• Journal of Pharmaceutical Investigation
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• v.36 no.2
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• pp.97-102
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• 2006

The aim of this study was to investigate the feasibility and optimize permeability of slim patch type as a transdermal delivery system of caffein. Slim patch type was formulated and tested in modified Franz diffusion cell across cellulose membrane and hairless mouse skin in pH 5.8 phosphate buffer solution (PBS). The effect of $Pharmsolv^{\circledR}$ and drug concentration on permeation at four model, 1,2% $Pharmsolv^{\circledR}$ with $0.12\;mg/cm^2$ caffein and 0.12, $1.2\;mg/cm^2$ caffein with 2% $Pharmsolv^{\circledR}$ through hairless mouse skin was studied in vitro. The release of caffein from slim patch with various loading was fitted by the Higuchi's diffusion equation. The result showed that chemical $Pharmsolv^{\circledR}$ produced a large and significant increase of permeation. The effect of 2% $Pharmsolv^{\circledR}$ on permeation of caffein was greater about 10-fold greater than 1% $Pharmsolv^{\circledR}$ in first 60 minutes. The effect of drug concentration, however, was lower than that produced by chemical $Pharmsolv^{\circledR}$. Within the tested system, the most efficient combination for caffein slim patch type was $0.12\;mg/cm^2$ caffein with 2% $Pharmsolv^{\circledR},$ although $1.2\;mg/cm^2$ caffein with 2% $Pharmsolv^{\circledR}$ showed highest amounts permeation, because permeated percentages were significantly lower about $1/4{\sim}1/5$ times.

• Structural Engineering and Mechanics
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• v.71 no.4
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• pp.407-416
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• 2019

Novel steel fibre reinforced ultra-lightweight cement composite (ULCC) with compressive strength of 87.3MPa and density of $1649kg/m^3$ was developed for the flat slabs in civil buildings. This paper investigated structural behaviours of ULCC flat slabs according to a 4-specimen test program under concentrated loading and some reported test results. The investigated governing parameters on the structural behaviours of the ULCC slabs include volume fraction of the steel fibre and the patch loading area. The test results revealed that ULCC flat slabs with and without flexure reinforcement failed in different failure mode, and an increase in volume fraction of the steel fibre and loading area led to an increase in flexural resistance for the ULCC slabs without flexural reinforcement. Based on the experiment results, the analytical models were developed and also validated. The validations showed that the analytical models developed in this paper could predict the ultimate strength of the ULCC flat slabs with and without flexure reinforcement reasonably well.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.7 no.8
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• pp.1604-1611
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• 2003

For dual­band operation, it can be done by loading two pair of slits in the equilateral­triangular patch, one embeded close to the side edges of the patch and the other inserted at the bottom edge of the patch. The frequency ratio of the two operating frequencies can be tuned by varing the positions and lengths of the inserted slots at the bottom edge of the patch. While the calculated frequency ratio of the antenna by Ensemble 5.0 is $1.66 ({f_10}=1.928GHz, {f_20}=3.2GHz)$, the measured one is 2.04 $({f_10}=1.6806 GHz, {f_20}=3.435 GHz)$. The error in the frequency ratio is due on the fabrication dimension and feeding position error as well as on the permittivity dispersion effect.

• Journal of Pharmaceutical Investigation
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• v.40 no.1
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• pp.33-38
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• 2010

Sibutramine is a serotonin-norepinephrine reuptake inhibitor indicated for the management of obesity in conjunction with a reduced calorie diet. The oral administration of sibutramine is followed by its dose-related side effects. In this study, sibutramine was formulated into drug in adhesive (DIA) patches in an attempt to overcome these problems. The effects of different formulation variables including pressure-sensitive adhesive (PSA), loading amount of drug, thickness of matrix and enhancer on the skin permeation of the drug were evaluated using excised hairless mouse skin. In the acrylic adhesive with carboxyl functional group, low release of sibutramine was observed due to the strong interaction between carboxyl group of adhesive and amine group of sibutramine. The acrylic adhesive without functional group provided good adhesion force and allowed high drug loading. Changing drug load as well as thickness of the matrix was found to alter permeation rate. $Crovol^{(R)}$ PK40 and $Crovol^{(R)}$ A40, were found to be effective enhancers for sibutramine. The optimized patch contained 20% sibutramine, and 5% $Crovol^{(R)}$ A40 as permeation enhancer, in $80\;{\mu}m$ thick Duro-$Tak^{(R)}$ 87-9301 matrix.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.41 no.12
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• pp.967-974
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• 2013

Recently the authors had proposed the z-pinning patch concept to simply manufacture z-pinned composite structures at industrial production site and manufactured composite single-lap shear joint specimens using the concept. Through static tensile test on the specimens they had obtained 54~68% improvement of the joint strength. As a sequential study of it, in this study, fatigue test has performed to measure an improvement of joint strength under cyclic loading. The z-pin's material is stainless steel and its surface was specially machined into zagged shapes and chemically corroded to increase the connection force with composite materials. Approximately 98~125% improvement of the joint strength under cyclic loading was obtained.

• Journal of Pharmaceutical Investigation
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• v.31 no.4
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• pp.241-256
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• 2001

Alginate microspheres, containing fluorescein isothiocyanate-bovine serum albumin (FITC-BSA) or green fluorescent protein (GFP) were prepared and used as a model drug to develop the oral vaccine delivery system. The alginate microspheres were coated with poly-L-lysine or chitosan. Two methods, w/o-emulsion and spray, were used to prepare alginate microspheres. To optimize preparation conditions, effects of several factors on the particle size and particle morphology of microsphere, and loading efficiency of model antigen were investigated. In both preparation methods, the particle size and the loading efficiency were enhanced when the concentration of sodium alginate increased. In the w/o-emulsion preparation method, as the concentration of Span 80 was increased from 0.5% to 2%, the particle size was decreased, but the loading efficiency was increased. The higher the emulsification speed was, the smaller the particle size and loading efficiency were. The concentration of calcium chloride did not show any effect on the particle size and loading efficiency. In the spray preparation method, the particle size was increased as the nozzle pressure $(from\;1\;kgf/m^2\;to\;3\;kgf/m^2)$ and spray rate was raised. Increasing calcium chloride concentration (<7%) decreased the particle size, in contrast to no effect of calcium chloride concentration on the w/o-emulsion preparation method. Alginate microspheres prepared by two methods were different in the particle size and loading efficiency, the particle size of microspheres prepared by the spray method was about $2-6\;{\mu}m$, larger than that prepared by the w/o emulsion method $(about\;2{\mu}m)$, and the loading efficiency was also higher with spray method. Furthermore, drying process for the microspheres prepared by the spray was simpler and easier, compared with the w/o emulsion preparation. Therefore, the spray method was chosen to prepare alginate microspheres for further experiments. Release pattern of FITC-BSA in alginate microspheres was evaluated in simulated intestinal fluid and PBS (phosphate buffered saline). Dissolution rate of FITC-BSA from alginate/chitosan microsphere was lower than that from alginate microsphere and alginate/poly-L-lysine microsphere. By confocal laser scanning microscope, it was revealed that alginate/FITC-poly-L-lysine microspheres were present in close apposition epithelium of the Peyer's patches of rabbits following inoculation into lumen of intestine, which proved that microspheres could be taken up by Peyer's patch. In conclusion, it is suggested that alginate microsphere prepared by spray method, showing a particle size of & $10\;{\mu}m$ and a high loading efficiency, can be used as a model drug for the development of oral vaccine delivery system.

• Structural Engineering and Mechanics
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• v.52 no.1
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• pp.137-147
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• 2014

The present paper deals with the first ply failure analysis of the laminated composite plates under various static and dynamic loading conditions. Static analysis has been carried out under patch load and triangular load. The dynamic failure analysis has been carried out under triangular pulse load. The formulation has been carried out using the finite element method and a computer code has been developed. The first order shear deformation theory has been applied in the present formulation. The displacement time history analysis of laminated composite plate has been carried out and the results are compared with those published in literature to validate the formulation. The first ply failure load for laminated composite plates with various lamination schemes under static and dynamic loading conditions has been calculated using various failure criteria. The failure index-time history analysis has also been carried out and presented in this paper.

• Journal of Mechanical Science and Technology
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• v.19 no.11
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• pp.1967-1974
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• 2005

The subsurface stress field caused by both normal loads and tangential loads has been evaluated using the rectangular patch solution. The effect of tangential loading on the subsurface stress field has been investigated in detail for both the cylinder-on-cylinder contact and a spur gear teeth contact. For the cylinder-on-cylinder contact, the subsurface stress fields are moved more to the direction of tangential loads and the positions where the maximum stress occur are getting closer to the surface with the increasing tangential loads. The subsurface stress fields of the gear teeth contact are expanded more widely to the direction of tangential loads with the increasing tangential loads. The friction coefficient of a gear teeth contact is low because they are operated in a lubricated condition, and therefore surface tractions in the EHL condition hardly affect on the subsurface stress field.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2008.05a
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• pp.685-688
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• 2008

Planar antennas are very efficient for the use of the out-door data transmission applications due to their low-profile characteristics. But the size of the antenna in UHF band blocks the practical usage. In this paper, a miniaturized planar antenna is investigated for the application of AMR system in UHF band. The designed antenna is fabricated in the form of the microstrip patch on the FR-4 substrate. The miniaturization is achieved by slot-loading on the patch. First, effects of simple slots on the size reduction are analyzed, followed by the design using more complex slots resulting in the reduction ratio of 37.9% in 425.6 MHz and bandwidth of 3.8 MHz. The effect of epoxy coating for the protection is also investigated.

• Structural Engineering and Mechanics
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• v.50 no.4
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• pp.525-539
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• 2014

Bonded composite-patch repair has been widely used to restore or extend the service life of damaged structures due to its effectiveness as a mechanical repair technique. In this paper using extended finite element method (XFEM), three-dimensional crack models are developed to examine the fracture behavior of centrally cracked aluminum plates repaired with single and double sided composite patches. Stress intensity factor (SIF) at the crack tip is used as the fracture criterion. In this regard, the effects of the crack lengths, patch materials, orientation of plies, adhesive and patch thickness are examined to estimate the SIF of the repaired plate and the repair performance. The obtained results show that composite patches have significant effect on reduction of the SIF at the crack tip. It is also proved that using double symmetric repair, in comparison to single one, reduces considerably SIF at the crack tip. Hence, the residual strength can be improved significantly as well as fatigue life of the structure. Investigation of ply orientation effects shows SIF increase as the ply orientation is changed from $0^{\circ}$ (perpendicular to the advancing crack) to $90^{\circ}$ (parallel to the crack line). However, the effectiveness of the ply orientation depends on the loading direction and the crack direction.