• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2012.11a
• /
• pp.13-14
• /
• 2012

This study investigates the effect of adhesive type applying to surface-strengthening Ondol floor on level of attachment. Adhesive materials of four types produced in different companies were prepared and their attaching performance was examined. Test results showed that the water-based epoxy type produced in S company was the most effective on attaching the pieces of the surface-strengthening Ondol floor product.

• Journal of the Korean Society of Manufacturing Technology Engineers
• /
• v.19 no.2
• /
• pp.216-223
• /
• 2010

The general way to process the surface by means of the laser was heat treatment for strengthening the surface hardness. They have used the laser for changing the property of the surface, especially for metal. Generally, it is recent increasing tendency to use the thin plate panel for making things smaller and lightweight. However, thin plate should be strengthened or let the thin plate panel have moment of inertia by means of engraving the groove or wave on them for lightweight and strengthening. Therefore it is expected that the thin plate panel can be harder and more stable through processing the metal surface by laser beam irradiation and the hardness of thin plate possibly can be also changed how many parts of them are harden. Through this research, it can be grasped how the hardness and mechanical characteristic changes according to width and depth of groove by laser affect the max stress by the ratio of $A_H/A_T$ (hardening area/total area) and characteristic of displacement and structural characteristic for making the thin plate harder by the strengthening metal surface of thin plate by laser through the experiment and analysis of FEA can be presented.

• Journal of the Korean Society of Safety
• /
• v.24 no.3
• /
• pp.39-46
• /
• 2009

A recent and promising method for shear strengthening of reinforced concrete(RC) members is the use of near surface mounted(NSM) fiber reinforced polymer(FRP) reinforcement. In the NSM method, the reinforcement is embedded in grooves cut onto the surface of the member to be strengthened and filled with an appropriate binding agent such as epoxy paste or cement grout. This paper illustrates a research program on shear strengthening of RC beams with NSM channel-type FRP beams which is developed in this study. The objective of this study is to clarify the role of channel-type FRP beam embedded to the beam web for shear strengthening of reinforced concrete beams. Included in the study are effectiveness in terms of spacing and angle of channel-type FRP beams, strengthening method, and shear span ratio. the study also aims to understand the additional shear capacity due to glass fiber reinforced polymer beams and carbon reinforced polymer beams. And anther objective is to study the failure modes, shear strengthening effect on ultimate force and load deflection behavior of RC beams embedded with channel-type FRP beams on the shear region of the beams.

• Polymer(Korea)
• /
• v.38 no.5
• /
• pp.620-625
• /
• 2014

The effect of polyvinyl alcohol/polyamide-epichlorohydrin (PVA/PAE) complex strengthening additive on dry and wet strength and surface properties of paper was investigated. The enhancements of dry and wet strength and dimensional stability were found when PVA/PAE was applied as a complex strengthening additive compared with the cases of applying individual PVA or PAE. This was understood as physical crosslinking between PVA and PAE in the PVA/PAE complex strength additive. This complex strengthening additive also lowered surface roughness and increased sizing. As a result, PVA/PAE complex strengthening additive provided the distinctive gain dot in printed papers.

• Physical Therapy Rehabilitation Science
• /
• v.11 no.2
• /
• pp.189-197
• /
• 2022

Objective: The purpose of this study was to investigate the effect of a lower trapezius strengthening exercise program on an unstable support surface on pain, neck dysfunction, psychosocial factors, and postural alignment in neck pain patients with forward head posture. Design: A randomized controlled trial Methods: A total of 36 neck pain patients participated in this study. Screening tests were performed and assigned to experimental group (n=18) and control group (n=18) using randomization program. Both groups performed the lower trapezius strengthening exercise program. In addition, in the experimental group, an exercise program for lower trapezius muscle strengthening was performed on an unstable support surface. All interventions were performed 3 times a week, for a total of 5 weeks. quadruple visual analogue scale (QVAS), neck disability index (NDI), short form (SF)-12, and postural alignment were measured before and after the intervention to compare their effectiveness. Results: Both groups showed significant differences in QVAS, NDI, SF-12, and postural alignment before and after intervention (p<0.05). In addition, the experimental group showed significant differences in NDI and postural alignment compared to the control group (p<0.05). Conclusions: The lower trapezius strengthening exercise program on unstable support surfaces is an effective intervention method with clinical significance in improving neck disability and postural alignment in patients with neck pain with forward head posture.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2001.11a
• /
• pp.497-502
• /
• 2001

We examined the silicate-based material to develop the surface-treatment agent, which would be used to restore performance of the deteriorated concrete and to inhibit corrosion of the reinforcing bar. As a part of the study, we carried out experiments of the penetration and strengthening properties of concrete treated by the considering agent. The variables of experiment, were the type of silicates, the ratio of distilled water-silicate, the usage of surface-strengthening material, and the usage of biochemical material. The penetrating ability of concrete is assessed by viscosity and surface tension. Also assessments of strengthening effects of concrete are performed on compressive strength, absorption, and water permeability tests.

• Journal of International Academy of Physical Therapy Research
• /
• v.7 no.2
• /
• pp.1046-1050
• /
• 2016

The purpose of this study was to investigate the effects of strengthening and stretching exercises on forward head angle and static dynamic balance ability. 21 adults with the forward head posture were participated in this study. Subjects were randomly assigned to strengthening exercise group I(n=11) and stretching exercise group II (n=10) respectively. Each group were underwent six intervention over the period of 2 weeks, each session lasting 30 minutes. During a preliminary examination, forward head angle and static dynamic balance were measured, and a post examination was conducted that involved same procedure as preliminary examination. There were significant differences in forward head angle after exercise in both groups. In the strengthening group, center of gravity total sway distances was significantly changed under all conditions. In the stretching group, center of gravity total sway distances was significantly changed when subjects had their eyes open while standing on an foam surface. There were significant changes in center of gravity sway velocities in the strengthening group under all conditions, and the same was true in the stretching group only when the subjects had their eyes open while standing on an foam surface. In the comparison between groups, eyes closed while standing on a firm surface was significantly different. There was a significant difference in dynamic balance of the stretching group when the subjects tilted their bodies forward, and there was a statistically significant difference between groups under the same condition. The results of this study suggest that forward head posture can be corrected through therapeutic exercise, and muscle strengthening exercise more effective in improving static balance of forward head posture more than stretching exercise.

• Structural Engineering and Mechanics
• /
• v.65 no.5
• /
• pp.535-546
• /
• 2018

The objective of this study is to understand the behaviour of hollow core slabs strengthened with FRP and hybrid techniques through numerical and analytical studies. Different strengthening techniques considered in this study are (i) External Bonding (EB) of Carbon Fiber Reinforced Polymer (CFRP) laminates, (ii) Near Surface Mounting (NSM) of CFRP laminates, (iii) Bonded Overlay (BO) using concrete layer, and (iv) hybrid strengthening which is a combination of bonded overlay and NSM or EB. In the numerical studies, three-dimensional Finite Element (FE) models of hollow core slabs were developed considering material and geometrical nonlinearities, and a phased nonlinear analysis was carried out. The analytical calculations were carried out using Response-2000 program which is based on Modified Compression Field Theory (MCFT). Both the numerical and analytical models predicted the behaviour in agreement with experimental results. Parametric studies indicated that increase in the bonded overlay thickness increases the peak load capacity without reducing the displacement ductility. The increase in FRP strengthening ratio increased the capacity but reduced the displacement ductility. The hybrid strengthening technique was found to increase the capacity of the hollow core slabs by more than 100% without compromise in ductility when compared to their individual strengthening schemes.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2006.11a
• /
• pp.133-136
• /
• 2006

The main purpose of this study is to develop a Sprayed FRP repair and strengthening method, which is a new technique for strengthening the existing concrete structures by mixing carbon or glass shot fibers and the epoxy or vinyl ester resins with high-speed compressed air in open air and randomly spraying the mixture onto the concrete surface. At present, the Sprayed FRP repair and strengthening method using the epoxy resin has not been fully discussed. In this study, a series of experiments are carried out to evaluate the strengthening effects of the flexural and shear concret beams strengthened with the Sprayed FRP method. The results revealed that the strengthening effects of the flexural and shear specimens are similar, compared to those of the FRP sheet.

• Computers and Concrete
• /
• v.21 no.6
• /
• pp.607-622
• /
• 2018

A non-linear finite element model (FEM) was constructed using a three-dimensional software (ATENA-3D) to investigate the effect of strengthening on the behavior of prestressed hollow-core (PHC) slabs with or without openings. The slabs were strengthened using near surface mounted (NSM)-carbon fiber reinforced polymer (CFRP) strips. The constructed model was validated against experimental results that were previously reported by the authors. The validated FEM was then used to conduct an extensive parametric study to examine the influence of prestressing reinforcement ratio, compressive strength of concrete and strengthening reinforcement ratio on the behavior of such slabs. The FEM results showed good agreement with the experimental results where it captured the cracking, yielding, and ultimate loads as well as the mid-span deflection with a reasonable accuracy. Also, an overall enhancement in the structural performance of these slabs was achieved with an increase in prestressing reinforcement ratio, compressive strength of concrete, external reinforcement ratio. The presence of openings with different dimensions along the flexural or shear spans reduced significantly the capacity of the PHC slabs. However, strengthening these slabs with 2 and 4 (64 and $128mm^2$ that represent reinforcement ratios of 0.046 and 0.092%) CFRP strips was successful in restoring the original strength of the slab and enhancing post-cracking stiffness and load carrying capacity.