• The Journal of Korean Physical Therapy
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• 제24권6호
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• pp.393-397
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• 2012

Purpose: We investigated to identify the effect of robo-horseback riding exercise (RHRE) on trunk muscle activity ratios for patients with low back pain. Methods: Twelve patients with low back pain and twelve healthy adults were recruited for this study. Subjects performed the RHRE with the neutral spine position. The amplitude of electromyography activity was recorded from the selected trunk muscles (internal oblique [IO], rectus abdominis [RA], multifidus [MF], the thoracic part of the iliocostalis lumborum [ICLT]). The ratios of the relative local muscle activity to the global muscle activity in abdominal and lumbar parts were calculated. Results: There were significant differences in the change values of the IO/RA and the MF/ICLT between low back pain (LBP) patients and healthy adults. The IO/RA ratio and the MF/ICLT ratio showed significant increase in LBP patients after training. Conclusion: The RHRE improved the trunk muscle activity ratio in patients with low back pain. The information presented here is important for investigators who use lumbar stabilization exercises as a rehabilitation exercise.

• Wind and Structures
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• 제16권6호
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• pp.603-616
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• 2013

This study is aimed at formulating an empirical equation for the across-wind fluctuating moment and spectral density coefficient, which are needed to estimate the across-wind dynamic responses of tall buildings, as a function of the side ratios of buildings. In order to estimate an empirical formula, wind tunnel tests were conducted on aero-elastic models of the rectangular prisms with various aspect and side ratios in turbulent boundary layer flows. In this paper, criteria for the across-wind fluctuating moment and spectral density are briefly discussed and the results are analyzed mainly as a function of the side ratios of the buildings. Finally, empirical formulas for the across-wind fluctuating moment coefficient and spectral density coefficient according to variation of the aspect ratio are proposed.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 1996년도 추계학술대회논문집
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• pp.85-92
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• 1996

The Measurement method of the plastic strain ratio is various in Automotive sheet steel. In this paper, the measurement of the plastic strain are used two different methods, ASTM E 517 method and the automatic strain measurement tensile specimen during the tensile test, and compared the plastic strain ratios from the two methods. The experimental results showed that the measured plastic strain ratios from the automatic strain measurement method are coincide with that from the ASTM E 517 standard measurement in various specimens. Therefore, automatic strain measurement method by two extensometers shows good accuracy. Also, the strain dependance of plastic strain ratios could be recorded by the computer continuously and anisotropy of the strength coefficient, K, and strain hardening exponent, n ,could be compared with each direction automatically through the use of automatic strain measurement system.

• 대한핵의학회지
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• 제16권2호
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• pp.63-70
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• 1982

To evaluate the diagnostic usefulness and significance of quantitative sacroiliac joint scintigraphy in the assessment of sacroiliitis, we measured Sacroiliac Joint/Sacrum Uptake Ratio(SIS Ratio) by region of interest(ROI) method using $^{99m}Tc-methylene$ diphosphonate. The observed results were as follows: 1. Using ROI method, the SIS ratios for the control group of 65 persons were $1.05{\pm}0.08$(left) and $1.06{\pm}0.07$(right) which were narrower in range than those of slice method $(mean{\pm}S.D.)$. 2. The effects of age, gender and laterality on SIS ratio were not significant. 3. In left side, one of 6 patients with rheumatoid arthritis had SIS ratio in excess of 2 standard deviation of normal control group, and remainder had SIS ratios within normal limit. In right side, 3 patients had SIS ratios in excess of 2 standard deviation of normal control group, and remainder, within normal limit. 4. In both sacroiliac joint, 2 of 3 patients having sacroiliitis clinically with Reiter's syndrome whose pelvis A-P X-ray findings showed normal had high SIS ratios (left/right; 1.31/1.69, 1.90/1.80), but SIS ratio of one patient who had no evidence of sacroiliitis clinically was within normal limit. 5. In 6 patients with ankylosing spondylitis in both sacroiliac joints, 4 whose pelvis A-P Xray findings showed severe sclerotic change of sacroiliac joints had SIS ratio within normal limit or below that of normal control group, and SIS ratios of 2 patients whose pelvis A-P X-ray findings showed were increased. 6. 4 of 5 patients with low back pain of which cause could not be evaluated clinically and radiologically had SIS ratios in excess of that of normal control group. It would be concluded that quantitative sacroiliac joint scintigraphy is useful and sensitive screening method in the diagnosis as well as in the assessment clinical activity of sacroiliitis.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2001년도 가을 학술발표회 논문집
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• pp.477-482
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• 2001

This paper is to study the effect of longitudinal reinforcement ratios and axial deformation on the frame analysis in reinforced concrete(RC) columns and to investigate the effect of confined concrete core, the length-width ratio and longitudinal steel ratios on frame analysis in Concrete-Filled steel Tubular(CFT) columns. An equation if derived to evaluate the modulus of elasticity for core concrete. The 34 reference data have been collected for the purpose and are processed by the mean of a multiple regression analysis technique. The equation and longitudinal reinforcement ratios was applied to RC columns for structural analysis. Then, the difference of beam moment was identified. In general, the results of analysis was indicated reasonable differences in beam moment, in case of longitudinal reinforcement ratios applied to RC columns when compared with the plain concrete columns. In CFT columns the equation was also applied in order to the effect of confined concrete core on structural analysis. Beam moment was increased as volumetric ratio of lateral steel was decreased. The effect of longitudinal steel ratios was investigated in CFT columns and was confirmed beam moment variety. The result was appeared reasonable difference in beam moment as longitudinal steel was increased.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2023년도 가을학술발표대회논문집
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• pp.17-18
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• 2023

This study aims to compare the hardness value development characteristics according to the water-cement ratio during a series of experiments to develop a setting estimator for an AI-based concrete finishing automation system. For the test variables, water-cement ratios are varied with 30, 40 and 50%. Proctor penetration test and surface hardness test by setting time estimator are conducted to estimate the setting time. For the effect of water-cement ratios, they did not affect the surface hardness either, while initial set time and final set time are not constant with water-cement ratios.

• Steel and Composite Structures
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• 제14권4호
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• pp.349-365
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• 2013

Structures consisting of concrete and steel parts, which are irregular in damping ratios are investigated. This investigation is a code-based seismic design of such structures. Several practical difficulties encountered, due to inherent differences in the nature of dynamic response of each part, and the different damping ratios of the two parts. These structures are irregular in damping ratios and have complex modes of vibration so that their analysis cannot be handled with the readily available commercial software. Therefore, this work aims to provide simple yet sufficiently accurate constant values of equivalent damping ratios applied to the whole structure for handling the damping irregularity of such structures. The results show that the equivalent damping ratio changes with the height of the building and the kind of the structural system, but it is constant for all accelerations values. Thus, available software SAP2000 applied for seismic analysis, design and the provisions of existing seismic codes. Finally, evaluation of different kinds of structural system used in this research to find the most energy dissipating one found by finding the best value of quality coefficient.

• Journal of Magnetics
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• 제13권2호
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• pp.65-69
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• 2008

The magneto impedance (MI) behaviors of patterned $Co_{30}Fe_{34}Ni_{36}$ microwire were investigated with respect to its shape variation. After preparing $Co_{30}Fe_{34}Ni_{36}$ microwires using electrodeposition and photolithography methods, impedance measurements were conducted to compare the MI ratios of the devices with different aspect ratios. As a result, the anisotropy field and transverse permeability were found to be strongly affected by the aspect ratio of the device. The external field value at the maximum impedance and maximum sensitivity of the device was found to increase with increasing device width, which was attributed to the increased transverse anisotropy with decreasing aspect ratio. While an increase in the thickness also contributed to an increase in the MI ratio, a variation in the thickness not only increased the anisotropic field, but the variation in the MI ratio was as also affected by the skin effect. Conversely, the MI ratios of the present devices were hardly affected by variations in the length. Considering the typical aspect ratios of our devices, it was expected that the length effect would emerge when the aspect ratio was reduced to less than 10. Nevertheless, our results show that for the practical application of MI devices, the MI characteristics can be optimized by tailoring the aspect ratio of the devices.

• 유체기계공업학회:학술대회논문집
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• 유체기계공업학회 2006년 제4회 한국유체공학학술대회 논문집
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• pp.101-104
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• 2006

This study aims at verifying characteristics of torsional fluctuating moment coefficient and power spectral density, which is needed to estimate torsional response of tall buildings. In order to estimate characteristics, the wind tunnel tests have been conducted on 52 types aero-elastic model of the rectangular prisms with various aspects ratios, side ratios and surface roughness in turbulent boundary layer flows. In this paper, characteristics of torsional fluctuating wind force are briefly discussed and then these results were mainly analyzed as a function of the aspects ratios and side ratios of buildings.

• 설비공학논문집
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• 제11권5호
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• pp.615-623
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• 1999

The objective of present study is to analyze a hot steel-tube cooling system as a kind of concentric triple-passage heat exchanger, whose inner tube is moving with a constant speed. Velocities and temperatures of an antioxidant gas flowing between inner and outer tubes are calculated theoretically for both laminar and turbulent flow regimes and used to give Nusselt numbers and friction factors with respect to various radius ratios and velocity ratios. In addition, it is shown that heat transfer coefficients based on ratios of average heat fluxes from inner and outer tubes might result in great errors for the temperature distributions of the flows, since the local heat transfer coefficients are dependent on the local heat flux ratios.