• International Journal of Concrete Structures and Materials
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• v.11 no.1
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• pp.69-84
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• 2017

This paper presents results of an experimental investigation on the behaviour of bond between external glass fibre reinforced polymer reinforcement and concrete exposed to three different environmental conditions, namely, temperature cycles, wet-dry cycles and outdoor environment separately for extended durations. Single shear tests (pull-out test) were conducted to investigate bond strengths (pull-out strengths) of control (unexposed) and exposed specimens. Effect of the exposure conditions on the compressive strength of concrete were also investigated separately to understand the effect of changing concrete compressive strength on the pull-out strength. Based on the comparison of experimental results of exposed specimens to control specimens in terms of bond strengths, failure modes and strain profiles, the most significant degradation of pull-out strength was observed in specimens exposed to outdoor environment, whereas temperature cycles did not cause any deterioration of strength.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2001.11a
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• pp.40-45
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• 2001

The purposes of this study were mix design and quality control of high strength concrete for the construction of high rise complex structure. Desired performances of this high strength concrete were slump flow 50$\pm$10cm, air content 4.5$\pm$1.5% and design strength 400kgf/$cm^2$. Experimental flow was that optimal mix design was selected in the indoor experiment and after that, producing test was done in the batcher plant. Excel lent results of experiment was obtained from binder content 475kg/$m^2$ with replacement ratio 10% of fly ash. The results of field application of high strength concrete was sufficiently satisfied both flowability and compressive strength.

• Journal of Nutrition and Health
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• v.33 no.3
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• pp.279-288
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• 2000

The study examined BMIs, physical strength, activities, and the attitudes and behavior toward weight control among 7,968 Korean students{2,435 5th graders from elementary schools(ESs), 2,524 2nd graders from middle schools(MSs), 2,739 2nd graders from high schools(HSs)} nationwide. Compared to the 1987 data, there were increases of height(3-6cm) and weight(3-8kg), but decreases of physical strength and exercise. Lack of 'regular exercise' among girls from MSs and HSs and higher proportion of time spent on watching TV and using a computer for elementary schoolers were particularly noticeable. Proportions of students who were satisfied with their body weight were 49% for ESs, 35% for MSs, and 29% for HSs. There was no relationship between subjective and objective evaluations of body weight. Diet rather than exercise was more frequently chosen as a method of weight control. Compared to boys, girls showed stronger association between the amount of exercise and the subjective body weight in MSs and HSs, however this association was not found for the subjects from HSs. Values for the 50th percentile of BMI of boys and girls were 18.4 and 17.7 for ESs, 19.9 and 20.1for MSs, and 21.4 and 20.6 for HSs. In MSs and HSs, boys with BMI between 15th to 85th percentiles were physically stronger than those whose BMIs were lower than 15th kor higher than 85th percentiles. For the other groups, there was a trend of a positive relationship between BMI and physical strength. Based on the analyses of BMI and physical strength, this study suggests 22 and 21 for upper grades in ESs, 24 and 23 for MSs, and 27 and 25 for HSs as the respective cut off points of BMI for weight control n boys and girls. A need for implementing nutrition education program focused on weight control is also suggested.

• Journal of Technologic Dentistry
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• v.33 no.1
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• pp.25-35
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• 2011

Purpose: There are some advantages of the acrylic resin denture base ; appropriate strength, volume safety, simple processing apparatus, and low cost. But, it have a weakness for fracture by intense pressure or shock. However, the repairs for resin denture base are possible using various materials and techniques. There is a few studies in repairs for resin denture base, but not clinical researches. And there is no studies in absorbed saliva into the region of fracture and bond strength. This study is to observe re-bond strength of resin denture base after repairing under saliva absorption. Methods: The samples were made of heat curing resin and the rectangular parallelepiped specimens which were 50mm long, 10mm wide and 3mm high. The four different groups immersed in the artificial saliva for 2 weeks were prepared, 1) no repaired control samples, 2) immediately repaired samples, 3) repaired samples after 1 day dry, and 4) repaired samples after 3 days dry. The prepared samples were repaired by two different curing materials, self curing resin and heat curing resin method. Each groups composed of 10 specimens were experimented with the three point bending tests for bonding strength measuring Results: There were under condition absorbed in the artificial saliva and repaired by self curing resin method, repaired specimens after 1 day and 3 days dry groups had higher values of bonding strengths than control group, and bonding strengths of immediately repaired samples were similar to those of control samples (p<0.05). There were under condition immersed in the artificial saliva and repaired by heat curing resin method, immediately repaired samples showed similar values to bonding strengths of control groups, and repaired samples after 1 day and 3 days dry groups were lower than those of control group (p>0.05). Conclusion: In this study, the repairs for resin denture base were remarkably high values of bonding strengths than those of the past, and showed that have stable bonding strengths independent of saliva absorption of denture base, so present repairs for resin denture base can be performed, regardless of saliva conditions.

• Journal of the Korean Applied Science and Technology
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• v.38 no.5
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• pp.1345-1353
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• 2021

The purpose of this study was to investigate the effects of 6 weeks hip joint strengthen on muscle strength, dynamic posture control and low extremity injury criterion. Twenty athletics were divided into two groups, the exercise group was conducted for three times a week, 60 minutes, and six weeks. The dependent variables of this study were flexibility, muscular strength, dynamic posture control, and lower body injury criterion. The results of this study showed that the flexibility was not significant, but muscle strength was significant difference. The dynamic posture control was significantly effective in the left posterolateral and posteromedial. In addition, total score was significantly exercise effect, and there was no difference between left and right leg length. In conclusion, hip joint strengthen increased muscle strength and dynamic posture control, and decreased the concern of low extremity injury criterion.

• Journal of The Korean Society of Integrative Medicine
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• v.9 no.1
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• pp.101-108
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• 2021

Purpose : The purpose of this study is to verify the effect of selective muscle strengthening of the knee joint extensor muscles using a pressure biofeedback unit to improve knee extensor strength and the balance ability of total knee replacement patients. Through this, we tried to provide clinical information. Methods : In this study, 12 patients with total knee replacement were recruited from a rehabilitation hospital. They were divided into two groups: a feedback group (n=6) and a control group (n=6). All patients received 30 minutes of continuous passive motion and leg-strengthening exercises for 15 minutes five times a week for two weeks. Subjects performed knee extension exercises with or without biofeedback units in the sitting position. The knee extensor strength and balance ability were measured before and after exercise. Knee extensor strength was measured by Biodex system 3 and balance ability was measured by Balancia software. Results : Both the experimental group and the control group showed a significant difference in the muscle strength of the knee joint extensor muscles after intervention (p<.05). In comparison, the experimental group showed a significant difference than the control group (p<.05). Both the experimental group and the control group showed a significant difference in the velocity average, path length, area 95 % center of pressure (COP), weight distribution, five times sit to stand test (FTSST) after intervention. In comparison, the experimental group showed a significant difference in velocity average, area 95 % COP, and FTSST than the control group (p<.05). Conclusion : In order to strengthen the knee extensor muscle and improve the balance ability in total knee replacement patients, it is necessary to consider providing pressure biofeedback unit during leg strengthening exercises.

• Journal of The Korean Society of Integrative Medicine
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• v.10 no.1
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• pp.49-60
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• 2022

Purpose : The purpose of this study was to identify whether gym-ball exercise in standing position was an effective intervention for improving muscle strength, balance, gait, and fall efficacy in stroke patients. Methods : Twenty-four stroke patients were randomized into three groups: experimental group 1 (n=8), experimental group 2 (n=8), and control group (n=8). Experimental groups 1, 2 and the control group performed the gym-ball exercise in standing position, same exercise without a gym-ball, and general physical therapy for 4 weeks, five times a week in 30-minute sessions. Muscle strength, balance, gait, and fall efficacy were assessed using a handheld dynamometer, the Berg Balance Scale (BBS), the wearable BTS G-WALK® sensor, and the Korean version of the Falls Efficacy Scale (K-FES), before and after training, respectively. Comparisons within and between groups were analyzed using the Wilcoxon signed rank test, Kruskal Wallis H test, and Mann-Whitney U test. Bonferroni correction was performed when significant differences between groups were identified (p<.017, .05/3). Results : Regarding muscle strength, BBS score, cadence and FES-K were significantly improved after intervention in all three groups. The weight bearing rate, gait speed and step length in experimental group 1 and 2 were significantly improved after the intervention. The stride length in experimental group 1 were significantly improved after the intervention. Experimental group 1 had significantly improved BBS score and stride length after intervention than experimental group 2 and control group. Experimental group 1 and 2 improved muscle strength, weight bearing rate, and FES-K score more than the control group. Experimental group 1 showed significant improvement in cadence, gait speed, and step length after the intervention than control group. Conclusion : This study showed that exercise with gym-ball in standing position can be an effective intervention to improve balance and gait in stroke patients than the same exercise without gym-ball.

• Journal of Korean Public Health Nursing
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• v.14 no.1
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• pp.12-25
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• 2000

The purpose of this study was to determine the effects of aerobic rhythmical exercise program on $VO_2$ max, leg strength, grip strength, flexibility, exercise self-efficacy and quality of life in elderly. This quai-experimental study was designed as a non-equivalent control group pretest-posttest study. 36 subjects, aged between 65 and 73 years who have normal cognition. sensory function and cerebellum function participated in this study. 19 experimental group subjects participated aerobic rhythmical exercise program. Aerobic rhythmical exercise program was developed on the basis of calisthenics, stretching, aerobic exercise, Korean traditional dance and music by the author. The program consisted of approximately 1 hours of exercise, 3 times a week for 9 weeks. During 1 hours workout, there were 15 minutes of warm-up dancing, 35 minutes of conditioning dance and 10 minutes of cool-down dancing. The intensity for the conditioning phase was between $40\%\;and\;60\%$ of age adiusted maximum heart rates. The $VO_2$ max, grip strength, leg strength, flexibility, exercise self-efficacy and quality of life were measured prior to and following the experimental treatment. Data were analyzed with $x^2-test$, t-test, mean, standard deviation. percentage of change and ANCOVA test using SAS program. Results were obtained as follows. 1. The $VO_2$ max of the experimental group were significantly lower than those of the control group following the aerobic rhythmical exercise program(F=7.76, p=0.008). 2. The grip strength of the experimental group were significantly lower than those of the control group following the aerobic rhythmical exercise program(F=4.61, p=0.039). 3. The leg strength of the experimental group were significantly lower than those of the control group following the aerobic rhythmical exercise program(F=9.29, p=0.000). 4. The was no significantly difference of flexibility between experimental and control group 5. The self-efficacy of the experimental group were significantly lower than those of the control group following the aerobic rhythmical exercise program(F=43.40, p=0.000). 6. The quality of life of the experimental group were significantly lower than those of the control group following the aerobic rhythmical exercise program(F=8.91. p=0.005). The results suggest that aerobic rhythmical exercise program can improve $VO_2$ max, grip strength. leg strength. exercise self-efficacy and quality of life elderly. Thus. aerobic rhythmical exercise program was a useful nursing intervention for elderly.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.20 no.9
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• pp.61-69
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• 2006

The tensile strength of an overhead transmission line's conductor in response to an aging is being assessed in this paper. It is our view that, the decrement in the conductor's tensile strength is a key index that can be used to determine a conductor's end of life and a current limits. This paper describes a probabilistic method of assessing this index for main transmission lines which are responsible for the north bound power flow in the Seoul metropolitan area. Such an assessment can be a useful guide for economic system operation.

• Journal of the Korean Society of Safety
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• v.31 no.4
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• pp.75-81
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• 2016

This study presents the effect of urea and sulfur admixture on compressive strength, chloride diffusion coefficient, and internal void distribution of concrete. Compressive strength of concretes with urea admixture by 5% increased by 5% relative to Control. However, that of concretes with urea admixture over 10% decreased. Chloride diffusion coefficient of concrete with urea and sulfur admixture decreased by 40% relative to Control. Additionally, the volume of internal void of concrete with urea and sulfur admixture decreased by 20% relative to Control. Therefore, it can be mentioned from test results that the use of adequate urea and sulfur admixture improves the mechanical properties and durability of concrete.