• Advances in nano research
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• v.14 no.3
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• pp.285-294
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• 2023

The dynamic and sensing performances of nanomechanical resonators with their different boundary conditions are studied based on surface elasticity-based modeling and simulation. Specifically, the effect of surface stress is included in Euler-Bernoulli beam model for different boundary conditions. It is shown that the surface effect on the intrinsic elastic property of nanowire is independent of boundary conditions, while these boundary conditions affect the frequency behavior of nanowire resonator. The detection sensitivity of nanowire resonator is remarkably found to depend on the boundary conditions such that double-clamping boundary condition results in the higher mass sensitivity of the resonator in comparison with simple-support or cantilever boundary condition. Furthermore, we show that the frequency shift of nanowire resonator due to mass adsorption is determined by its length, whereas the frequency shift is almost independent of its thickness. This study enables a design principle providing an insight into how the dynamic and sensing performances of nanomechanical resonator is determined and tuned.

• Journal of Korean Society for Atmospheric Environment
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• v.14 no.3
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• pp.219-228
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• 1998

In the present investigation, a numerical model developed for the prediction of the wind flow over complex terrain is validated by comparing with the field experiments. For the solution of the Reynolds - Averaged Clavier- stokes equations which are the governing equations of the microscale atmospheric flow, the model is constructed based on the finite-volume formulation and the SIMPLEC pressure-correction algorithm for the hydrodynamic computation. The boundary- fitted coordinate system is employed for the detailed depiction of topography. The boundary conditions and the modified turbulence constants suitable for an atmospheric boundary- layer are applied together with the k- s turbulence model. The full- scale experiments of Cooper's Ridge, Kettles Hill and Askervein Hill are chosen as the validation cases . Comparisons of the mean flow field between the field measurements and the predicted results show good agreement. In the simulation of the wind flow over Askervein Hill , the numerical model predicts the three dimensional flow separation in the downslope of the hill including the blockage effect due to neighboring hills . Such a flow behavior has not been simulated by the theoretical predictions. Therefore, the present model may offer the most accurate prediction of flow behavior in the leeside of the hill among the existing theoretical and numerical predictions.

• Structural Engineering and Mechanics
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• v.76 no.4
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• pp.479-489
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• 2020

This paper proposed a novel form of reinforced concrete (RC) shear wall confined with boundary columns. The structural effect of applying steel fiber reinforced concrete (SFRC) in the wall-column systems was studied. Three full-scale wall samples were constructed including two RC wall-RC column samples with different stirrup ratios and one RC wall-SFRC column sample. Low frequency cyclic testing was carried out to investigate the failure modes, hysteretic behavior, load-bearing capacity, ductility, stiffness degradation and energy dissipation. ABAQUS models were set up to simulate the structural behavior of tested samples, and good agreement was achieved between numerical simulation and experimental results. A further supplementary parametric study was conducted based on ABAQUS models. Both experimental and numerical results showed that increasing stirrup ratio in boundary columns did not affect much on load bearing capacity or stiffness degradation of the system. However, applying SFRC in boundary columns showed significant enhancement on load bearing capacity. Numerical simulation also shows that the structural performances of RC wall-SFRC column system were comparable to a wall-column system fully with SFRC.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.10 no.4
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• pp.11-24
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• 1990

The effect of end restraints for adjoining members is the different variables influencing the column ultimate strength and the behavior. The propose of this study is to analyze eccentrically loaded reinforced concrete columns with the end restraind effect having rectangular cross-section and general boundary conditions. Accordingly, this investigation are to construct a typical analytical model of the reinforced concrete columns with general end boundary conditions. The mechanical components of the analytical model are to be rationally defined the actual behavior as possible, and the different variables influencing the behavior and the ultimate strength of the reinforced concrete columns are investigated by using a parametric study.

• Asia Marketing Journal
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• v.15 no.2
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• pp.49-73
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• 2013

In this study, the author develops and tests a model that incorporates the mediating effects of two frontline employee psychological variables (emotional exhaustion and intrinsic motivation) based on job demand and resource model. As a form of environmental resource, person-organization fit was proposed as a leading factor of frontline employee boundary spanning behavior through emotional exhaustion and intrinsic motivation. All measures were adapted from or developed based on prior research. Data for the study were collected from a cross-sectional sample of retail bank employees in South Korea. Questionnaires were distributed to 500 frontline employees across several banks. Of these, 322 usable questionnaires were returned. To analyze the data, a structural equation model procedure using LISREL 8.5 was employed. Results show that an employee's perceived fit with his/her organization enhances intrinsic motivation and reduces emotional exhaustion. These mechanisms, in turn, increase the employee's boundary spanning behavior. These results support the notion that person-organization fit should be one of the factors affecting motivation, affect and attachment, and extends such an understanding to a purely service-based environment among customer contact employees. Results also confirms that P-O fit can be viewed as environmental resources, and the JD-R model provides a theoretical base in further studying the antecedent role of P-O fit on frontline employees's boundary spanning behavior through intrinsic motivation and emotional exhaustion. These results suggest that organizations have to do their best to manage P-O fit, be it through employee screening or training and workshops to try and align organization and employee values and objectives. If managers of organizations are positively evaluated by the employees, it will be easier for them to, give things of value to employees, such as sense of direction, values, and recognition, and receive other things in return such as esteem and responsiveness. Consequently, organizational leaders are not only able to manage employee experiences, but also their fit with the organization. Even if a manager cannot control employee P-O fit, this research suggests, that a focus on reducing emotional exhaustion rather than increasing intrinsic motivation seems optimal. This research also supports the idea that motivation has a direct association with a frontline employee's boundary spanning behavior. Even in situations where emotional exhaustion cannot be reduced, organizations may still influence frontline behaviors through motivation.

• Tribology and Lubricants
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• v.14 no.3
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• pp.39-45
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• 1998

Reynolds equation, which describes behavior of fluid film in journal bearings, basically satisfies mass conservation. But, boundary conditions usually used with this equation, e.g. half Sommerfeld or Reynolds boundary conditions, cannot fulfill this natural law of conservation. In the case of connecting rod bearing, where applied load is dynamic and its magnitude is relatively large, such unrealistic boundary conditions have serious influence on calculation results, especially on lubricant flow rate or power disspation which are important parameters in thermal analysis. In this paper, mass-conserving boundary condition was applied in the finite element analysis of connecting rod bearings. Lubricant flow rate and power dissipation rate were calculated together with journal center locus, minimum film thickness and maxmium film pressure. These computation results were compared with those of the case of Reynolds boundary condition. Balance between inlet and outlet flow rate was well achieved in the case of mass-conserving boundary condition.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 1998.04a
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• pp.212-217
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• 1998

Reynolds equation, which describes behavior of fluid film in journal bearing, basically satisfies mass conservation. But, boundary conditions usually used with this equation, e.g. half Sommerfeld or Reynolds boundary conditions, cannot fulfill this natural law of conservation. In the case of connecting rod bearing, where applied load is dynamic and its magnitude is relatively large, such unrealistic boundary conditions have serious influence on calculation results, especially on lubricant flow rate or power dissipation which are important parameters in thermal analysis. Another important factor in the analysis of connecting rod bearing is elastic deformation of bearing support structure which is relatively flexible. In this paper, EHL analysis of connecting rod beating is performed using mass-conserving boundary condition. Elastic deformation of bearing support structure and application of mass-conserving boundary condition have significant effects on the performances of connecting rod bearing.

• Structural Engineering and Mechanics
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• v.86 no.3
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• pp.361-371
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• 2023

Boundary condition is an important factor affecting the vibration characteristics of structures, under different boundary conditions, structures will exhibit different vibration behaviors. On the basis of the previous work, this paper extends to the nonlinear resonance behavior of axially moving graphene platelets reinforced metal foams (GPLRMF) plates with geometric imperfection under different boundary conditions. Based on nonlinear Kirchhoff plate theory, the motion equations are derived. Considering three boundary conditions, including four edges simply supported (SSSS), four edges clamped (CCCC), clamped-clamped-simply-simply (CCSS), the nonlinear ordinary differential equation system is obtained by Galerkin method, and then the equation system is solved to obtain the nonlinear ordinary differential control equation which only including transverse displacement. Subsequently, the resonance response of GPLRMF plates is obtained by perturbation method. Finally, the effects of different boundary conditions, material properties (including the GPLs patterns, foams distribution, porosity coefficient and GPLs weight fraction), geometric imperfection, and axial velocity on the resonance of GPLRMF plates are investigated.

• Bulletin of the Korean Mathematical Society
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• v.26 no.2
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• pp.165-168
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• 1989

• Computational Structural Engineering
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• v.6 no.4
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• pp.89-98
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• 1993

As the construction of nuclear power plants are increased, nuclear wastes disposal has been faced as a serious problem. If nuclear wastes are to be buried in the underground stratum, thermo-mechanical behavior of stratum must be analyzed, because high temperature distribution has a significant effect on tunnel and surrounding stratum. In this study, in order to analyze the structural behavior of the underground which is subject to concentrated heat sources, a coupling method of nonlinear finite elements and linear boundary elements is proposed. The nonlinear finite elements (NFE) are applied in the vicinity of nuclear depository where thermo-mechanical stress is concentrated. The boundary elements are also used in infinite domain where linear behavior is expected. Using the similar method as for the problem in mechanical field, the coupled nonlinear finite element-boundary element (NFEBE) is developed. It is found that NFEBE method is more efficient than NFE which considers nonlinearity in the whole domain for the nuclear wastes depository that is expected to exhibit local nonlinearity behavior. The effect of coefficients of the rock mass such as Poisson's ratio, elastic modulus, thermal diffusivity and thermal expansion coefficient is investigated through the developed method. As a result, it is revealed that the displacements around tunnel are largely dependent on the thermal expansion coefficients.