• Korean Journal of Computational Design and Engineering
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• v.14 no.5
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• pp.297-305
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• 2009

Automatic generation of the mid-surfaces of a CAD model is becoming a useful function in that it can help increase the efficiency of engineering analysis as far as it does not affect the result seriously. Several methods had been proposed previously to automatically generate the mid-surfaces, but they often failed to generate the mid-surfaces of complex CAD models. Due to the inherent difficulty of this mid-surface generation problem, it may not be possible to come up with a complete and general method to solve this problem. Since a method that can handle a specific case may not work for different cases, it seems that developing case-specific methods ends up with solving only a fraction of the problem. In this paper, therefore, we propose a method to generate mid-surfaces based on a divide-and-conquer paradigm. This method first decomposes a complex CAD model into simple volumes. The mid-surfaces of the simple volumes are automatically generated by the existing methods, and then they are converted into the mid-surfaces of the original CAD model.

• Bulletin of the Korean Mathematical Society
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• v.56 no.1
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• pp.73-82
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• 2019

We consider Riemann surfaces with three or four symmetries, assuming that they have a maximal total number of ovals and find all the possible topological types of the symmetries realizing such a configuration.

• Archives of Pharmacal Research
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• v.28 no.3
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• pp.370-375
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• 2005

The objective of this study was to develop a new reverse micelle-based microencapsulation technique to load tetracycline hydrochloride into PLGA microspheres. To do so, a reverse micellar system was formulated to dissolve tetracycline hydrochloride and water in ethyl formate with the aid of cetyltrimethylammonium bromide. The resultant micellar solution was used to dissolve 0.3 to 0.75 g of PLGA, and microspheres were prepared following a modified solvent quenching technique. As a control experiment, the drug was encapsulated into PLGA microspheres via a conventional methylene chloride-based emulsion procedure. The micro­spheres were then characterized with regard to drug loading efficiency, their size distribution and morphology. The reverse micellar procedure led to the formation of free-flowing, spherical microspheres with the size mode of 88 ~m. When PLGA microspheres were prepared follow­ing the conventional methylene chloride-based procedure, most of tetracycline hydrochloride leached to the aqueous external phase: A maximal loading efficiency observed our experimental conditions was below $5\%$. Their surfaces had numerous pores, while their internal architecture was honey-combed. In sharp contrast, the new reverse micellar encapsulation technique permitted the attainment of a maximal loading efficiency of 63.19 $\pm$$0.64\%$. Also, the microspheres had smooth and pore-free surfaces, and hollow cavities were absent from their internal matrices. The results of this study demonstrated that PLGA microspheres could be successfully prepared following the new reverse micellar encapsulation technique.

• Communications of the Korean Mathematical Society
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• v.38 no.2
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• pp.401-430
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• 2023

In this paper, we prove L^p estimates of a class of singular integral operators on product domains along surfaces defined by mappings that are more general than polynomials and convex functions. We assume that the kernels are in L(log L)² (𝕊^n-1 × 𝕊^m-1). Furthermore, we prove L^p estimates of the related class of Marcinkiewicz integral operators. Our results extend as well as improve previously known results.

• Bulletin of the Korean Mathematical Society
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• v.31 no.1
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• pp.85-92
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• 1994

It is well known that there exist no closed minimal surfaces in a 3-dimensional Euclidean space R$^{3}$. Myers [4] generalized the result to the case of the higher dimension and proved that there are no closed minimal hypersurfaces in an open hemisphere. The complete and non-compact version concerning Myers' theorem is recently considered by Cheng [1] and the following theorem is proved.

• Kyungpook Mathematical Journal
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• v.49 no.2
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• pp.321-348
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• 2009

In this paper, we give two lower bounds on the diameter of the boundary slope set of a Montesinos knot. One is described in terms of the minimal crossing numbers of the knots, and the other is related to the Euler characteristics of essential surfaces with the maximal/minimal boundary slopes.

• Kyungpook Mathematical Journal
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• v.63 no.4
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• pp.577-591
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• 2023

In this paper we establish the L^p boundedness of Marcinkiewicz integral operators on product domains with rough kernels satisfying a weak size condition. We assume that our kernels are supported on surfaces generated by curves more general than polynomials and convex functions. This generalizes and extends previous results.

• Physical Therapy Korea
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• v.20 no.2
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• pp.1-10
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• 2013

The purpose of this study was to determine the effect of the changes that occur in the leg muscle activity of unstable surface with different levels of air pressures. Three groups of college students have been placed randomly on unstable surfaces with different air pressures at group 1.0 psi ($n_1$=36), group 1.4 psi ($n_2$=40), and group 1.8 psi ($n_3$=40). Using surface electromyography, the recruitment of the tibialis anterior, peroneus longus, and the gastrocnemius was measured. Maximal voluntary isometric contraction was measured at the different air pressures based on the manual muscle test, then normalizing the value to %maximal voluntary isometric contraction (%MVIC). The tibialis anterior muscle activity was significant change from the unstable surface with difference levels of air pressures between group 1.0 psi and 1.8 psi and between group 1.4 psi and 1.8 psi. peroneus longus muscle activity was significant changes in muscle activity occurred between 1.0 psi and 1.4 psi group and between 1.0 psi and 1.8 psi group. Gastrocnemius muscle activity was significant change in muscle activity occurred between 1.0 psi and 1.4 psi group and between 1.0 psi and 1.8 psi group. In conclusion it identify that 1.0 psi group is most effective on muscle activity than the other groups. These suggest that the rehabilitation or strengthening of patients with ankle injuries, balance exercise with low air pressure like 1.0 psi can be more effective.

• Journal of Periodontal and Implant Science
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• v.34 no.3
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• pp.499-508
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• 2004

Regeneration of Periodontium with PRP does not only improve regeneration rate and density of bone but have a possibility to estimate faster healing process for soft tissue. And also, autogenous bone and xenogenic bone graft are effective on regeneration of periodontium. The purpose of this study is to evaluate the effectiveness of autogenous bone and xenogenic bone $(BBP^{(R)})$ grafts with the PRP technique on regeneration of periodontium. 52 Generally healthy Pt. who had pocket depth 5mm at any of 6 surfaces of the teeth were in the study at Dept. of Perio. in Dankook Dental Hospital. Open Flap was treated for 18 infra-bony pockets as control group, autogenous bone with PRP was inserted for 25 infrabony pockets as first test group, and $(BBP^{(R)})$ with PRP was inserted for 22 infrabony pockets as 2nd test group. Then evaluation was made after 3 and 6 months 1. There were significant differences between average probing pocket depth and clinical attachment level of 3, 6 months and minimal and maximal attachment level after 6 months each other. 2. There were significant differences in average probing pocket depth of control group and 2nd experimental group between 1 and 6 months. For clinical attachment level and minimal and maximal proving attachment level, there was a significant difference after 6 month of surgery. 3. There was no significant difference between two test groups for average probing depth, clinical attachment level, and minimal and maximal probing attachment level. As the result, PRP with bone graft could be very effective for regeneration of periodontium and there was no difference between xenogenic bone and autogenous bone.

• Korean Journal of Materials Research
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• v.30 no.3
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• pp.105-110
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• 2020

Cu/PET composite films are widely used in a variety of wearable electronics. Lifetime of the electronics is determined by adhesion between the Cu film and the PET substrate. The formation of an anisotropic nanostructure on the PET surface by surface modification can enhance Cu/PET interfacial adhesion. The shape and size of the anisotropic nanostructures of the PET surface can be controlled by varying the surface modification conditions. In this work, the effect of Cu/PET interface nanostructures on the failure mechanism of a Cu/PET flexible composite film is studied. From observation of the morphologies of the anisotropic nanostructures on plasma-treated PET surfaces, and cross-sections and surfaces of the fractured specimens, the Cu/PET interface area and nanostructure width are analyzed and the failure mechanism of the Cu/PET film is investigated. It is found that the failure mechanism of the Cu/PET flexible composite film depends on the shape and size of the plasmatreated PET surface nanostructures. Cu/PET interface nanostructures with maximal peel strength exhibit multiple craze-crack propagation behavior, while smaller or larger interface nanostructures exhibit single-path craze-crack propagation behavior.