• Journal of the Korean Society of Manufacturing Process Engineers
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• v.21 no.5
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• pp.16-21
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• 2022

This study investigates the effect of the deformation on the sensitivity of a flexible polydimethylsiloxane (PDMS) membrane sensor. A PDMS membrane sensor was developed to measure the impact force of a water droplet using a silver nanowire (AgNW). The initial deformation of the membrane was confirmed with the application of a tensile force (i.e., tension) and fixing force (i.e., compressive force) at the gripers, which affects the sensitivity. The experimental results show that as the tension applied to the membrane increased, the sensitivity of the sensor decreased. The initial electrical resistance increased as the fixing force increased, while the sensitivity of the sensor decreased as the initial resistance increased. The movement of the membrane due to the impact force of the water droplet was observed with a high-speed camera, and was correlated with the measured sensor signal. The analysis of the motion of the membrane and droplets after collision confirmed the periodic movement of not only the membrane but also the change in the height of the droplet.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.36 no.2
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• pp.105-113
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• 2010

This study introduces a flexible approach to enhance skin permeation by using ethosomes with deformable lipid membranes as well as controllable sizes. To demonstrate this, a set of ethosomes encapsulating an anti-hair loss ingredient, Triaminodil$^{TM}$, as a model drug, were fabricated with varying their size, which was achieved by solely applying the different level of mechanical energy, while maintaining their chemical composition. After characterization of the ethosomes with dynamic light scattering, transmission electron microscopy, and deformability measurements, it was found that their membrane deformability depended on the particle size. Moreover, studies on in vitro skin permeation and murine anagen induction allowed us to figure out that the membrane deformability of ethosomes essentially affects delivery efficiency of Triaminodil$^{TM}$ through the skin. It was noticeable in our study that there existed an optimum particle size that can not only maximize the delivery of the drug through the skin, but also increase its actual dermatological activity. These findings offer a useful basis for understanding how ethosomes should be designed to improve delivery efficiency of encapsulated drugs therein in the aspects of changing their length scales and membrane properties.

• Proceedings of the KSME Conference
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• 2004.11a
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• pp.108-113
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• 2004

Korea Gas Corp. has developed the design technology of the LNG storage tank. The membrane to be applied inside of the LNG storage tank is provided with corrugations to absorb thermal contraction and expansion caused by LNG temperature changes. It is very important to measure their thermal strains under LNG temperatures by analytical and experimental stress analysis of the membrane. We have developed a stress measurement system using strain gages and measured the strain during cooldown and storing the LNG. We also analyzed the measured data by comparison with the FEM data. On the basis of these results, we could design and assure the application of the Kogas Membrane to large scale LNG storage.

• Journal of the Korean Institute of Gas
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• v.6 no.4 s.18
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• pp.47-52
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• 2002

Analytical studies have been performed to investigate the strength of the membrane and the reaction force at the anchor point. Using nonlinear FEM code and experiments, the stress analysis of the corrugated membrane related the cryogenic liquid pressure and thermal loading is performed to ensure the stability and fatigue strength of the membrane. This paper reports on the FEM results of membrane.

• Journal of the Korean Geotechnical Society
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• v.19 no.6
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• pp.335-342
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• 2003

In order to analyze the deformational behavior accurately, the in-situ testing technique which provides the reliable deformational characteristics at whole strain ranges, needs to be developed. The pressuremeter is a unique method for assessing directly the in-situ shear modulus of soils with strain amplitude. This paper introduces a new alternative, the cavity strain measuring system in pressuremeter designed for whole strain ranges of $10^{-5}$%∼20%. Not only in the synthetic calibration chamber but also in the field, the pressuremeter tests were performed to determine the compliance of the new developed pressuremeter system. The variation in shear modulus with strain amplitude above $5\times 10^{-2}$% was reliably determined by the developed pressuremeter. It is concluded that the major cause of error in small cavity strain measuring is not from the cavity strain measuring system but from the friction between measuring arm and membrane during unloading-reloading loops.

• 한국가스학회:학술대회논문집
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• 2003.05a
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• pp.159-164
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• 2003

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.35 no.10
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• pp.905-911
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• 2007

In this paper, geometrically and materially non-linear finite element analyses were performed to study the crease behavior of thin membranes. The cross-section of the membrane was modeled with 2-dimensional plane strain elements. To simulate the creasing process, the membrane mesh was folded, compressed to prescribed crease gauge by activating two rigid contact surfaces, and then released to give the crease topology. Various crease gauges were considered to investigate the effect of crease intensity on the initial deployment angle. The crease geometry was also obtained by experiments and the results were compared.

• Membrane Journal
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• v.31 no.1
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• pp.16-34
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• 2021

Water supplies are decreasing in comparison to increasing clean water demands. Using nanofiltration is one of the most effective and economical methods to meet the need for clean water. Common methods for desalination are reverse osmosis and nanofiltration. However, pristine membranes lack the essential features which are, stability, economic efficiency, antibacterial and antifouling performances. To enhance the properties of the pristine membranes, graphene oxide (GO) is a promising and widely researched material for thin film composites (TFC) membrane due to their characteristics that help improve the hydrophilicity and anti-fouling properties. Modification of the membrane can be done on different layers. The thin film composite membranes are composed of three different layers, the top filtering active thin polyamide (PA) layer, supporting porous layer, and supporting fabric. Forward osmosis (FO) process is yet another energy efficient desalination process, but its efficiency is affected due to biofouling. Incorporation of GO enhance antibacterial properties leading to reduction of biofilm formation on the membrane surface. Pressure retarded osmosis (PRO) is an excellent process to generate clean energy from sea water and the biofouling of membrane is reduced by introduction of GO into the active layer of the TFC membrane. Different modifications on the membranes are being researched, each modification with its own advantages and disadvantages. In this review, modifications of nanofiltration membranes and their composites, characterization, and performances are discussed.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.27 no.4
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• pp.265-271
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• 2014

304L stainless steel sheets are used as a primary barrier for the insulation of membrane-type liquefied natural gas(LNG) carrier cargo containment system. 304L stainless steel is a transformation-induced-plasticity(TRIP) steel that exhibits complex material behavior, because it undergoes phase transformation during plastic deformation. Since the TRIP behavior is very important mechanical characteristics in a low-temperature environment, significant amounts of data are available in the literature. In the present study, a uniaxial tensile test for 304L stainless steel was performed to investigate nonlinear mechanical characteristics. In addition, a viscoplastic model and damage model is proposed to predict material fractures under arbitrary loads. The verification was conducted not only by a material-based comparative study involving experimental investigations, but also by a structural application to the LNG membrane of a Mark-III-type cargo containment system.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.3C
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• pp.201-207
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• 2006

Soil tests are generally conducted using a membrane to measure a pore water pressure. However, it has also been recognized that the membrane penetrates into the specimen by the change of the confining pressure, and it results in the erroneous measurement in the pore water pressure and the volumetric strain. This study examined the effectiveness of the correction equation of the membrane penetration on the basis of the experimental data acquired during the isotropic unloading and the cyclic shear process using the hollow cylindrical shear test equipment. The results showed that the membrane penetration by the correction equation could be overestimated when the mean effective stress was lower than 20kPa in this study. The limitations originated from the sudden increase near the zero effective stress, and in order to prevent the overestimation in low effective stress condition, the use of the constant a was proposed in this study. Furthermore, the correction equation for the membrane penetration had to be applied carefully when the initial relative density was high and the density changes were occurred by the relocation of the soil particle by the liquefaction.