• Journal of the Korean Society of Physical Medicine
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• v.18 no.3
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• pp.65-72
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• 2023

PURPOSE: This study assessed the influence of bilateral coordination exercises on unstable support surfaces on leg muscle activation and balance in stroke patients. METHODS: Two groups were recruited for comparison: an experimental group of 10 individuals who performed bilateral coordination exercises on unstable surfaces and a control group of 10 individuals who performed the same exercises on stable surfaces. All participants were assigned randomly. Pre-tests were conducted to measure the leg muscle activation and balance levels of the participants prior to the experiment. The intervention was comprised of three 30-minute weekly sessions for four weeks, followed by a post-test after the four-week period. RESULTS: Significant differences were identified within the experimental group in relation to all muscles (p < .01) and balance (p < .05). Within the control group, significant differences were identified in relation to the rectus femoris muscle, biceps femoris muscle, and balance (p < .05). Significant differences between the two groups were only observed in relation to the tibialis anterior and soleus muscles (p < .05). CONCLUSION: Only the tibialis anterior and soleus muscles showed significant differences between the two groups. This effectiveness may be attributed to using an ankle strategy to maintain body balance during exercise on unstable surfaces.

• 한국전기화학회:학술대회논문집
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• 2002.04a
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• pp.56-56
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• 2002

• Computational Structural Engineering
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• v.11 no.1
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• pp.227-235
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• 1998

A method of calculating the natural frequency corresponding to the first mode of vibration of beams and tower structures, with irregular cross-sections and with arbitrary boundary conditions was developed and reported by D. H. Kim in 1974. This method has been developed for two-dimensional problems including the laminated composite plates and was proved to be very effective for the plates with arbitrary boundary conditions and irregular sections. In this paper, the result of application of this method to the building slabs with passive and active control devices is presented. Finite difference method is used to obtain the deflection influence surfaces needed for this vibration analysis in this paper. The influence of the modulus of the foundation on the natural frequency is thoroughly studied.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 1990.11a
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• pp.16-35
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• 1990

The mechanism of failure of lubricated surfaces at high sliding speeds was Investigated. Experiments were performed with the ball-on-flat and cylinder-on-flat geometries, using lubricants of four different chemical reactivities. Surface failure was found to not be predictable using the ratlo, $\lambda$, of fluid film thickness to composite surface roughness except when chemically inert lubricants are used. Even then the influence of temperature rise on fluid film thickness does not adequately explain the low load carrying capacity of lubricants at high sliding speeds. which causes surface failure. The protective layers on sliding surfaces that form by chemical reaction with the lubricant were found to reduce the surface roughentrig and Increase the load carrying capacity of surfaces to values of $\lambda$ as low as 0.03. Neither the surface toughening nor the formation of the protective layers have been incorporated Into failure models for lubricated systems.

• Tribology and Lubricants
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• v.7 no.1
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• pp.16-27
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• 1991

The mechanism of failure of lubricated surfaces at high sliding speeds was investigated. Experiments were performed with the ball-on-flat and cylinder-on-flat geometries, using lubricants of four different chemical reactivities. Surface failure was found to not be predictable using the ratio, $\lambda$, of fluid film thickness to composite surface roughness except when chemically inert lubricants are used. Even then the influence of temperature rise on fluid film thickness does not adequately explain the low load carrying capacity of lubricants at high sliding speeds, which causes surface failure. The protective layers on sliding surfaces that form by chemical reaction with the lubricant were found to reduce the surface roughening and increase the load carrying capacity of surfaces to values of $\lambda$ as low as 0.03. Neither the surface roughening nor the formation of the protective layers have been incorporated into failure models for lubricated systems.

• Carbon letters
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• v.5 no.4
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• pp.186-190
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• 2004

In this work, a nickel metal (Ni) electroplating on the activated carbon fiber (Ni/ACFs) surfaces was carried out to remove the toxic hydrogen chloride (HCl) gas. The surface properties of the treated ACFs were determined by using nitrogen adsorption isotherms at 77 K, SEM, and X-ray diffraction (XRD) measurements. HCl removal efficiency was confirmed by a gas-detecting tube technique. As a result, the nickel metal contents on the ACF surfaces were increased with increasing the plating time. And, it was found that the specific surface area or the micropore volume of the ACFs studied was slightly decreased as increasing the plating time. Whereas, it was revealed that the HCl removal efficiency containing nickel metal showed higher efficiency values than that of untreated ACFs. These results indicated that the presence of nickel metal on the ACF surfaces played an important role in improving the HCl removal over the Ni/ACFs, due to the catalytic reactions between nickel and chlorine.

• Structural Engineering and Mechanics
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• v.53 no.1
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• pp.27-40
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• 2015

The rational analytical solutions are presented for functionally graded beams subjected to arbitrary tractions on the upper and lower surfaces. The Young's modulus is assumed to vary exponentially along the thickness direction while the Poisson's ratio keeps unaltered. Within the framework of symplectic elasticity, zero eigensolutions along with general eigensolutions are investigated to derive the homogeneous solutions of functionally graded beams with no body force and traction-free lateral surfaces. Zero eigensolutions are proved to compose the basic solutions of the Saint-Venant problem, while general eigensolutions which vary exponentially with the axial coordinate have a significant influence on the local behavior. The complete elasticity solutions presented here include homogeneous solutions and particular solutions which satisfy the loading conditions on the lateral surfaces. Numerical examples are considered and compared with established results, illustrating the effects of material inhomogeneity on the localized stress distributions.

• Analytical Science and Technology
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• v.35 no.3
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• pp.124-128
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• 2022

Blood-sensitive reagents may exhibit false positives or negatives under the influence of substances other than blood. Since these reactions lead to the misinterpretation of blood evidence, it is essential to investigate the possibility of false-positive and -negative reactions of blood-sensitive reagents. Acidic hydrogen peroxide (AHP) is a recently discovered blood-sensitive reagent, and it is not yet known whether it causes false-positive or -negative reactions. To confirm this, 20 µL of blood was placed on metal surfaces, plastic surfaces, paper surfaces, paint surfaces, foods, vegetable oils, detergents, and petroleum hydrocarbons, and then AHP was applied. The blood was observed through an orange filter under a 505-nm light source, and no false-positive or false-negative reactions were observed with any of the substances/materials. However, it was confirmed that polyethylene terephthalate surfaces, polyvinylchloride surfaces, some paint surfaces, and foods exhibit their own photoluminescence under the conditions of blood observation, which interferes with blood observation.

• Journal of the Korean institute of surface engineering
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• v.42 no.5
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• pp.208-215
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• 2009

We employed atmospheric plasma to reactively remove the lubricant sprayed onto such industrial electronic parts as LCD chassis during sheet-metal forming processes and investigated basically the effect of plasma parameters on cleansing the surfaces of zinc-electroplated steel plates (EGI). Specimen prepared with some controlled amount of lubricant sprayed on their surfaces beforehand were subjected to two different kinds of atmospheric plasma, one being generated by using air and the other generated by using nitrogen (99.9% purity). Locating the plasma beams at the height range between 3.5 and 13.5 mm from the surface of each specimen and radiating for 5 to 30 seconds resulted out that the cases with a position of 3.5 mm and a duration of 5 seconds or longer showed the surfaces completely cleansed without a trace of lubricant. Furthermore we found out that the plasma generated by using simple air depicted higher cleansing ability than the other one generated by using expensive nitrogen, interestingly useful very much for industrial purposes. On another aspect, we confirmed that the drilled or cut surfaces of Zn-plated steel substrate would not be oxidized even under the influence of plasma during its cleansing process. Therefore, we could probably conclude from this fore-survey that a dry process adopting atmospheric plasma for cleansing industrial parts might be determined to become successful in terms of commercialization, cautiously.

• 한국전산유체공학회:학술대회논문집
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• 2009.04a
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• pp.363-367
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• 2009

Recently, the manufacturing of micro-cavity by means of laser surface texturing (LST) technique and low friction study by the LST have been in great progress. Most of current works have been dealing with the effect of cavity on friction and wear. The main objective of the present study was to investigate numerically two-dimensional lubrication characteristics of micro-dimple shapes fabricated on solid surfaces, and this study utilized the commercial CFD code (Fluent V.6.3). For the evaluation, preliminary simulation was conducted and numerical predictions were compared with the analytic solution obtained from the Reynolds's equation. Mainly, the present study investigated the influence of dimple depth, pattern shapes, and film thickness on lubrication characteristics related to the reduction of friction. It is found that the existence of micro-dimpled surface makes it possible to substantially reduce the friction forces exerted on the surfaces. In particular, substantial decrease in shear stresses was observed as the lubricant film thickness decreases. For instance, in the case of the film thickness of 0.01 mm, the estimated shear stress decreases up to about 40%. It indicates that the film thickness would be important factor in designing the micro-dimpled surfaces. Furthermore, it was observed that such a optimum dimple depth would be present because the dimple depth larger than the optimum value did no longer affect the reduction in shear stresses.