• Interaction and multiscale mechanics
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• v.3 no.2
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• pp.192-211
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• 2010

In most framed structures the nonlinearities and the damages are localized, extending over a limited length of the structural member. In order to capture the details of the local damage, the segments of a member that have entered the nonlinear range may need to be analyzed using the three-dimensional element (3D) model whereas the rest of the member can be analyzed using the simpler one-dimensional (1D) element model with fewer degrees of freedom. An Element-Coupling model was proposed to couple the small scale solid 3D elements with the large scale 1D beam elements. The mixed dimensional coupling is performed imposing the kinematic coupling hypothesis of the 1D model on the interfaces of the 3D model. The analysis results are compared with test results of a reinforced concrete pipe column and a structure consisting of reinforced concrete columns and a steel space truss subjected to static and dynamic loading. This structure is a reduced scale model of a direct air-cooled condenser support platform built in a thermal power plant. The reduction scale for the column as well as for the structure was 1:8. The same structures are also analyzed using 3D solid elements for the entire structure to demonstrate the validity of the Element-Coupling model. A comparison of the accuracy and the computational effort indicates that by the proposed Element-Coupling method the accuracy is almost the same but the computational effort is significantly reduced.

• Steel and Composite Structures
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• v.18 no.2
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• pp.425-442
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• 2015

This paper addresses theoretically the bending and buckling behaviors of size-dependent nanobeams made of functionally graded materials (FGMs) including the thickness stretching effect. The size-dependent FGM nanobeam is investigated on the basis of the nonlocal continuum model. The nonlocal elastic behavior is described by the differential constitutive model of Eringen, which enables the present model to become effective in the analysis and design of nanostructures. The present model incorporates the length scale parameter (nonlocal parameter) which can capture the small scale effect, and furthermore accounts for both shear deformation and thickness stretching effects by virtue of a sinusoidal variation of all displacements through the thickness without using shear correction factor. The material properties of FGM nanobeams are assumed to vary through the thickness according to a power law. The governing equations and the related boundary conditions are derived using the principal of minimum total potential energy. A Navier-type solution is developed for simply-supported boundary conditions, and exact expressions are proposed for the deflections and the buckling load. The effects of nonlocal parameter, aspect ratio and various material compositions on the static and stability responses of the FGM nanobeam are discussed in detail. The study is relevant to nanotechnology deployment in for example aircraft structures.

• The Journal of the Korea institute of electronic communication sciences
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• v.16 no.5
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• pp.845-850
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• 2021

In this study, the energy conversion characteristics and design of electric vehicle (EV: Electric Vehicle) powertrain were performed. An interior permanent magnet synchronous motor (IPMSM) was targeted as a power source for the EV powertrain, and control was performed. In order to drive the IPMSM, two regions are considered: a constant torque and a constant output (field-weakening) region. The design of the control system for IPMSM was constructed based on the d-q reference frame (vector control). To determine the static characteristics of motor torque appearing in two areas of IPMSM, a torque control system and a d axis current control system of IPMSM were implemented and proposed. Matlab-Simulink software was used for characteristic analysis. Finally, by applying IPMSM to the powertrain model under the actual EV vehicle level conditions, simulation results of the proposed control system were performed and characteristics were analyzed.

• Steel and Composite Structures
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• v.39 no.2
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• pp.215-228
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• 2021

This paper investigates the effect of micromechanical models on the bending behavior of bidirectional functionally graded (BDFG) beams subjected to different mechanical loading. The material properties of the beam are considered to be graded in both axial and thickness directions according to a power law. The beam's behavior is modeled by the mean of quasi 3D displacement field that contain undetermined integral terms and involves a reduced unknown functions. Navier's method is employed to determine and compute the displacements and stress for a simply supported beam. Different homogenization schemes such as Voigt, Reus, and Mori-Tanaka are employed to analyze the response of the BDFG beam subjected to linear, uniform, exponential and sinusoidal distributed loading. The results obtained by the present method are compared with available results in the literature and a good agreement was found. Several numerical results are presented in tabular form and in figures to examine the effects of the material gradation, micromechanical models and types of loading on the bending response of BDFG beams. It can be concluded that the present theory is not only accurate but also simple in predicting the bending response of BDFG beam subjected to different static loads.

• Journal of Biosystems Engineering
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• v.43 no.4
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• pp.311-319
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• 2018

Purpose: The aim of this study is to develop a small combine for harvesting miscellaneous cereal crops. Methods: A prototype small combine was designed and constructed. Its specifications and basic performance were investigated. Results: The prototype small combine for harvesting miscellaneous cereal crops was designed and constructed to reflect similar specifications as those of the conventional combine. The prototype small combine comprises a diesel engine with the rated power/speed of 22.0 kW/2,600 rpm, three-stage primary and two-stage speed range transmission shifts, and a double acting threshing part. The maximum travel speeds of the prototype combine are approximately 0.72 m/s, 2.50 m/s, 0.30 m/s at the low, high speed range shifts in the forward direction, and while traversing in the reverse direction, respectively. The minimum radius of turning was approximately 1.50 m. In a static lateral overturning test, the prototype combine overturned neither to the right nor to left on a $30^{\circ}$ slope. The results of an oilseed rape harvesting test included the maximum operating speed of 0.32 m/s, the grain loss ratio of approximately 9.0%, and the effective field capacity of approximately 10.3 a/h. Additionally, among the outputs in grain outlet, the whole grains, damage grains, and materials other than grain (MOG) ratios accounted for 97.4%, 0.0%, and 2.6%, respectively. Conclusions: The prototype small combine for harvesting miscellaneous cereal crops indicates good driving ability and stability. The results of the oilseed rape harvesting test reveal that the harvesting performance must be enhanced such that the separating and cleaning parts are more suitable for each type of crop, thus reducing grain loss and foreign substances among the outputs in grain outlet. An improved small prototype combine could be used effectively to mechanize the harvesting of miscellaneous cereal crops in small family farms or semi-mountainous areas.

• Agribusiness and Information Management
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• v.10 no.1
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• pp.1-15
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• 2018

Many paddy cultivating farmers in the country are forced to use their limited resources to produce adequate food for their family, leading to the degradation and reduction in potential of these resources. The yield levels of paddy at the farmers' level and in the Front Line Demonstrations (FLDs) conducted in the farmers' fields is not at par with potential yield of the paddy variety. The gap between potential yield of crop variety and yield realized in FLDs refers to Research gap and the yield gap between FLDs and due to farmers' practice refers to Extension gap. The earlier studies conducted in India in general and in Andhra Pradesh in particular highlighted the existence of both research and extension gaps with reference to paddy. It is essential that, the narrowing of both research and extension gaps is not static, but dynamic considering the influence of technological interventions in boosting paddy yields at FLDs level and at farmers' level and also with the improvement of the yield potential of paddy varieties. This calls for integrated and holistic approaches to address these two gaps and with this background, the researcher aimed at this in depth study. The findings revealed that, research gaps are high with reference to weed management and pest management and extension gaps are high with reference to farm mechanization followed by fertilizer management. Reliable source of seed, capital use and frequency of meetings with Scientists or Agricultural Officers significantly influence the extension gaps in paddy. Farmers also prioritized socio-economic and technical constraints and the analysis infers that, it is high time now for the farmers to adopt the planned technological interventions on scientific scale to minimize the extension gaps to the extent possible. As the enabling environment in the State of Andhra Pradesh is highly encouraging for the farmers with relevant policy instruments in the form of subsidized inputs, free power, credit at concessional rates of interest, constructing irrigation projects etc., the adoption of the proposed technological interventions significantly contribute to minimizing both research and extension gaps in paddy cultivation in Kurnool district of Andhra Pradesh.

• Journal of IKEEE
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• v.23 no.3
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• pp.832-838
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• 2019

In this paper, 4H-SiC MOSFET, the next generation power semiconductor device, was studied. In particular, Semi-SJ MOSFET structures with improved electrical characteristics than conventional DMOSFET structures were proposed in the class of 3300V, and static characteristics of conventional and proposed structures were compared and analyzed through TCAD simulations. Semi-SuperJunction MOSFET structure is partly structure that introduces SuperJunction, improves Electric field distribution through the two-dimensional depletion effect, and increases breakdown voltage. Benefit from the improvement of breakdown voltage, which can improve the on resistance as high doping is possible. The proposed structure has a slight reduction in breakdown voltage, but has an 80% decrease in on resistance compared to the conventional DMOSFET structure, and a 44% decrease in on resistance compared to the Current Spreading Layer(CSL) structure that improves the conventional DMOSFET structure.

• Journal of The Korean Society of Integrative Medicine
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• v.9 no.4
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• pp.119-127
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• 2021

Purpose : The aim of this study was to examine the relationships of everyday creativity and self-esteem, with sociality in college students majoring in nursing science and to identify factors that influence sociality. Methods : In the study 209 college students majoring in nursing science in B city were surveyed for the period of July through September 2020. The collected data were analyzed using SPSS statistics 22.0 for Windows to determine the frequency, percentage ratio, average, and standard deviation. Statistical analyses included the t-test, analysis of variance, Scheffe test, Pearson correlation coefficient, and multiple regression analysis. Results : The everyday creativity of the nursing students was 3.65±0.43, self-esteem was 3.70±0.63, and sociality was 3.21±.33. Significant differences were observed for self-esteem according to the participant's grade (F=3.11, p=.027), monthly income (F=2.41, p=.050), health condition (F=4.87, p=.001) and clinical experience (t=-2.17, p=.031). Significant differences were not observed with regard to sociality. A static correlation was observed between everyday creativity and self-esteem (r=.478, p<.001) and between everyday creativity and sociality (r=.342, p<.001). Self-esteem and sociality were also statistically correlated (r=.168, p<.05). Factors that influenced the participants' sociality included monthly income (𝛽=.168, p=.015), health condition (𝛽=.178, p=.022), clinical experience (𝛽=-.161, p=.048), ability to find alternative solutions (𝛽=.245, p=.015), and in dependent nature (𝛽=.224, p=.003); The explanatory power was 15.60 %. Conclusion : More research is needed to understand the relationship between everyday creativity, self-esteem, and sociality in college students majoring in nursing science, Greater efforts are needed to develop programs that nurture the sociality of college student majoring in nursing science.

• Journal of Industrial Convergence
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• v.20 no.4
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• pp.39-46
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• 2022

This descriptive survey study identified the factors influencing the abiliy of healthcare perceived by high school students. The survey was conducted from May 7, 2020, to Sep. 17, 2020 for 119 high school students in City D. SPSS WIN 22.0 program was used to for t-test and one-way ANOVA with Pearson's correlation coefficients and hierarchical regression analysis. The ability of healthcare perceived by high school students had a static correlation with the sub-domains of family function, that is, family cohesion(r=.65, p<.001) and family adaptability(r=.54, p<.001). For male students(β=.17, p=.012), those who reported a high level of perceived health status showed a high level of ability of healthcare(β=.25, p<.001). Significant influencing factors on high school students' health management ability were identified as gender (β=.17), their own health status perception (β=.23), and family cohesion (β=.45), and the explanatory power of the model was 50%. appear. Further research is hereby suggested for validation of the mediating role and effects of health care education programs to improve the family function perceived by high school students, encourage their practicing of health care management and help them to enter into healthy adulthood.

• Steel and Composite Structures
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• v.42 no.3
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• pp.407-426
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• 2022

Superior to traditional welded studs, high strength friction-grip bolted shear connectors facilitate the assembling and demounting of the composite members, which maximizes the potential for efficiency in the construction and retrofitting of new and old structures respectively. Hence, it is necessary to investigate the structural properties of high strength friction-grip bolts used in steel concrete composite beams. By means of push-out tests, an experimental study was conducted on post-installed high strength friction-grip bolts, considering the effects of different bolt size, concrete strength, bolt tensile strength and bolt pretension. The test results showed that bolt shear fracture was the dominant failure mode of all specimens. Based on the load-slip curves, uplifting curves and bolt tensile force curves between the precast concrete slab and steel beam obtained by push-out tests, the anti-slip performance of steel-concrete interface and shear behavior of bolt shank were studied, including the quantitative analysis of anti-slip load, and anti-slip stiffness, frictional coefficient, shear stiffness of bolt shank and ultimate shear capacity. Meanwhile, the interfacial anti-slip stiffness and shear stiffness of bolt shank were defined reasonably. In addition, a total of 56 push-out finite element models verified by the experimental results were also developed, and used to conduct parametric analyses for investigating the shear behavior of high-strength bolted shear connectors in steel-concrete composite beams. Finally, on ground of the test results and finite element simulation analysis, a new design formula for predicting shear capacity was proposed by nonlinear fitting, considering the bolt diameter, concrete strength and bolt tensile strength. Comparison of the calculated value from proposed formula and test results given in the relevant references indicated that the proposed formulas can give a reasonable prediction.