• Structural Engineering and Mechanics
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• v.89 no.1
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• pp.1-11
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• 2024

This article introduces a novel analytical model for examining the impact of porosity on shear correction factors (SCFs) in functionally graded porous beams (FGPB). The study employs uneven and logarithmic-uneven modified porosity-dependent power-law functions, which are distributed throughout the thickness of the FGP beams. Additionally, a modified exponential-power law function is used to estimate the effective mechanical properties of functionally graded porous beams. The correction factor plays a crucial role in this analysis as it appears as a coefficient in the expression for the transverse shear stress resultant. It compensatesfor the assumption that the shear strain is uniform across the depth of the cross-section. By applying the energy equivalence principle, a general expression for static SCFs in FGPBs is derived. The resulting expression aligns with the findings obtained from Reissner's analysis, particularly when transitioning from the two-dimensional case (plate) to the one-dimensional case (beam). The article presents a convenient algebraic form of the solution and provides new case studies to demonstrate the practicality of the proposed formulation. Numerical results are also presented to illustrate the influence of porosity distribution on SCFs for different types of FGPBs. Furthermore, the article validates the numerical consistency of the mechanical property changesin FG beams without porosity and the SCF by comparing them with available results.

• Structural Engineering and Mechanics
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• v.89 no.3
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• pp.225-238
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• 2024

In this paper, a quasi-3D hyperbolic shear deformation theory for the bending responses of a functionally graded (FG) porous micro-beam is based on a modified couple stress theory requiring only one material length scale parameter that can capture the size influence. The model proposed accounts for both shear and normal deformation effects through an illustrative variation of all displacements across the thickness and satisfies the zero traction boundary conditions on the top and bottom surfaces of the micro-beam. The effective material properties of the functionally graded micro-beam are assumed to vary in the thickness direction and are estimated using the homogenization method of power law distribution, which is modified to approximate the porous material properties with even and uneven distributions of porosity phases. The equilibrium equations are obtained using the virtual work principle and solved using Navier's technique. The validity of the derived formulation is established by comparing it with the ones available in the literature. Numerical examples are presented to investigate the influences of the power law index, material length scale parameter, beam thickness, and shear and normal deformation effects on the mechanical characteristics of the FG micro-beam. The results demonstrate that the inclusion of the size effects increases the microbeams stiffness, which consequently leads to a reduction in deflections. In contrast, the shear and normal deformation effects are just the opposite.

• Advances in nano research
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• v.16 no.3
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• pp.289-301
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• 2024

In this work, an analytical model employing a new higher-order shear deformation beam theory is utilized to investigate the bending behavior of axially randomly oriented functionally graded carbon nanotubes reinforced composite nanobeams. A modified continuum nonlocal strain gradient theory is employed to incorporate both microstructural effects and geometric nano-scale length scales. The extended rule of mixture, along with molecular dynamics simulations, is used to assess the equivalent mechanical properties of functionally graded carbon nanotubes reinforced composite (FG-CNTRC) beams. Carbon nanotube reinforcements are randomly distributed axially along the length of the beam. The equilibrium equations, accompanied by nonclassical boundary conditions, are formulated, and Navier's procedure is used to solve the resulting differential equation, yielding the response of the nanobeam under various mechanical loadings, including uniform, linear, and sinusoidal loads. Numerical analysis is conducted to examine the influence of inhomogeneity parameters, geometric parameters, types of loading, as well as nonlocal and length scale parameters on the deflections and stresses of axially functionally graded carbon nanotubes reinforced composite (AFG CNTRC) nanobeams. The results indicate that, in contrast to the nonlocal parameter, the beam stiffness is increased by both the CNTs volume fraction and the length-scale parameter. The presented model is applicable for designing and analyzing microelectromechanical systems (MEMS) and nanoelectromechanical systems (NEMS) constructed from carbon nanotubes reinforced composite nanobeams.

• Steel and Composite Structures
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• v.52 no.3
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• pp.343-356
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• 2024

This paper presents an analytical solution for correctly predicting the Lateral-Torsional Buckling critical moment of simply supported castellated beams, the solution covers uniformly distributed loads combined with compressive loads. For this purpose, the castellated beam section with hexagonal-type perforation is treated as an arrangement of double "T" sections, composed of an upper T section and a lower T section. The castellated beam with regular openings is considered as a periodic repeating structure of unit cells. According to the kinematic model, the energy principle is applied in the context of geometric nonlinearity and the linear elastic behavior of materials. The differential equilibrium equations are established using Galerkin's method and the tangential stiffness matrix is calculated to determine the critical lateral torsional buckling loads. A Finite Element simulation using ABAQUS software is performed to verify the accuracy of the suggested analytical solution, each castellated beam is modelled with appropriate sizes meshes by thin shell elements S8R, the chosen element has 8 nodes and six degrees of freedom per node, including five integration points through the thickness, the Lanczos eigen-solver of ABAQUS was used to conduct elastic buckling analysis. It has been demonstrated that the proposed analytical solution results are in good agreement with those of the finite element method. A parametric study involving geometric and mechanical parameters is carried out, the intensity of the compressive load is also included. In comparison with the linear solution, it has been found that the linear stability underestimates the lateral buckling resistance. It has been confirmed that when high axial loads are applied, an impressive reduction in critical loads has been observed. It can be concluded that the obtained analytical solution is efficient and simple, and offers a rapid and direct method for estimating the lateral torsional buckling critical moment of simply supported castellated beams.

• Journal of radiological science and technology
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• v.40 no.2
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• pp.187-195
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• 2017

Early diagnosis for upper facial trauma is difficult by using the standard Water's view (S-Water's) in general radiograph due to overlapping of anatomical structures, the uncertainty of patient positioning, and specific patients with obese, pediatric, old, or high-risk. The purpose of this study was to analyze appropriate exposure angles through a comparison of two different protocols (S-Water's vs. reverse Water's view (R-Water's)) by using a head phantom. A head phantom and general radiograph with 75 kVp, 400 mA, 45 ms 18 mAs, and SID 100 cm. Images of R-Water's were obtained by different angles in the range of $0^{\circ}$ to $50^{\circ}$, which adjusted an angle at 1 degree interval in supine position. Survey elements were developed and three observers were evaluated with four elements including the maxillary sinus, zygomatic arch, petrous ridge, and image distortion. Statistical significant analysis were used the Krippendorff's alpha and Fleiss' kappa. The intra-class correlation (ICC) coefficient for three observers were high with maxillary, 0.957 (0.903, 0.995); zygomatic arch, 0.939 (0.866, 0.987); petrous ridge, 0.972 (0.897, 1.000); and image distortion, 0.949 (0.830, 1.000). The high-quality image (HI) and perfect agreement (PA) for acquired exposure angles were high in range of the maxillary sinus ($36^{\circ}-44^{\circ}C$), zygomatic arch ($33^{\circ}-40^{\circ}$), petrous ridge ($32^{\circ}-50^{\circ}$), and image distortion ($44^{\circ}-50^{\circ}$). Consequently, an appropriate exposure angles for the R-Water's view in the supine position for patients with facial trauma are in the from $36^{\circ}$ to $40^{\circ}$ in this phantom study. The results of this study will be helpful for the rapid diagnosis of facial fractures by simple radiography.

• Korean Journal of Poultry Science
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• v.44 no.4
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• pp.253-258
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• 2017

This study was aimed at evaluating the additivity of crude protein digestibility in mixed diets of corn and soybean meal (SBM), and comparing direct and indirect methods for evaluating crude protein (CP) digestibility. Totally, five hundred and twenty-five 18-day-old broiler chickens were grouped into 7 blocks based on body weight, and randomly allocated to 6 treatment groups in a randomized complete block design. The basal diet, diet 3, was corn-SBM-based, containing 65% corn and 28% SBM. Diets 1 and 5 contained corn and SBM, respectively, as the sole CP source. To use the difference method, 2 diets, diets 2 and 4, were prepared by mixing corn and SBM at the expense of the basal diet, respectively. Diet 2 contained 79% corn and 14% SBM, and diet 4 contained 32.5% corn and 34% SBM. To evaluate the additivity of digestibility values, the difference between measured values for the mixed diets (diets 2, 3, and 4) and predicted values calculated using the measured values for diets 1 and 5 was examined. The apparent (AID) and standardized (SID) ileal digestibility of CP in SBM differed between the direct and indirect methods; however, corresponding digestibility did not differ for corn. Additionally, the predicted and measured digestibility of both AID and SID differed in diets 2 and 3, implying that the digestibility values obtained from diets 1 and 5 were not additive for mixed diets. In conclusion, this study showed that digestibility evaluated by direct and indirect methods depends on the ingredients having different CP concentrations, and this finding may be considered to improve the accuracy of feed formulation for broiler chickens.

• Journal of the Korean Society of Radiology
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• v.10 no.5
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• pp.327-335
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• 2016

The study is enforce to study image quality evaluation of condition provide the IEC and combination of clinical conditions each quality of radiation that image quality to assess the conditions provided to IEC in the clinical environment to conduct image quality assessment of the digital radiography system in the detector have environmental limits. First, image quality evaluation was evaluated by measuring the MTF, NPS using four quality of radiation and Using MCNPX simulation lastly DQE make a image quality evaluation after calculating the particle fluence to analyze spectrum quality of radiation. Second, Using MCNPX simulation of four quality of radiation was evaluated absorbed dose rate about electronic 1 per unit air, water, muscle, bone by using Radiation flux density and energy, mass-energy absorption coefficient of matter. Results of evaluation of image quality, MTF of four quality of radiation was satisfied diagnosis frequency domain 1.0 ~ 3.0 lp/mm of general X-ray that indicated 1.13 ~ 2.91 lp/mm spatial frequency. The NPS has added filter, spatial frequency 0.5 lp/mm at standard NPS showed a tendency to decrease after increase. Unused added filter, spatial frequency 0.5 lp/mm at standard NPS showed a certain NPS result value after decrease. DQE in 70 kVp / unuesd added filter(21 mm Al) / SID 150 cm that patial frequency 1.5 lp/mm at standard showed a tendency to decrease after certain value showed. Patial frequency in the rest quality of radiation was showed a tendency to decrease after increase. Results of evaluation of absorbed dose, air < water < muscle < bone in the order showed a tendency to increase. Based on the results of this study provide to basic data that present for the image quality evaluation method of a digital radiation imaging system in various the clinical condition.

• Journal of Life Science
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• v.26 no.8
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• pp.875-880
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• 2016

The plasma membrane plays a crucial role in relaying signals from the outside environment to the inside of the cells. In eukaryotic cells, the inner leaflets of the plasma membrane are composed mostly of phospholipids, including phosphatidylethanolamine (PE), phosphatidylserine (PS), and phosphatidylinositides (PIs). In this study, we tried to analyze the morphological changes induced by EGFP-fused membrane binding proteins, which are targeted to the plasma membrane via specific phospholipids binding. As a result, we found that overexpression of EGFP-P4M-SidM, a specific PI4P binding protein, or EGFP alone, did not induce any morphological changes. On the other hand, overexpression of EGFP-PLCδ1(PH), which is a specific PI(4,5)P₂ binding protein, EGFP-AKT1(PH) which binds to PI(3,4,5)P₃, or EGFP-OSH2(PH)×2 which binds to PI4P and PI(4,5)P₂, could induce the filopodia and lamilapodia formation as well as cell shrinkage. Overexpression of Lact-C2-EGFP which is a specific PS-binding probe, EGFP fused Aplysia phosphodiesterase 4 (ApPDE4) long-form (L(N20)-EGFP) which is localized to the plasma membrane via hydrophobic interaction, or EGFP fused Aplysia PDE4 short-form (S(N-UCR1-2)-EGFP) which is localized to the plasma membrane via electrostatic interaction, could induce cell shrinkage, but not filopodia or lamilapodia formation. Taken together, our data support that the different phospholipid bindings in the plasma membrane could induce different characteristic morphological changes. Thus, we can analyze, characterize, and classify the cellular morphological changes induced by the various phospholipid binding proteins.

• Journal of the Korean Society of Radiology
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• v.17 no.7
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• pp.1149-1155
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• 2023

This study aims to investigate the effect of changes in the Sub ROI on exposure index(EI) and to present indicators of changes in EI values that may occur when changing Sub ROI in clinical practice. This study was conducted on a subject of 20 cm of acrylic for a setting similar to abdominal radiography, and the specifications of one acrylic sheet is 20 × 20 × 5 cm. The survey conditions were the same as 80 kVp , 320 mA, 25 ms, SID 110 cm and the Sub ROI obtained 30 images for each type using five types provided by the equipment company. The EI value provided by the equipment and entrance skin exposure(ESE) were compared and analyzed. The mean value of EI according to the change in Sub ROI was 101.18±0.27 for LS, 106.57±0.31 for AEC, 107.74±0.39 for VR, 107.90±0.38 for HR, and 109.72±0.32 for SS (p<0.01). The average value of ESE by sub ROI type (LS, AEC, VR, HR, SS) was measured to be 476.45±1.71 μGy, 476.92±1.48 μGy, 476.14±2.30 μGy, 475.61±1.96 μGy, and 477.14±1.46 μGy, with statistically significant differences (p<0.01). As a result of this study, the EI according to the sub ROI type is based on LS(109.72), which represents the minimum value. AEC increased 5.3%, VR increased 6.4%, HR increased 6.6%, SS increased 8.4%, and overall, increased by about 5.3%. As for the average value of ESE, HR(475.61 μGy)type showed the minimum value, and based on this, AEC increased 0.27%, VR increased 0.11%, LS increased 0.17%, SS increased 0.32%, and overall, increased by about 0.17%.

• Journal of the Korean Society of Radiology
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• v.18 no.5
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• pp.523-529
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• 2024

The purpose of this study is to investigate the effect of differences in grid focal distance used in general radiography on the exposure index and image quality, and to provide useful information for the application of grids in clinical radiography. With AEC applied and SID set to 110 cm, 30 images were obtained for each focus distance of the grid at 110 cm, 140 cm, and 180 cm under the same exposure conditions. The dose was measured using the DAP and ESD, while image quality was evaluated using the SNR and CNR. The exposure index (EI) was determined based on the values shown in the image. EI was derived from the values indicated in the images. The mean DAP values at focus distances of 180, 140, and 110 cm were 10.944±0.613, 10.687±0.516, and 9.74±0.588 cGy·cm², respectively. The ESD values were 1041.75±57.92, 1019.99±49.61, and 930.86±55.77 μGy, while the EI values were 205.97±11.77, 210.59±10.37, and 193.8±11.86. The SNR values were 28.48±0.62, 28.41±0.64, and 27.13±0.72 dB, and the CNR values were 0.09859±0.004276, 0.09864±0.004378, and 0.09026±0.004783 dB. The differences in the mean values were statistically significant (p < 0.01). The values were significantly higher at focal distances of 140 cm and 180 cm compared to 110 cm, but there was no significant difference between the focal distances of 140 cm and 180 cm. The correlation analysis results revealed significant negative correlations between FD and DAP (r = -0.642, p < 0.01), ESD (r = -0.629, p < 0.01), EI (r = -0.376, p < 0.01), SNR (r = -0.615, p < 0.01), and CNR (r = -0.575, p < 0.01) for all variables. The results of this study showed a moderate negative correlation between the focus distance of the grid and the SNR, CNR, DAP, and ESD, and a weak negative correlation with the EI. Therefore, radiological technologists should be aware that even when the same exposure conditions are applied using an AEC system, variations in focus distance of the grid can affect the exposure index, dose, and image quality. Careful consideration is needed when setting the target exposure index.