• Smart Structures and Systems
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• v.24 no.4
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• pp.507-524
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• 2019

A Bayesian dynamic linear model (BDLM) is presented for a data-driven analysis for response prediction and load effect separation of a revolving auditorium structure, where the main loads are self-weight and dead loads, temperature load, and audience load. Analyses are carried out based on the long-term monitoring data for static strains on several key members of the structure. Three improvements are introduced to the ordinary regression BDLM, which are a classificatory regression term to address the temporary audience load effect, improved inference for the variance of observation noise to be updated continuously, and component discount factors for effective load effect separation. The effects of those improvements are evaluated regarding the root mean square errors, standard deviations, and 95% confidence intervals of the predictions. Bayes factors are used for evaluating the probability distributions of the predictions, which are essential to structural condition assessments, such as outlier identification and reliability analysis. The performance of the present BDLM has been successfully verified based on the simulated data and the real data obtained from the structural health monitoring system installed on the revolving structure.

• Structural Engineering and Mechanics
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• v.81 no.3
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• pp.267-280
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• 2022

Multiscale structure has attracted significant interest due to its high stiffness/strength to weight ratios and multifunctional performance. However, most of the existing concurrent topology optimization works are carried out under deterministic load conditions. Hence, this paper proposes a robust concurrent topology optimization method based on the bidirectional evolutionary structural optimization (BESO) method for the design of structures composed of periodic microstructures subjected to uncertain dynamic loads. The robust objective function is defined as the weighted sum of the mean and standard deviation of the module of dynamic structural compliance with constraints are imposed to both macro- and microscale structure volume fractions. The polynomial chaos expansion (PCE) method is used to quantify and propagate load uncertainty to evaluate the objective function. The effective properties of microstructure is evaluated by the numerical homogenization method. To release the computation burden, the decoupled sensitivity analysis method is proposed for microscale design variables. The proposed method is a non-intrusive method, and it can be conveniently extended to many topology optimization problems with other distributions. Several numerical examples are used to validate the effectiveness of the proposed robust concurrent topology optimization method.

• Steel and Composite Structures
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• v.43 no.1
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• pp.31-54
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• 2022

This paper is concerned with the buckling behavior of functionally graded graphene reinforced porous nanocomposite beams based on the finite element method (FEM) using two variables trigonometric shear deformation theory. Both Young's modulus and material density of the FGP beam element are simultaneously considered as grading through the thickness of the beam. The finite element approach is developed using a nonlocal strain gradient theory. The governing equations derived here are solved introducing a 3-nodes beam element, and then the critical buckling load is calculated with different porosity distributions and GPL dispersion patterns. After a convergence and validation study to verify the accuracy of the present model, a comprehensive parametric study is carried out, with a particular focus on the effects of weight fraction, distribution pattern of GPL reinforcements on the Buckling behavior of the nanocomposite beam. The effects of various structural parameters such as the dispersion patterns for the graphene and porosity, thickness ratio, boundary conditions, and nonlocal and strain gradient parameters are brought out. The results indicate that porosity distribution and GPL pattern have significant effects on the response of the nanocomposite beams, and the results allows to identify the most effective way to achieve improved buckling behavior of the porous nanocomposite beam.

• Journal of Biomedical Engineering Research
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• v.7 no.2
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• pp.111-112
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• 1986

Radiation-induced fibrosarcoma tumors were grown on the flanks of C3H mice. The mice were divided into two groups. One group was injected with Photofrin II, intravenously (2.5mg/kg body weight). The other group received no Photofrin II. Mice from both groups were irradialed for approximately 15 minutes at 100, 300, or 500 mW/cm2 with the argon (488nm/514.5 nm), dye(628nm) and gold vapor (pulsed 628 nm) laser light. A photosensitizer behaved as an added absorber. Under our experimental conditions, the presence of Photolfrin II increased surface temperature by at least 40% and the temperature rise due to 300 mW/cm2 irradiation exceeded values for hyperthermia. Light and temperature distributions with depth were estimated by a computer model. The model demonstrated the influence of wavelength on the thermal process and proved to be a valuable tool to investigate internal temperature rise.

• Geomechanics and Engineering
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• v.28 no.5
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• pp.477-491
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• 2022

In the present study, the effects of thermal loading on the buckling and resonance frequency of graphene platelets (GPL) reinforced nano-composites are examined. Functionally graded (FG) material properties are considered in thickness direction for the thermal responses of the composite. The equivalent material properties are obtained using Halphin-Tsai nano-mechanical model for composite layers. Moreover, the effects of nano-scale sizes are taken into account, employing functionally modified couple stress (FMCS) parameter. In this regard, for the first time, it is demonstrated that at certain values of GPL weight fraction, thermal buckling occurs. In obtaining results of vibrational behavior, both analytical solution and deep neural network (DNN) methods are used. The DNN method needs low computational costs to predict the resonance behavior. A comprehensive parametric study is conducted to indicate the effects of several geometrical, material, and loading conditions on the vibrational and buckling behavior of cylindrical shell structures made of GPL-nanocomposites. It is shown that the effect of temperature change on the occurrence of buckling is vital while it has a negligible impact on the resonance frequency of the structure. Moreover, the size-dependency of the results is demonstrated, and it cannot be neglected in nano-scales.

• Advances in nano research
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• v.16 no.1
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• pp.11-26
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• 2024

In this study, free vibration analysis of FG porous spherical cap reinforced by graphene platelets resting on Winkler-type elastic foundation has been surveyed for the first time. Three different types of porosity patterns are considered for the spherical cap whose two types of porosity patterns in the metal matrix are symmetric and the other one is uniform. Besides, five GPL patterns are assumed for dispersing of GPLs in the metal matrix. Tsai-Halpin and extended rule of the mixture are used to determine the Young modulus and mass density of the shell, respectively. Employing 3D FEM elasticity in conjunction with Hamilton's Principle, the governing motion equations of the structure are obtained and solved. The impact of various parameters including porosity coefficient, various porosity distributions in conjunction with different GPL patterns, the weight fraction of graphene Nano fillers, polar angles and stiffness coefficient of elastic foundation on natural frequencies of FG porous spherical cap reinforced by GPLs have been reported for the first time.

• Structural Engineering and Mechanics
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• v.91 no.1
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• pp.87-102
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• 2024

In recent years, the focus on vibration analysis of multilayer smart structures has attracted considerable attention in many engineering applications. In this work, vibration analysis of a three-layer microporous beam with a core amplified by a composite material reinforced with graphene platelets and two piezoelectric thin films is discussed. It is assumed that piezoelectric layers with a thickness of 0.01 core are very thin and the properties of the matrix and reinforcement vary in the thickness directions. The governing equations of motion are obtained using an energy approach and the method of numerical differential quadrature to solve them. The results of this work are compared to other research and there is good agreement between them. The influences of the volumetric weight fraction of graphene wafers, different graphene platelets distributions, porosity distribution, mass scale parameters and thin ratio of graphene platelets take into account the natural dimensionless frequencies of the micro-beam. The results of this study show that the symmetric distribution of graphene platelets based on the symmetric porosity distribution has a great influence on the natural frequencies without basic dimension of the micro-beam, while the shape ratios of graphene platelets do not have a significant influence on natural frequency changes.

• Journal of the East Asian Society of Dietary Life
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• v.25 no.1
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• pp.30-38
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• 2015

The purpose of this study was to compare energy intake according to expected body mass index (BMI) in adolescents. A total of 280 middle school students were divided into current or/and expected obesity groups (underweight group; UWG, normal weight group; NWG, and overweight group; OWG) by BMI to compare energy intake and perception on body shape and weight control. The average age of total subjects was 15 years, and the distributions of boys and girls were 52.5% and 47.5%, respectively. The distribution of boys and girls was not significantly different among current obesity groups but was among expected obesity groups (15% and 82% in UWG vs. 71.4% and 16.5% NWG vs. 13.6% and 1.5% in OWG; P<0.001), indicating that girls wanted to lose weight more than boys. For body shape, most subjects in current obesity groups responded "fitness" in UWG (38.7%), "fitness" and "slightly chubby" in NWG (45.5% and 39%), and "slightly chubby" in OWG (65.2%), showing a significant difference (P<0.001). For interest in weight control, most subjects responded "average" in current UWcinterested" in current OWG (52.2%), whereas they responded "very interested" in expected UWG (55.7%), "average" in expected NWG (51.2%), and "not interested" in expected OWG (45.5%), showing a significant difference (P<0.001). The percentage of subjects with experience with weight control was significantly high in current OWG (71.7%), NWG (51.2%) and UWG (34.2%) as well as in expected UWG (57.3%), NWG (40.2%) and OWG (36.4%) in descending order (P<0.001). The daily energy intake of total subjects was 2,057.1 kcal without any significant difference among current obesity groups. However, it was significantly lower in expected UWG than expected NWG and OWG (1,943.1 kcal vs. 2,165.0 kcal or/and 2,152.1 kcal; P<0.001). To sum up these results, girls wanted to lose weight more than boys. The more students wanted to lose weight, the greater their experience and interest in weight control and the lower their energy intake.

• Journal of Nutrition and Health
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• v.23 no.2
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• pp.124-134
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• 1990

To investigate nutritional and growth status of premature infants, survey was conducted against 19 premature infants admitted to Nursery of Pediatrics, Young nam University Hospital from Jan. 1984 to July 1988. Variations in feeding patterns as analyzed through the five feeding phases of dextrose, dextrose/hyperal, dextrose/formula, dextrose/hyperal/formula and formula. During 30days from birth, dietary intake, feeding phase, selective anthropometric measurements, biochemical parameters and demograpic information of premature infants were as follows: Distributions of birth weight by gestational age and apgar score showed preamture infants below 1499g were 31 weeks, 4/7(1min/5min) and premature infants from 1500g to 1999g were 33 weeks, 8/9(1min/5min) and premature infants from 2000g to 2500g were 33 weeks, 8/9(1min/5min). Average calorie intakes of premature infants below 1499g, premature infants from 1500g to 1999g and premature infants from 2000g to 2500g were 102.0㎉/kg/day, 119.3㎉/kg/day and 101.7㎉/kg/day. The mean values Na, K, Ca, P for all premature infants remained within the normal level for full term infants throughtout the 25days of this study period. Percentages of inital weight loss showned premature infants below 1499g were 5.4%, premature infants from 1500g to 1999g were 6.4%, premature infants from 2000g to 2500g were 11.4%. Percentages of inital weight loss of the amino acid injection group and the amino acid control group were 9.4% and 9.0%.

• Food Science and Preservation
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• v.10 no.1
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• pp.54-59
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• 2003

To get basic data for quality grading of Mandarin oranges, the oranges were collected from five major areas distributed in Cheju Island, Korea for 3 years and the quality characteristics such as greenness, size, weight, uniformity, sweetness, pH and titratable acidity and its distributions were analyzed. The mean value of greenness (100- yellowness) of peel color in Mandarin oranges was 2.58% and its variation was very large, 9.04%. The average height and diameter of the oranges were 47.51 mm and 56.05 mm, respectively. The average weight was 82.24 g and its variation was 29.92g. The sweetness varied between 5.60$^{\circ}$Brix and 17.2$^{\circ}$Brix and its average value was 10.53$^{\circ}$Brix. The average values of the pH and total acidity of the oranges were 3.90 and 0.71 ％, individually. In quality characteristics of Mandarin oranges according to the cultivated areas, area D had the lowest value in the strength of greenness, 1.14% and area D had the highest value, 3.53%. The highest values of the height and diameter in Mandarin oranges were 49.35mm and 57.48mm for area A and the lowest values of them were 46.35mm and 54.87mm for area E, respectively. The highest value of the weight in Mandarin oranges was 87.61 g for area A and the lowest value was 76.77g fer area E. Although the sweetness ranged from 10.2$^{\circ}$Brix for area E to 10.75$^{\circ}$Brix for area D, the difference by the areas was insignificant. For pH values, area B had the highest value, 3.96, while area E showed the lowest value, 3.78. Area A and E in titratable acidity were the areas shown the highest value, 0.75%, whereas area B marked the lowest value, 0.64%.