Moon Son

Alginate fouling reduction of functionalized carbon nanotube blended cellulose acetate membrane in forward osmosis.

Functionalized multi-walled carbon nanotube blended cellulose acetate (fCNT-CA) membranes were synthesized for forward osmosis (FO) through phase inversion. The membranes were characterized through SEM, FTIR, and water contact angle measurement. AFM was utilized to investigate alginate fouling mechanism on the membrane. It reveals that the fCNT contributes to advance alginate fouling resistance in FO (57% less normalized water flux decline for 1% fCNT-CA membrane was observed than that for bare CA membrane), due to enhanced electrostatic repulsion between the membrane and the alginate foulant. Furthermore, it was found that the fCNT-CA membranes became more hydrophilic due to carboxylic groups in functionalized carbon nanotube, resulting in approximately 50% higher water-permeated flux than bare CA membrane. This study presents not only the fabrication of fCNT-CA membrane and its application to FO, but also the quantification of the beneficial role of fCNT with respect to alginate fouling in FO.

Fabrication of ultra-thin polyelectrolyte/carbon nanotube membrane by spray-assisted layer-by-layer technique: characterization and its anti-protein fouling properties for water treatment

Abstract Polyethersulfone (PES) membranes are extensively used as ultrafiltration (UF) membrane owing to their superior thermal, mechanical, and chemical stability. However, commercial PES membranes are more prone to fouling, which contributes to severe decline in permeate flux with operation time. To improve the commercial PES UF membrane anti-protein fouling properties, negatively charged functionalized multi-walled carbon nanotube (f-MWCNTs), blended poly(sodium 4-styrenesulfonate) (PSS), and positively charged poly(diallyldimethylammonium chloride) (PDDA) were deposited on 20 kDa PES substrate through spray-assisted layer-by-layer (LbL) technique. Further cross-flow UF tests were conducted with bovine serum albumin (BSA) as model protein. The total flux loss results show that surface-modified PES membranes are less susceptible to protein fouling by one-hour BSA filtration. Moreover, flux recovery ratios show that 20-min de-ionized (DI) water flushing is effective to restore water flux of the prepared ...

Efficacy of CNT-bound polyelectrolyte membrane by spray-assisted layer-by-layer (LbL) technique on water purification

This study demonstrates the properties of surface-modified polyethersulfone (PES) composite ultrafiltration (UF) membranes prepared by a spray-assisted layer-by-layer (LbL) technique. The coating layers on the PES substrate consist of polyelectrolyte multilayers (PEMs) with and without functionalized multiwall carbon nanotubes (f-MWCNTs) as the blending additive. The composite membrane acquired a negative surface charge and the hydrophilicity of the membrane increased after adding hydrophilic f-MWCNTs. The pure water permeation tests revealed that the water flux was dependent on the f-MWCNTs/polyelectrolyte weight ratio and the number of PEMs. The prepared membrane showed slower flux reduction and lower fouling ratio (Rt) by humic acid (HA) filtration tests. Moreover, the flux recovery ratio (FRR) after deionized (DI) water flushing was improved significantly (up to 81%) compared with the PES substrate (46%), which indicated the enhancement of anti-fouling properties. The current work presents a facile way to modify the commercial membrane surface with tuned water flux and enhanced anti-fouling properties.

Improved antifouling performance of polyethersulfone (PES) membrane via surface modification by CNTs bound polyelectrolyte multilayers

In this study, commercial polyethersulfone (PES) membranes were surface-modified by the deposition of functionalized carbon nanotubes (f-CNTs) bound polyelectrolyte multilayers (PEMs) through spray-assisted layer-by-layer (LbL) technique. To investigate the anti-organic fouling properties of fabricated membranes, two representative organic foulants, bovine serum albumin (BSA) and sodium alginate (SA), were selected. Single and binary organic feed solutions in the presence or absence of calcium ions were tested in cross-flow ultrafiltration apparatus. In addition, to examine the membrane resistance to bacteria fouling, the prepared membranes were immersed into Gram-negative Escherichia coli (E. coli) and Gram-positive Staphylococcus aureus (S. aureus) suspension for 4 hours and the adhesion of bacteria cells were observed by scanning electron microscope (SEM). The fouling and antifouling mechanisms were proposed according to the specific scenarios in this study. It was found that the enhancement of hydrophilicity and surface charge of the PES membrane mitigated organic/bio-fouling under all circumstances; the fouling and antifouling of membranes were governed by a complex interplay of interactions between foulants and membrane. Among various interactions, hydration forces and electrostatic repulsion presumably contributed significantly for reducing the adhesion of foulants. The flux of fouled membranes could be restored by the simple flushing of DI water without any chemical treatment.

Curvature-aware adaptive capture of 3D geometry and appearance

Various vision-based measurement systems have been developed to reconstruct the 3D shape and appearance of an object. To achieve this, a large number of the samples need to be captured. However, most of the existing measurement system requires a long acquisition time because of system complexity. Although some systems present effective acquisition strategy in the adaptive manner, they focus on only 2D planar samples so that they cannot handle complex 3D object and its reflectance property. In this paper, we present the multi-camera and multi-light source based measurement system that capture the 3D geometry and appearance simultaneously. We also proposed a novel curvature-aware acquisition strategy for reducing the acquisition time and data storage requirement. Since the proposed method can efficiently capture the appearance of 3D objects with complicated shape, expect to progress the digitization in the various field such as museum and industry.

MudGet: Reproduction of the desired lighting environment using a smart-LED☆

Abstract With the emergence of smart LEDs, lighting based interior design is becoming popular. However, most of the smart LED-based lighting systems rely on expert-human intervention to create a desired atmosphere. For convenience, commercial lighting systems offer a number of options but their usability is fairly restricted. Therefore, an intuitive interface is required for novice users to generate the desired lighting environment. In this paper, we have developed a software, named MudGet, which automatically extracts the light mood from a digital image and controls the LED lamps to reproduce a desired lighting effect according to the extracted light mood. In our method, the light mood is regarded as a set of the representative colors of the digital image. The representative colors are extracted by utilizing K-means clustering algorithm. The dimming parameters are set for which each of the LED lamps create the lighting environment with the mood extracted by the software. To evaluate the feasibility of mood reproduction qualitatively, the degree of similarity between the light mood in the digital image and the reproduced result using LEDs is evaluated by a user study under a miniaturized experimental set. We observe that users can easily produce a desired atmosphere through the proposed MudGet software.

A method for realistic 3D projection mapping using multiple projectors

Recently researchers have shown much interest in 3D projection mapping systems but relatively less work has been done to make the contents look realistic. Much work has been done for multi-projector blending, 3D projection mapping and multi-projector based large displays but existing color compensation based systems still suffer from contrast compression, color inconsistencies and inappropriate luminance over the three dimensional projection surface giving rise to an un-appealing appearance. Until now having a realistic result with projection mapping on 3D objects when compared with a similar original object still remains a challenge. In this paper, we present a framework that optimizes projected images using multiple projectors in order to achieve an appearance that looks close to a real object whose appearance is being regenerated by projection mapping.

Realistic 3D projection mapping using polynomial texture maps

Projection mapping has been widely used to efficiently visualize real world objects in various areas such as exhibitions, advertisements, and theatrical performances. To represent the projected content in a realistic manner, the appearance of an object should be taken into consideration. Although there have been various attempts to realistically represent the appearance through digital modeling of appearance materials in computer graphics, it is difficult to combine it with the projection mapping because it takes huge amount of time and requires large space for the measurement. To counteract these challenges of time and space, [Malzbender et al. 2001] present polynomial texture maps (PTM) that can represent the reflectance properties of the surface such as diffuse and shadow artifacts by relighting of the 3D objects according to varying light direction around the object. PTM does not have temporal or spatial constraints requiring only several tens of images of different light directions so that it makes it possible to easily produce an appealing appearance.

A SAR-based interactive digital exhibition of Korean cultural artifacts

Digital reconstruction and exhibition of cultural heritages have been actively explored in recent years due to the advancement of AR techniques and the development of software and hardware of camera and projector systems. In addition, realistic representation of material appearance is greatly improved by the advancement in computer graphics research. For example, polynomial texture maps (PTM) and reflectance transformation imaging (RTI) are being efficiently employed to represent heterogeneous materials that often have been the characteristics of cultural artifacts. Although advanced computer graphics technology can generate realistic results, an exhibition of cultural heritage is still a challenging task. This is because experiencing these reconstructed digital replicas of the cultural artifacts through a traditional display system could inhibit immersive experience due to its contrived impression. In this paper, we present a novel interactive digital exhibition system based on the spatial augmented reality, which can authentically represent and explore cultural artifacts using polynomial texture maps and projection mapping techniques. Experimental results show that our digital exhibition system generates realistic scenes, representing Korean cultural artifacts authentically, and well provides immersive experience through user interaction.