• Structural Engineering and Mechanics
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• v.45 no.1
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• pp.53-67
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• 2013

This study aimed to develop a model to accurately predict the acceleration of structural systems during an earthquake. The acceleration and applied force of a structure were measured at current time step and the velocity and displacement were estimated through linear integration. These data were used as input to predict the structural acceleration at next time step. The computation tool used was the Volterra/Wiener neural network (VWNN) which contained the mathematical model to predict the acceleration. For alleviating problems of relatively large-dimensional and nonlinear systems, the VWNN model was utilized as the signal processing tool, including the Taylor series components in the input nodes of the neural network. The number of the intermediate layer nodes in the neural network model, containing the training and simulation stage, was evaluated and optimized. Discussions on the influences of the gradient descent with adaptive learning rate algorithm and the Levenberg-Marquardt algorithm, both for determining the network weights, on prediction errors were provided. During the simulation stage, different earthquake excitations were tested with the optimized settings acquired from the training stage to find out which of the algorithms would result in the smallest error, to determine a proper simulation model.

• Wind and Structures
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• v.18 no.5
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• pp.567-598
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• 2014

In this paper, wind induced aerodynamic loads on a standard tall building have been evaluated through large-eddy simulation (LES) technique. The flow parameters of an open terrain were recorded from the downstream of an empty boundary layer wind tunnel (BLWT) and used to prescribe the transient inlet boundary of the LES simulations. Three different numerically generated inflow boundary conditions have been investigated to assess their suitability for LES. A high frequency pressure integration (HFPI) approach has been employed to obtain the wind load. A total of 280 pressure monitoring points have been systematically distributed on the surfaces of the LES model building. Similar BLWT experiments were also done to validate the numerical results. In addition, the effects of adjacent buildings were studied. Among the three wind field generation methods (synthetic, Simirnov's, and Lund's recycling method), LES with perturbation from the synthetic random flow approach showed better agreement with the BLWT data. In general, LES predicted peak wind loads comparable with the BLWT data, with a maximum difference of 15% and an average difference of 5%, for an isolated building case and however higher estimation errors were observed for cases where adjacent buildings were placed in the vicinity of the study building.

• Journal of Distribution Science
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• v.18 no.3
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• pp.37-41
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• 2020

Purpose: The purpose of this paper is to examine the recent resurgence of popularism and the possible impacts it may have on contemporary business and economics. Research design, data and methodology: This is an exploratory case study that examines the rise of popularism and identifies and analyzes the likely implications for contemporary business and economics. Results: Although populists tend to reject elitism, capitalism, economic globalization, and political establishment, their ethnocentric behavior is no different from those of the corrupt political and economic elites. Popularism does enable nationalism and protectionism and negatively impacts business and economic growth. Conclusions: Popularism existed for a long time, and this phenomenon will continue to exist as long as a triggered mechanism exist, e.g., income inequality, resurgence of immigration, recession, insufficient factors of resources and social welfare. The recent rise of popularism is not a fad or a short-lived anti-establishment and anti-elitism movements but, rather, a force to be reckoned with in the near future. The rise of economic nationalism limits international trade, integration, and cooperation. As a result, international capital, service, and product flows will decline, and countries and multinational corporations have to develop and restructure their international supply and value chain to cope with this phenomenon.

• Korean Journal of Materials Research
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• v.24 no.4
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• pp.186-193
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• 2014

A thin Cu seed layer for electroplating has been employed for decades in the miniaturization and integration of printed circuit board (PCB), however many problems are still caused by the thin Cu seed layer, e.g., open circuit faults in PCB, dimple defects, low conductivity, and etc. Here, we studied the effect of heat treatment of the thin Cu seed layer on the deposition rate of electroplated Cu. We investigated the heat-treatment effect on the crystallite size, morphology, electrical properties, and electrodeposition thickness by X-ray diffraction (XRD), atomic force microscope (AFM), four point probe (FPP), and scanning electron microscope (SEM) measurements, respectively. The results showed that post heat treatment of the thin Cu seed layer could improve surface roughness as well as electrical conductivity. Moreover, the deposition rate of electroplated Cu was improved about 148% by heat treatment of the Cu seed layer, indicating that the enhanced electrical conductivity and surface roughness accelerated the formation of Cu nuclei during electroplating. We also confirmed that the electrodeposition rate in the via filling process was also accelerated by heat-treating the Cu seed layer.

• Smart Structures and Systems
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• v.17 no.5
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• pp.753-771
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• 2016

This paper addresses the free and transient responses of a SDOF linear complex stiffness system by making use of the Hilbert transform and the convolution integral. Because the second-order differential equation of motion having the complex stiffness give rise to the conjugate complex eigen values, its time-domain analysis using the standard time integration scheme suffers from the numerical instability and divergence. In order to overcome this problem, the transient response of the linear complex stiffness system is obtained by the convolution integral of a green function which corresponds to the unit-impulse free vibration response of the complex system. The damped free vibration of the complex system is theoretically derived by making use of the state-space formulation and the Hilbert transform. The convolution integral is implemented by piecewise-linearly interpolating the external force and by superimposing the transient responses of discretized piecewise impulse forces. The numerical experiments are carried out to verify the proposed time-domain analysis method, and the correlation between the real and imaginary parts in the free and transient responses is also investigated.

• The Journal of Advanced Prosthodontics
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• v.7 no.1
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• pp.62-68
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• 2015

PURPOSE. The purpose of this research was to evaluate the amount of reosseointegration after counter torquing (reverse torque) and transposing the installed implants at different times. MATERIALS AND METHODS. This study was done on ten tibiae of five cross-bred dogs. At the first day one implant was installed in each tibia. After one week half of the implants were randomly counter torqued (1WCT) and the other half were explanted and reimplanted in a new juxtaposition site (transposed)(1WT). At the same time three new implants were installed in each dog, one of them was considered as one week control (1WC) and remaining two as 8 week groups (8WCT&8WT). After eight weeks the 1WCT and 1WT implants were loosened by counter torque and the quantity of needed force for liberation was measured with the digital device (BGI). At the same time one implant was installed in each dog as eight week control (8WC) and the same protocol was repeated for 8 week groups after another 8 weeks. RESULTS. All implants were osseointegrated. Mean quantities of osseointegration in case groups indicated better amounts rather than control groups. CONCLUSION. Counter torque or transposition of the installed implants one week or eight weeks after the implantation did lead to osseointegration.

• Korean Journal of Occupational Health Nursing
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• v.26 no.3
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• pp.125-132
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• 2017

Purpose: This study was performed to identify the impact of aggressiveness of patients and a sense of coherence on posttraumatic stress in psychiatric nurses. Methods: After collecting data from 162 psychiatric nurses, we carried out a t-test, ANOVA, Pearson's correlation coefficient, and multiple regression using IBM SPSS Statistics 19.0. Results: The mean score of posttraumatic stress was $20.75{\pm}16.59$ points. Verbal aggression, aggressiveness about property, aggression toward oneself, and aggression toward others had a positive correlation with posttraumatic stress, while a sense of coherence had a negative correlation with post-traumatic stress. It was concluded that the significant predictors of posttraumatic stress in psychiatric nurses were aggression toward oneself, a sense of coherence, and aggression toward others, all of which accounted for 38.9% of the variability. Conclusion: The results of this study indicate that the factors influencing posttraumatic stress in psychiatric nurses were aggression toward oneself, aggression toward others, and a sense of coherence. Therefore, education programs should be developed in consideration of the fact that aggressive behavior against the patient himself and against others intensify the posttraumatic stress of the psychiatric nurse, but the integration force mitigates it.

• Journal of Ocean Engineering and Technology
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• v.12 no.2 s.28
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• pp.33-42
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• 1998

In the presence of incident waves with different frequencies, the second order sum and difference frequency waves due to the nonlinearity of the incident waves come into existence. Although the magnitudes of the forces produced on a Tension Leg Platform(TLP) by these nonlinear waves are small, they act on the TLP at sum and difference frequencies away from those of the incident waves. So, the second order sum and difference frequency wave loads produced close to the natural frequencies of TLPs often give greater contributions to high and low frequency resonant responses. The second order wave exciting forces and moments have been obtained by the method based on direct integration of pressure acting on the submerged surface of a TLP. The components of the second order forces which depend on first order quantities have been evaluated using the three dimensional source distribution method. The numerical results of time domain analysis for the nonlinear wave exciting forces in regular waves are compared with the numerical ones of frequency domain analysis. The results of comparison confirmed the validity of the proposed approach.

• Journal of Mechanical Science and Technology
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• v.17 no.1
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• pp.85-96
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• 2003

In the present investigation, the nonlinear dynamic buckling of a curved plate subjected to sinusoidal loading is examined. By the theoretical analyses, a highly nonlinear snap-through motion of a clamped-free-clamped-free plate and its effect on the overall vibration response are investigated. The problem is reduced to that of a single degree of freedom system with the Rayleigh-Ritz procedure. The resulting nonlinear governing equation is solved using Runge-Kutta (RK-4) numerical integration method. The snap-through boundaries, which vary with different damping coefficient and linear circular frequency of the flat plate are studied and given in terms of force and displacement. The relationships between static and dynamic responses at the start of a snap-through motion are also predicted. The analysis brings out various characteristic features of the phenomenon, i.e. 1) small oscillation about the buckled position-softening spring type motion, 2) chaotic motion of intermittent snap-through, and 3) large oscillation of continuous snap-through motion crossing the two buckled positions-hardening spring type. The responses of buckled plate were found to be greatly affected by the snap-through motion. Therefore, better understanding of the snap-through motion is needed to predict the full dynamic response of a curved plate.

• Structural Engineering and Mechanics
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• v.16 no.2
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• pp.153-176
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• 2003

From the equation of motion of a "bare" non-uniform beam (without any concentrated elements), an eigenfunction in term of four unknown integration constants can be obtained. When the last eigenfunction is substituted into the three compatible equations, one force-equilibrium equation, one governing equation for each attaching point of the concentrated element, and the boundary equations for the two ends of the beam, a matrix equation of the form [B]{C} = {0} is obtained. The solution of |B| = 0 (where ${\mid}{\cdot}{\mid}$ denotes a determinant) will give the "exact" natural frequencies of the "constrained" beam (carrying any number of point masses or/and concentrated springs) and the substitution of each corresponding values of {C} into the associated eigenfunction for each attaching point will determine the corresponding mode shapes. Since the order of [B] is 4n + 4, where n is the total number of point masses and concentrated springs, the "explicit" mathematical expression for the existing approach becomes lengthily intractable if n > 2. The "numerical assembly method"(NAM) introduced in this paper aims at improving the last drawback of the existing approach. The "exact"solutions in this paper refer to the numerical results obtained from the "continuum" models for the classical analytical approaches rather than from the "discretized" ones for the conventional finite element methods.