• Journal of KSNVE
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• v.3 no.4
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• pp.325-330
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• 1993

The longitudinal vibration of the tape in the tape transport system influences the performance of the nagnetic tape-recording system. Generally it is controlled by a passive method with impedance roller which is easy to implement and cost-effective. Therefore the effect of the impedance roller in reducing the tape vibration was analyzed in this paper. The practical tape transport system was modelled mathematically as a mass-spring system. Both simulation and experimental study were carried out in order to show the vibration reduction effect of the impedance roller.

• Journal of Korea Association of Health Promotion
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• v.3 no.1
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• pp.24-34
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• 2005

Background: A reasonable weight reduction is to reduce fat-body mass while preserving free-fat mass. Recently, many people in Korea have been trying reckless diet therapy for weight reduction by low calory and protein diets, which gave rise to many side effects consequently. For reasonable weight reduction, this study was undertaken to investigate the influential diet factors that change body composition during short-term low calory diet. Methods: 26 healthy obese women aged 23-27 years whose BMI was greater than 24volunteered for the 6 week diet therapy from January to April in 2003. All subjects were instructed to eat approximately 1200kca1/day and write dietary diary. In the beginning of the study, the 3rd week and the 6th week, subjects' body weight and fat body weight were measured by BlA. In the 6th week, the analysis of dietary diary was conducted. Results : There was significant positive correlation between protein intake per ideal bodyweight in the first 3 weeks and free fat mass increase in the later 3 weeks (P<0.05). At the same time, fat intake in the first 3 weeks had positive correlation with free fat mass in the second 3 weeks, too(P<0.05). But, we could not find any significant values that had effect on free fat mass increase in multiple regression analysis. Conclusion: The protein intake in the first 3 weeks helps preserve fat free mass in the later 3 weeks, and has positive effects.

• Membrane and Water Treatment
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• v.2 no.2
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• pp.75-89
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• 2011

The predicting equations for mass transfer rate in cross-flow rectangular dialyzers with double flow and recycle, have been derived by mass balances. The recycling operation has two conflicting effects. One is the desirable effect of the increase in fluid velocity, resulting in an increased mass transfer coefficient. The other is the undesirable effect of the reduction in concentration difference due to remixing, resulting in decreased mass-transfer driving force. In contrast a single-pass device without recycling, considerable improvement in mass transfer is achieved if the cross-flow rectangular dialyzer of same size is operated with double pass and external recycling. It is concluded that recycle can enhance mass transfer, especially for larger reflux ratio.

• Journal of Korean Association for Spatial Structures
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• v.14 no.3
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• pp.75-84
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• 2014

When adjacent tall buildings experience earthquake excitation, structural pounding may happen. In order to mitigate seismic pounding damage to adjacent structures, many studies have been done to date. Tuned mass dampers (TMD) are widely used for reduction of dynamic responses of building structures subjected to earthquake excitations. If a TMD is shared between adjacent buildings and it shows good control performance, it will be effective and economic means to reduce seismic responses of adjacent structures. In this study, control performance of a shared tuned mass damper (STMD) for seismic response reduction of adjacent buildings has been evaluated. For this purpose, two 8-story example buildings were used and multi-objective genetic algorithms has been employed for optimal design of the stiffness and damping parameters of the STMD. Based on numerical analyses, it has been shown that a STMD can effectively control dynamic responses and reduce the effect of pounding between adjacent buildings subjected to earthquake excitations in comparison with a traditional TMD.

• Preventive Nutrition and Food Science
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• v.11 no.3
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• pp.226-231
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• 2006

This study evaluated the weight reduction effect of Angook cereal mixture. The cereal mixture was prepared with barley, unpolished rice, corn, soybean, Garcinia cambogia, guar-gum, maltodextrin, glucomannan and a vitamin mixture. Eighteen female college students participated in this 8 weeks weight control program. All subjects were randomly assigned to the treatment and placebo groups. Mean energy intake of the treatment group was $1,356.4{\pm}79.9\;kcal$ (carbohydrate: 67.1%, protein: 18.7%, fat: 14.2%) and placebo group consumed $1,367.6{\pm}71.8\;kcal$ (carbohydrate: 64.2%, protein: 19.7%, fat: 16.1%) during program. The placebo group lost $3.9{\pm}0.8\;kg$ of body weight and the treatment group lost $5.9{\pm}0.7\;kg$ of body weight. There were significant differences in the decrease of total body weight, absolute fat mass, waist circumference (WC) and hip circumference (HC) between the two groups (p<0.05), however, the lean body mass was not significantly decreased in the treatment group compared to the placebo group. There were no differences in the changes in blood glucose, total-cholesterol, HDL-choloesterol, LDL-cholesterol and triglycerides between groups. These findings suggest that the intake of Angook cereal mixture may be beneficial for the reduction of the body weight, absolute fat mass, WC and HC.

• Clinical Nutrition Research
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• v.12 no.4
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• pp.245-256
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• 2023

A randomized, double-blind, placebo-controlled trial was conducted to confirm whether collagen peptide supplementation for 12 week has a beneficial effect on body fat control in older adults at a daily physical activity level. Participants were assigned to either the collagen group (15 g/day of collagen peptide) or the placebo group (placebo drink). Body composition was measured by bioelectrical impedance analysis (BIA) and dual-energy X-ray absorptiometry (DEXA). In total, 74 participants (collagen group, n = 37; placebo group, n = 37) were included in the final analysis. The collagen group showed a significant reduction in total body fat mass compared with the placebo group, as evidenced by both BIA (p = 0.021) and DEXA (p = 0.041) measurements. Body fat mass and percent body fat of the whole body and trunk reduced at 12 weeks compared with baseline only in the collagen group (whole body: body fat mass, p = 0.002; percent body fat, p = 0.002; trunk: body fat mass, p = 0.001; percent body fat, p = 0.000). Total fat mass change (%) (collagen group, -0.49 ± 3.39; placebo group, 2.23 ± 4.20) showed a significant difference between the two groups (p = 0.041). Physical activity, dietary intake, and biochemical parameters showed no significant difference between the groups. The results confirmed that collagen peptide supplementation had a beneficial effect on body fat reduction in older adults aged ≥ 50 years with daily physical activity level. Thus, collagen peptide supplementation has a positive effect on age-related changes.

• Smart Structures and Systems
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• v.31 no.1
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• pp.89-100
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• 2023

This paper conducts a parametric study of a new tuned mass damper with pre-strained superelastic SMA helical springs (SMAS-TMD) on the vibration reduction effect. First, a force-displacement relation model of superelastic SMA helical spring is presented based on the multilinear constitutive model of SMA material, and the tension tests of the six SMA springs fabricated are implemented to validate the mechanical model. Then, a dynamic model of a single floor steel frame with the SMAS-TMD damper is set up to simulate the seismic responses of the frame, which are testified by the shaking table tests. The wire diameter, initial coil diameter, number of coils and pre-strain length of SMA springs are extracted to investigate their influences on the seismic response reduction of the frame. The numerical and experimental results show that, under different earthquakes, when the wire diameter, initial coil diameter and number of coils are set to the appropriate values so that the initial elastic stiffness of the SMA spring is between 0.37 and 0.58 times of classic TMD stiffness, the maximum reduction ratios of the proposed damper can reach 40% as the mass ratio is 2.34%. Meanwhile, when the pre-strain length of SMA spring is in a suitable range, the SMAS-TMD damper can also achieve very good vibration reduction performance. The vibration reduction performance of the SMAS-TMD damper is generally equal to or better than that of the classic optimal TMD, and the proposed damper effectively suppresses the detuning phenomena that often occurs in the classic TMD.

• Solar Energy
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• v.19 no.2
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• pp.37-44
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• 1999

Experimental investigation has been carried out to determine drag reducing effects of polymer additives for a plate type heat exchanger(evaporator or condenser) in OTEC power plant applications, where the pressure drop in the heat exchangers takes up $70{\sim}80%$ of the total pumping power in the existing system. The rate of drag reduction was investigated with various polymer concentrations and mass flow rates. Experiments were undertaken for a test section in Alfa-Laval plate heat exchanger utilizing Poly Ethylene Oxide(Mw $5{\times}10^6$) as polymer additives. Concentrations of polymer additives were 5, 10, 20, 30, 40, 50, 100, 200, 400 wppm at $25^{\circ}C$ and mass flow rates were 0.6kg/s, 0.7kg/s, 0.8kg/s and 0.9kg/s in normal operating ranges for a 15kW Alfa-Laval plate heat exchanger. The maximum effects of drag reductions were found at approximately 0.7kg/s of mass flow rate. The results show that there exists the optimum mass flow rate for the plate heat exchanger to obtain maximum drag reductions. Drag reduction of 20% means considerable savings in pumping power for a large size of OTEC plant.

• Tunnel and Underground Space
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• v.21 no.2
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• pp.138-144
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• 2011

Mine closure does often accompany the flooding of mine galleries due to ceasing a pumping operation. When a mine gallery is flooded, rocks around the gallery are fully saturated and the gallery is subject to a water pressure. The uniaxial unconfined compressive strength of a rock depends on its water content and decreases as the water content increases. A water pressure may originate the crack growth of a rock or the discontinuity growth of rock mass. Although the water in a gallery will give some support pressure inside the gallery, the degradation of rock mass properties caused by a water pressure will reduce the stability of the gallery. In this study, 2-dimensional discontinuous and 3-dimensional continuous numerical analyses have been conducted to evaluate an effect that a reduction of rock mass properties around the gallery induced by a water pressure has on the stability of mine gallery. The numerical analyses show that a reduction of rock mass properties caused by a water pressure increases displacements of rock mass around mine gallery. 2-dimensional model is found to give larger values of displacement than 3-dimensional model.

• Physical Therapy Korea
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• v.30 no.3
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• pp.202-210
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• 2023

Background: The elderly population is increasing rapidly worldwide. Muscle mass, usual walking speed (UWS), knee extension strength (KES), hand grip strength (HGS), peak expiratory flow (PEF), and depression is used for sarcopenia diagnosis. All four of these factors (KES, HGS, PEF, and depression) correlated with UWS and also to muscle mass. But, many studies have suggested that no correlation exists between muscle mass and UWS. Objects: This study aimed: 1) to investigate whether muscle mass reduction affected UWS, as mediated by KES, HGS, PEF and depression, and 2) to explored whether significant changes in these mediators varied by the body segment in which muscle mass evaluated in elderly female aged 65-80 years. Methods: A total of 100 female aged 65-80 years were surveyed. Muscle mass was measured by body segment (upper and lower segment), and KES, HGS, PEF, depression, and UWS were also assessed. Median analyses were progressed in IBM SPSS software (ver. 23.0, IBM Co.) using a downloaded INDIRECT macro. Results: The direct effect of the KES and PEF were significant, and the indirect effect of KES and PEF were not significant. Thus, KES and PEF served as full mediators of the effect of muscle mass on UWS. Regardless of bodily region, KES and PEF combined with muscle mass were significant mediators of UWS, with similar indirect effect sizes. Conclusion: KES and PEF are the only mediators regardless of body part. Therefore, mediating the KES and PEF may prevent sarcopenia progression in elderly female. Also, sarcopenia can be readily assessed by evaluating either the upper or lower body; it is not necessary to measure total muscle mass.