• Physical Therapy Rehabilitation Science
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• v.13 no.1
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• pp.36-42
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• 2024

Objective: The aim of this study is to investigate the effect of hamstring eccentric exercise on pain and functional activity in patients with chronic low back pain. Design: Randomized controlled trial Methods: Participants comprised 27 subjects with back pain persisting for 3 months. They were randomly assigned to the experimental group (Eccentric exercise: n=13) and the control group (Stretching: n=14). The experimental group performed gastrocnemius, iliopsoas, and quadratus lumborum stretching along with hamstring eccentric exercise, while the control group engaged in the same stretches along with hamstring stretching. The eccentric exercise for the hamstrings was Nordic curl exercise. Each group practiced for 1 hour a day, 3 times a week, for 4 weeks. Pain, disability index, balance, and hamstring length were measured. Results: Significant differences were observed in the comparison of changes in back pain, back disability index, and hamstring length before and after exercise within each group (p<0.05). The balance ability of the experimental group showed a difference before and after exercise (p<0.05), whereas no significant difference in the control group. There were no significant differences in back pain and hamstring length between the groups. Changes in back disability index and balance ability significantly increased in the experimental group compared to the control group (p<0.05). Conclusion: Hamstring eccentric exercise using Nordic curls has a positive effect on back pain, back disability index, balance ability, and hamstring length changes.

• 한국전산유체공학회:학술대회논문집
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• 2003.10a
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• pp.276-278
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• 2003

• Journal of Korean Ophthalmic Optics Society
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• v.19 no.1
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• pp.99-104
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• 2014

Purpose: This study was to investigate the functional improvement in peripheral vision following eccentric viewing training. Methods: 14 subjects with normal vision took a part with their right eye, peripheral retinal which is $20^{\circ}$ lateral area from the fovea was examined for contrast sensitivity(CS). Eccentric viewing training was performed for 21days with an hour image viewing and examination was repeated. Results: The critical durations for 0.7 cpd were increased 2.67(467 ms) for pre-eccentric viewing training to 2.79(616 ms) for post-eccentric viewing training (p>0.05). The critical durations for 3.0 cpd were also increased 2.53(341 ms) for pre-eccentric viewing training to 3.04(1102 ms) for post-eccentric viewing training (p>0.05). Conclusions: It is recommended to use higher spatial frequency with higher CS for eccentric viewing training and to train more frequently for a short time. Moreover, the study on Korean standardizing of the visual rehabilitation for low vision based on the etiology is sorely required.

• Korean Journal of Applied Biomechanics
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• v.19 no.1
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• pp.139-148
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• 2009

D. W. HAN. Y. R. AHN., N. J. LEE and E. J. LEE. Effects of Combined Restistance Training Program of Concentric and Eccentric Contraction Using Theraband on Shoulder Rotation Torque Max and Peak Power. Korean Joumal of Sport Biomechanics, Vol. 19, No. 1, pp. 139-148, 2009. The purpose of this study was to find out that combined concentric with eccentric resistance training program using Thera-Band was more effective than only concentric resistance training program on shoulder rotation torque max and peak power. 30 female students were randomly assigned to 3 equal group; concentric and eccentric, concentric, non training group. Subjects were tested in concentric and eccentric torque max and peak power of internal and external rotation using a CON-TERX isokinetic dynamometer. Subjects in training group participated in their regular five times a week for 4 weeks. After exercise, in concentric and eccentric training group, concentric and eccentric torque max, and peak power of internal rotator at 60 deg/sec were increased significantly. concentric peak power at 120 deg/sec were increased significantly. In concentric training group, only concentric peak power of internal rotator at 60 and 120 deg/sec was increased. In conclusion, we found out that combined concentric with eccentric resistance training program using Thera-Band was more effective than only concentric resistance training program on shoulder rotation torque max and peak power.

• Steel and Composite Structures
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• v.18 no.4
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• pp.833-852
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• 2015

Self-compacting Concrete Filled steel Tubes (SCFT), which combines the advantages of steel and concrete materials, can be applied to strengthen the RC columns. In order to investigate the eccentric loading behavior of the strengthened columns, this paper presents an experimental and numerical investigation on them. The experimental results showed that the use of SCFT is interesting since the ductility and the bearing capacity of the RC columns are greatly improved. And the performance of strengthened columns is significantly affected by four parameters: column section type (circular and square), wall thickness of the steel tube, designed strength grade of strengthening concrete and initial eccentricity. In the numerical program, a generic fiber element model which takes in account the effect of confinement is developed to predict the behavior of the strengthened columns subjected to eccentric loading. After the fiber element analysis was verified against experimental results, a simple design formula based on the model is proposed to calculate the ultimate eccentric strength. Calibration of the calculated results against the test results shows that the design formula closely estimates the ultimate capacities of the eccentrically compressed strengthened columns by 5%.

• Journal of Industrial Technology
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• v.22 no.A
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• pp.229-240
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• 2002

This paper is an experimental and numerical work of Investigating the bearing capacity of shallow foundation of rubble mound under eccentric loads. Parametric centrifuge model tests at the 50g level environments with the model footings in the form of strip footing were performed by changing the loading location of model footing, relative density and materials for ground foundation. For the model ground, crushed rock sampled from a rocky mountain was prepared with a grain size distribution of having an identical coefficient of uniformity to the field condition. Model ground was also prepared with relative densities of 50 % and 80 %. For loading condition, model tests with and without eccentric load were carned out to investigate the effect of eccentric loads and a numerical analysis with the commertially available software of FLAC was performed. For numerical estimation with FLAC, the hyperbolic model of a nonlinear elastic constitutive relationship was used to simulate the stress-stram constitutive relationship of model ground and a series of triaxial compression test were carried out to find the parameters for this model Test results were analyzed and compared with Meyerhof method (1963), effective area method based on the limit equilibrium method, and a numerical analysis with FLAC.

• Journal of the Society of Naval Architects of Korea
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• v.46 no.5
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• pp.545-551
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• 2009

In naval architecture and offshore engineering, the development and a broad use has been achieved in the field of flow control valves for pipe system. Butterfly valves are also widely used for flow control, but there are not many studies for triple-eccentric butterfly valves. Moreover, if the fluid of pipeline flows in the bi-direction then it makes more complicate to adapt triple-eccentric butterfly valves to flow control. In this study, we are trying to develop a bi-directional triple-eccentric butterfly valve through sealing mechanism and stem design study. Digital mockup using 3D CAD was constructed for shape interference check and structural analysis was conducted for structural safety. Also we performed leakage test to check out the durability of the bi-directional pressure for the developed valve.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.53 no.3
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• pp.164-172
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• 2004

This paper presents the comparison results of some kinds of control method in circumstance of eccentric load. The plant to be controlled is a computed tomography(CT) driven by a permanent magnet synchronous motor. In a CT system, many units are attached on the rotationally part of a gantry such as x-ray tube, detector, heat exchanger, and data acquisition unit etc. Therefore keeping many components to balance which have different weight is not easy; this is inescapable problem in the all CT systems. To solve this problem against eccentric load, some kinds of control method have been compared and analysed by using protype CT. From the experimental results it is vilified that the CT drive system with model reference control method indicates higher speed regulation ability regardless of variable eccentric weight and uncertain position, and also in the limit condition of constant eccentric weight and fixed position, the compensation method with sinusoidal form is a strong candidate in view of speed ripple reduction.

• Journal of Korean Society of Steel Construction
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• v.14 no.6
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• pp.823-834
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• 2002

Maximum-strength concrete-filled steel square tubular columns were tested under concentric and biaxial eccentric load. Buckling length-section depth ratio $L_k/D$, magnitude of eccentricity e, and angle of eccentric load ${\theta}$ were selected as experimental parameters. Strength and behavior were also examined. Test results showed that the maximum strength of columns under biaxial eccentric load could be predicted using the previously proposed strength formula of columns undr uniaxia eccentric load. Likewise, the behavior and maximum strength of columns could be predicted using the analysis.

• Structural Engineering and Mechanics
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• v.52 no.1
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• pp.173-203
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• 2014

The cross-section warping due to the passage of high-speed trains can be a relevant issue to consider in the dynamic analysis of bridges due to (i) the usual layout of railway systems, resulting in eccentric moving loads; and (ii) the use of cross-sections prone to warping deformations. A thin-walled beam formulation for the dynamic analysis of bridges including the cross section warping is presented in this paper. Towards a numerical implementation of the beam formulation, a finite element with seven degrees of freedom is proposed. In order to easily consider the compatibility between elements, and since the coupling between flexural and torsional effects occurs in non-symmetric cross-sections due to dynamic effects, a single axis is considered for the element. The coupled flexural-torsional free vibration of thin-walled beams is analysed through the presented beam model, comparing the results with analytical solutions presented in the literature. The dynamic analysis due to an eccentric moving load, which results in a coupled flexural-torsional vibration, is considered in the literature by analytical solutions, being therefore of a limited applicability in practice engineering. In this paper, the dynamic response due to an eccentric moving load is obtained from the proposed finite element beam model that includes warping by a modal analysis.