed by coagulation floc was easily removed by physical cleaning, the recovery rate by physical cleaning was 54~90%. It was confirmed from the results that the combined process was more efficient to recover the filtration performance by physical cleaning due to higher formation ratio of reversible fouling, resulted in the mitigation of the frequency of chemical cleaning.
In water treatment process using microfiltration membranes, manganese is a substance that causes inorganic membrane fouling. As a result of analysis on the operation data taken from I WTP(Water Treatment Plant), it was confirmed that the increase of TMP was very severe during the period of manganese inflow. The membrane fouling fastened the increase of TMP and shortened the service time of filtration or the cleaning cycle. The TMP of the membrane increased to the maximum of 2.13 kgf/cm2, but it was recovered to the initial level (0.17 kgf/cm2) by the 1st acid cleaning step. It was obvious that the main membrane fouling contaminants are due to inorganic substances. As a result of the analysis on the chemical waste, the concentrations of aluminum(146-164 mg/L) and manganese(110-126 mg/L) were very high. It is considered that aluminum was due to the residual unreacted during coagulation step as a pretreatment process. And manganese is thought to be due to the adsorption on the membrane surface as an adsorbate in feed water component during filtration step. For the efficient maintenance of the membrane filtration facilities, optimization of chemical concentration and CIP conditions is very important when finding the abnormal level of influent including foulants such as manganese.
In this study, it is estimated that ceramic membrane process which can operate stably in harsh conditions replacing existing organic membrane connected with coagulation, sedimentation etc. . Jar-test was conducted by using artificial raw water containing kaolin and humic acid. It was observed that coagulant (A-PAC, 10.6%) 4mg/l is the optimal dose. As a results of evaluation of membrane single filtration process (A), coagulation-membrane filtration process (B) and coagulation-sedimentation-membrane filtration process (C), TMP variation is stable regardless of in Flux 2 m3/m2･day. But in Flux 5 m3/m2･day, it show change of 1-89.3 kpa by process. TMP of process (B) and (C) is increased 11.8, 0.6 kpa each. But, the (A) showed the greatest change of TMP. When evaluate (A) and (C) in Flux 10 m3/m2･day, TMP of (A) stopped operation being exceeded 120 kpa in 20 minutes. On the other hand, TMP of (C) is increased only 3 kpa in 120 minutes. Through this, membrane filtration process can be operated stably by using the linkage between the pretreatment process and the ceramic membrane filtration process. Turbidity of treated water remained under 0.1 NTU regardless of flux condition and DOC and UV254 showed a removal rate of 65-85%, 95% more each at process connected with pretreatment. Physical cleaning was carried out using water and air of 500kpa to show the recovery of pollutants formed on membrane surface by filtration. In (A) process, TMP has increased rapidly and decreased the recovery by physical cleaning as the flux rises. This means that contamination on membrane surface is irreversible fouling difficult to recover by using physical cleaning. Process (B) and (C) are observed high recovery rate of 60% more in high flux and especially recovery rate of process (B) is the highest at 95.8%. This can be judged that the coagulation flocs in the raw water formed cake layer with irreversible fouling and are favorable to physical cleaning. As a result of estimation, observe that ceramic membrane filtration connected with pretreatment improves efficiency of filtration and recovery rate of physical cleaning. And ceramic membrane which is possible to operate in the higher flux than organic membrane can be reduce the area of water purification facilities and secure a stable quantity of water by connecting the ceramic membrane with pretreatment process.
We present an improved sketch-based image search technique through which users can search their target images from the images in database. This technique can be used in constructing an efficient game development framework. Our basic approach is to search the database by comparing the user-created sketch with the graph extracted from the images in the database and estimating the similarity. The images of high similarities are suggested as the candidates that match the target image. To improve the accuracy of the matching process, we substitute the graph-based representation of images with vectorized coherent lines, which are known as one of the most precise schemes in extracting and describing important features in an image. By the experiments on 820 images of 32 categories, we prove that our scheme shows higher matching accuracy than the existing schemes.
본 연구는 생태형을 달리한 사료용 피를 이용해서 파종 기를 5월 1일부터 10일 간격으로 6회 파종하여 생육, 사료 수량 및 사료가치를 경기도 수원 지방에서 검토한 내용은 다음과 같다. 조생종 피의 초장은 파종기가 늦어질수록 작 아졌고, 수장은 파종기에 따른 변화가 크지 않았다. 조생종 피의 조사료 건물수량은 파종기가 늦어질수록 감소하는 경 향을 나타냈다. 중부지방에서 조생종 피의 최대 건물수량 을 얻기 위해서는 5월 1일까지는 파종기를 빨리하는 것이 유리하며, 안전한 조사료 수량을 얻기 위해서는 6월 1일 이전에 파종해야 하는 것으로 나타났다. 만생종 피의 초장 은 파종기가 빠르거나, 너무 늦어지면 짧아지는 경향을 보 였고, 수장 역시 초장과 같은 경향을 보였다. 만생종 피의 조사료 건물수량은 파종기가 빠르거나, 너무 늦은 경우 감 소하는 결과를 보였다. 따라서 만생종의 경우에 최대수량 을 얻기 위해서는 5월 21일경에 파종을 하고, 안정된 수량 을 얻기 위해서는 6월 1일 이전에 파종을 해야 한다. 조생 종 피는 빨리 파종할수록 조사료 수량이 높아지고, 만생종 피는 5월 21일경에 파종할 때 가장 수량이 높아 두 생태형 간의 차이를 보였으나, 절대적 수량은 만생종 피가 어느 파종기에서나 조생종 피에 비해 수량이 높아 실제 재배적 측면에서는 만생종 피를 선택하는 것이 유리한 것으로 나 타났다. 조생종 피의 조단백 함량은 파종기가 늦을수록 증 가하는 경향이었으나, ADF 함량과 NDF 함량은 파종기의 차이에 따른 변화가 적었다. 만생종 피의 조단백 함량도 파종기가 늦어질수록 증가하였으며 ADF 함량과 NDF 함량 의 경우에는 조생종 피의 경우와 같은 경향을 보였다. TDN 수량은 조사료 건물수량과 동일한 경향을 보여 조생 종 피는 파종기가 빠를수록, 만생종 피는 5월 21일경의 파종에서 가장 수량이 높아 적정 파종기로 판단되며, 두 생 태형 모두 6월 1일 이전까지는 파종을 해야 안정적 수량을 얻을 수 있다. 동계 조사료작물을 도입한 작부체계에서는 동계작물의 종류에 따라 연중 최대생산을 얻을 수 있는 하 계 사료피의 생태형과 파종기를 선택해야 할 것이다. 따라 서 이러한 하계사료피+동계사료작물의 작부체계 구축에 파종기별 사료피의 수량성과 사료품질 특성은 유용한 정보 가 될 수 있을 것이다.