• Physical Therapy Rehabilitation Science
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• v.10 no.3
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• pp.278-288
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• 2021

Objective: The purpose of this study is to investigate the effect of stabilization exercise on whole-body vibration on pain, dysfunction, psychosocial factors, balance ability, and abdominal contraction with patients with low back pain. Design: A randomized controlled trial Methods: A total of 34 patients with low back pain were assigned randomly to experimental group (n=17) and control group (n=17). Both groups underwent a neuromuscular stabilization exercise program. In addition, the experimental group implemented the neuromuscular stabilization exercise program using whole-body vibration. All interventions were applied 60 min per session, 3 times per week for total 4 weeks. Numeric Rating Scale (NRS), Korean version of Oswestry Disability Index (K-ODI), Fear-Avoidance Beliefs Questionnaire (FABQ), balance ability, muscle thickness and contraction ratio were compared to evaluate the effect on intervention. Results: Both groups showed significant differences in NRS, balance ability, and muscle thickness in contraction, contraction ratio before and after intervention (p<0.05). In addition, the experimental group showed significant difference in the amount of change in NRS, balance ability and muscle thickness in contraction, contraction ratio values than the control group (p<0.05). Conclusions: Neuromuscular stabilization exercise program combined with whole-body vibration stimulation has been proven to be an effective and clinically useful method to decrease pain, dysfunction, increase balance ablilty, and transverse abdominis muscle thickness in contraction and contraction ratio for patients with low back pain.

• Journal of the Architectural Institute of Korea Structure & Construction
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• v.36 no.2
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• pp.117-126
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• 2020

The main objective of this experimental study is to investigate shear strength of reinforced concrete beams according to longitudinal reinforcement ratio (ρ) and size effect. In order to find out the shear strength according to the tensile reinforcement ratio, in particular, the main variables are 100%, 75% and 50% of ρ=0.01 which is widely used in construction field. A total of twelve RC beams were tested under 4-point loading conditions. In addition to the existing proposal equations, the theoretical values such as KBC and ACI equations are compared with the experimental data. Through this analysis, this study is designed to provide more reasonable equations for shear design of reinforced concrete beams. When shear reinforcement bar spacing of nine specimens (R^*-1, R^*-2, and R^*-3 series) fixed as d/s=2.0 and three specimens of R^*-4 series fixed as d/s=1.5 are compared, the shear strength of two groups showed similar values. As a result, the current standard of d/s=2.0 for shear reinforcement bar spacing may be somewhat alleviated.

• Asia-Pacific Journal of Business
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• v.11 no.3
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• pp.185-198
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• 2020

Purpose - The purpose of this study is to examine the effect of performance-related pay on gender labor productivity differences theoretically and empirically. Design/methodology/approach - This study analyzes the Principal-Agent model in which a firm employes many male and female workers under moral hazard, and uses large survey data from Survey of Business Activities of MDIS (MicroData Integrated Service) in Korea. The fixed-effect model is employed in order to analyze the data. Findings - The theoretical result is that, after performance-related pay is offered to workers, the effect of performance-related pay on gender productivity is determined by whether the female ratio within firm affects firm's performance(such as revenue and profit) per capita. The empirical result is that, before performance-related pay is provided for all workers, the firm's female ratio does not affect firm's revenue and profit per capita at all, but after it is offered, the female ratio positively affects firm's performance per capita. Research implications or Originality - Fixed pay does not bring about the difference between male and female productivity, but performance-related pay affects female productivity more positively than male productivity in Korean firms. It means that female workers are more sensitive to incentives than men in Korea.

• Steel and Composite Structures
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• v.43 no.2
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• pp.241-256
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• 2022

In this article, an analytical procedure is presented for static analysis of composite cylinders with the geometrically nonlinear behavior, and non-uniform thickness profiles under different loading conditions by considering moderately large deformation. The composite cylinder includes two inner and outer isotropic layers and one honeycomb core layer with adjustable Poisson's ratio. The Mirsky-Herman theory in conjunction with the von-Karman nonlinear theory is employed to extract the governing equations which are a system of nonlinear differential equations with variable coefficients. The governing equations are solved analytically using the matched asymptotic expansion (MAE) method of the perturbation technique and the effects of moderately large deformations are studied. The presented method obtains the results with fast convergence and high accuracy even in the regions near the boundaries. Highlights: • An analytical procedure based on the matched asymptotic expansion method is proposed for the static nonlinear analysis of composite cylindrical shells with a honeycomb core layer and non-uniform thickness. • The effect of moderately large deformation has been considered in the kinematic relations by assuming the nonlinear von Karman theory. • By conducting a parametric study, the effect of the honeycomb structure on the results is studied. • By adjusting the Poisson ratio, the effect of auxetic behavior on the nonlinear results is investigated.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2009.10a
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• pp.459-460
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• 2009

• Environmental Mutagens and Carcinogens
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• v.16 no.2
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• pp.109-116
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• 1996

To study the effect of dietary $\omega 6/\omega 3$ fatty acid ratios on the preneoplastic lesions and lipid peroxidation in rat hepatocellular chemical carcinogenesis, placental glutathione S-transferase(GST-P) positive foci area and numbers, glucose 6-phosphatase(G6Pase) activity, thiobarbituric acid reactive substances (TBARS) were measured. Male Sprague-Dawley rats were fed 5 different diets-low $\omega 6/\omega 3$ ratio with fish oil (Low-F), low $\omega 6/\omega 3$ ratio with perilia oil(Low-P), moderate ratio with perilia oil(Moderate), blend of 10 different commercial fats and oils(High-BL) and high $\omega 6/\omega 3$ ratio(High)-for 8 weeks. Hepatocarcinogenesis was induced by modified Ito model. The area of GST-P positive loci was the lowest in Moderate group and in ascending order of Low-F < Low-P < High-BL < High. But statistically, only Moderate and High groups were significantly different. The number of GST-P positive foci showed the same trend as foci area. The activities of G6Pase, membrane stability marker, were increased as $\omega 6/\omega 3$ ratio decreased. Lipid peroxidation values (TBARS) were the lowest in Low-F group and it is significantly different from Moderate, High-BL and High groups. When dietary $\omega 6/\omega 3$ ratio was moderate(4.06), hepatocarcinogenesis was suppressed compared with high or low $\omega 6/\omega 3$ ratios. Blend fat, commonly consumed among Koreans, did not show any suppressive effect on carcinogenesis because of high ratio(6.7). These results suggest that dietary $\omega 6/\omega 3$ ratio influences hepatocellular chemical carcinogenesis. It is recommended that appropriate $\omega 6/\omega 3$ ratio should be around 4.0. and we recommend to use more $\omega 3$ fatty acid in food preparation to reduce the risk of hepatocarcinogenesis.

• Journal of the Korean Institute of Landscape Architecture
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• v.14 no.3
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• pp.3-19
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• 1987

The purpose of this study was to investigate desirable width / height ratio of enclosed space and to offer basic information for the design of enclosed spaces. The data of this study were gathered from the experiment through simulation. Photographic sampling of 7 campus sites located in Kwanak campus of Seoul National University and slides of perspective drawings of enclosed spaces with various D/H ratio (12, 1, 2, 4, 6, 9, 12)were used for simulation. A response format was made using the method of paired comparison and students from various departments were randomly selected for evaluation. In the method of analysis of data Thurstone's equation of Comparative Judgement was used for calculating preference score. A1so non-linear regression analysis was used for finding out relations between preference and D/H ratio. The other method of data analysis were correlation, Chi - test. And the results were summarized as follows. 1. In sketch simulation the ratio of D/H 4 got the highest preference store. This result suggests that desirable D/H ratio of enclosed space is D/H 4. And at the lower range of D/H ratio, as ratio increases, the preference score increases. At the higher range of D/H ratio, however, as ratio increases, the preference score starts to decrease from the cardinal point of D/H 4. 2. In campus photograph simulation preference is influenced by slope, elevation change of floor, trees, lawn area, familiarity, space arrangement, and exterior shape of building besides D/H ratio. 3. The preference virtue was not significantly affected by order effect. This result suggests that order effect can be ignored in the study of visual preference. 4. There are so many factors related to preference that it is difficult to explore those factors without scientific information based on scientific method. We must carry out study for scientific approach of planning and design based on precise, complete simulation technique.

• Journal of Korean Society of Water and Wastewater
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• v.35 no.2
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• pp.163-174
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• 2021

Heatwaves are one of the most common phenomena originating from changes in the urban thermal environment. They are caused mainly by the evapotranspiration decrease of surface impermeable areas from increases in temperature and reflected heat, leading to a dry urban environment that can deteriorate aspects of everyday life. This study aimed to calculate daily maximum ground surface temperature affecting heatwaves, to quantify the effects of urban thermal environment control through water cycle restoration while validating its feasibility. The maximum surface temperature regression equation according to the impermeable area ratios of urban land cover types was derived. The estimated values from daily maximum ground surface temperature regression equation were compared with actual measured values to validate the calculation method's feasibility. The land cover classification and derivation of specific parameters were conducted by classifying land cover into buildings, roads, rivers, and lands. Detailed parameters were classified by the river area ratio, land impermeable area ratio, and green area ratio of each land-cover type, with the exception of the rivers, to derive the maximum surface temperature regression equation of each land cover type. The regression equation feasibility assessment showed that the estimated maximum surface temperature values were within the level of significance. The maximum surface temperature decreased by 0.0450℃ when the green area ratio increased by 1% and increased by 0.0321℃ when the impermeable area ratio increased by 1%. It was determined that the surface reduction effect through increases in the green area ratio was 29% higher than the increasing effect of surface temperature due to the impermeable land ratio.

• 한국연소학회:학술대회논문집
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• 2004.11a
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• pp.124-129
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• 2004

The ratio pyrometry has been investigated experimentally for the measurement of soot particle temperatures in a diffusion flame. A tungsten lamp calibration system was constructed and used in order to calibrate the ratio pyrometry and two-color pyrometry using a KL-factor method. Once the ratio pyrometry is properly calibrated, temperatures measured using a ratio pyrometry were virtually identical to those obtained from a KL-factor method. The effect of soot volume fraction on temperature measurement was almost negligible, and therefore, the ratio pyrometry could provide the useful temperature information of sooting flames. The potential application of a ratio pyrometry to a 2-D temperature measurement without sacrificing the accuracy was demonstrated.

• Journal of environmental and Sanitary engineering
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• v.13 no.2
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• pp.57-65
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• 1998

In this research, Effect of C/N ratio on nutrient removal in intermittently aerated activated sludge system(IAASS) was investigated with dormitary, building and swine wastewater. Three types (2-stage, 4-stage, modified) of IAASS were operated. Time interval of aeration/nonaeration in IAASS was 1hr/1hr. In treatment of Dormitary wastewater(BOD/T-N ratio : 4.4), Building wastewater (BOD/T-N ratio : 3.14) and swine wastewater(BOD/T-N ratio : 3.84), Nitrogen removal efficiency of 80, 70 and 90.4% was achieved, respectively. Nitrogen removal in IAASS was a great influenced on influent C/N ratio, efficient nitrogen removal was achieved at BOD/T-N ratio over 4. In IAASS operation, $\Delta $BOD mg/L/$\Delta $ nitrogen mg/L ratio was about 4-6. Simultaneous removal of organic, nitrogen and phosphorus in IAASS can achieved. And influent organic was efficiently utilized in denitrification. IAASS could be one of the best alternative process for the retrofit of conventional activated sludge system for the removal of nutrients.