• Structural Engineering and Mechanics
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• v.40 no.5
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• pp.637-654
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• 2011

The present paper studies the variation of the natural frequencies and mode shapes of rectangular plates carrying a three degree-of-freedom spring-mass system (subsystem), when the subsystem changes (stiffness, mass, moment of inertia, location). An analytical approach based on Lagrange multipliers as well as a finite element formulation are employed and compared. Numerically reliable results are presented for the first time, illustrating the convenience of using the present analytical method which requires only the solution of a linear eigenvalue problem. Results obtained through the variation of the mass, stiffness and moment of inertia of the 3-DOF system can be understood under the effective mass concept or Rayleigh's statement. The analysis of frequency values of the whole system, when the 3-DOF system approaches or moves away from the center, shows that the variations depend on each particular mode of vibration. When the 3-DOF system is placed in the center of the plate, "new" modes are found to be a combination of the subsystem's modes (two rotations, traslation) and the bare plate's modes that possess the same symmetry. This situation no longer exists as the 3-DOF system moves away from the center of the plate, since different bare plate's modes enable distinct motions of the 3-DOF system contributing differently to the "new' modes as its location is modified. Also the natural frequencies of the compound system are nearly uncoupled have been calculated by means of a first order eigenvalue perturbation analysis.

• Korean Chemical Engineering Research
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• v.48 no.2
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• pp.157-163
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• 2010

A new etchant formulation was developed in this study to increase the shadow mask production rate, utilizing the $Fe(ClO_4)_3$ as an additive in the aqueous $FeCl_3$ solution. The shadow mask etch rate increased substantially with the increase of $Fe(ClO_4)_3$ concentration in the etchant. The etch rate difference between Ni and Invar steel was also reduced with the addition of $Fe{(ClO_4)_3}$ for most of the operating conditions, which was caused by the enhanced etch rate of both Ni and Fe by the new etchant. The increase in etch rate with the addition of $Fe(ClO_4)_3$ to aqueous ferric chloride solution was attributed to the superior electron transfer capability of $ClO^{4-}$ ion to that of $Cl^-$ ion.

• Proceedings of the Korean Society of Crop Science Conference
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• 1998.10a
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• pp.288-312
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• 1998

In Korea, chemical fertilizers and agricultural chemicals have had a significant impact on food production and these are today thought to be an indispensable part of modern agriculture. On the other hand, socioeconomical and IMF and WTO status in Korea are constant reminders of the vulnerability of our fossil fuel dependent agriculture. A new crop production system to improve economic, environmental and production efficiency must be exploited. Our particular concern has been given to an integrated cropping system involving recycling of crop residues, soil and N management, biological N fixation and multipurpose legumes. As a new integrated crop production system, a no-till direct-sown rice-vetch relaying cropping system has been proposed in this paper. The formulation of this system is based on the conception that N fertilizers being neither limitlessly available nor affordable, the current high-input crop production systems have produced troubled results severe labour shortage ill rural areas, balance of payment, environmental degradation and reduction of human health far exceed economic concerns. A natural and logical consequence is that long-term sustainability of agricultural systems must rely on the use and effective management of internal resources. Based on the information obtained throughout a series of experiments last years we have proved that the no-till direct-sown rice-vetch relaying cropping system dictates biological alternative which can augment, and in some cases replace, N fertilizers. Comprehensive discussions were made for the proposed system and it concluded that the system can offer an economically attractive and ecologically sound means of reducing external nitrogen input and improving the quality and quantity of internal resources, and consequently improving the farmers as well as the national returns.

• Journal of the Korean Society for Nondestructive Testing
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• v.21 no.1
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• pp.69-79
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• 2001

A volume integral equation method(VIEM) is applied for the effective analysis of elastic wave scattering problems in unbounded solids containing general anisotropic inclusions. It should be noted that this newly developed numerical method does not require the Green's function for anisotropic inclusions to solve this class of problems since only the Green's function for the unbounded isotropic matrix is Involved In their formulation for the analysis. nis new method can also be applied to general two-dimensional elastodynamic problems with arbitrary shapes and number of anisotropic inclusions. Through the analysis of plane elastodynamic problems in unbounded isotropic matrix with an orthotropic inclusion, it is established that this new method is very accurate and effective for solving plane elastic problems in unbounded solids containing general anisotropic inclusions.

• Korean Journal of Clinical Pharmacy
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• v.29 no.1
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• pp.18-24
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• 2019

Background: Although a growing number of guidelines and clinical researches are available for immunosuppressive treatment of post-transplantation, there is no clinical practice guideline for the care of kidney transplant recipients in Korea. Selection of a researchable question is the most important step in conducting qualified guideline development. Thus, we aimed to formulate key questions for Korean guideline to aid clinical decision-making for immunosuppressive treatment. Methods: Based on previous published guidelines review, a first survey was constructed with 29 questions in the range of immunosuppressive treatments. The experts were asked to rate the clinical importance of the question using a 5-point Likert scale. The questions reached 60% or more from the first survey and additional new questions were included in the second survey. In analyzing the responses to items rated on the 9-point scale, consensus agreement on each question was defined as 75% or more of experts rating 7 to 9. Results: In the first survey, 50 experts were included. Among the 29 questions, 27 were derived to get 60% or more importance and 3 new questions were additionally identified. Through the second survey, 9 questions were selected that experts reached consensus on 75% and over of the options. Finally, we developed key questions using PICO (patient, intervention, comparison, and outcome) methodology. Conclusion: The experts reached a high level of consensus on many of key questions in the survey. Final key questions provide direction for developing clinical practice guideline in the immunosuppressive treatment of transplantation.

• Structural Engineering and Mechanics
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• v.68 no.5
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• pp.603-619
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• 2018

In this research, an effective computational technique is carried out for nonlinear and post-buckling analyses of cracked imperfect composite plates. The laminated plates are assumed to be moderately thick so that the analysis can be carried out based on the first-order shear deformation theory. Geometric non-linearity is introduced in the way of von-Karman assumptions for the strain-displacement equations. The Ritz technique is applied using Legendre polynomials for the primary variable approximations. The crack is modeled by partitioning the entire domain of the plates into several sub-plates and therefore the plate decomposition technique is implemented in this research. The penalty technique is used for imposing the interface continuity between the sub-plates. Different out-of-plane essential boundary conditions such as clamp, simply support or free conditions will be assumed in this research by defining the relevant displacement functions. For in-plane boundary conditions, lateral expansions of the unloaded edges are completely free while the loaded edges are assumed to move straight but restricted to move laterally. With the formulation presented here, the plates can be subjected to biaxial compressive loads, therefore a sensitivity analysis is performed with respect to the applied load direction, along the parallel or perpendicular to the crack axis. The integrals of potential energy are numerically computed using Gauss-Lobatto quadrature formulas to get adequate accuracy. Then, the obtained non-linear system of equations is solved by the Newton-Raphson method. Finally, the results are presented to show the influence of crack length, various locations of crack, load direction, boundary conditions and different values of initial imperfection on nonlinear and post-buckling behavior of laminates.

• Steel and Composite Structures
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• v.39 no.1
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• pp.51-64
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• 2021

This paper presents a high-order shear and normal deformation theory for the bending of FGM plates. The number of unknowns and governing equations of the present theory is reduced, and hence makes it simple to use. Unlike any other theory, the number of unknown functions involved in displacement field is only four, as against five or more in the case of other shear and normal deformation theories. Based on the novel shear and normal deformation theory, the position of neutral surface is determined and the governing equilibrium equations based on neutral surface are derived. There is no stretching-bending coupling effect in the neutral surface-based formulation, and consequently, the governing equations of functionally graded plates based on neutral surface have the simple forms as those of isotropic plates. Navier-type analytical solution is obtained for functionally graded plate subjected to transverse load for simply supported boundary conditions. The accuracy of the present theory is verified by comparing the obtained results with other quasi-3D higher-order theories reported in the literature. Other numerical examples are also presented to show the influences of the volume fraction distribution, geometrical parameters and power law index on the bending responses of the FGM plates are studied.

• Structural Engineering and Mechanics
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• v.85 no.3
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• pp.289-304
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• 2023

The main objective of this paper is to study the effect of porosity on the buckling behavior of thick functionally graded sandwich plate resting on various boundary conditions under different in-plane loads. The formulation is made for a newly developed sandwich plate using a functional gradient material based on a modified power law function of symmetric and asymmetric configuration. Four different porosity distribution are considered and varied in accordance with material propriety variation in the thickness direction of the face sheets of sandwich plate, metal foam also is considered in this study on the second model of sandwich which containing metal foam core and FGM face sheets. New quasi-3D high shear deformation theory is used here for this investigate; the present kinematic model introduces only six variables with stretching effect by adopting a new indeterminate integral variable in the displacement field. The stability equations are obtained by Hamilton's principle then solved by generalized solution. The effect of Pasternak and Winkler elastic foundations also including here. the present model validated with those found in the open literature, then the impact of different parameters: porosities index, foam cells distribution, boundary conditions, elastic foundation, power law index, ratio aspect, side-to-thickness ratio and different in-plane axial loads on the variation of the buckling behavior are demonstrated.

• Nutrition Research and Practice
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• v.17 no.1
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• pp.73-90
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• 2023

BACKGROUND/OBJECTIVES: Meat eaters face conflicts over meat consumption due to recent increasing demands for reduced-meat diets to promote human and environmental health. Attitudes toward consuming meat have been shown to be culture-specific. Thus, this study was performed to examine cultural differences in attitudes, beliefs, and patterns of meat consumption among meat eaters in a group homogeneous in terms of age and sex but with diverse ethnicities. SUBJECTS/METHODS: In this cross-sectional study conducted in New York City in 2014, 520 female meat eaters (Whites = 25%; Blacks = 20%; East Asians = 35%; Hispanics = 20%) aged 20-29 completed a questionnaire consisting of a series of questions on meat consumption behaviors, which addressed amounts of consumption, cooking methods, past and future changes in meat consumption, and attitudes and beliefs regarding relationships between health and meat consumption. Logistic and multiple regression analyses were used to assess the effects of variables on meat consumption. RESULTS: Blacks had the highest annual total meat consumption (64.2 kg), followed by East Asians (53.6 kg), Whites (46.9 kg), and Hispanics (35.8 kg). Blacks ate significantly more chicken than the other ethnic groups (P < 0.001), and East Asians ate significantly more pork and processed meat (P < 0.001). Regardless of ethnicity, grilling/roasting/broiling were the preferred cooking methods, and vegetables were most consumed as a side dish. More than half of the participants expressed an intention to decrease future meat consumption. East Asians more strongly perceived meat as a festive food (P < 0.001) and were less guilty about the slaughtering animals (P = 0.11) than other groups. No differences were found between the ethnic groups regarding negative attitudes to meat consumption. CONCLUSIONS: The results show that ethnicities differ in terms of attitudes, beliefs, and patterns of meat consumption. Irrespective of ethnicity, the meat-eating participants almost unanimously demonstrated a willingness to reduce future meat consumption. It is hoped these findings aid the formulation of culturally-tailored interventions that effectively reduce meat consumption.

• Structural Engineering and Mechanics
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• v.86 no.4
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• pp.443-459
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• 2023

This study investigates the theoretical thermal buckling analyses of thick porous rectangular functionally graded (FG) plates with different geometrical boundary conditions resting on a Winkler-Pasternak elastic foundation using a new higher-order shear deformation theory (HSDT). This new theory has only four unknowns and involves indeterminate integral variables in which no shear correction factor is required. The variation of material properties across the plate's thickness is considered continuous and varied following a simple power law as a function of volume fractions of the constituents. The effect of porosity with two different types of distribution is also included. The current formulation considers the Von Karman nonlinearity, and the stability equations are developed using the virtual works principle. The thermal gradients are involved and assumed to change across the FG plate's thickness according to nonlinear, linear, and uniform distributions. The accuracy of the newly proposed theory has been validated by comparing the present results with the results obtained from the previously published theories. The effects of porosity, boundary conditions, foundation parameters, power index, plate aspect ratio, and side-to-thickness ratio on the critical buckling temperature are studied and discussed in detail.