• Nuclear Engineering and Technology
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• v.56 no.2
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• pp.624-635
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• 2024

In two-fluid simulations of flow boiling, the modeling of the mean bubble diameter is a key parameter in the closure relations governing the intefacial transfer of mass, momentum, and energy. Monodispersed approach proved to be insufficient to describe the significant variation in bubble size during flow boiling in a heated pipe. A population balance model (PBM) has been employed to address these shortcomings. During nucleate boiling, vapor bubbles of a certain size are formed on the heated wall, detach and migrate into the bulk flow. These bubbles then grow, shrink or disintegrate by evaporation, condensation, breakage and aggregation. In this study, a parametric analysis of the PBM aggregation and breakage models has been performed to investigate their effect on the radial distribution of the mean bubble diameter and vapor volume fraction. The simulation results are compared with the DEBORA experiments (Garnier et al., 2001). In addition, the influence of PBM parameters on the local distribution of individual bubble size groups was also studied. The results have shown that the modeling of aggregation process has the largest influence on the results and is mainly dictated by the collisions due to flow turbulence.

• The Mathematical Education
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• v.49 no.2
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• pp.199-221
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• 2010

The purpose of the study were to investigate how secondary pre-service teachers conceptualize arithmetic mean and how their conceptualization was formed for solving the problems involving arithmetic mean. As a result, pre-service teachers' conceptualization of arithmetic mean was categorized into conceptualization by "mathematical knowledge(mathematical procedural knowledge, mathematical conceptual knowledge)", "analog knowledge(fair-share, center-of-balance)", and "statistical knowledge". Most pre-service teachers conceptualized the arithmetic mean using mathematical procedural knowledge which involves the rules, algorithm, and procedures of calculating the mean. There were a few pre-service teachers who used analog or statistical knowledge to conceptualize the arithmetic mean, respectively. Finally, we identified the relationship between problem types and conceptualization of arithmetic mean.

• The Journal of Korean Academy of Orthopedic Manual Physical Therapy
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• v.16 no.1
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• pp.37-42
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• 2010

Purpose : The purpose of this study was to evaluate the influence of sensory integration training on equilibrium ability in the college students of the twenties. Methods : The sensory integration training group(male: n=10, female: n=9) was measured an equilibrium ability by Kinesthetic Ability Trainer(KAT) at pre-intervention and post-intervention in 4weeks. Results : Mean value of eye close both leg standing and eye close one leg standing tests of the sensory integration training group were significantly reduced among the intervention period(p<.05). Conclusion : We were found that sensory integration training could reduce mean value of eye close both leg standing and eye close one leg standing tests and improve a balance for the college students of the twenties.

• Journal of Korean Physical Therapy Science
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• v.25 no.1
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• pp.31-43
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• 2018

Purpose: The purpose of this study is to investigate and to verification of changes that the effect of treadmill and body weight support treadmill training on balance and gait ability for sub-acute stroke patients during 4 week. Method: 16 subjects who was diagnosed stroke were divided into 2 groups(8-treadmill training group, 8-body weight support treadmill group) by randomized control trial. Both training programs were consisted with 40 minuted, 5 times a week for 4 weeks and after training programs. Analysis: We analysed effects and changes on balance and gait ability. Analyses were performed using PASW ver. 18.0 and results were reported as mean ${\pm}$ standard deviation (S.D.). To investigate within group comparisons and to verification on effects of exercise, we did paired t test and repeated measured ANOVA test. Significance was set at p<.05. Result: Both training programs showed positive changes in Limit of Stability but significant results which is area of hemiside, area of intact side, area of posterior, total area were reported in body weight support treadmill training group. Changes of Berg Balance Scale was significantly increase and it had significant correlation between groups. Changes of 6 Minutes Walking Test was significant increase in both groups but there was no significant changes on Foot print and Romberg test. Conclusion: After considering all factors, both training programs showed effect on improvement of balance and gait ability in sub-acute stroke patients, but body weight support treadmill training group had better improvement in dynamic balance than treadmill training group. For the increase of balance and gait ability in sub-acute stroke patients, we need to continues study on difference of treadmill and body weight support treadmill and then we will give stroke patients a better satisfaction if we develop and provide a rehabilitation program for improvement of balance and gait ability.

• Journal of the Korean Society of Physical Medicine
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• v.15 no.2
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• pp.129-136
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• 2020

PURPOSE: This study aimed to determine the most effective feedback condition for static balance in elderly subjects. METHODS: Thirty-eight elderly subjects (12 men and 26 women with a mean age of 77.21 years) participated in this study. They each completed a questionnaire on their general characteristics, excluding personal identification codes. The static balance ability of the participants was evaluated using a Wii Balance Board and the Balancia program (version 2.0). The following three feedback conditions were considered: condition 1 (tactile feedback), condition 2 (visual feedback), and condition 3 (no feedback). One-way repeated-measures analysis of variance was used for the comparisons according to sway length and sway velocity. The statistical significance level was set to α = .05 for all variables. RESULTS: Significant differences in the sway length and sway velocity were observed between the three conditions (p < .05). Significant differences in the sway length were noted in the order of conditions 1, 2, and 3 (p < .05), and significant differences in the sway velocity in the order of conditions 3, 2, and 1 (p < .05). CONCLUSION: Significant differences in static balance ability were observed between the three conditions. In this study, tactile feedback was found to be the most effective feedback for balance training. Owing to aging and impairment of the senses, such as that observed in the tactile receptors, visual receptors, and proprioceptors, it is recommended that elderly subjects participate in balance training.

• Physical Therapy Korea
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• v.13 no.4
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• pp.47-55
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• 2006

The purpose of this study was to compare the static balance of standing position between adolescent idiopathic scoliosis (AIS) and a normal group that were aged-matched. There were forty subjects included in this study. Twenty-seven healthy subjects (age, $13.9{\pm}1.2$ yrs; height, $161.9{\pm}7.5$ cm; weight, $52.2{\pm}7.7$ kg) and thirteen AIS subjects (age, $14.2{\pm}2.2$ yrs; height, $161.5{\pm}8.7$ cm; weight, $48.1{\pm}8.1$ kg) were participated in the study. The thirteen subjects in the AIS group had a major Cobb angle between $20.1^{\circ}$ and $49^{\circ}$. Each group was tested with the Balance Performance Monitor (BPM). The parameters for static balance were sway area, sway path, max velocity, mean balance, anterior-posterior angle, and left-right angle of each group with their eyes opened and again with their eyes closed. Both sides of the forward reach test and the lateral reach test were also performed on each group. Results from the BPM tested showed significantly increases in all parameters of static balance with those patients with AIS under the conditions where eyes were opened and closed. In the right and left forward reach test, there was no significant difference between normal and AIS groups. However, in the lateral reach test with right and left direction, there were significant differences between normal and AIS groups. For the normal subjects, there were significant differences in the parameters with sway path and anterior-posterior sway angle between the eyes opened and closed. However, there were no significant differences in the all parameters between eyes opened and closed for the AIS subjects. These results suggest that, balance programs could be used in the rehabilitation setting for intervention of AIS and evaluation of AIS. Further study is needed to measure many patients with AIS and other functional balance scales for clinical application.

• Journal of The Korean Society of Integrative Medicine
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• v.7 no.2
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• pp.49-57
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• 2019

Purpose: This study aimed to investigate the application of temperature to balance the training by observing the effect of sensory changes in the foot sole area on dynamic equilibrium ability through change in the sole temperature. Methods: Participants (n=49), who were selected as a certain standard, applied cold and hot packs for ten minutes at two-week intervals, and the laboratory's internal temperature was maintained at $25^{\circ}C$. The subjects were measured before and after the cold and hot applications in the stable condition with bare feet. Before each experiment applied the cold and hot packs, the balance ability of the ordinary temperature was measured once by conducting a limit of stability test using Biorescue, and the changes in balance ability were observed by measuring once after applying the temperature to the foot sole by means of the ice pack and the hot pack. Results: The results of the dynamic balance test, both before and after the temperature application, were compared, and it was confirmed that the moving area before and after cold application decreased significantly, and the moving area before and after application was not significantly different. The mean of pre-post area differences was found to have decreased at a statistically significant rate in the forward, backward, rightward, leftward, and total areas for the group that received the cold application compared to the group that received the hot application. Conclusion: These findings showed that cold application to the foot sole decreased dynamic balance. There was no significant difference in the dynamic balance ability both before and after the hot application to the foot sole, so it is difficult to conclude that the hot application affected dynamic balance.

• Journal of the Korean Society of Physical Medicine
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• v.5 no.4
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• pp.667-674
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• 2010

Purpose : The purpose of this study was to investigate the effect of motion-based game exercise program and stretching exercise program on static and dynamic standing balance in elderly women. Methods : Subjects participated in the exercise program was 40 eldery women took part in this study. The average age of the elderly was 70.60 years. All subjects could walk without an assistive device. All subjects were participated in this study during 4 weeks(3 days per week, 30min/day). All participants were assessed on berg balance scale(BBS), functional reach test(FRT), timed up&go test(TUG). Results : The data were analyzed using paired t-test. After 4 weeks exercise training, the result of this study were as follows: The BBS of the elderly was significant difference between test-retest(p<0.05). The TUG of the elderly were significant difference between test-retest(p<0.05). The Motion-Based game from FRT of the was more significant difference than stretching exercise program(p<0.05). we also found significant differences for both groups FRT scores, and changes in mean BBS, TUG scores, but BBS, TUG were not significant. Conclusion : We findings suggest that elderly women person could improve their standing balance through Motion-Based game exercise program, and stretching exercise program.

• Korean Journal of Clinical Laboratory Science
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• v.52 no.1
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• pp.36-44
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• 2020

With the advent of westernized diet and a lack of exercise, young female college students are paying more attention to their bodyweight and health. Whole-body vibration has been demonstrated to be a suitable training method for improving knee extension maximal strength in young female athletes, as well as the gait performance in elderly women. This study aimed to evaluate the effects of a vertical vibration intervention on the physical fitness and postural balance in young females. Fifty-four young women were recruited; all subjects were randomly assigned to the intervention group and control group. The intervention group underwent vertical vibration with a platform for 12 weeks. The results showed that body mass index and body fat percentage had decreased (P<0.05). In addition, their muscle endurance as indicated by a sit-up test and their flexibility as indicated by a sit-and-reach test were both increased. With regard to postural balance, their 30-second sit-to-stand and timed up and go test results were improved. At the same time, their mean single-leg stance with eyes closed time increased (P<0.05). However, there were no significant differences, meanwhile, for the control group. Overall, the results showed that the whole body vibration (WBV) intervention had some beneficial effects on physical fitness and postural balance in young women.

• Biomedical Science Letters
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• v.25 no.2
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• pp.149-158
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• 2019

The objective of this study was to evaluate the effects of thoracic mobilization (TM) on the angle of thoracic kyphosis, and static and dynamic balances by application period. The subjects of this study were 18 adult males and females (${\geq}20years\; old$) who had the angle of thoracic kyphosis equal to or higher than $40^{\circ}$. A pre-test was conducted for all subjects and TM was carried out. Data were collected before the intervention, 3 weeks after the intervention, and 6 weeks after the intervention. It was measured three times per measurement and mean values were used for the analysis. The results of this study showed that the angle of thoracic kyphosis significantly (P<.05) decreased after applying TM. However, the migration area ($mm^2$) of the center of pressure (COP) in the static balance did not vary significantly. In the case of the dynamic balance, when eyes were open, the migration area ($mm^2$) of the COP significantly (P<.05) decreased after 3 weeks. When eyes were open, the migration area ($mm^2$) of the COP significantly (P<.05) decreased after 3 weeks and 6 weeks. Therefore, an intervention for improving the human body alignment and balance should be applied for a long-term, rather than a short-term, in order to be effective.