• Advances in nano research
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• v.13 no.5
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• pp.465-474
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• 2022

Based on the nonlocal strain gradient (NSG) theory and considering the influence of moment of inertia, the governing equations of motion of porous functionally graded (FG) nanoplates with four edges clamped are established; The Galerkin method is applied to eliminate the spatial variables of the partial differential equation, and the partial differential governing equation is transformed into an ordinary differential equation with time variables. By satisfying the boundary conditions and solving the characteristic equation, the dispersion relations of the porous FG strain gradient nanoplates with four edges fixed are obtained. It is found that when the wave number is very small, the influences of nonlocal parameters and strain gradient parameters on the dispersion relation is very small. However, when the wave number is large, it has a great influence on the group velocity and phase velocity. The nonlocal parameter represents the effect of stiffness softening, and the strain gradient parameter represents the effect of stiffness strengthening. In addition, we also study the influence of power law index parameter and porosity on guided wave propagation.

• Steel and Composite Structures
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• v.50 no.2
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• pp.149-158
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• 2024

Considering that different boundary conditions can have an important impact on structural vibration characteristics. In this paper, the nonlinear forced vibration behavior of functionally graded material (FGM) doubly curved shells with initial geometric imperfections under different boundary conditions is studied. Considering initial geometric imperfections and von Karman geometric nonlinearity, the nonlinear governing equations of FGM doubly curved shells are derived using Reissner's first order shear deformation (FOSD) theory. Three different boundary conditions of four edges simply supported (SSSS), four edges clamped (CCCC), clamped-clamped-simply-simply (CCSS) were studied, and a system of nonlinear ordinary differential equations was obtained with the help of Galerkin principle. The nonlinear forced vibration response of the FGM doubly curved shell is obtained by using the modified Lindstedt Poincare (MLP) method. The accuracy of this method was verified by comparing it with published literature. Finally, the effects of curvature ratio, power law index, void coefficient, prestress, and initial geometric imperfections on the resonance of FGM doubly curved shells under different boundary conditions are fully discussed. The relevant research results can provide certain guidance for the design and application of doubly curved shell.

• Advances in nano research
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• v.16 no.3
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• pp.265-272
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• 2024

In this paper, the problem of static bending of axially functionally graded (AFG) nanobeam is formulated with the local stress(Lσ)- and strain-driven(εD) two-phase local/nonlocal integral models (TPNIMs). The novelty of the present study aims to compare the size-effects of nonlocal integral models on bending deflections of AFG Euler-Bernoulli nano-beams. The integral relation between strain and nonlocal stress components based on two types nonlocal integral models is transformed unitedly and equivalently into differential form with constitutive boundary conditions. Purely LσD- and εD-NIMs would lead to ill-posed mathematical formulation, and Purely εD- and LσD-nonlocal differential models (NDM) may result in inconsistent size-dependent bending responses. The general differential quadrature method is applied to obtain the numerical results for bending deflection and moment of AFG nanobeam subjected to different boundary and loading conditions. The influence of AFG index, nonlocal models, and nonlocal parameters on the bending deflections of AFG Euler-Bernoulli nanobeams is investigated numerically. A consistent softening effects can be obtained for both LσD- and εD-TPNIMs. The results from current work may provide useful guidelines for designing and optimizing AFG Euler-Bernoulli beam based nano instruments.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.2
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• pp.1109-1117
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• 2014

We study free vibration analysis of sigmoid functionally graded materials(S-FGM) nano-scale plates, using a nonlocal elasticity theory of Eringen in this paper. This theory has ability to capture the both small scale effects and sigmoid function in terms of the volume fraction of the constituents for material properties through the plate thickness. Numerical solutions of S-FGM nano-scale plate are presented using this theory to illustrate the effect of nonlocal theory on natural frequency of the S-FGM nano-scale plates. The relations between nonlocal and local theories are discussed by numerical results. Further, effects of (i) power law index (ii) nonlocal parameters, (iii) elastic modulus ratio and (iv) thickness and aspect ratios on nondimensional frequencies are investigated. In order to validate the present solutions, the reference solutions are compared and discussed. The results of S-FGM nano-scale plates using the nonlocal theory may be the benchmark test for the free vibration analysis.

• Journal of the Korean Society of Clothing and Textiles
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• v.39 no.3
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• pp.337-352
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• 2015

This study selected a case study method conforming to qualitative research in order to analyzed how each type of fashion enterprises uses SNS in-side of fashion marketing based on content the researcher monitored and selected from the Facebook website for each enterprise. The standard to select fashion brands in this study is a graded list made based on ranking 5 analysis sites on social media (Socialbakers, socialDigm, Pulse K, BigFoot9, L2). The researcher sorted and then analyzed 2 brands that have many fan joiners and followers among fashion brands that were ranked top of the graded list, work in Facebook animatedly, and had representativeness in each type (SPA, Sports Brands). The study was conducted from January 2013 to March 2013, and the index of Facebook consisted of 3 kinds of elements (comment, like, and share). Each numerical value was counted to decide the monthly ranking. Content analysis was divided into public relations about brand, public relations about products, and customer participation and activities; consequently, the researcher investigated which content was post conforming to the ranking. The study analyzed the analysis results of each brand derived through the method of study compared to other brands. The results are as follows. In case of SPA brands, the category accounting for high rank in index analysis are public relation events to attract customer attention and products and offering information. The results of the monthly trend about whole post category were also similarly analyzed so the promotion goal that the brand wants to seek in priority coincides with the customer compliance rate. Next, in the case of sports brand, public relations for products offering information, event for arousing customer concern, and participation activities accounted for a high rank in the index analysis and posted the most in the analysis of the monthly trend for whole post category. The researcher came to understand that the direction of content for brands shown through Facebook coincides with customer sympathy.

• Korean Journal of Veterinary Service
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• v.35 no.2
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• pp.119-128
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• 2012

This study was performed to investigate the freshness and nutritive components of eggs from Incheon area. The eggs of 64 brands collected from 7 hypermarkets and 6 brands collected from farms were examined to test the Haugh unit (HU), egg yolk index and specific gravity. HU and specific gravity were higher in farm eggs than in hypermarket eggs (P<0.05), and there was no difference in the egg yolk index. Among hypermarket eggs, HU and egg yolk index were higher in the graded eggs than in non-graded eggs (P<0.05), and specific gravity was not different between them. HU and egg yolk index of the eggs collected in March were higher than those in August (P<0.05). To monitor the bacterial contamination, total coliforms, total bacterial counts (TBC) and Salmonella enteritidis were examined. Salmonella enteritidis and total coliforms were not detected from all eggs. TBC of farm eggs were less than $10^1$ CFU/mL in all samples and TBC of hypermarket eggs were less than $10^1$ CFU/mL in 187 samples, $10^1{\sim}10^2$ CFU/mL in 3 samples and $10^3{\sim}10^4$ CFU/mL in 2 samples, respectively. Antimicrobial residues were not detected from all eggs tested. The vitamin E contents in the vitamin E enriched eggs from 6 brands hypermarket were 1.98~22.96 mg/yolk100 g ($14.04{\pm}8.81$ mg/yolk100g), and those of 5 brands among them were higher than the average of ordinary eggs. In one brand egg, vitamin E content was lower than the average of ordinary eggs. The vitamin E contents of ordinary eggs were 1.75~16.36 mg/yolk100 g (average $5.57{\pm}2.76$ mg/yolk100 g) and there were no price differences between vitamin E enriched eggs and ordinary eggs. In the contents of vitamin E, docosahexaenoic acid (DHA) and cholesterol, there were no significant differences according to the price. These results suggests that egg production, distribution, and management system should be improved for supplying fresh eggs to consumers at reasonable prices.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.28 no.1
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• pp.85-92
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• 2015

This article presents the dynamic instability response of sigmoid functionally graded material plates on elastic foundation using the higher-order shear deformation theory. The higher-order shear deformation theory has ability to capture the quadratic variation of shear strain and consequently shear stress through the plate thickness. The governing equations are then written in the form of Mathieu-Hill equations and then Bolotin's method is employed to determine the instability regions. The boundaries of the instability regions are represented in the dynamic load and excitation frequency plane. The results of dynamic instability analysis of sigmoid functionally graded material plate are presented using the Navier's procedure to illustrate the effect of elastic foundation parameter on dynamic response. The relations between Winkler and Pasternak elastic foundation parameter are discussed by numerical results. Also, the effects of static load factor, power-law index and side-to-thickness ratio on dynamic instability analysis are investigated and discussed. In order to validate the present solutions, the reference solutions are used and discussed. The theoretical development as well as numerical solutions presented herein should serve as reference for the dynamic instability study of S-FGM plates.

• Journal of Chest Surgery
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• v.18 no.1
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• pp.79-85
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• 1985

The effect of graded increments in positive end-expiratory pressure [PEEP] on hemodynamics required to ventilate 8 critically ill patients is reported. Acute respiratory insufficiency was a cause of death in only one patient of drug inoxication among the 8 patients studied. The cardiac output was not changed significantly after the increment of PEEP to the level of 20 cm H2O. The heart rate was increased significantly from 15 cm H2O PEEP [P<0.01] as compared to 0 cm H2O PEEP; and the stroke volume was decreased significantly from 15 cm H2O PEEP [P<0.05]. The blood pressure was not affected at any level of PEEP, but the pulmonary artery pressure was elevated significantly at 10 cm H2O PEEP [P<0.01]. The right ventricular transmural filling pressure was not affected at the level of 10 cm H2O PEEP, but from 15 cm H2O PEEP it was increased significantly. With the increment of PEEP, the left ventricular stroke work index was decreased slightly; and at 20 cm H2O PEEP, it was decreased significantly. The right ventricular stroke work index was increased only at 10 cm H2O PEEP. The systemic vascular resistance was decreased significantly from 15 cm H2O PEEP [P<0.01].

• Magazine of the Korean Society of Agricultural Engineers
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• v.39 no.2
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• pp.86-94
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• 1997

For the efficient operation and maintenance( 0 & M), irrigation facilities were graded on the basis of their indices related to the 0 & M condition and the characteristics of reservoirs managed by Farmland Improvement Association(FIA) were examined. The results obtained are summarized as follows : 1. Characteristics of reservoirs include effective storage capacity, irrigation area, basin area, height and length of bank. Each characteristic is scored by the principle component analysis method. Variables which compose one index are categorized on the basis of their unit and each variable is scored so that the score of each unit sums to 100 for each index. 2. The Optimum MAnagement System of Irrigation Facilities(OMASIF) for Pyoungtaek area was developed by connecting general data of the irrigation facilities to image data. The database system is divided into three tables; LookUp Table, Facility Table, and Image Table. Image Table is again divided into five sub-tables, Image Table, Construction Cost Table, Acreage Table, 0 & M Cost Table, and Specification Table. 3. The evaluating criteria for the 0 & M of irrigation facilities can be established using the OMASIF. Irrigation facilities evaluated as poor state by the criteria should be repaired.

• Current Photovoltaic Research
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• v.5 no.2
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• pp.55-58
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• 2017

We investigated the influences of dielectric thin film coating on the optical characteristics of c-Si wafers with nanocone (NC) arrays using finite-difference time-domain (FDTD) simulations. Dielectric thin films on high-refractive-index surface can lower optical reflection and reflection dips appear at the wavelengths where destructive interference occurs. The optical reflection of the NC arrays was lower than that of the dielectric-coated planar wafer in broad wavelength range. Remarkable antireflection effects of the NC array could be attributed to beneficial roles of the NCs, including the graded refractive index, multiple reflection, diffraction, and Mie resonance. Dielectric thin films modified the optical reflection spectra of the NC arrays, which could not be explained by the interference alone. The optical properties of the dielectric-coated NC arrays were determined by the inherent optical characteristics of the NC arrays.