• Applied Science and Convergence Technology
• /
• v.25 no.3
• /
• pp.47-50
• /
• 2016

Low temperature test for half-wave resonator (HWR) cryomodule is performed at the superfluid helium temperature of 2 K. The effective temperature is defined for non-uniform temperature distribution. Helium leak detection techniques are introduced for cryogenic system. Experimental set up is shown to make the low temperature test for the HWR cryomodule. The cooldown procedure of the HWR cryomodule is shown from room temperature to 2 K. The cryomodules is precooled with liquid nitrogen and then liquid helium is supplied to the helium reservoirs and cavities. The pressure of cavity and chamber are monitored as a function of time. The vacuum pressure of the cryomodule is not increased at 2 K, which shows leak-tight in the superfluid helium environment. Static heat load is also measured for the cryomodule at 2.5 K.

• Journal of the Korean Society of Physical Medicine
• /
• v.9 no.3
• /
• pp.325-331
• /
• 2014

PURPOSE: Improving elderly people's balance ability through pilates which may be easily applied in ordinary life is considered an important intervention method for elderly people. Therefore, this study examines the effects of pilates training on elderly people's static and dynamic balance abilities and provides clinical data to improve this ability. METHODS: The pilates program was applied to 19 elderly subjects three times per week for 8 weeks. Their training level took into consideration their age and was set so that the rating scales of perceived exertion became 13 to 14. Prior to the initiation of the experiment, the subjects had an adaptation period in order to practice the order and motions of pilates. After the adaptation period, the subjects received training. The program was conducted three times per week, for eight weeks. Their dynamic balance ability was observed through the timed up and go (TUG) test and tandem walk test (TWT), and their static balance ability was evaluated by the center of pressure (COP) area, medial-lateral displacement, and anterior-posterior displacement. RESULTS: The results of the TUG test and TWT and evaluations of the COP area and medial-lateral displacement were significantly different after the pilates exercise program compared to those before the program began. CONCLUSION: The results show that an 8-week pilates exercise program is an effective method to increase elderly people's static and dynamic balance abilities. In addition, the application result of the pilates exercise program will provide useful information for future research on elderly people's balance ability.

• Geomechanics and Engineering
• /
• v.29 no.2
• /
• pp.99-111
• /
• 2022

Instability of bolted rock mass has been a major hazard in the underground coal mining industry for decades. Developing effective support guidelines requires understanding of complex bolted rock mass failure mechanisms. In this study, the dynamic failure behavior, mechanical behavior, and energy evolution of a laboratory-scale bolted specimens is studied by conducting laboratory static-dynamic coupled loading tests. The results showed that: (1) Under static-dynamic coupled loading, the stress-strain curve of the bolted rock mass has a significant impact velocity (strain rate) correlation, and the stress-strain curve shows rebound characteristics after the peak; (2) There is a critical strain rate in a rock mass under static-dynamic coupled loading, and it decreases exponentially with increasing pre-static load level. Bolting can significantly improve the critical strain rate of a rock mass; (3) Compared with a no-bolt rock mass, the dissipation energy ratio of the bolted rock mass decreases exponentially with increasing pre-static load level, the ultimate dynamic impact energy and dissipation energy of the bolted rock mass increase significantly, and the increasing index of the ratio of dissipation energy increases linearly with the pre-static load; (4) Based on laboratory testing and on-site microseismic and stress monitoring, a design method is proposed for a roadway bolt support against dynamic load disturbance, which provides guidance for the design of deep underground roadway anchorage supports. The research results provide new ideas for explaining the failure behavior of anchorage supports and adopting reasonable design and construction practices.

• Journal of Korean Physical Therapy Science
• /
• v.31 no.2
• /
• pp.63-74
• /
• 2024

Background: This study aimed to determine the effects of static stretching on the pain and range of motion (ROM) of shoulder joints in middle aged women patients with frozen shoulders. Design: One group pretest-posttest design Methods: The participants were 15 middle aged women patients with frozen shoulders in their 40s to 60s. Subjective and objective pain and joint ROM(range of motion) were measured, and the static stretching intervention consisted of 15 minutes of flexion, abduction and external rotation stretching. Results: The results of this study indicated that the daily pain of shoulder joints and pressure pain thresholds of the muscles surrounding the shoulder joints were generally improved after the intervention with the static stretching, for which significant differences were observed (p<0.05). The ROM of shoulder joint flexion, abduction, and external rotation was significantly increased (p<0.05) after the intervention with the static stretching. Conclusion: Static stretching intervention in patients with frozen shoulders relieved shoulder joint pain and had positive effects on the ROM of shoulder joints. Thus, the application of static stretching in middle aged womenpatients who experience severe pain could be effective at enhancing the function of shoulder joints without pain.

• Journal of the Korean Society for Precision Engineering
• /
• v.9 no.1
• /
• pp.126-136
• /
• 1992

In this paper, a simple structured feedback compensation scheme for a electro-hydraulic servo system to keep the response characteristics unchanged regardless of the load variation is proposed. In electro-hydraulic servo system, servovalve is most important control element. But the relation between input corrent and output flowrate of the servovalve has properties as follows; firstly, in spite of constant input current, output flowrate decreases as load pressure increases, secondly, according to frequency response of typical servovalve, the characteristics of gain and phase shift is something like 2'nd order system. Load pressure feedback compensation method has been applied to eliminate the first influence, the second influence has been improved by phase lead compensation method. As a result of above compensation methods, regardless of variation load condition, spring and inertia load, the compensation scheme has been verified to be effective within the range of frequency less than 25Hz by static response and dynamic response in time domain and frequency domain through experiments.

• Proceedings of the KSME Conference
• /
• 2000.11b
• /
• pp.479-484
• /
• 2000

For the purpose of a cost effective design of practical subsonic/supersonic ejector systems, an experiment was carried out using a superheated steam as a primary driving flow. The superheated steam jet was produced by several different kinds of subsonic and supersonic nozzles. The secondary flow of atmospheric air inside a plenum chamber was drawn into the primary steam jet. The vacuum performance of the plenum chamber was investigated for a wide range of the ejector operation pressure ratio. The result showed that the static pressure of the mixed flow at the ejector throat is only a function of the ejector operation pressure ratio, regardless of the primary nezzle type employed.

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

• Journal of the Ergonomics Society of Korea
• /
• v.32 no.6
• /
• pp.489-494
• /
• 2013

Objective: This study compared the effects of streamlined shoes on dynamic gait and foot plantar pressure in healthy young adults. Background: With the importance of ankle and lower extremity mechanism, streamlined shoes are contributing to a static gait factors. However, the study of dynamic gait factor is still insufficient. Method: Sixty subjects were randomly allocated to two groups: experimental group(n=30) and control(n=30), respectively. The experimental group performed streamlined shoes, whereas the control group applied usual shoes. Main outcome measurements were assessed contact time, step length and foot plantar pressure using gait analysis with the treadmill. Independent t-test was used to compare the both groups. Results: Compared with control group, contact time of forefoot, midfoot and hindfoot decreased significantly in experimental group(p<.05), Step length increased significantly in experimental group(p<.05). Foot plantar pressure of midfoot and hindfoot increased significantly in experimental group(p<.05), whereas that of forefoot did not show significantly in experimental group(p>.05). Conclusion: Our findings suggest that streamlined shoes was more effective than usual shoes in dynamic gait change including contact time and step length and foot plantar pressure in healthy young adults. Application: The results of streamlined shoes might help to control for the gait of industrial workers.

• Steel and Composite Structures
• /
• v.27 no.4
• /
• pp.525-536
• /
• 2018

This paper focuses on the application of the first-order shear deformation theory (FSDT) to thermo-elastic static problems of functionally graded carbon nanotubes reinforced composite (FG-CNTRC) cylindrical pressure vessels. A symmetric displacement field is considered as unknown function along the longitudinal direction, whereas a linear distribution is assumed along the thickness direction. The cylindrical pressure vessels are subjected to an inner and outer pressure under a temperature increase. Different patterns of reinforcement are applied as distribution of CNTs. The effective material properties of FG-CNTRC cylindrical pressure vessels are measured based on the rule of mixture, whereas the governing equations of the problem are here derived through the principle of virtual works. A large parametric investigation studies the effect of some significant parameters, such as the pattern and volume fraction of CNTs, on the longitudinal distribution of deformation, strain and stress components, as useful tool for practical engineering applications.

• Journal of International Academy of Physical Therapy Research
• /
• v.9 no.4
• /
• pp.1642-1650
• /
• 2018

The purpose of this study was to identify the effect of proprioceptive neuromuscular facilitation (PNF) stretching exercise and joint mobilization on ankle joint range of motion (ROM), plantar pressure, and balance in subjects with stroke. Thirty patients (n=30) were organized into three groups, each of which received different treatments: PNF stretching (n=10), joint mobilization (n=10), and joint mobilization and PNF stretching combined (n=10). Each group received three exercise sessions per week for four weeks. The ankle ROM was measured using a goniometer, and plantar pressure and balance ability were measured using BioResque static posturography. In comparison within each group, the joint mobilization group and the joint mobilization with PNF stretching group showed significant improvements in ankle ROM, plantar pressure, and balance ability (p<.05). In comparison between the groups, a statistically significant difference was found in SECS change between the PNF stretching group, joint mobilization group and the joint mobilization with PNF stretching group. This study found demonstrates that the joint mobilization and joint mobilization with the PNF stretching methods were effective in improving ankle ROM, plantar pressure, and balance ability in stroke patients.