• Steel and Composite Structures
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• v.31 no.6
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• pp.601-615
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• 2019

In cold-formed steel (CFS) structures, such as trusses, wall frames and columns, the use of back-to-back built-up CFS angle sections are becoming increasingly popular. In such an arrangement, intermediate fasteners are required at discrete points along the length, preventing the angle-sections from buckling independently. Limited research is available in the literature on the axial strength of back-to-back built-up CFS angle sections. The issue is addressed herein. This paper presents the results of 16 experimental tests, conducted on back-to-back built-up CFS screw fastened angle sections under axial compression. A nonlinear finite element model is then described, which includes material non-linearity, geometric imperfections and explicit modelling of the intermediate fasteners. The finite element model was validated against the experimental test results. The validated finite element model was then used for the purpose of a parametric study comprising 66 models. The effect of fastener spacing on axial strength was investigated. Four different cross-sections and two different thicknesses were analyzed in the parametric study, varying the slenderness ratio of the built-up columns from 20 to 120. Axial strengths obtained from the experimental tests and finite element analysis were used to assess the performance of the current design guidelines as per the Direct Strength Method (DSM); obtained comparison showed that the DSM is over-conservative by 13% on average. This paper has therefore proposed improved design rules for the DSM and verified their accuracy against the finite element and test results of back-to-back built-up CFS angle sections under axial compression.

• Physical Therapy Rehabilitation Science
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• v.10 no.3
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• pp.263-269
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• 2021

Objective: The purpose of this study was to examine the effects lumbar stabilization exercise with kinesio taping on pain, muscle strength, and oswestry disability index (ODI) in patients with chronic low back pain. Design: Two groups pre-post randomized controlled design Methods: Thirty-two subjects were randomly divided in two groups; 1) lumbar stabilization exercise with kinesio taping group (Experimental group, n=16), 2) lumbar stabilization exercise with sham kinesio taping group (Control group, n=16). The intervention was conducted in each group for thirty minutes a day, 5 times a week, for 4 weeks. Both group did 30 minutes of lumbar stabilization application. Evaluations were performed before the commencement of training and again 4 weeks after training was initiated. Visual analog scale (VAS) was used to evaluate pain level of patients with chronic low back pain. Distal muscle test was used to evaluate muscle strength of trunk extension. In addition, ODI was used to evaluate activity daily life of low back pain. Results: After training, the VAS, muscle strength of trunk extension and ODI were significantly more improvement in Experimental group than in the control group (p<0.05). Conclusions: We confirmed that the effects of lumbar stabilization exercise with kinesio taping group on pain, muscle strength, and ODI in patients with chronic low back pain.

• Journal of International Academy of Physical Therapy Research
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• v.8 no.1
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• pp.1105-1113
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• 2017

The Purpose of this study was to determine the effects of sciatic nerve mobilization on pain and lower back muscle strength in female patients in their 40s who have been diagnosed with lumbar radiculopathy. Using a simple blinded method, 20 female patients with neuropathy in the nerve segments between L4-S1 were randomly divided into one group (n=10) that would undergo sciatic nerve mobilization, and another group (n=10) that would perform lower back segment stabilization exercises. The two groups attended 3 sessions per week, with each session taking 30 minutes, for a duration of 4 weeks. In the preliminary examinations, the pain index as well as the isometric muscle strength of the lower back extensor and flexor muscles were measured. After the passing of 4 weeks. The same method of measurement was used for the concluding examinations. Comparison of the pain indices in the two groups revealed that they both experienced a statistically significant decrease, and further inspection revealed that the there was a more substantial difference in the sciatic nerve mobilization group. Results of comparing changes in the Isometric Muscle Strength lower back muscle and bending muscle by group, In comparison between groups, the isometric strength of the lower back extensor showed a more significant difference in the sciatic nerve mobilization group (p <.05). Conclulsion, it can be inferred that application of sciatic nerve mobilization has a positive effect on the pain index and isometric muscle strength of the lower back in female patients with lumbar radiculopathy in their 40s.

• Physical Therapy Rehabilitation Science
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• v.10 no.2
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• pp.156-160
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• 2021

Objective: Low back pain easily becomes chronic and has a high recurrence rate. Therefore, it is most important to prevent chronicity and reduce the risk of recurrence in the early stages of back pain or at the stage with mild pain. Therefore, this study was conducted to compare hip joint muscle strength, trunk muscle endurance, and pelvic alignment between subjects with mild low back pain and subjects without back pain. Design: Crossed-sectional study Methods: The study was conducted by recruiting 30 students in their twenties who are enrolled in K University in Gyeongsangnam-do, and classifying them into 15 patients with mild back pain and 15 patients with normal. The subjects who participated in the experiment were measured for hip flexor and extensor muscle strength, trunk flexion and extension muscle endurance, and pelvic alignment. To measure hip joint muscle strength, biodex was used, and muscle endurance of the trunk was recorded at the end range of the trunk flexion and extension. And pelvic alignment was measured using Formetric 4D. Results: There were no significant differences in hip joint muscle strength, pelvic alignment, and trunk extension muscle endurance. The retention time was found to be significantly shorter in the mild low back pain group than in the normal group for trunk flexion muscle endurance. Conclusions: In the early stages of back pain or in the mild pain stage, training to increase muscle endurance of the flexor muscles may be helpful.

• The Journal of Korean Physical Therapy
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• v.16 no.1
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• pp.14-31
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• 2004

The Purpose of this study was to investigate the change of lumbar extensor strength according to lumbosacral angle on chronic lumbar back pain patients. For this investigation lumbar extensor strength was administered to 60 patients who were diagnosed chronic lumbar back pain The subjects was to investigate lumbosacral angle in standing position and it were calculated lumbar extensor strength by using Medex. The result of this study summarized are as follows ; 1. Total experimental group exhibited significantly higher difference than control group in lumbar extensor strength among all degree lumbosacral angle. 2. In the relationship between experimental group and control group in lumbar extensor strength among lumbosacral angle, all degree difference was revealed II, I, III order. 3. In the relationship between experimental group and control group in lumbar extensor strength among lumbosacral angle, I group difference was did not. 4. In the relationship between experimental group and control group in lumbar extensor strength among lumbosacral angle, all degree among II group was noted significantly difference except 24, 72 angle. 5. In the relationship between experimental group and control group in lumbar extensor strength among lumbosacral angle, control group was revealed higher muscle strength 48, 60, 72 angle, however no significantly difference was noted 0, 12, 24 angle. The study was objected difference of other group in both of experimental and control group. Because lumbar extensor weakness with bad position was gradually increased back pain, to Maintain normal lumbosacral angle befor exercising lumbar extensor strength was most important.

• Journal of The Korean Society of Integrative Medicine
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• v.4 no.4
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• pp.1-6
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• 2016

Purpose : This study determines the effect and sustainability of the trunk stability exercise program, specifically using the bridge exercise, by measuring Visual Analogue Scale(VAS), Menstrual Distress Questionaire(MDQ) and muscle strength in women university students complaining of low back pain. Methods : The trunk stability exercise program was progressed by 22 women university students, for 4 weeks, (3 times a week, 1 hour per session). At this time, low back pain happened at the period of menstruation and was measured using VAS, Dysmenorrhea using the MDQ tool and abdominal and back muscle strength using HUR. This study was evaluated 4 times (before and after the exercise program, after 4 weeks and 8 weeks) to investigate the effect of time variation after the exercise program. Results : The trends showed a decrease in VAS and MDQ and an increase in abdominal and back muscle strength. Therefore, these results were evaluated positively from a statistical perspective(p<.05). Conclusions : The trunk stability exercise results in a decreased VAS and MDQ, and increases the muscle strength in women university students who complained of low back pain form dysmenorrhea. Therefore, the low back pain from dysmenorrhea could have been avoided and quality of everyday life improved.

• Steel and Composite Structures
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• v.33 no.4
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• pp.595-614
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• 2019

In cold-formed steel (CFS) structures, such as trusses, transmission towers and portal frames, the use of back-to-back built-up CFS unequal angle sections are becoming increasingly popular. In such an arrangement, intermediate welds or screw fasteners are required at discrete points along the length, preventing the angle sections from buckling independently. Limited research is available in the literature on axial strength of back-to-back built-up CFS unequal angle sections. The issue is addressed herein. This paper presents an experimental investigation on both the welded and screw fastened back-to-back built-up CFS unequal angle sections under axial compression. The load-axial shortening and the load verses lateral displacement behaviour along with the deformed shapes at failure are reported. A nonlinear finite element (FE) model was then developed, which includes material non-linearity, geometric imperfections and modelling of intermediate fasteners. The FE model was validated against the experimental test results, which showed good agreement, both in terms of failure loads and deformed shapes at failure. The validated FE model was then used for the purpose of a parametric study to investigate the effect of different thicknesses, lengths and, yield stresses of steel on axial strength of back-to-back built-up CFS unequal angle sections. Five different thicknesses and seven different lengths (stub to slender columns) with two different yield stresses were investigated in the parametric study. Axial strengths obtained from the experimental tests and FE analyses were used to assess the performance of the current design guidelines as per the Direct Strength Method (DSM); obtained comparisons show that the current DSM is conservative by only 7% on average, while predicting the axial strengths of back-to-back built-up CFS unequal angle sections.

• The Journal of Korean Academy of Orthopedic Manual Physical Therapy
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• v.26 no.2
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• pp.19-27
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• 2020

Background: The purpose of this study was to examine the effects of a multi-modal exercise program for patients with chronic low back with respect to pain intensity, trunk muscle strength and Oswestry disability index. Methods: Thirty patients with chronic low back pain were recruited and divided equally into two groups. The multi-modal training program comprised a series of exercises such as warm-up, stabilization exercises, stretching, endurance exercises, and cool down whereas the control group performed only stabilization exercises. The both group spent an equal amount of time performing 60 minutes per day, three times per week, for five weeks. Results: The experimental group demonstrated statistically significant improvements in range of motion, trunk muscle strength, the visual analogue scale, and the Oswestry Disability Index (p<.05). Intergroup comparison showed a statistically significant difference in the range of motion of the lumbar spine and the degree of disability in the experimental group. Muscle strength and pain were statistically significant in both groups. Conclusion: The multi-modal exercise program is effective for patients with chronic low back pain, as it reduces lower back pain, increases trunk muscles strength, and decrease the potential for becoming disabled.

• The Journal of Korean Physical Therapy
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• v.34 no.3
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• pp.110-115
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• 2022

Purpose: The purpose of this study was to examine the effect of sling exercise on pain, trunk strength, and balance in patients with chronic low back pain in their 40s and 50s. Methods: Twenty patients with chronic low back pain were divided into two groups, 10 patients in the exercise group using a sling and 10 patients in the waist stabilization exercise group, applying a random assignment, draw-out method, and sling exercise was applied for 50 minutes a day, 3 times a week, for a total of 5 weeks. For data analysis, a corresponding t-test was performed for within-group changes and an independent t-test was performed for inter-group changes, and the significance level was α=0.05. Results: After 5 weeks, there were significant differences in all items of within-group changes, and the inter-group changes after 5 weeks demonstrated significant differences in pain, trunk flexion strength, and balance. Conclusion: The results of this study showed that exercise using a sling had positive effects on pain, trunk flexion strength, and balance changes in chronic low back pain patients. It is suggested that sling exercise can be used as an intervention method for pain reduction and functional improvement of patients with chronic low back pain in clinical practice.

• Journal of Korean Physical Therapy Science
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• v.2 no.4
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• pp.779-783
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• 1995

The number of the subjects of this study were all sixteen including 8 male and 8 female. They were chronic low back pain patients and treated at hospital out patient. The patients took lumbar extension strength training. The results of examination and analysis isometric lumbar extension muscular strength before and after the training are as follows; 1. TFT increased after lumbar extension muscular strength exercise than before the exercise. Inspire of difference of each angle. The reciprocal action didn't happen between training and angle. 2. NMT increased after lumbar extension muscular strength exercise than the before the exercise and the difference of each angle didn't happen. The reciprocal action also didn't happen between the training and angle. 3. Comparing presented standard point with individual point, 13persons' muscle strength of first step increased, on the other and 3 person's muscle strength a little increased in a same category. 4. The grade of low back pain decreased for all subjects. Concluding this study, lumbar extension muscular strength exercise through isokinetic device decreases the grade of low back pain and increase lumbar extension muscular strength. It is that equal exercise effect happen in full range of motion, for the exercise effect doesn't show the difference of each angle.