• Membrane Journal
• /
• v.33 no.4
• /
• pp.191-200
• /
• 2023

Polyethersulfone (PES) is a widely employed membrane material for water and industrial purification applications owing to its hydrophilicity and ease of phase separation. However, PES membranes and filters prepared using the nonsolvent induced phase separation method often encounter significant flux decline due to pore clogging and cake layer formation on the dense membrane surfaces. Our investigation revealed that tight microfiltration or loose ultrafiltration membranes can be subject to physical fouling due to the formation of a dense skin layer on the bottom side caused by water intrusion to the gap between the shrank membrane and the substrate. To investigate the effect of the bottom surface porosity on membrane fouling, two membranes with the same selective layers but different sub-layer structures were prepared using single and double layer casting methods, respectively. The double layered PES membrane with highly porous bottom surface showed high flux and physical fouling tolerance compared to the pristine single layer membrane. This study highlights the importance of physical optimization of the membrane structure to prevent membrane fouling.

• Polymer(Korea)
• /
• v.37 no.3
• /
• pp.393-398
• /
• 2013

Two types of polymeric micro-needles with 250 and $750{\mu}m$ lengths were prepared by a micromolding process. The geometry of dissolving micro-needles with minoxidil was investigated and the mechanical property of polymer micro-needles was also evaluated. Water dissolving micro-needles containing minoxidil were successfully inserted into skin and delivered minoxidil to the skin layer after 30 min of insertion. The observed hair growth was less when the minoxidil treatment was not applied or used without the micro-needles than that the minoxidil was applied by micro-needles. Histologically, these hair follicles became bigger, and the hair papillae were totally encircled by the hair bulbs. In this feasibility test, we show the successful delivery of minoxidil, and effective treatment of hair loss can be possible by using dissolving micro-needles with minoxidil.

• Applied Chemistry for Engineering
• /
• v.10 no.6
• /
• pp.939-943
• /
• 1999

Recently there has been an explosion of interest in the topic of biodegradable polymers for medical applications. In this study, films were prepared by solution casting method using natural polymers (xanthan, locust bean, guar gum, chitosan and algin) as biomaterials. Biocompatibility of films prepared from natural polymer as a skin implant was evaluated. These biodegradable films were subcutaneously implanted in the back of rats and their biodegradability was investigated by the evaluation of changes in structure, film weight and hematology as a function of time for the biotransformation. The result of rats test showed that locust bean and guar gum induced some suspects of non-biocompatibility in the tissue by foreign body reaction 24 and 48 hrs after implantation. These results showed the potential of partial biodegradable films prepared from natural polymer for ideal skin biomaterials at short period.

• Membrane Journal
• /
• v.9 no.3
• /
• pp.170-177
• /
• 1999

Asymmetric membranes for pervaporation were prepared with poly sulfone and sulfonated poly sulfone in order to separate water from 90% by weight butanol solution. Chlorosulfonic acid was reacted with trimethylchlorosilane for using as a sulfonating agent. The prepared polymers were characterized with FT-IR and $^1H$-NMR. The thermal properties of the polymers were examined with DSC and TGA. Back titration method was used for the evaluation of the degree of sulfonation or the ion ex¬change capacity. N-methyl-2-pyrrolidone (NMP) and diethyleneglycol dimethyl ether (DGDE) cosolvent were used for the preparation of asymmetric membranes. The cross section and skin layer of the mem¬branes were examined with scanning electron michroscopy to investigate membrane structure formed with cosolvent composition in the casting solution. In this article, the selectivity of the dense films were not different from each other so much. However, the permeation rates were significantly increased as much as 80 times compared to that of dense film.

• International Journal of CAD/CAM
• /
• v.6 no.1
• /
• pp.105-115
• /
• 2006

Thickness is a commonly used parameter in product design and manufacture. Its intuitive definition as the smallest dimension of a cross-section or the minimum distance between two opposite surfaces is ambiguous for intricate solids, and there is very little reported work in automatic computation of thickness. We present three generic definitions of thickness: interior thickness of points inside an object, exterior thickness for points on the object surface, and radiographic thickness along a view direction. Methods for computing and displaying the respective thickness values are also presented. The internal thickness distribution is obtained by peeling or successive skin removal, eventually revealing the object skeleton (similar to medial axis transformation). Another method involves radiographic scanning along a viewing direction, with minimum, maximum and total thickness options, displayed on the surface of the object. The algorithms have been implemented using an efficient voxel based representation that can handle up to one billion voxels (1000 per axis), coupled with a near-real time display scheme that uses a look-up table based on voxel neighborhood configurations. Three different types of intricate objects: industrial (press cylinder casting), sculpture (Ganesha idol), and medical (pelvic bone) were used for successfully testing the algorithms. The results are found to be useful for early evaluation of manufacturability and other lifecycle considerations.

• Journal of Microbiology and Biotechnology
• /
• v.7 no.4
• /
• pp.267-271
• /
• 1997

We developed a dermal equivalent (DE) which was engineered using human dermal fibroblasts and a matrix of collagen gel. The in vitro construction of the DE was accomplished by casting a porcine collagen type I solution plus concentrated medium with isolated and cultured fibroblasts. These constructs were attached to culture dishes or left floating in culture medium. Contraction of attached gels results in decreased gel thickness without a change in gel diameter, and contraction of floating gels results in decreased gel thickness and diameter. After contraction, there was no increase in cell number in floating gels, but cells in attached gels began to increase after about 4 days of the lag phase in cell growth curve. At this lag phase, addition of fibroblast growth factor (FGF) at a concentration of $0.1{\mu}$/ml promoted cell proliferation in the attached collagen gels, but no effect in floating gels. These results indicate that the method of contraction had an influence on the extracellular matrix (ECM) organization, and this influenced not only cell growth but also fibroblast responsiveness to FGF. This suggests that attached collagen gel is more suitable as a dermal equivalent than the floating gel. And the final contracted area of attached gel is much larger than that of the floating gel since floating gel is contracted in all directions but attached gel is contracted only vertically.

• Journal of Industrial Convergence
• /
• v.19 no.5
• /
• pp.151-157
• /
• 2021

Along with hair beauty, skin beauty, and nail beauty, according to the rapidly changing social flow of industrialization and appearanceism, makeup is acting as an important means for successful social life and smooth human relationships. Accordingly, the realistic need to increase sales of the beauty industry by investigating individual preferred makeup colors from various angles is emerging. Therefore, the makeup interest and color preference according to the pursuit of appearance management were analyzed for women in their teens to 40s living in Gwangju Metropolitan City and Jeollanam-do. As a result of the study, it was found that service workers, students, and teenagers and younger usually wear a lot of makeup. ) was found to be the most used. Through this study, I believe that it will be used as basic data for future makeup product development as well as application data for color selection by makeup artists as well as to increase sales of beauty shops.

• Membrane Journal
• /
• v.21 no.4
• /
• pp.389-397
• /
• 2011

In this study, polymer composite membranes based on sulfonated poly(arylene ether sulfone) (SPAES) were prepared using a solution casting method with different amount of vermiculite (VMT) content. The dispersion of VMT particles in the SPAES matrix was confirmed by means of a scanning electron microscopy observation. The composite membrane containing less than 1 wt% of VMT has a smooth skin on the top and bottom, which means there is a good dispersion of VMT in the matrix. The water uptake of the composite membranes gradually increases as the temperature increases, and the results confirm that all the adsorbed water is bound water because VMT has a strong water affinity on account of its high cation exchange value. A composite membrane with a VMT content of less than 1 wt% increases the proton conductivity and reduces the methanol permeability. Of all the composite membranes, the membrane SPAES/VMT 1.0 has the best fuel cell performance in terms of membrane selectivity. The performance value of SPAES/VMT 1.0 is double that of Nafion 112, which suggests that SPAES/VMT1.0 could be an excellent candidate for direct methanol fuel cells.