• Journal of the Korea institute for structural maintenance and inspection
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• v.10 no.1
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• pp.183-189
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• 2006

When RC structures are repaired or strengthened using FRP, it is required to cure for some Period under certain air temperature and then it is hopeful to avoid detrimental action caused by external vibration sources during that period. Therefore, an effect of repeated loading during Carbon Fiber Sheet(CFS) strengthening Process on the strengthening efficiency is studied through an experiment for a number of RC beams. Experimental results showed that the curing time of 24 hours without any repeated loading after CFS attachment were recommended for 1 ply strengthening, and 12 hours for 2 plies strengthening.

• Computers and Concrete
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• v.33 no.4
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• pp.399-407
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• 2024

This study nondestructively examined the evolution of crack density in ultra-high performance concrete (UHPC) upon cyclic loading. Uniaxial compression was repeatedly applied to the cylindrical specimens at levels corresponding to 32% and 53% of the maximum load-bearing capacity, each at a steady strain rate. At each stage, both P-wave and S-wave velocities were measured in the absence of the applied load. In particular, the continuous monitoring of P-wave velocity from the first loading prior to the second loading allowed real-time observation of the strengthening effect during loading and the recovery effect afterwards. Increasing the number of cycles resulted in the reduction of both elastic wave velocities and Young's modulus, along with a slight rise in Poisson's ratio in both tested cases. The computed crack density showed a monotonically increasing trend with repeated loading, more significant at 53% than at 32% loading. Furthermore, the spatial distribution of the crack density along the height was achieved, validating the directional dependency of microcracking development. This study demonstrated the capability of the crack density to capture the evolution of microcracks in UHPC under cyclic loading condition, as an early-stage damage indicator.

• Journal of Korean Academy of Nursing
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• v.37 no.6
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• pp.844-854
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• 2007

Purpose: This study was to verify the effect of muscle strengthening exercises using a Thera-Band on the lower limbs. Methods: The design utilized for this study was a nonequivalent control group pretest-posttest design. A control group (16) and experimental group (16) were selected from stroke patients of K Oriental Medicine Hospital who were hospitalized for 5 months from December 2005 through April 2006. While only acupuncture therapy and physical therapy were used on the control group, acupuncture, physical therapy and additional muscle strengthening exercises using a red thera band were used on the experimental group. Muscle strengthening was performed 20 minutes per session, more than one session a day for 4 weeks. Hypotheses for this study were verified using Two-way repeated ANOVA and ANCOVA using a pre test score as a covariate. Results: The experimental group with thera band muscle strengthening exercises showed a decrease in asymmetry weight loading percentage(F=14.704, P= .010), range of knee (Z=-3.15, P= .001) & deep tendon reflex score(Z=-2.52, P= .012) and moving performance(F=12.328, P= .001)compared to the control group. Conclusion: It is confirmed that muscle strengthening exercises using a Thera-Band can be used as an effective nursing intervention to improve the function of the lower limb of hemiplegic stroke patients.

• Journal of the Korean Geotechnical Society
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• v.21 no.7
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• pp.73-80
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• 2005

There are several major practical consequences of stress-dependent properties of unbound pavement foundations. Among those are the stress-dependent modulus and Poisson's ratio's that may change, the compressive stresses that are generated in materials under load, the stiffening and strengthening effect of repeated loading to progressively increase the unbound pavement materials resistance to permanent deformation. In order to study these, the algorithm for predicting deformations on conventional flexible pavements are proposed and the stress-dependent effects on layer deformation are presented in this paper by the developed stress-dependent finite element analysis program with the selected models.

• Journal of the Korean Wood Science and Technology
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• v.17 no.2
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• pp.34-64
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• 1989

Corner block with anchor bolt(CBA) joint method used in knock-down type table furniture manufacturing can reduce the packing and transporting cost. Unfortunately. it also has the disastrous defect to be loosend and unstable during the service life mainly due to fatigue and creep(repeated and prolonged loading). So 22 joint groups constructed were tested to evaluate the effect of some design factors related to the size of side rail(apron). block attachment to side rail. and the number of anchor bolt as well as the effect of the type of corner block(mitered type vs. rectangular type) Usable strength from the stiffness coefficients of each joint group were analysed with SPSS /PC+ and described as the criteria of CBA joint construction. The conclusions were as follows: The height of side rail(50, 75 and 100 mm) and the addition of polyvinyl acetate(PVAc) emulsion in the corner block attactment to side rail had the effect on raising the usable strength of CBA joint with remarkable high significance. And the effect of 2 - anchor bolts was also superior to that of 1 - bolt significantly. However. the thickness of side rail(22 mm vs. 25 mm) had no effect on the strengthening the table joint rigidity. Mitered type corner block joint appeared to he recommendable for CBA jointed table construction rather than the rectangular type one regardless of the method of block attachment to side rail. The best result identified from Duncan's multiple comparison was in the construction with 25 mm thick and 100 mm height of side rail fastened using 2 - anchor bolts in mitered type corner block. But it would be reasonable to use 22 mm thick & 75 mm high side rail and mitered corner block with PVAc emulsion & 2 bolts considering the productivity and production cost down in the MDF furniture manufacturing industries.