• 한국전문물리치료학회지
• /
• 제18권3호
• /
• pp.38-48
• /
• 2011

The aim of the study was to identify which fall-prevention program offered in community settings in Korea is the most effective in strengthening muscles. Muscle weakness is one of the major risk factors causing falls among the elderly. Randomized controlled trials and clinical controlled trials published between 1996 and February 2011 were included in this study. Seventeen of the 69 identified studies met the study's criteria and were included in this meta-analysis. The overall effect size of the program was .822 (95% confidence interval= .717~.927). The general strengthening exercise (1.608), dance sports training (1.538), Thera-band exercise for lower extremities (1.517), Seniorobic exercise (1.146), gait training (.959), balance training (.909), gradual resistive exercise (.888), and multifactorial fall prevention (.842) programs all show positive effects on muscle strengthening. Subgroup analyses found that more relative effects are seen in programs offered to the more elderly. In this study, the effect of increasing muscle strength on the prevention of falls can only be indirectly suggested; there are few available studies that report the frequency or history of falls in Korea. Further studies are needed to examine the direct effect of fall prevention exercise programs among the elderly.

• 콘크리트학회논문집
• /
• 제14권1호
• /
• pp.49-57
• /
• 2002

합성재료중 강섬유(Steel fiber)로 보강된 콘크리트는 보강되지 않은 콘크리트에 비하여 전단, 휨, 피로강도 증진 및 균열제어 효과가 우수한 것으로 평가되고 있다. 특히 전단에 대한 강섬유 보강효과는 취성적인 전단파괴에서의 안정적인 휨 파괴로의 파괴 양상 변화를 보이는 것으로 보고되고 있다. 따라서, 본 연구에서는 기존연구결과 및 총 10개의 실험체를 대상으로 철근콘크리트 기둥에 대한 강섬유의 전단보강 효과를 평가하였다. 실험결과, 강섬유 혼입율 1.5 %에서 전단강도 증진효과가 가장 우수한 것으로 평가되었으며, 연성능력의 증진도 우수한 것으로 평가되었다. 그러나, 강도 및 연성능력 증진에 비하여 강성 및 에너지 소산 능력에 대한 강섬유 보강효과는 다소 미흡한 것으로 평가되었다.

• 한국구조물진단유지관리공학회 논문집
• /
• 제4권4호
• /
• pp.141-148
• /
• 2000

Recently the Carbon Fiber Sheet(CFS) is widely used for strengthening damaged RC structures. Strengthening compression members such as column can increase ductility and strength due to the confinement effect. In this experiment, the behavior of concrete cylinders confined by CFS was examined. The confinement pressure is increased linearly as axial stress is increased in low axial stress, and the confinement effect of CFS was rapidly developed after near maximum axial stress, thus axial strength and ductility was improved. As the ratio of CPS is increased, concrete cylinders failed due to local fracture of CFS. The confinement effect of circular section is more efficient than that of rectangular section. And significant improvement of axial strength, axial strain, transverse strain at failure is observed in circular section. This is because in rectangular section the local fracture of CFS near corner may be occured, thus the strain efficiency ratio must be considered for RC structures with CFS.

• 한국콘크리트학회:학술대회논문집
• /
• 한국콘크리트학회 2000년도 봄 학술발표회 논문집
• /
• pp.775-780
• /
• 2000

This paper was aimed to investigate the shear strengthening effect of the pre-loaded reinforced concrete beams strengthened by carbon fiber sheet (CFS) & steel plate. Main test parameters were the magnitude of pre-loading at the time of the retrofit, the strengthening methods of carbon fiber sheet and aid ratio. A series of seventeen specimens was tested to evaluate the corresponding effect of each parameters such as maximum load capacity, load-deflection relationship, load-strain relationship and failure mode. As a result, using the steel plate can increase the capacity of not only shear but also bending moment.

• 한국구조물진단유지관리공학회 논문집
• /
• 제2권3호
• /
• pp.205-211
• /
• 1998

The purpose of this study is to evaluate shear strengthening effects of R/C beams with carbon fiber sheets. The major variables are shear reinforcement ratios, CFS strengthening ratios and strengthening methods of CFS. Following conclusions can be extracted. The shear capacity of beam strengthened with CFS is about 32~87% higher than that of beams without shear reinforcement. The strengthening effects of patch type is larger than those of strip type. The strain distribution in CFS intersected with shear crack is similar to that in stirrup and larger strain is observed in the middle of the shear span. It can be estimated that shear strength reduction factor ${\alpha}$=0.3 is appropriate for peeling effect of CFS.

• 한국해양공학회지
• /
• 제14권1호
• /
• pp.52-59
• /
• 2000

Flexural fracture characteristics of newly-developed Grid-type carbon fiber plastics in the deteriorated reinforced concrete structures were investigated by the four-points fracture test to verify the strengthening effects in the beam specimens. Results showed that initial cracks appeared in the boundary layers of fibers embedded in the newly-placed mortar concrete slowly progressed to the direction of supports and showed fracture of fiber plastics and brittle failure of concrete in compression in sequence after the yielding of steel reinforcement. Accordingly the reasonable area of Grid-type carbon-fiber plastics in the strengthening design of deteriorated RC structures should be limited and given based on the ultimate strength design method to avoid the brittle failure of concrete structures.

• Steel and Composite Structures
• /
• 제31권2호
• /
• pp.159-172
• /
• 2019

Strengthening of civil infrastructure with advanced composites have recently become one of the most popular methods. The use of Fiber Reinforced Polymer (FRP) strips plates and fabric for strengthening of reinforced concrete structures has well established design guidelines and standards. Research on the application of FRP composites to steel structures compared to concrete structures is limited, especially for shear strengthening applications. Whereas, there is a need for cost-effective system that could be used to strengthen steel high-way bridge girders to cope with losses due to corrosion in addition to continuous demands for increasing traffic loads. In this study, a parametric finite element study is performed to investigate the effect of applying thick CFRP strips diagonally on webs of plate girders on the shear strength of end-web panels. The study focuses on illustrating the effect of several geometric parameters on nominal shear strength. Hence, a formula is developed to determine the enhancement of shear strength gained upon the application of CFRP strips.

• 대한통합의학회지
• /
• 제10권4호
• /
• pp.57-69
• /
• 2022

Purpose : The purpose of this study was to investigate the effect of ankle strengthening exercise combined with sling-assisted gluteus medius strengthening on ankle instability score, and static and dynamic balance ability, muscle strength in adults in their 20s with chronic ankle instability. Methods : Twenty-eight adults in their 20s with chronic ankle instability were recruited. After screening test, they were randomized through R studio program as an experimental group (n=14) to apply an ankle strengthening exercise combined with sling-assisted gluteus medius strengthening and a control group (n=14) to apply ankle strengthening exercise. The intervention lasted two times a week for 6 weeks. To compare the intervention effects, the Cumberland ankle instability tool (CAIT) score, static and dynamic balance ability, and muscle strength of lower extremities were measured. Results : The experimental group showed a significant increase in pre and post-intervention Cumberland ankle instability tool (CAIT) score, static and dynamic balance ability, and muscle strengt (p<.05). The control group showed a significant increase in pre and post-intervention CAIT score, dynamic balance ability, and muscle strength (p<.05). The experimental group showed a significant increase in CAIT score, dynamic balance ability, and muscle strength compared to the control group (p<.05), and showed a high effect size. Conclusions : The results of this study confirmed that ankle strengthening exercise combined with sling-assisted gluteus medius strengthening on people with chronic ankle instability the possibility that it could be effective in improving ankle instability and improving dynamic balance ability, and strength by movement. Although additional research is needed to increase the number of participants due to the small sample size, it is hoped that this study will be an optimistic clinical protocol for people with chronic ankle instability.

• 동력기계공학회지
• /
• 제2권2호
• /
• pp.35-40
• /
• 1998

In this study, the author investigated the effects of strengthening treatments on the mechanical properties of plasma sprayed Ni-base self fluxing alloy. Strengthening treatments for sprayed specimens were carried out in 4 different temperature conditions in vacuum furnace. The mechanical properties, such as microhardness, thermal shock resistance and erosion resistance were tested for the sprayed specimens after strengthening treatments. And it was proved that the mechanical properties of coating layer were much improved by strengthening treatments.

• 한국구조물진단유지관리공학회 논문집
• /
• 제4권4호
• /
• pp.121-128
• /
• 2000

When RC beams are strengthening in flexure with steel plate, they have initial strain due to dead load. Strain of steel used in strengthening member is zero. The effect of strengthening in flexure at member changes in accordance with the quantity of initial strain. But in most cases, Quantity of reinforcement is determined without regard to the difference of initial strain when there are calculated the strengthening in flexure at beams. Such method is possible to suggest inadequate quantity of reinforcement. Thus, the object of the study is to suggest practical design equation and reinforcement proposal using comparison and analysis reinforcement efficiency about fexural strength in case with regard and without regard to the initial strain when Re beams are strengthening in flexure with steel plate.