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Nguyen, Thanh-Tin,Kook, Seungho,Lee, Chulmin,Field, Robert W.,Kim, In S. Elsevier 2019 Journal of membrane science Vol.570 No.-
<P><B>Abstract</B></P> <P>Membrane fouling is closely related to the concept of critical flux. Therefore, a fouling control strategy for forward osmosis (FO) membranes that is based on the critical flux is necessary. This study systematically investigated the critical flux behavior of FO membranes (CTA and PA-TFC) in the short-term using a stepping method (draw solution (DS) concentration stepping). In addition, to test the reliability of this method, long-term experiments were conducted to evaluate the influences of operational critical flux on the fouling behavior (sustainable operation and fouling reversibility/irreversibility), thereby determining the critical flux for reversibility. Our results showed that the DS concentration stepping could be applied for critical flux determination in FO. Both membranes exhibited higher critical flux values for alginate fouling compared to other single foulants such as colloidal silica or gypsum. The values were 15.9 LMH for a cellulose triacetate membrane (CTA) and 20.5 LMH for the polyamide thin-film composite (PA-TFC). Whilst these values should be adequate in FO applications they were determined for single foulants. The presence of multispecies of foulants caused a significant decline in the critical flux values. This study found 5.4 LMH for the CTA membrane and 8.3 LMH for the PA-TFC membrane for the combined foulants of alginate + gypsum. This indicates that the critical flux behavior in FO was dependent on the foulant type and membrane type. Importantly, the high restoration of water flux was achieved with the PA-TFC membrane at an operation either close to critical flux (92–98%) or below critical flux (98–100%) (i.e., with negligible irreversible fouling). The critical fluxes for reversibility obtained in this study will aid the efficient operation of practical FO processes.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Draw Solution stepping method was used to determine the critical flux value. </LI> <LI> Critical flux behavior in FO was dependent on foulants and membrane types. </LI> <LI> Plant operation below the critical flux is vital for the minimization of chemical cleaning. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
김동호,이철민,Thanh-Tin Nguyen,Rusnang Syamsul Adha,김채연,Sang-Jun Ahn,손희종,김인수 한국공업화학회 2021 Journal of Industrial and Engineering Chemistry Vol.98 No.-
In recent years, pressure-assisted forward osmosis (PAFO) process has been studied to overcome the lowwater productivity in FO-RO hybrid seawater desalination. Our research group demonstrated a pilot-scalePAFO-RO plant for seawater desalination operations using secondary treated wastewater and naturalseawater. A pretreatment stage of mesh tubefilter media (MTF) and cartridgefilter (CF) was implementedfor a pilot-scale PAFO. In this study, the water quality and fouling index (SDI15 and MFI0.45) of the influentand treated water at each process stage of the plant were measured. For the influent of both wastewaterand seawater feature, it showed linear correlations between the concentration of microbial ATP (i.e., anindicator of microbial activity) and MFI0.45. After the PAFO was operated for 76 days, the fouling of thefiltration media and the FO membrane was also analyzed. The observation of the fouled membranes bySEM showed that fouling was hardly observed on the side contacting with seawater, but severe bacterialbiofilms were observed on the side contacting with wastewater. FT-IR results also confirmed protein-likesubstances on the membrane surface contacting with wastewater, indicating irreversible fouling. Thisstudy suggests that an advanced pretreatment process to remove bacteria and organic matter is essentialfor the protection of the FO membranes.
Kook, Seungho,Lee, Chulmin,Nguyen, Thanh Tin,Lee, Jangho,Shon, Ho Kyong,Kim, In S. Elsevier 2018 Desalination Vol.448 No.-
<P><B>Abstract</B></P> <P>Due to the improved dilution of draw streams, employing pressure-assisted forward osmosis (PAFO) to the hybrid system of forward osmosis (FO) followed by reverse osmosis (RO) for seawater desalination has been expected to reduce the overall economics. However, replacing FO with PAFO causes an additional energy cost in the seawater dilution step which inevitably leads to a question that PAFO-RO hybrid is truly an economically beneficial option. More importantly, though serial connection of FO elements improves the dilution of initial draw water, this economic benefit is also compensated with the additional membrane. To rationalize its overall performance and economic benefit, thorough performance and economic evaluations were conducted based on actual pilot-scale PAFO operations for serial connection of up to three 8040 FO elements. The results showed the FO-RO hybrid is not an economically feasible option unless a significant unit FO element cost cut-down is guaranteed. Meanwhile, PAFO-RO showed benefits with regards to target RO recovery and unit FO element cost, particularly when two FO elements are serially connected (SE2). It was found that PAFO-RO, indeed, has higher economic potential than FO-RO. A graphical overlapping method suggested in this work can help determine optimal serial configuration and operating conditions of PAFO-RO.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Significant impact of initial draw flowrate and hydraulic pressure on the PAFO-RO economics </LI> <LI> Hydraulic pressure dependence of FO membrane element performance </LI> <LI> Drastic pressure-drop in the draw channel of the last element in serial configuration </LI> <LI> Target RO recovery and unit FO element cost in PAFO-RO hybrid are important for economics </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
Meme Analysis using Image Captioning Model and GPT-4
( Marvin John Ignacio ),( Thanh Tin Nguyen ),( Jia Wang ),( Yong-guk Kim ) 한국정보처리학회 2023 한국정보처리학회 학술대회논문집 Vol.30 No.2
We present a new approach to evaluate the generated texts by Large Language Models (LLMs) for meme classification. Analyzing an image with embedded texts, i.e. meme, is challenging, even for existing state-of-theart computer vision models. By leveraging large image-to-text models, we can extract image descriptions that can be used in other tasks, such as classification. In our methodology, we first generate image captions using BLIP-2 models. Using these captions, we use GPT-4 to evaluate the relationship between the caption and the meme text. The results show that OPT6.7B provides a better rating than other LLMs, suggesting that the proposed method has a potential for meme classification.
Asta Blazyte,Abayomi Babatunde Alayande,Thanh-Tin Nguyen,Rusnang Syamsul Adha,장재원,Mar Mar Aung,김인수 한국공업화학회 2021 Journal of Industrial and Engineering Chemistry Vol.94 No.-
In the forward osmosis (FO) process, biofouling is well pronounced on the active side where wastewaterand seawater are used as feed and draw solution, respectively. However, the biofouling tendencies withinthe support layer are not clear. Therefore, the objective of this study was to investigate the effect of TEPpre-conditioning on hydophobicity and initial bacterial attachment of FO membrane support layer. Twostructurally distinct FO membranes from different manufacturers were preconditioned by soaking inartificial sea waterfiltrates containing size fractioned TEP. The conditioning solution pre-treated with a0.4 mm pore sizefilter, contributed to the highest bacterial adhesion rates during bacterial attachmenttesting in both steady state and cross-flow mode in a lab-scale FO system for both membrane types. CTA-ES support exhibited higher numbers of adhered bacteria when compared to PA-TFC support in a steadystate. Conversely, in cross-flow lab-scale testing, a negative impact of fouling on PA-TFC was moreapparent than the CTA-ES membrane. This was attributed to the higher porosity and surface roughness ofthe PA-TFC membrane. Overall, ourfindings reinforce the potential impact of hydrodynamics conditionsand membrane properties on the fouling behavior of FO membrane support layer.