• Interaction and multiscale mechanics
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• 제7권1호
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• pp.525-542
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• 2014

The state-based peridynamics is considered a nonlocal method in which the equations of motion utilize integral form as opposed to the partial differential equations in the classical continuum mechanics. As a result, the enforcement of boundary conditions in solid mechanics analyses cannot follow the standard way as in a classical continuum theory. In this paper, a new approach for the boundary condition enforcement in the state-based peridynamic formulation is presented. The new method is first formulated based on a convex kernel approximation to restore the Kronecker-delta property on the boundary in 1-D case. The convex kernel approximation is further localized near the boundary to meet the condition that recovers the correct boundary particle forces. The new formulation is extended to the two-dimensional problem and is shown to reserve the conservation of linear momentum and angular momentum. Three numerical benchmarks are provided to demonstrate the effectiveness and accuracy of the proposed approach.

• 한국정밀공학회지
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• 제10권4호
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• pp.54-63
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• 1993

This paper presents the dynamic modeling and control methodology to arrest structural deflections of industrial robotic manipulators featuring elastic members retrofitted with surface bonded pizoelectric actuators and sensors. The cynamic modeling is accomplished by employing a variational theorem, prior to developing a finite element formulation. This finite element formulation accounts for both original robot member elements and also bonded piezoelectric material elements. The governing equation of motion is then modified by condensing the electric potential vectors and subsequently two different negative velocity feedback controllers are established; a constant-gain feedback controller and a constant- amplitude feedback controller. By adopting a Model P50 articulating industrial robot manufactured by Gerneral Electric Company, conputer simulations are underlaken in order to demonstrate superior performance characteristics to be accrued from this proposed methodology such as smaller deflections at the end-effector.

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

• 대한기계학회논문집
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• 제7권3호
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• pp.270-277
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• 1983

Plastic plane stress solutions are given for a center cracked strip, characterized by the Ramberg-Osgood plastic index, under bi-axial tension. Using a power law hardening stress-strain relation, an incremental plasticity finite element formulation is developed, and simple formulation is given for computing J-integral with nodal displacements. The near tip angular distribution of von Mises effective stress doesn't differ significantly in magnitude according to the change of loading stress and bi-axial load combination factor. But, for smaller plastic index, the location of its maximum value moves vertically at a head of crack. J-integral value, in the plastic zone near crack tip, decreases with load combination factor for large and small plastic index.

• Structural Engineering and Mechanics
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• 제13권4호
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• pp.437-453
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• 2002

In this paper, dynamic stiffness and flexibility for circular membranes are analytically derived using an efficient mixed-part dual boundary element method (BEM). We employ three approaches, the complex-valued BEM, the real-part and imaginary-part BEM, to determine the dynamic stiffness and flexibility. In the analytical formulation, the continuous system for a circular membrane is transformed into a discrete system with a circulant matrix. Based on the properties of the circulant, the analytical solutions for the dynamic stiffness and flexibility are derived. In deriving the stiffness and flexibility, the spurious resonance is cancelled out. Numerical aspects are discussed and emphasized. The problem of numerical instability due to division by zero is avoided by choosing additional constraints from the information of real and imaginary parts in the dual formulation. For the overdetermined system, the least squares method is considered to determine the dynamic stiffness and flexibility. A general purpose program has been developed to test several examples including circular and square cases.

• Journal of Pharmaceutical Investigation
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• 제34권2호
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• pp.107-114
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• 2004

External lyogels containing prostaglandin $E_1$ ethyl ester $(PGE_1-EE)$, a prodrug of prostaglandin $E_1\;(PGE_1)$ as a therapeutic agent for erectile dysfunction, were formulated to overcome the aqueous instability and enhance the percutaneous absorption. Lyogels of $PGE_1-EE$ were prepared with ethanol (EtOH)/proplyene glycol (PG) cosolvent system as a vehicle, cineol as an enhancer, and hydroxypropylcellusose as a gelling agent. In vitro percutaneous absorption studies were performed to determine the rate of $PGE_1$ absorption through rat or hairless mouse skin. The permeability of $PGE_1-EE$ lyogel with enhancer was 16-fold greater than that of lyogel without enhancer. Cosolvent produced 9-fold increase in percutaneous absorption. Pharmacodynamic effects of lyogels were evaluated in mature male cats in terms of intracavernosal pressure (ICP). Lyogels containing 0.1 % of $PGE_1-EE$ showed higher ICP compared to intraurethral preparation of $PGE_1$ (1 %) and enhancer-free control lyogel. The shelf-life $(t_{10%})$ of lyogel at refrigerated condition $(4^{\circ}C)$ was calculated as 928 days, which is 4.2 times longer than that of control hydrogel. As a result, $PGE_1-EE$ was formulated successfully to a lyogel system with a selective enhancer and cosolvent system for the topical delivery of $PGE_1$.

• 약학회지
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• 제42권3호
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• pp.265-274
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• 1998

In order to attain a sustained release at targeted organs in a prolonged time which can reduce the side effects and maximize the therapeutic effect, aclarubicin (ACL) was entrap ped into liposomes of different lipid compositions using Microfluidizer, and dry liposomes were prepared by lyophilization. The dry aclarubicin-entrapped liposomes were evaluated in terms of mean particle size and size distribution, entrapment efficiency and in vitro drug release profile. The Entrapment efficiency of liposome, when the concentration of aclarubicin and lipid were 0.5 to 1.0mg/ml and $200{\mu}mol$/ml, respectively, was over 80% using Microfluidizer, in contrast to 70% of entrapment efficiency using hand-shaking method. Mean particle size and size distribution of aclarubicin-entrapped liposomes of various lipid compositions did not change considerably by the freeze drying. The range of particle size was between 80 and 200nm. Among aclarubicin-entrapped liposomes, ACL-liposome of PC/DPPC/CH0L/TA displayed the most significant sustained release. The addition of DPPC appeared to be favorable for the control of release. In general, aclarubicin entrapped in liposomes was less stable than free aclarubicin either in pH 7.4 phosphate buffer or in human plasma. Formulation I($t_{1/2}$, 20.3 hr) devoid of lipid additive was the most unstable in the phosphate-buffer solution while formulation II($t_{1/2}$, 40.7 hr) with cardiolipin was the most stable. Half lives of aclarubicin-entrapped liposomes in human plasma were 43.2, 50.7, 35.9 and 35.3 hr for formulation I. II, III and IV, respectively, in contrast to 57.8 hr for free aclarubicin.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1994년도 추계학술대회 논문집
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• pp.223-228
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• 1994

A new velocity formulation technique, which contains the advantage of UBET and the shape function of FEM, is proposed. In the proposed technique, a shape function is used to improve the unreasonableness of elemental partition and to solve the difficulty of velocity-field determination. In order to verify the effectiveness of this rechnique, T-shaped forging processes are simulated. The results are compared with these obtained by experimental measurements in T-shaped forging. In T-shaped forging, good agreements between theory and experiment are also confined.

• Medical Lasers
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• 제10권3호
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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.

• 소성∙가공
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• 제4권3호
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• pp.222-232
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• 1995

The planar anisotripic FEM analysis for predicting earing profiles and draw-in amounts in the deep-drawing process is introduced. An implicit, incremental, updated Lagrangian formulation with a rigid-viscoplastic constitutive equation is employed. Contact and friction are considered through the mesh-based unit vector and normal contact pressure. The consistent full set of governing relations, which is comprising euilbrium and geometric constraint equations, is appropriately linearized. Barlat's strain-rate potential is employed, whose in-plane anisotropic properties are taken into account with anisotropic coefficients and potential parameters. The linear triangular membrane elements are used for depicting the formed sheet. In the numerical simulations of deep drawing processes of a flat-top cylindrical cup for 2090-T3 aluminum alloy sheet show good agreement with experiments, although some discrepancies were observed in the directional trend of cup height and thickness strains.