• Journal of the Korean Mathematical Society
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• v.34 no.1
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• pp.87-118
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• 1997

This paper is concerned with a mixed Lagrangian formulation of the wiscous, stationary, incompressible Navier-Stokes equations $$ (1.1) -\nu\Delta u + (u \cdot \nabla)u + \nabla_p = f in \Omega $$ and $$ (1.2) \nubla \cdot u = 0 in \Omega $$ along with inhomogeneous Dirichlet boundary conditions on a portion of the boundary $$ (1.3) u = ^{0 on \Gamma_0 _{g on \Gamma_g, $$ where $\Omega$ is a bounded open domain in $R^d, d = 2 or 3$, or with a boundary $\Gamma = \partial\Omega$, which is composed of two disjoint parts $\Gamma_0$ and $\Gamma_g$.

• Coupled systems mechanics
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• v.3 no.1
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• pp.1-25
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• 2014

In this work, we present the theoretical formulation, operator split solution procedure and partitioned software development for the coupled thermomechanical systems. We consider the general case with nonlinear evolution for each sub-system (either mechanical or thermal) with dedicated time integration scheme for each sub-system. We provide the condition that guarantees the stability of such an operator split solution procedure for fully nonlinear evolution of coupled thermomechanical system. We show that the proposed solution procedure can accommodate different evolution time-scale for different sub-systems, and allow for different time steps for the corresponding integration scheme. We also show that such an approach is perfectly suitable for parallel computations. Several numerical simulations are presented in order to illustrate very satisfying performance of the proposed solution procedure and confirm the theoretical speed-up of parallel computations, which follow from the adequate choice of the time step for each sub-problem. This work confirms that one can make the most appropriate selection of the time step with respect to the characteristic time-scale, carry out the separate computations for each sub-system, and then enforce the coupling to preserve the stability of the operator split computations. The software development strategy of direct linking the (existing) codes for each sub-system via Component Template Library (CTL) is shown to be perfectly suitable for the proposed approach.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.21 no.11
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• pp.1912-1920
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• 1997

In the analysis of metal forming process, ALE(Arbitrary Lagrangian Eulerian) finite element methods have been increasingly used for the capability to control mesh independently from material flow. The methods can be divided into two groups i.e., coupled and split formulations. In the present work, the split ALE formulation is used for computational efficiency. A split ALE finite element method developed for rigid-viscoplastic materials and applied to the analysis of hot square die extrusion. Since thermal state greatly affects the product quality, an ALE scheme for temperature analysis is also presented. As computational examples, profile shapes as square and cross-like sections are chosen.

• Bulletin of the Korean Chemical Society
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• v.24 no.7
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• pp.931-936
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• 2003

By the use of multi-loop thermodynamic boxes developed here by us, we show that models of enzyme catalysis (e.g., split-site model) developed in an attempt to emphasize the importance of the reactant-state destabilization and, thus, demonstrate misleading nature of the fundamentalist position which defines Pauling's transition-state stabilization as the entire and sole source of enzyme catalytic power, should be reduced to the fundamentalist formulation which completely neglects dynamical aspects of mechanism between the reactant and the transition states and dwells only on events restricted to the reactant and transition states alone, because the splitsite (and other canonical) formulations as well as fundamentalist formulations are based, in common, on equilibrium assumptions stipulated by the thermodynamic box logics. We propose to define the equilibrium assumptions as the requisite and sufficient conditions for the fundamentalist position to enjoy its primacy as central dogma, but not as sufficient conditions for its validity, because it is subjected to contradictions presented by existing data.

• Korean Journal of Clinical Pharmacy
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• v.21 no.4
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• pp.347-352
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• 2011

Health insurance review & Assessment service (HIRA) has enforced cutting the drug costs when physicians prescribe split extended release drugs, starting from December, 2010. The objective of this study is to analyze extended release and enteric coated drugs on pharmaceutical reimbursement list in Korea, and to investigate the impact and barriers of the health insurance review on splitting extended-release formulation drugs. By using the ingredient code, extended release and enteric coated formulations make up 7.8% of all drugs in April, 2011. The most frequently used drugs are agent affecting circulatory and digestive system. From the extended release and enteric coated formulations (n=112), 34.8% (n=39) were not available in other dosage forms. According to questionnaire survey for 169 pharmacists (response rate: 73.8%), the rate of splitting and crushing of extended release and enteric coated drugs decreased. When pharmacists correct physician's prescription errors, the biggest problem was lack of other dosage forms. So it is necessary to develop variety of other dosage forms, and computerized checking system for splitting extended-release drugs. It is also important to inform physicians and patients in regard to the problems of split prescription of extended release and enteric coated drugs.

• Journal of Ginseng Research
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• v.46 no.2
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• pp.296-303
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• 2022

Background: Skin microbiota is important for maintenance of skin homeostasis; however, its disturbance may cause an increase in pathogenic microorganisms. Therefore, we aimed to develop a red ginseng formulation that can selectively promote beneficial bacteria. Methods: The effects of red ginseng formulation on microorganism growth were analyzed by comparing the growth rates of Staphylococcus aureus, S. epidermidis, and Cutibacterium acnes. Various preservatives mixed with red ginseng formulation were evaluated to determine the ideal composition for selective growth promotion of S. epidermidis. Red ginseng formulation with selected preservative was loaded into a biocompatible polymer mixture and applied to the faces of 20 female subjects in the clinical trial to observe changes in the skin microbiome. Results: Red ginseng formulation promoted the growth of S. aureus and S. epidermidis compared to fructooligosaccharide. When 1,2-hexanediol was applied with red ginseng formulation, only S. epidermidis showed selective growth. The analysis of the release rates of ginsenoside-Rg1 and -Re revealed that the exact content of Pluronic F-127 was around 11%. The application of hydrogel resulted in a decrease in C. acnes in all subjects. In subjects with low levels of S. epidermidis, the distribution of S. epidermidis was significantly increased with the application of hydrogel formulation and total microbial species of subjects decreased by 50% during the clinical trial. Conclusion: We confirmed that red ginseng formulation with 1,2-hexanediol can help maintain skin homeostasis through improvement of skin microbiome.

• Medical Lasers
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• v.10 no.3
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• pp.161-169
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• 2021

Background and Objectives Fractional microneedle radiofrequency systems are popular options to increase elasticity in aging skin. Laser-assisted drug delivery is a promising method for the epidermal injection of topically applied drugs and cosmetic ingredients. This study assesses the safety and efficacy of topical delivery of L-ascorbic acid, vitamin E, and ferulic acid after fractional microneedle radiofrequency treatment for reducing photodamage. Materials and Methods In this prospective, single-center, split-face, controlled pilot study, six women (mean age, 48.0 years; range, 35-57 years; Fitzpatrick skin types III and IV) exhibiting mild to moderate photodamage, underwent a single session of fractional microneedle radiofrequency treatment. The patients were instructed to apply the antioxidant formulation to only one side of the face. Patients were evaluated 3 days, 7 days, and 4 weeks thereafter, using three-dimensional imaging and ultrasound. Ex vivo, the full-thickness human skin was used for molecular and histological evaluation. Statistical analysis was achieved by applying t-tests, Mann-Whitney U tests, and one-way analyses of variance. Results Compared to the untreated side, the antioxidant-treated side exhibited a significant increase in dermal thickness (10.32% vs. 17.54%, p < 0.05), but not in skin elasticity (4.76% vs. 4.69%, p > 0.05). The difference in erythema between the sides was statistically not significant (p > 0.05). In the ex vivo model, expression of FGF2 in the skin was significantly increased after application of the antioxidant formulation, as compared to results obtained subsequent to fractional microneedle radiofrequency treatment only (p < 0.01). Conclusion This study demonstrates that for the treatment of photodamaged skin, laser-assisted delivery of the antioxidant formulation is a safe and effective adjuvant modality following fractional microneedle radiofrequency.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2004.04a
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• pp.381-388
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• 2004

We propose a 2D 'crack' element for the simulation of propagating crack with minimal remeshing. A regular finite element containing the crack tip is replaced with this novel crack element, while the elements which the crack has passed are split into two transition elements. Singular elements can easily be implemented into this crack element to represent the crack-tip singularity without enrichment. Both crack element and transition element proposed in our formulation are mapped from corresponding master elements which are commonly built using the moving least-square (MLS) approximation only in the natural coordinate. In numerical examples, the accuracy of stress intensity factor K/sub I/ is demonstrated and the crack propagation in a plate is simulated.

• 한국전산유체공학회:학술대회논문집
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• 2004.10a
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• pp.215-220
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• 2004

A mathematical formulation based on two-phase, two-fluid hyperbolic conservation laws is developed to investigate propagation of shock waves in one- and two-dimensions. We used a high resolution upwind scheme called the split-coefficient matrix method. Two extreme cases are computed for validation of the computer code: the states of a pure gas and a pure liquid. Computed results agreed well with the previous experimental and numerical results. It is studied how the shock wave propagation pattern is affected by the void fraction in the two-phase flow. The shock structure in a two-phase flow turned out, in fact, much deviated from the shape well known in the gas only phase.

• Proceedings of the KSME Conference
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• 2004.04a
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• pp.551-556
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• 2004

We propose a 2D 'crack' element for the simulation of propagating crack with minimal remeshing. A regular finite element containing the crack tip is replaced with this novel crack element, while the elements which the crack has passed are split into two transition elements. Singular elements can easily be implemented into this crack element to represent the crack-tip singularity without enrichment. Both crack element and transition element proposed in our formulation are mapped from corresponding master elements which are commonly built using the moving least-square (MLS) approximation only in the natural coordinate. In numerical examples, the accuracy of stress intensity factor $K_I$ is demonstrated and the crack propagation in a plate is simulated.