• Structural Engineering and Mechanics
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• 제8권6호
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• pp.623-637
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• 1999

This paper presents a four-noded quadrilateral $C^0$ strain plate element for the analysis of thick laminated composite plates. The element formulation is based on: 1) the third-order shear deformation theory; 2) assumed strain element formulation; and 3) interrelated edge displacements and rotations along element boundaries. Unlike the existing displacement-type composite plate elements based on the third-order theory, which rely on the $C^1$-continuity formulation, the present plate element is of $C^0$-continuity, and its element stiffness matrix is evaluated explicitly. Because of the third-order expansion of the in-plane displacements through the thickness, the resulting theory and hence elements do not need shear correction factors. The explicit element stiffness matrix makes the present element more computationally efficient than the composite plate elements using numerical integration for the analysis of thick layered composite plates.

• 한국산업융합학회 논문집
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• 제12권3호
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• pp.149-155
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• 2009

A new finite element equation is derived by applying quadratic and cubic time integration scheme to the variational formulation in time-integral for the analysis of the transient elastodynamic problems to increase the numerical accuracy and stability. Emphasis is focused on methodology for cubic time integration scheme procedure which are never presented before. In this semidiscrete approximations of the field variables, the time axis is divided equally and quadratic and cubic time variation is assumed in those intervals, and space is approximated by the usual finite element discretization technique. It is found that unconditionally stable numerical results are obtained in case of the cubic time variation. Some numerical examples are given to show the versatility of the presented formulation.

• 소성∙가공
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• 제1권1호
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• pp.95-103
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• 1992

The plane strain analysis for simulating the stretch/draw forming operation with an arbitrarily-shaped tool profile is introduced. An implicit, incremental, updated Lagrangian formulation with a rigid-viscoplastic constitutive equation is employed. Contact and friction are considered through the mesh-normal, which compatibly describes arbitrary tool surfaces and FEM meshes without depending on the explicit spatial derivatives of tool surfaces. The linear line elements are used for depicting the formed sheet, based on membrane approximation. The FEM formulation is tested in the sections of automotive inner panel and two-side draw-in. Not only the excellent agreement between measured and computed strains is obtained in the stretched section, but also the numerical stability of formulation is verified in the draw-in section.

• Interaction and multiscale mechanics
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• 제6권2호
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• pp.83-105
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• 2013

In this paper, a multi-scale meshfree-enriched finite element formulation is presented for the analysis of acoustic wave propagation problem. The scale splitting in this formulation is based on the Variational Multi-scale (VMS) method. While the standard finite element polynomials are used to represent the coarse scales, the approximation of fine-scale solution is defined globally using the meshfree enrichments generated from the Generalized Meshfree (GMF) approximation. The resultant fine-scale approximations satisfy the homogenous Dirichlet boundary conditions and behave as the "global residual-free" bubbles for the enrichments in the oscillatory type of Helmholtz solutions. Numerical examples in one dimension and two dimensional cases are analyzed to demonstrate the accuracy of the present formulation and comparison is made to the analytical and two finite element solutions.

• 약학회지
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• 제37권4호
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• pp.370-382
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• 1993

In order for formulation of rectal containing OMZ, the OMZ suppositories were prepared using water-soluble base, PEG 4000 base and oil-soluble base, Witepsol H 15. Chemical stability of OMZ in suppositories was increased when Witepsol H 15 was used as a suppository base and arginine was added as a stabilizer. The decomposition of OMZ in suppository bases followed the first-order kinetics and their rate constants were 0.11 day $^{1}(t_{1/2}$=/6.25 days) for Witepsol H 15 suppository and 0.48 day $^{1}(t_{1/2}$=/1.43 days) for PEG 4000 suppository, respectively. On the other hand, the decomposition rate constants of Witepsol suppository and PEG suppository stabilized with arginine were 3.89$\times$10$^{-3}$(t$_{1/2}$=171.1 days) and 8.76$\times$10$^{-3}$ day $^{1}(t_{1/2}=79.9 days), respectively. Shelf-lives of the Witepsol and PEG suppositories stabilized with arginine were t$_{90%}$=291.8 days and t$_{90%}$=282.1 days at $35^{\circ}C$ and 75% RH, respectively. The dissolution test of OMZ suppositories was performed by rotating dialysis cell(RDC) method and the release rate constant was calculated by the simplified Higuchi's equation, Q'=K' t$^{1/2}$. Dissolution of OMZ from suppositories was augmented as arginine was added, particle size of OMZ was reduced and a suitable surfactant such as SLS was added. RDC method was more appropriate and available than Paddle method to evaluate the dissolution rate of lipophilic-base suppositoies. Arginine was found to be a very useful exipient for the enhancement of stability and dissolution of OMZ in suppositories.

• Structural Engineering and Mechanics
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• 제22권4호
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• pp.483-510
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• 2006

The dynamic instability characteristics of laminated composite stiffened shell panels subjected to in-plane harmonic edge loading are investigated in this paper. The eight-noded isoparametric degenerated shell element and a compatible three-noded curved beam element are used to model the shell panels and the stiffeners respectively. As the usual formulation of degenerated beam element is found to overestimate the torsional rigidity, an attempt has been made to reformulate it in an efficient manner. Moreover the new formulation for the beam element requires five degrees of freedom per node as that of shell element. The method of Hill's infinite determinant is applied to analyze the dynamic instability regions. Numerical results are presented to demonstrate the effects of various parameters like shell geometry, lamination scheme, stiffening scheme, static and dynamic load factors and boundary conditions, on the dynamic instability behaviour of laminated composite stiffened panels subjected to in-plane harmonic loads along the boundaries. The results of free vibration and buckling of the laminated composite stiffened curved panels are also presented.

• 대한조선학회논문집
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• 제47권2호
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• pp.210-224
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• 2010

The aim of the present study is to investigate the buckling strength of plates and stiffened panels with opening under transverse thrust and shear actions. It is observed that the existing design formulation for critical-buckling strength of plates are not valid for perforated plates, because the current design formulation trends can significantly overestimate or underestimate the load-carrying capacity of plates when plates have large opening and/or are thick. A series of eigen value and elastic.plastic large deflection finite element analyses are carried out with varying the aspect ratio of plate, the opening size and location on plate until and after the ultimate strength is reached. Based on the results obtained from the present study, closed-form design formulations for the elastic buckling strength of plates and stiffened panels with opening are derived. The derived design formulations are considered plasticity correction of the material and verified by experimental tests and results of nonlinear finite element computations.

• 대한본초학회지
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• 제33권2호
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• pp.69-77
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• 2018

Objectives : Daesiho-tang (DSHT) has been widely used in the treatment of cerebral infarct in traditional medicine. However, there was not report on the anti-obesity-related diseases efficacy of DSHT. In this study, we investigated the effects for the new formulation of DSHT, on the adipocyte differentiation cycle in 3T3-L1 cells. Methods : 3T3-L1 cells were treated with DSHT (50, 100, $200{\mu}g/m{\ell}$) during differentiation for 6 days. Also, the inhibitory effect of DSHT against 3T3-L1 adipogenesis was evaluated in various stage of adipogenesis such as early (0-2day), intermediate (2-4day), and terminal stage (4-6day). The accumulation of lipid droplets was determined by Oil Red O staining. and, the expressions of genes related to adipogenesis were measured by RT-PCR and Western blot analyses. Results : DSHT showed inhibitory activity on adipocyte differentiation at 3T3-L1 preadipocytes without affect cell toxicity as assessed by measuring fat accumulation and adipogenesis. In addition, DSHT significantly reduced the expression levels of several adipocyte marker genes including proliferator activated $receptor-{\gamma}$ ($PPAR-{\gamma}$) and CCAAT/ enhancer-binding $protein-{\alpha}$ ($C/EBP-{\alpha}$). Also, the anti-adipogenic effect of DSHT was strongly limited in the intermediate (2-4 day), terminal stage (4-6 day) of 3T3-L1 adipogenesis. In addition, the DSHT treatment down- regulated mRNA expression levels of $PPAR-{\gamma}$,, $C/EBP-{\alpha}$ in mature 3T3-L1 adipocytes. Conclusions : These results suggest that, the ability of DSHT has inhibited overall adipogenesis and lipid accumulation in the 3T3-L1 cells. The new formulation of DSHT may be a promising medicine for the treatment of obesity and related metabolic disorders.

• Archives of Pharmacal Research
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• 제18권6호
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• pp.385-390
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• 1995

The analytical methods for the analysis of cyclosporine (CsA), a fluorescence polarization immunoassay (FPIA) and HPLC method, were compared in a pharmacokinetic study of two CsA soft capsule formultaions ($Sandimmun^{\circledR}$; Sandoz, $Implanta^{\circledR}$; Hanmi). Sixteen healthy volunteers completed the study and each subjected single doses ($4{\tiems}100$ mg) of the test and the reference formulations in a two-way crossover design with a one-week drug-free interval between doses. Following each administration, whole blood concentrations of CsA were monitored over a period of 24 hour by both FPIA and HPLC methods. Blood concentrations nad pharmacokinetic parameters determined by either analytical method showed large intersubject variation, with the FPIA data showing relatively higher magnitude of intersubjecte variation than the HPLC data. The blood concentrations determined by FPIA were 1.1-1.3 times higher than those determined by HPLC. There were strong and significant correlations between the two methods (r>0.83 : p<0.0001). Intersubuject variation for the $AUC_{inf}{\;}and{\;}AUC_{24hr}$ of the test formulation was slightly reduced without statistical significance (paried -t test : p>0.05 $t_{max}$ was earlier nad $C_{max}$ was slightly lower for the test formulation, $AUC_{24h}, {\;}C_{max}, {\;}T_{max}$ and MRT determined separately from the data obtained by the two methods for the two formulations were examined by analyses of variance (ANOVA) for the bioequivalency evaluation. Results of ANOVA and confidence limits of terst/reference ratios of $AUC_{24th}$, $C_{max}$, $t_{max}$ and MRT, and statistical tests indicated the bioequivalence of the two formulations (i.e., test/reference ratio was within $100{\times}20%$) except for $C_{max}$ and $t_{max}$. The mean of tmax also showed 11.1% and 9.3% differences but the detection limit were 29.2% and 29.6% as determined by FPIA and HPLC resepctively. This experiments suggest that the data yielded for the two formulations demonstrated that they were bioequivalent.

• Journal of the Korean Statistical Society
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• 제18권1호
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• pp.26-37
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• 1989

When we select the t best out of k populations in the indifference zone formulation, a lower confidence bound on the probability of a correct selection is derived for families with monotone likelihood ratio. The result is applied to the normal means problem when the variance is common, and to the normal variances problem. Tables to implement the confidence bound for the normal variances problem are provided.