• 대한통합의학회지
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• 제8권1호
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• pp.57-66
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• 2020

Purpose : This study aimed to identify whether resistance exercise using elastic bands for six weeks can improve muscle strength, muscle tone, balance, and gait in patients with stroke. Methods : In total, 35 patients with stroke were randomly divided into three groups: resistance exercise using elastic band training combined with less affected side training group, more affected side training group, and both sides training group. Muscle strength, muscle tone, balance, and gait were assessed using a hand-held dynamometer, the modified Ashworth scale, the Berg Balance scale (BBS), and wireless 3-axis accelerometer, before and after training. Results : All three groups showed a significant increase in muscle strength of the lower extremity after training, and there was a significant difference among the groups. There was no change in muscle tone in all three groups. BBS scores increased significantly in all three groups after training, but these scores were not significantly different. The gait speed increased significantly in all three groups after the training, but the difference was not significant. The cadence increased significantly in Group 2 after training; however, there was no significant difference between Groups 1 and 3. There were no significant differences between the groups before and after the training. Step length increased significantly in Groups 2 and 3 after the training, but it was not significantly different in Group 1. After training, Groups 2 and 3 were significantly greater than Group 1 in the change in step length. Conclusion : The results show that resistance exercise using elastic bands can improve strength, balance, and gait in patients with chronic stroke. Especially, more affected side training was more effective in improving muscle strength than less affected side training. More affected side and both sides training are thought to be more effective than less affected side training to improve step length.

• 대한통합의학회지
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• 제7권4호
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• pp.231-240
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• 2019

Purpose : This study aimed to determine whether resistance exercise using elastic bands for 6 weeks could improve the muscle strength, muscle tone, balance and gait among stroke patients. Methods : A total of 11 stroke patients who had agreed to participate in the study were randomly divided into 3 groups receiving elastic band resistance training on their less affected side (experimental group 1, n=4), affected side (experimental group 2, n=3), and both the sides (experimental group 3, n=4). Muscle strength, muscle tone, balance and gait were assessed using a hand-held dynamometer, the modified ashworth scale (MAS), the berg balance scale (BBS), and G-walk respectively, before and after training. Wilcoxon signed-rank test was used to analyze intergroup changes after the intervention, whereas the Kruskal Wallis H test, and Mann-Whitney U test were used to analyze intergroup changes in all variables. Results : Strength in all the muscle, except for the flexor and extensor muscles in the affected knees, was increased in all the groups, however, no significant difference was observed. No change in the muscle tone (MAS) was found in any group. All the groups showed increased BBS scores walking speed, and walking symmetry following training, although, the differences were not significant. Changes in the affected step length of experimental group 1 were significantly greater than those of experimental group 3, whereas changes in the affected step length in experimental group 3 were significantly greater than those of experimental group 2. Conclusion : Our results suggest that resistance exercise using elastic bands are a potential intervention for improving lower extremity muscle strength, balance, and gait among stoke patients.

• Journal of Welding and Joining
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• 제17권5호
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• pp.77-82
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• 1999

Resistance spot welding process is completed in very short time and there are many factors affecting on the generation of heat. It is difficult to control these experimental factors and monitor distribution of the temperature and stresses in the experimental analysis case. and too much time and expense are required for the experimental trials to fine proper welding condition. So numerical analyses have been attempted steadily, but most numerical analyses on the resistance spot welding are mainly focused on thermal behavior. Therefore, in this paper, the numerical analysis of mechanical behavior as well as heat conduction is carried out for the spot welding process. For this numerical analysis, axial symmetric computer program for the spot welding analysis by F.E.M. has been developed considering heat conduction and thermal elastic-plastic theory. Material properties depending on temperature such as density, heat conductivity, heat expansion coefficient, specific heat, yield stress, elastic modulus, and specific resistance are considered. Using the results of temperature distribution obtained from heat conduction analysis, the thermal elastic-plastic analysis is carried out to clarify mechanical behavior of spot welded specimen. In order to evaluate the effect of residual stresses, numerical analyses are carried out under tension-shear load in two cases respectively; one with residual stress, the other without residual stresses.

• Computers and Concrete
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• 제31권6호
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• pp.469-484
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• 2023

The response mechanism of simply supported two-way reinforced concrete (RC) slabs under fire was numerically studied from the view of stress redistribution using the finite element software ABAQUS. Results show that: (1) Simply supported two-way RC slabs undergo intense stress redistribution, and their responses show four stages, namely elastic, elastic-plastic, plastic and tensile membrane stages. There is no cracking in the fire area of the slabs until the tensile membrane stage. (2) The inverted arch effect and tensile membrane effect improve the fire resistance of the two-way slabs. When the deflection is L/20, the slab is in an inverted arch effect state, and the slab still has a good deflection reserve. The deformation rate of the slab in the tensile membrane stage is smaller than that in the elastic-plastic and plastic stages. (3) Fire resistance of square slabs is better than that of rectangular slabs. Besides, increasing the reinforcement ratio or slab thickness improves the fire resistance of the slabs. However, an increase of cover thickness has little effect on the fire resistance of two-way slabs. (4) Compared with one-way slabs, the time for two-way slabs to enter the plastic and tensile cracking stage is postponed, and the deformation rate in the plastic and tensile cracking stage is also slowed down. (5) The simply supported two-way RC slabs can satisfy with the requirements of a class I fire resistance rating of 90 min without additional fire protection.

• 한국해양공학회지
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• 제8권2호
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• pp.157-165
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• 1994

Effect of an accelerated iso-thermal aging (375 degree C x 66days, 375 degree C x 200days) on elastic-plastic fracture resistance curve were examined in SA533B low alloy steel. Fracture toughness test are conducted by unloading compliance method at room temperature. But the apparent negative crack growth phenomenon, usually arise in partial unloading compliance test. The phenomenon of negative crack growth may be eliminated by the offset technique. There is no effect of aging on J sub(IC) and dJ/da in iso-thermal aged (375 degree C x 66 days) specimen, but there is very little effect in iso-thermal aged (375 degree C x 200 days) specimen.

• Steel and Composite Structures
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• 제51권4호
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• pp.441-456
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• 2024

This paper aims to develop Machine Learning (ML) algorithms to predict the buckling resistance of cold-formed steel (CFS) channels with restrained flanges, widely used in typical CFS sheathed wall panels, and provide practical design tools for engineers. The effects of cross-sectional restraints were first evaluated on the elastic buckling behaviour of CFS channels subjected to pure axial compressive load or bending moment. Feedforward multi-layer Artificial Neural Networks (ANNs) were then trained on different datasets comprising CFS channels with various dimensions and properties, plate thicknesses, and restraining conditions on one or two flanges, while the elastic distortional buckling resistance of the elements were determined according to the Finite Strip Method (FSM). To develop less biased networks and ensure that every observation from the original dataset has the chance of appearing in the training and test set, a K-fold cross-validation technique was implemented. In addition, the hyperparameters of the ANNs were tuned using a grid search technique to provide ANNs with optimum performances. The results demonstrated that the trained ANNs were able to predict the elastic distortional buckling resistance of CFS flange-restrained elements with an average accuracy of 99% in terms of coefficient of determination. The developed models were then used to propose a simple ANN-based design formula for the prediction of the elastic distortional buckling stress of CFS flange-restrained elements. Finally, the proposed formula was further evaluated on a separate set of unseen data to ensure its accuracy for practical applications.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1996년도 춘계학술대회 논문집
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• pp.635-640
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• 1996

A thermo-elastic system in the production machine has highly nonlinear dynamic characteristics. In general, the finite element method is utilized for accurate analysis. However, it requires large computing time. Thus, thermo-elastic systems are usuallymodeled as electric and fluid system using lumped para,eter. In this paper. we propose the bondgraph model and transient simulation methodology of thermo-elastic system in consideration of various boundary and joint contact conditions. Consequently, the proposed method ensures a possibility of its on-line compensation about undesirable phenomena by using real time estimate process and electronic cooling device for thermal appropriate behavior. Thermo-elastic model consisting of bush and shaft including contact condition is presented.

• PNF and Movement
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• 제17권3호
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• pp.421-429
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• 2019

Purpose: This study evaluated the relationship between pelvic pressure and irradiation of the proprioceptive neuromuscular facilitation (PNF) upper arm pattern exercises with an elastic band while in a sitting position. Methods: Fourteen subjects with asymptomatic pelvic pressure participated in this study. Pelvic pressure was measured using a Gaitview® system while sitting and performing PNF bilateral upper arm patterns. Resistance strength was provided by the blue elastic band. The statistical significance of the results was evaluated using a repeated one-way ANOVA and the independent t-test. The Bonferroni method was used for the post-hoc test. Results: The results revealed a significant change in the pelvic pressure when performing the PNF arm pattern. The average resistance pressure on the pelvis, with the elastic band, significantly increased after the initial sitting position (F=3.91, 3.92; p<0.05). No significant pelvic pressure changes were noted for each PNF upper arm pattern (p>0.05). Conclusion: The results of this study showed a positive relationship between pelvic pressure and the irradiation of PNF upper arm pattern exercises with resistance in the sitting position.

• Structural Engineering and Mechanics
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• 제38권5호
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• pp.573-592
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• 2011

Comprehensive and accurate analysis of a finite foundation beam is a challenging engineering problem and an important subject in foundation design. One of the limitation of the traditional Winkler elastic foundation model is that the model neglects the effect of the interface resistance between the beam and the underneath foundation soil. By taking the beam-soil interface resistance into account, a deformation governing differential equation for a finite beam resting on the Winkler elastic foundation is developed. The coupling effect between vertical and horizontal displacements is also considered in the presented method. Using Galerkin method, semi-analytical solutions for vertical and horizontal displacements, axial force, shear force and bending moment of the beam under symmetric loads are presented. The influences of the interface resistance on the behavior of foundation beam are also investigated.

• 근관절건강학회지
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• 제27권2호
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• pp.71-80
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• 2020

Purpose: This thesis study aimed to examine the effects of elastic-band resistance exercise on physical fitness, activities of daily living (ADLs), falls efficacy, and quality of life among older women receiving home nursing care under long-term care insurance. Methods: We used an equivalent control group pre-test/post-test design. We assigned older women at the nursing care center J to the experimental group (n=21), and older adult women at the nursing care center H to the control group (n=21). The experimental group engaged in an elastic band resistance exercise twice per week from February 18 to April 12, 2019. Results: There were significant differences in the Short Physical Performance Battery score (t=4.15 p<.001), left grip strength (t=0.57, p<.569), right grip strength (t=1.38 p<.177), flexibility test scores (t=2.34, p<.024), ADLs (t=6.86, p<.001), falls efficacy (t=5.16, p<.001), and quality of life (t=3.87, p<.001). Grip strength was increased slightly in the experimental group, but the increase was not significant. Conclusion: Elastic band resistance exercise is an effective nursing intervention to enhance physical fitness, flexibility, ADLs, falls efficacy, and quality of life among older women receiving home nursing care under long term care insurance.