• 대한수학회지
• /
• 제34권1호
• /
• pp.87-118
• /
• 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 $\Gamma_g$.

• 한국지반공학회논문집
• /
• 제27권3호
• /
• pp.75-83
• /
• 2011

일반적인 불포화지반의 거동뿐만 아니라, 열과 관련된 분야, 지반환경 분야 등 다양한 분야에서 불포화 다공질 재료의 열적-수리적-역학적으로 결합된 문제들이 대두되면서 이러한 문제들을 해석하기 위한 수치도구 개발의 필요성이 대두되고 있다. 본 논문에서는 거시적 접근법(macroscopic approach)에 근거하여 불포화지반에 대한 열-수리-역학거동의 수식화를 하였다. 흙, 물, 공기에 대한 질량보존의 법칙, 에너지 보존법칙, 그리고 하중평형 조건식으로부터 결합된(coupled) 4개의 지배방정식을 유도하였다. Galerkin 간략화와 시간적분으로부터 주 변수인 변위(u), 가스압($P_g$), 유체압($P_1$), 온도(T)를 Newton의 반복과정을 이용하여 구하는 유한요소 프로그램(FEM)을 작성하였다. 개발된 프로그램을 이용하여 다공질재료에서 2상 흐름 문제 중 일차원 배수실험(u-$P_g-P_1$), 온도 압밀(u-$P_1$-T), 그리고 지표면 온도변화에 의한 말뚝의 주변지반에 대한 영향(u-$P_1$-T)에 대하여 수치해석을 수행하고 논의하였다.

• 한국균학회지
• /
• 제30권1호
• /
• pp.50-55
• /
• 2002

국내 느타리버섯 재배지의 버섯파리 사충으로부터 분리하여 버섯파리 유충에 높은 독성을 나타낸 Bacillus thuringiensis subsp. israelensis Bti-D와 Bti-U 균주를 이용하여 느타리 버섯파리에 대한 생물학적 방제효과를 검정한 결과, 느타리버섯 병재배시는 Bti-D와 Bti-U의 방제가가 각각 74.4%와 64.2%이었으며, 소형상자재배시는 75.8%와 56.8%였다. Bti-D와 Bti-U의 제제화를 위한 대량배양용 염가배지를 개발하기 위하여 배지종류별 세균증식량을 OD를 측정하여 비교한 결과, 2균주 모두 비지배지에서 가장 높았다. 두 균주 중 방제효과가 더 높은 Bti-D 균주를 비지배지에서 대량배양하여 몇 종류의 수화형 미생물 살충제를 만들고 느타리버섯 병재배와 상자재배에서 방제효과를 검정한 결과, 병재배에서 bio-gel로서 옥수수전분을 이용하여 만든 WCS 제제의 방제가가 86.4%로 가장 높았으며, 생균처리의 69.1%보다도 효과적이었다. 또한, 이 WCS 제제를 살포하기 위하여 희석할 때 pH 8로 보정된 물을 사용할 경우에는 방제가가 93.2%로 제고되었다. 상자재배에서는 pH 8로 보정된 물을 사용한 WCS 제제와 화학살충제인 주론수화제의 방제효과와 버섯수량에 미치는 영향을 동시에 비교하였는데, WCS 제제 처리시 방제가는 74.3%로서 주론수화제 처리시 92.2% 보다 낮았다. 그러나 버섯수량 비교에서는 WCS 제제를 처리할 경우 무처리나 주론수화제 처리에 비해 수량이 증가되었다.

• East Asian mathematical journal
• /
• 제14권1호
• /
• pp.63-76
• /
• 1998

we consider the hp-version to solve non-constant coefficients elliptic equations $-div(a{\nabla}u)=f$ with Dirichlet boundary conditions on a bounded polygonal domain $\Omega$ in $R^2$. In [6], M. Suri obtained an optimal error-estimate for the hp-version: ${\parallel}u-u^h_p{\parallel}_{1,\Omega}{\leq}Cp^{(\sigma-1)}h^{min(p,\sigma-1)}{\parallel}u{\parallel}_{\sigma,\Omega}$. This optimal result follows under the assumption that all integrations are performed exactly. In practice, the integrals are seldom computed exactly. The numerical quadrature rule scheme is needed to compute the integrals in the variational formulation of the discrete problem. In this paper we consider a family $G_p=\{I_m\}$ of numerical quadrature rules satisfying certain properties, which can be used for calculating the integrals. Under the numerical quadrature rules we will give the variational form of our non-constant coefficients elliptic problem and derive an error estimate of ${\parallel}u-\tilde{u}^h_p{\parallel}_{1,\Omega}$.

• 대한기계학회논문집A
• /
• 제22권2호
• /
• pp.365-371
• /
• 1998

In the present study, we attempted to add the incompatible functions as additional variable terms to the conventional u-p formulation. It is derived from the four-field generalized variational principle that encompasses velocity, pressure, velocity strains and stress fields as independent interpolated variables. As a severe test of the present formulation, we have investigated the driven cavity with the corner velocity singularity like leaky lid. Through the test, the present element performs very well without unstable oscillation of pressure distribution.

• Structural Engineering and Mechanics
• /
• 제18권1호
• /
• pp.79-90
• /
• 2004

A high precision shear deformable triangular element has been proposed for bending analysis of triangular plate. The element has twelve nodes at the three sides and four nodes inside the element. Initially the element has thirty-five degrees of freedom, which has been reduced to thirty by eliminating the degrees of freedom of the internal nodes through static condensation. Plates having different boundary conditions, side ratios (b/a) and thickness ratios (h/a = 0.001, 0.1 and 0.2) have been analyzed using the proposed shear locking free element. Concentrated and uniformly distributed transverse loads have been used for the analysis. The formulation is made based on first order shear deformation theory. For validation of the present element and formulation few results of thin triangular plate have been compared with the analytical solutions. Results for thick plate have been presented as new results.

• Advances in Traditional Medicine
• /
• 제7권5호
• /
• pp.466-476
• /
• 2008

We have developed the tablet formulation of Triticum aestivum (wheatgrass) and investigated clinically, its effects in patients suffering from b-thalassemia (major) at K. T. Children Hospital, Civil Hospital, Rajkot. The tablets (wheatgrass powder 250 mg.) were given 3 times in a day for 9 months. Blood samples were collected at the start, after 6 months and 9 months and analyzed for various biochemical and hematological parameters. Treatment with wheatgrass formulation for 9 months produced significant decrease in hemoglobin, total RBC, eosinophil and reticulocyte counts. The mean corpuscular volume (MCV) and mean corpuscular hemoglobin concentration (MCHC) were significantly increased was significantly increased. The serum ferritin was also significantly decreased. There was no influence on serum magnesium, serum iron and Thiobarbituric acid reacting substances (TBARS). Our data indicate that treatment with wheatgrass on patients with $\beta$-thalassemia (major) may have beneficial effects in the form of a decrease in ineffective erythropoiesis, stimulation of hemoglobin synthesis in RBC, decrease in iron load and decrease in eosinophil count.

• Medical Lasers
• /
• 제10권3호
• /
• pp.161-169
• /
• 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.

• 한국지반공학회:학술대회논문집
• /
• 한국지반공학회 2010년도 추계 학술발표회
• /
• pp.808-812
• /
• 2010

A great deal of attention is focused on coupled Thermo-Hydro-Mechanical (THM) behavior of multiphase porous media in diverse geo-mechanical and geo-environmental areas. This paper presents general governing equations for coupled THM processes in unsaturated porous media. Coupled partial differential equations are derived from 3 mass balances equations (solid, water, and air), energy balance equation, and force equilibrium equation. Finite element code is developed from the Galerkin formulation and time integration of these governing equations for 4 main variables (displacement $\underline{u}$, gas pressure $P_g$, liquid pressure $P_l$), and temperature T). The code is validated with theoretical solutions for linear material with simple boundary conditions.

• Geomechanics and Engineering
• /
• 제32권3호
• /
• pp.255-270
• /
• 2023

One of the main parameters that affect the design of suction caisson-supported offshore structures is uplift behavior. Pull-out of suction caissons is profoundly utilized as the offshore wind turbine foundations accompany by a tensile resistance that is a function of a complex interaction between the caisson dimensions, geometry, wall roughness, soil type, load history, pull-out rate, and many other parameters. In this paper, a parametric study using a 3-D finite element model (FEM) of a single offshore suction caisson (SOSC) surrounded by saturated soil is performed to examine the effect of some key factors on the tensile resistance of the suction bucket foundation. Among the aforementioned parameters, caisson geometry and uplift loading as well as the difference between the tensile resistance and suction pressure on the behavior of the soil-foundation system including tensile capacity are investigated. For this purpose, a full model including 3-D suction caisson, soil, and soil-structure interaction (SSI) is developed in Abaqus based on the u-p formulation accounting for soil displacement (u) and pore pressure, P.The dynamic responses of foundations are compared and validated with the known results from the literature. The paper has focused on the effect of geometry change of 3-D SOSC to present the soil-structure interaction and the tensile capacity. Different 3-D caisson models such as triangular, pentagonal, hexagonal, and octagonal are employed. It is observed that regardless of the caisson geometry, by increasing the uplift loading rate, the tensile resistance increases. More specifically, it is found that the resistance to pull-out of the cylinder is higher than the other geometries and this geometry is the optimum one for designing caissons.