• Proceedings of the Computational Structural Engineering Institute Conference
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• 2002.10a
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• pp.146-152
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• 2002

In this study, the singular thermal stresses induced during cooling down from high temperature to room temperature have been analyzed for the viscoelastic thin layer. The time domain boundary element method has been employed to investigate the behavor of stresses for the whole interface. Within the context of a linear viscoelastic theory, a stress singularity exists at the point where the interface between the elastic substrate and the viscoelastic thin layer intersects the free surface.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 1996.04a
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• pp.95-102
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• 1996

The stress intensity factor for an interface crack in dissimilar elastic and viscoelastic materials is derived and the time-domain boundary element analysis is performed. Numerical results show that the proposed method is very useful for the analysis of the interface crack in elastic and viscoelastic bimaterials.

• Interaction and multiscale mechanics
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• v.3 no.1
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• pp.81-94
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• 2010

The steady state response of a rotating generalized thermoelastic solid to a moving point load has been investigated. The transformed components of displacement, force stress and temperature distribution are obtained by using Fourier transformation. These components are then inverted and the results are obtained in the physical domain by applying a numerical inversion method. The numerical results are presented graphically for a particular model. A particular result is also deduced from the present investigation.

• Research in Community and Public Health Nursing
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• v.13 no.2
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• pp.321-331
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• 2002

Purpose: The purpose of this study was to describe perceived family support, life satisfaction, and health promoting behavior (HPB), and to identify factors influencing HPB among the elderly. Method: Study participants were 165 elderly over 65 years of age who were living in C city, Korea. The instruments included the Family Support Scale developed by Kang, Life Satisfaction Scale developed by Choi, Health Promoting Behavior Scale designed by Walker, et al. The data were analyzed using the SAS program by t-test, ANOVA, Pearson correlation coefficients, and stepwise multiple regression. Results: 1. The scores for family support ranged from 11 to 55, with a mean score of 41.55. The scores for life satisfaction ranged from 0 to 40, with a mean of 22.02. The scores for HPB ranged from 40 to 160 with a mean score of 98.07. In the sub-dimensions of HPB, the participants showed the highest level of engagement in the nutrition domain, and the lowest level of engagement in the exercise domain. 2. Higher levels of family support and life satisfaction were correlated with more engagement in HPB. 3. The most influencing factor on HPB in the elderly was family support. accounting for 11% of the total variance in HPB. A combination of education level and types of living patterns accounted for 18% of the total variance in HPB. Life satisfaction accounted for 14% of the self-actualization domain, and 5% of the stress management domain, in the sub-dimensions of HPB. Conclusion: Perceived family support was identified as an important factor to predict HPB in the elderly. However, life satisfaction was identified as only partially influencing HPB among the elderly.

• The Journal of the Acoustical Society of Korea
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• v.15 no.5
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• pp.21-29
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• 1996

Industrial equipment, such as power plant, is required to operate reliably, continuously and economically under rather severe conditions of temperature, stress, and enbironment. To test structural integrity and fitness, ultrasonic nondestructive testing is used because of effectiveness and simplicity. In this paper, wavelet transform based least mean square(LMS) algorithm is applied to reduce the influence of the interference occurring between randomly positioned small scatters. The RUN test is performed to check the nonstationarity of the speckle noise signal. The performance of this new approach is compared with that of the time domain LMS algorithm by means of condition numbers, signal-to-noise ratio and 3-D image. As a result, the wavelet transform based LMS algorithm shows better performance than the time domain LMS algorithm in this experiment.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.16 no.4
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• pp.431-437
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• 2003

In this paper, an approximate optimization program based on GUI(graphic user interface) environment is developed. This program is coded by using Fortran and Visual basic. Fortran is used to Progress approximate optimization process. Visual basic is used to make user environment for user to use conveniently. Inside of this program, it uses two independent programs. One is commercial program, ANSYS, and the other is optimization program, PLBA(Pshenichny-Lim-Belegundu Arora). The former is used to obtain approximate equation of stress and displacement of a structure. The latter is used to solve approximate optimization. This algorithm uses second-order information of a function and active set strategy. This program is connecting ANSYS and PLBA. And it progress the process repeatedly until it obtain optimum value. As a method of approximate optimization, sequential design domain(SDD) is introduced. SDD starts with a certain range which is offseted from midpoint of an initial design domain and then SDD of the next step is determined by optimal point of a prior step.

• Journal of the Korean Society of Radiology
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• v.15 no.4
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• pp.499-505
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• 2021

In this study, HRV signals are analyzed to compare the autonomic nervous system activity of non-pregnant women and pregnant women. 99 disease-free pregnant women and 27 non-pregnant women from W Hospital participated in the study. The acquired HRV signals were used by the program to perform time domain analysis and frequency domain analysis. The measured values were statistically analyzed for differences between pregnancy periods through a one-way ANOVA. In the results, SDNN and RMSSD in time domain analysis had significantly higher results in early pregnancy and non-pregnant women compared to mid- and late pregnancy. In frequency domain analysis, LF and HF had significantly higher values for pregnancy and non-pregnancy compared to midand late-term, but there was no significant difference between VLF and LF/HF. his means that as pregnancy progresses, the ability to control autonomous nerves decreases in the middle and late stages of pregnancy and increases physical fatigue and mental fatigue. Therefore, the longer the pregnancy period, the more special care is needed to maintain mental and physical stability of pregnant women.

• Structural Engineering and Mechanics
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• v.84 no.4
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• pp.547-560
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• 2022

By presetting various reinforcement diameters in topology optimization with the discrete model finite element analysis, an algorithm of bidirectional evolutionary structural optimization of multi-level reinforcement diameter is presented to obtain the optimal reinforcement topologies which describe the degree of stress of different parts. The results of a comparative study on different reinforcement feasible domain demonstrate that the more angle types of reinforcement are arranged in the initial domain, the higher utilization rate of reinforcement of the optimal topology becomes. According to the nonlinear finite element analysis of some deep beam examples, the ones designed with the optimization results have a certain advantage in ultimate bearing capacity, although their failure modes are greatly affected by the reinforcement feasible domain. Furthermore, the bearing capacity can be improved when constructional reinforcements are added in the subsequent design. However the adding would change the relative magnitude of the bearing capacity between the normal and inclined section, or the relative magnitude between the flexural and shear capacity within the inclined section, which affects the failure modes of components. Meanwhile, the adding would reduce the deformation capacity of the components as well. It is suggested that the inclined reinforcement and the constructional reinforcement should be added properly to ensure a desired ductile failure mode for components.

• Journal of applied mathematics & informatics
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• v.7 no.2
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• pp.493-506
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• 2000

Recently the first author and his coworker report a new finite element method for the Poisson equations with homogeneous Dirichlet boundary conditions on a polygonal domain with one re-entrant angle [7], They use the well-known fact that the solution of such problem has a singular representation, deduced a well-posed new variational problem for a regular part of solution and an extraction formula for the so-called stress intensity factor using tow cut-off functions. They use Fredholm alternative an Garding's inequality to establish the well-posedness of the variational problem and finite element approximation, so there is a maximum bound for mesh h theoretically. although the numerical experiments shows the convergence for every reasonable h with reasonable size y imposing a restriction to the support of the extra cut-off function without using Garding's inequality. We also give error analysis with similar results.

• Corrosion Science and Technology
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• v.8 no.1
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• pp.11-14
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• 2009

The osmotic blistering behavior of polymeric coating film which is in contact with an aqueous environment has been investigated. In this study, the coating film has been assumed to be linearly viscoelastic. Interfacial stresses induced in a laminate model consisting of the viscoelastic film and the elastic substrate as the film absorbs moisture from the ambient environment have been investigated using the time-domain boundary element method. The overall stress intensity factor for interfacial cracks subjected to a uniform osmotic pressure has been computed using the tractions at the crack tip node. The magnitude of stress intensity factors decreases with time due to viscoelastic relaxation, but remains constant at large times.