• 상하수도학회지
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• 제28권3호
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• pp.287-297
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• 2014

It is important to predict chlorine decay with different water purification processes and distribution pipeline materials, especially because chlorine decay is in direct relationship with the stability of water quality. The degree of chlorine decay may affect the water quality at the end of the pipeline: it may produce disinfection by-products or cause unpleasant odor and taste. Sand filtrate and dual media filtrate were used as influents in this study, and cast iron (CI), polyvinyl chloride (PVC), and stainless steel (SS) were used as pipeline materials. The results were analyzed via chlorine decay models by comparing the experimental and model parameters. The models were then used to estimate rechlorination time and chlorine decay time. The results indicated that water quality (e.g. organic matter and alkalinity) and pipeline materials were important factors influencing bulk decay and sand filtrate exhibited greater chlorine decay than dual media filtrate. The two-component second-order model was more applicable than the first decay model, and it enabled the estimation of chlorine decay time. These results are expected to provide the basis for modeling chlorine decay of different water purification processes and pipeline materials.

• 폴리머
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• 제38권5호
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• pp.626-631
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• 2014

물을 정수하기 위해서는 그에 상응하는 막대한 양의 에너지가 소모되고, 이 때 소모되는 에너지는 환경오염을 야기할 수 있다. 이러한 문제 때문에 정수 공정 중에 상대적으로 낮은 에너지를 요구하는 정삼투 방법이 많은 관심을 받아왔다. 그러나 정삼투 방법은 오염수로부터 물을 끌어오기 위해서 높은 삼투압을 발생시킬 수 있는 유도용질이 필요하다는 점 때문에 어려움이 있었고 본 연구에서는 poly(N-isopropylacrylamide)(PNIPAM)이라는 온도 감응성 고분자 하이드로젤을 기본으로 하는 양쪽성 이온 물질과의 공중합체와 interpenetrating polymer network(IPN) 구조를 가지는 하이드로젤을 제작하고 이를 정삼투막에 부착시켜 성공적으로 유도용질 역할을 수행함을 확인하였다. 공중합체의 경우 팽윤비가 급격히 증가한 것을 확인할 수 있었으나, 그 만큼의 온도감응성이 떨어지는 모습을 보였고 IPN 구조의 경우는 온도감응성과 팽윤비 값이 PNIPAM 젤에 약간 못 미쳤다. 여기에 팽윤비 값과 삼투압의 관계를 확인하였다.

• 한국세라믹학회지
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• 제54권1호
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• pp.66-69
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• 2017

In this study, the fabrication and electrical properties of aligned single-walled carbon nanotube (SWCNT) networks using a template-based fluidic assembly process are presented. This complementary metal-oxide-semiconductor (CMOS)-friendly process allows the formation of highly aligned lateral nanotube networks on $SiO_2/Si$ substrates, which can be easily integrated onto existing Si-based structures. To measure outstanding electrical properties of organized SWCNT devices, interfacial contact resistance between organized SWCNT devices and Ti/Au electrodes needs to be improved since conventional lithographic cleaning procedures are insufficient for the complete removal of lithographic residues in SWCNT network devices. Using optimized purification steps and controlled developing time, the interfacial contact resistance between SWCNTs and contact electrodes of Ti/Au is reached below 2% of the overall resistance in two-probe SWCNT platform. This structure can withstand current densities ${\sim}10^7A{\cdot}cm^{-2}$, equivalent to copper at similar dimensions. Also failure current density improves with decreasing network width.

• Biotechnology and Bioprocess Engineering:BBE
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• 제2권2호
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• pp.113-116
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• 1997

The hydrogel process is a different form of ultrafiltration and has been used to separate biological molecules. In this study, the gel pore size was predicted by pulse NMR technique and neural network using a database obtained from gel filtration chromatography and diffusion experiment. Recombinant alkaline phosphatase expressed in insect cells was concentratred 1.5 times by hydrogel ultrafiltration by swelling at 2$0^{\circ}C$ and collapsing at 35$^{\circ}C$ at 53-65% separation efficiency and 78-83% enzyme recovery. Wild and recombinant Autographa californica unclear polyhedrosis viruses (AcNPV) were also concentrated 1.4 and 1.6 times of the feed solution at 48.5 and 60.0% separation efficiency, respectively Hydrogel ultrafiltration appears to be an attractive alternative for the concentration of AcNPV and recombinant proteins from insect cells.

• Journal of Advanced Marine Engineering and Technology
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• 제20권4호
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• pp.11-19
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• 1996

Recently, fuzzy and neural network techniques have been successfully applied to control of complex and ill-defined system in a wide variety of areas, such as robot, water purification, automatic train operation system and automatic container crane operation system, etc. In this paper, we present a neuro-fuzzy controller which unifies both fuzzy logic and multi-layered feedforward neural networks. Fuzzy logic provides a means for converting linguistic control knowledge into control actions. On the other hand, feedforward neural networks provide salient features, such as learning and parallelism. In the proposed neuro-fuzzy controller, the parameters of membership functions in the antecedent part of fuzzy inference rules are identified by using the error backpropagation algorithm as a learning rule, while the coefficients of the linear combination of input variables in the consequent part are determined by using the least square estimation method. Finally, the effectiveness of the proposed controller is verified through computer simulation of an inverted pendulum system.

• 농촌계획
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• 제6권2호
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• pp.43-49
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• 2000

Buffer zone selection technique for natural purification of livestock wastewater within a small agricultural watershed was developed using Geographic Information Systems. The technique was applied to $4.12\;km^2$ watershed located in Gosan-myun, Ansung-gun which have 20 livestock farmhouses. As a necessary data for selecting process, feedlot site map, digital Elevation Model (DEM), stream network, soil and land use map were prepared. By using these data, wastewater moving-path tracing program from each feedlot to the stream was developed to get the basic topographic factors; average slope through the paths, distance to the nearest stream and watershed outlet. To identify the vulnerable feedlots for storm event, the grid-based storm runoff model (Kim, 1998; Kim et al., 1998) was adopted. The result helps to narrow down the suitable area of buffer zone, and finally by using subjective but persuasive conditions related to elevation, slope and land use, the suitable buffer zones were selected.

• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2013년도 추계학술대회
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• pp.943-945
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• 2013

슈반세포의 수초화에 대한 연구는 일차 슈반세포의 분리와 배양의 성공에 의해 가능해지고 있다. 본 연구에서는 슈반세포의 근원으로서 마우스 배아의 척수신경절이 사용되었다. 이 방법에는 세 가지 단계가 있다. 첫 단계는 배아의 척수신경절의 파쇄이고 두 번째 단계는 섬유아세포로부터 슈반세포-뉴런 연합체의 기계적인 분리에 의한 슈반세포의 전구세포의 확장이며 세 번째 단계는 뉴런으로 부터 슈반세포의 분리와 분리된 슈반세포의 확장이다. 우리는 본 과정을 통해 짧은 시간이내에 슈반세포-뉴런 연합체와 슈반세포를 고순도로 분리하였다.

• 상하수도학회지
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• 제33권1호
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• pp.17-29
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• 2019

This study developed prediction models of chlorine bulk decay coefficient by each condition of water quality, measuring chlorine bulk decay coefficients of the water and water quality by water purification processes. The second-reaction order of chlorine were selected as the optimal reaction order of research area because the decay of chlorine was best represented. Chlorine bulk decay coefficients of the water in conventional processes, advanced processes before rechlorination was respectively $5.9072(mg/L)^{-1}d^{-1}$ and $3.3974(mg/L)^{-1}d^{-1}$, and $1.2522(mg/L)^{-1}d^{-1}$ and $1.1998(mg/L)^{-1}d^{-1}$ after rechlorination. As a result, the reduction of organic material concentration during the retention time has greatly changed the chlorine bulk decay coefficient. All the coefficients of determination were higher than 0.8 in the developed models of the chlorine bulk decay coefficient, considering the drawn chlorine bulk decay coefficient and several parameters of water quality and statistically significant. Thus, it was judged that models that could express the actual values, properly were developed. In the meantime, the chlorine bulk decay coefficient was in proportion to the initial residual chlorine concentration and the concentration of rechlorination; however, it may greatly vary depending on rechlorination. Thus, it is judged that it is necessary to set a plan for the management of residual chlorine concentration after experimentally assessing this change, utilizing the methodology proposed in this study in the actual fields. The prediction models in this study would simulate the reduction of residual chlorine concentration according to the conditions of the operation of water purification plants and the introduction of rechlorination facilities, more reasonably considering water purification process and the time of chlorination. In addition, utilizing the prediction models, the reduction of residual chlorine concentration in the supply areas can be predicted, and it is judged that this can be utilized in setting plans for the management of residual chlorine concentration.

• 한국환경복원기술학회지
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• 제12권5호
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• pp.92-100
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• 2009

This study was surveyed from May to October, 2008 in order to classify type distribution and evaluate the function of inland wetland as a ecological axis in Chungnam province. Assessment was done by modified-RAM (Rapid Assessment Method). RAM is consisted of total 8 functions and divided into high, moderate, low. The conservation grade of RAM is divided into 4 grades; absolute conservation, conservation, improvement and restoration. Throughout survey on total 13 wetlands of Lacustrine, Palustrine wetland which are distributed in Chungnam province, their function was assessed. As result, the 2 wetlands were judged as absolute conservation grade by assessment of 8 functional contents, and 7 sites were improvement wetlands and 4 sites were conservation wetlands. The function of wetlands assessed as conservation grade showed high in water quality protection and improvement. Also, showed high in vegetation diversity, wildlife habitat and aesthetic recreation. Meanwhile, showed low in Water quality purification, Shoreline/Stream Bank Protection. Of wetlands evaluated as conservation grade, Jeong-juk Ji and Dun-ri reservoir were assessed as absolute conservative area. These wetlands are essential to be managed continuously as a area having high ecological value. Farther, these wetlands will be done as a axis of ecological network related to 'Kumbuk jeongmaek' ecosystem.

• 한국가시화정보학회지
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• 제19권2호
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• pp.41-47
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• 2021

River and stream are the important water supply source in our lives. Eutrophication causes excessive green algae growth including microcystis, which makes harmful to ecosystem and human health. Therefore, the water purification process to remove green algae is essential. In Korea, green algae alarm system exists depending on the concentration of green algae cells in river or stream. To maintain the growth amount under control, green algae monitoring system is being used. However, the unmanned, small and automatic monitoring system would be preferable. In this study, we developed the 3D printed device to measure the concentration of green algae cell using microfluidic droplet generator and deep learning. Deep learning network was trained by using transfer learning through pre-trained deep learning network. This newly developed microfluidic cell counter has sufficient accuracy to be possibly applicable to green algae alarm system.