• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.7
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• pp.3057-3064
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• 2012

In this study, we have tried to identify the relationship between the patient's health belief and the implementation of functional movement rehabilitation and ability to perform ADL in stroke patient, and have done this study to use this as evidence in treating stroke patients in clinical trials by providing a basis data of stroke patients' successful rehabilitation program. We targeted stroke patients who were diagnosed with stroke and are hospitalized in D hospital in J City, Jeollabuk-do, South Korea. More over, we distributed a total of 150 questionnaires to patients who understand the purpose of the research and agreed to participate. We were able to collect 132questionnaires at the end. However, 11 had insufficient data so we only analyzed and evaluated 121 of the said questionnaires. We did frequency analysis to understand the general characteristics by using SPSS for Windows(ver.12.0) program and we used Pearson's Correlation Coefficient and regression analysis to know the relationship between the patient's health beliefs and the implementation of rehabilitation and ability to perform ADL in stroke patients. The results of this study shows that patients with higher perceived sensitivity, perceived benefit and perceived severity equates to an implementation of the rehabilitation better, however patients with a lower perceived disability equates an implementation of functional movement rehabilitation better than those with a higher perceived disability.

• Journal of Korean Society of Environmental Engineers
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• v.31 no.5
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• pp.332-340
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• 2009

This study was conducted to analyze and determine formation potentials for chlorination disinfection by-products (DBPs) from twenty amino acid compounds with or without $Br^-$. Two of twenty amino acid compound were tryptophan and tyrosine that were relatively shown high for formation of trihalomethanes (THMs)/dissolved organic carbon (DOC) whether or not $Br^-$ presented. Other 18 compounds were shown low for formation of THMs/DOC whether or not $Br^-$ presented. Five amino acid compounds that were tryptophan, tyrosine, asparagine, aspartic acid and histidine were shown high for formation of haloacetic acids (HAAs)/DOC whether or not $Br^-$ presented. Although formation of dichloroacetic acid (DCAA) was dominated in asparagine, aspartic acid and histidine, trichloroacetic acid (TCAA) was dominated in tryptophan and tryptophan. The formation of haloacetnitriles (HANs)/DOC whether or not $Br^-$ presented was high in Aspartic acid, histidine, asparagine, tyrosine and tryptophan. Specially, aspartic acid was detected 660.2 ${\mu}$g/mg (HAN/DOC). Although the formation of chloralhydrate (CH)/DOC was shown high in asparagine, aspartic acid, histidine, methionine, tryptophan and tyrosine, the formation of Chloropicrin (CP)/DOC was low (1 ${\mu}$g/mg) in twenty amino acid compounds. The formations of THM, HAA and HAN were also investigated in functional groups of amino acids. The highest formation of THM was shown in amino acids compounds (tryptophan and tyrosine) with an aromatic functional group. Highest, second-highest, third-highest and fourth-highest functional groups for formation of HAA were aromatic, neutral, acidic and basic respectively. In order of increasing functional groups for formation of HAN were acidic, basic, neutral and aromatic.

• Smart Structures and Systems
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• v.22 no.3
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• pp.341-358
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• 2018

This present study investigates Love-type wave propagation in composite structure consists of a loosely bonded functionally graded piezoelectric material (FGPM) stratum lying over a functionally graded initially-stressed fibre-reinforced material (FGIFM) substrate. The closed-form expressions of the dispersion relation have been obtained analytically for both the cases of electrically open and electrically short conditions. Some special cases of the problem have also been studied and the obtained results are found in well-agreement with the classical Love wave equation. The emphatic influence of wave number, bonding parameter associated with bonding of stratum with substrate of the composite structure, piezoelectric coefficient as well as dielectric constant of the piezoelectric stratum, horizontal initial stresses, and functional gradedness of the composite structure on the phase velocity of Love-type wave has been reported and illustrated through numerical computation along with graphical demonstration in both the cases of electrically open and electrically short condition for the reinforced and reinforced-free composite structure. Comparative study has been carried out to analyze the distinct cases associated with functional gradedness of the composite structure and also various cases which reveals the influence of piezoelectricity, reinforcement and horizontal initial stress acting in the composite structure, and bonding of the stratum and substrate of the composite structure in context of the present problem which serves as one of the major highlights of the study.

• Advances in Computational Design
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• v.5 no.4
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• pp.363-380
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• 2020

In this paper, a cylindrical shell is immersed in a non-viscous fluid using first order shell theory of Sander. These equations are partial differential equations which are solved by approximate technique. Robust and efficient techniques are favored to get precise results. Employment of the Rayleigh-Ritz procedure gives birth to the shell frequency equation. Use of acoustic wave equation is done to incorporate the sound pressure produced in a fluid. Hankel's functions of second kind designate the fluid influence. Mathematically the integral form of the Lagrange energy functional is converted into a set of three partial differential equations. Throughout the computation, simply supported edge condition is used. Expressions for modal displacement functions, the three unknown functions are supposed in such way that the axial, circumferential and time variables are separated by the product method. Comparison is made for empty and fluid-filled cylindrical shell with circumferential wave number, length- and height-radius ratios, it is found that the fluid-filled frequencies are lower than that of without fluid. To generate the fundamental natural frequencies and for better accuracy and effectiveness, the computer software MATLAB is used.

• Smart Structures and Systems
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• v.7 no.5
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• pp.379-392
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• 2011

This paper presents a multi-functional system, consisting of a magnetorheological (MR) damper and an electromagnetic induction (EMI) device, and its applications in stay cables. The proposed system is capable of offering multiple functions: (1) mitigating excessive vibrations of cables, (2) estimating cable tension, and (3) harvesting energy for wireless sensors used health monitoring of cable-stayed bridges. In the proposed system, the EMI device, consisting of permanent magnets and a solenoid coil, can converts vibration energy into electrical energy (i.e., induced emf); hence, it acts as an energy harvesting system. Moreover, the cable tension can be estimated by using the emf signals obtained from the EMI device. In addition, the MR damper, whose damping property is controlled by the harvested energy from the EMI device, can effectively reduce excessive cable vibrations. In this study, the multi-functionality of the proposed system is experimentally evaluated by conducting a shaking table test as well as a full-scale stay cable in a laboratory setting. In the shaking table experiment, the energy harvesting capability of the EMI device for wireless sensor nodes is investigated. The performance on the cable tension estimation and the vibration mitigation are evaluated using the full-scale cable test setup. The test results show that the proposed system can sufficiently generate and store the electricity for operating a wireless sensor node twice per day, significantly alleviate vibration of a stay cable (by providing about 20% larger damping compared to the passive optimal case), and estimate the cable tension accurately within a 2.5% error.

• Computers and Concrete
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• v.23 no.1
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• pp.1-10
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• 2019

The use of non-linear analysis of structures in a functional way for evaluating the structural seismic behavior has attracted the attention of the engineering community in recent years. The most commonly used functional method for analysis is a non-linear static method known as the "pushover method". In this study, for the first time, a cyclic pushover analysis with different loading protocols was used for seismic investigation of curved bridges. The finite element model of 8-span curved bridges in plan created by the ZEUS-NL software was used for evaluating different pushover methods. In order to identify the optimal loading protocol for use in astatic non-linear cyclic analysis of curved bridges, four loading protocols (suggested by valid references) were used. Along with cyclic analysis, conventional analysis as well as adaptive pushover analysis, with proven capabilities in seismic evaluation of buildings and bridges, have been studied. The non-linear incremental dynamic analysis (IDA) method has been used to examine and compare the results of pushover analyses. To conduct IDA, the time history of 20 far-field earthquake records was used and the 50% fractile values of the demand given the ground motion intensity were computed. After analysis, the base shear vs displacement at the top of the piers were drawn. Obtained graphs represented the ability of a cyclic pushover analysis to estimate seismic capacity of the concrete piers of curved bridges. Based on results, the cyclic pushover method with ISO loading protocol provided better results for evaluating the seismic investigation of concrete piers of curved bridges in plan.

• Computers and Concrete
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• v.27 no.4
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• pp.333-341
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• 2021

Steel slag, an industrial reject from the steel rolling process, has been identified as one of the suitable, environmentally friendly materials for concrete production. Given that the coarse aggregate portion represents about 70% of concrete constituents, other economic approaches have been found in the use of alternative materials such as steel slag in concrete. Unfortunately, a standard framework for its application is still lacking. Therefore, this study proposed functional model equations for the determination of strength properties (compression and splitting tensile) of steel slag aggregate concrete (SSAC), using gene expression programming (GEP). The study, in the experimental phase, utilized steel slag as a partial replacement of crushed rock, in steps 20%, 40%, 60%, 80%, and 100%, respectively. The predictor variables included in the analysis were cement, sand, granite, steel slag, water/cement ratio, and curing regime (age). For the model development, 60-75% of the dataset was used as the training set, while the remaining data was used for testing the model. Empirical results illustrate that steel aggregate could be used up to 100% replacement of conventional aggregate, while also yielding comparable results as the latter. The GEP-based functional relations were tested statistically. The minimum absolute percentage error (MAPE), and root mean square error (RMSE) for compressive strength are 6.9 and 1.4, and 12.52 and 0.91 for the train and test datasets, respectively. With the consistency of both the training and testing datasets, the model has shown a strong capacity to predict the strength properties of SSAC. The results showed that the proposed model equations are reliably suitable for estimating SSAC strength properties. The GEP-based formula is relatively simple and useful for pre-design applications.

• Geomechanics and Engineering
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• v.29 no.4
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• pp.377-390
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• 2022

The stability of the roof rock-coal pillar-floor rock composite structure is of great significance to coal mine safety production. The cracks existing in the composite structure seriously affect the stability of the roof rock-coal pillar-floor rock composite structure. The numerical simulation tests of rock-coal-rock composite structures with different crack characteristics were carried out to reveal the composite structures' mechanical properties and failure mechanisms. The test results show that the rock-coal-rock composite structure's peak stress and elastic modulus are directly proportional to the crack angle and inversely proportional to the crack length. The smaller the crack angle, the more branch cracks produced near the main control crack in the rock-coal-rock composite structure, and the larger the angle between the main control crack and the crack. The smaller the crack length, the larger the width of the crack zone. The impact energy index of the rock-coal-rock composite structure decreases first and then increases with the increase of crack length and increases with the increase of crack angle. The functional relationships between the different crack characteristics, peak stress, and impact energy index are determined based on the sensitivity analysis. The determination of the functional relationship can fully grasp the influence of the crack angle and the crack length on the peak stress and impact energy index of the coal-rock composite structure. The research results can provide a theoretical basis and guidance for preventing the instability and failure of the coal pillar-roof composite structure.

• Geomechanics and Engineering
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• v.36 no.6
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• pp.601-618
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• 2024

The joint probability distribution of uncertain geomechanical parameters of geotechnical strata is a crucial aspect in constructing the reliability functional function for roof structures. However, due to the limited number of on-site exploration and test data samples, it is challenging to conduct a scientifically reliable analysis of roof geotechnical strata. This study proposes a Copula method based on small sample exploration and test data to construct the intensity characteristics of roof geotechnical strata. Firstly, the theory of multidimensional copula is systematically introduced, especially the construction of four-dimensional Gaussian copula. Secondly, data from measurements of 176 groups of geomechanical parameters of roof geotechnical strata in 31 coal mines in China are collected. The goodness of fit and simulation error of the four-dimensional Gaussian Copula constructed using the Pearson method, Kendall method, and Spearman methods are analyzed. Finally, the fitting effects of positive and negative correlation coefficients under different copula functions are discussed respectively. The results demonstrate that the established multidimensional Gaussian Copula joint distribution model can scientifically represent the uncertainty of geomechanical parameters in roof geotechnical strata. It provides an important theoretical basis for the study of reliability functional functions for roof structures. Different construction methods for multidimensional Gaussian Copula yield varying simulation effects. The Kendall method exhibits the best fit in constructing correlations of geotechnical parameters. For the bivariate Copula fitting ability of uncertain parameters in roof geotechnical strata, when the correlation is strong, Gaussian Copula demonstrates the best fit, and other Copula functions also show remarkable fitting ability in the region of fixed correlation parameters. The research results can offer valuable reference for the stability analysis of roof geotechnical engineering.

• Advances in materials Research
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• v.2 no.1
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• pp.15-36
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• 2013

Incorporation of polar functional moieties into polyethylene (PE) film has been achieved by graft copolymerization of polar monomers such as methacrylic acid (MAAc) and acrylamide (AAm) on to PE film, preirradiated with ${\gamma}$-rays from $^{60}Co$ source, using benzoyl peroxide (BPO) as initiator in aqueous medium. Percentage of grafting of MAAc and AAm was determined as a function of irradiation dose, monomer and initiator concentration, temperature, reaction time and amount of water. Maximum percentage of grafting of MAAc (1453%) and AAm (21.28%) was obtained at [MAAc] = $235.3{\times}10^{-2}$ mol/L, [AAm] = $23.4{\times}10^{-2}$ mol/L, [BPO] = $5.5{\times}10^{-2}$ mol/L and $16.5{\times}10^{-2}$ mol/L at $80^{\circ}C$, $90^{\circ}C$ in 180 min and 90 min respectively. The grafted PE films were characterized by FTIR, Thermogravimetric analysis (TGA) Scanning Electron Micrography (SEM) and X-ray diffraction methods. Some selective properties of grafted films such as swelling behavior, ion and metal uptake have been carried out. The biodegradation studies of the grafted PE films have also been investigated. The grafted films developed superior swelling behavior with maximum swelling (480%) in water as compared to pristine PE (13.55%), better thermal stability and ion and metal uptake studies showed promising results that can be effectively used for desalination of brackish water and separation of metals from the industrial effluents.