• Journal of International Academy of Physical Therapy Research
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• v.8 no.1
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• pp.1077-1083
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• 2017

The purpose of this study was to investigate the effects of stable and unstable bridging exercises on the EMG activity of abdominal muscles. Twenty healthy women participated in this study and the muscle activities of left-right rectus abdominis (RA), external oblique (EO), and internal oblique (IO) muscles were recorded during 4 bridging exercises (unilateral/ bilateral, stable/unstable). The activity of the right EO muscle was the highest during unilateral exercise in unstable condition, and left EO muscle also produced the same result. The activity of the right IO muscle was the highest during unilateral exercise in an unstable condition, and left IO muscle also produced the same result. The activity of the right RA muscle was the highest during unilateral exercise in a stable condition, and left RA muscle produced the same result. Unstable/unilateral (USUL) represented the highest activity among the 4 exercises. EO/IO muscles represented the highest activity during the USUL exercise, and RA did so during the stable/unilateral exercise. These results suggest that specific posture (USUL) can be administered targeting a specific side of abdominal muscles.

• Journal of the Korean Ceramic Society
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• v.22 no.2
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• pp.25-32
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• 1985

Effect of alkali $SO_3$ and $C_2S$ content and cooling condition of clinker on the formation of unstable alkali and cooling condition of clinker on the formation of unstable alkali was investigated. As a result alkali and $SO_3$ content of clinker were the main factors of unstable alkali formation and equation (7) in which the two factors were the variables showed a good agreement with the observed results. Water soluble alkali content of sulphate was decreased with increase of $C_2S$ content of clinker resulted by the increase of solid solution rate of alkali to clinker minerals. But change of unsatble alkali content accordint to the increase of $C_2S$ content was slight. A increasing tendency of ignition loss of clinker with increase of unstable alkali content was found.

• Journal of International Academy of Physical Therapy Research
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• v.6 no.1
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• pp.788-794
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• 2015

This study examines changes in walking ability among patients with stroke after applying dual-task training under the condition of visual control and unstable supporting ground; the purpose is to provide reference data for selecting intervention methods that enhance the walking ability of patients with stroke. Among the patients with stroke who received rehabilitation treatment(at Rehabilitation Hospital B in Gyeonggi, South Korea from May 2014 to July 2014), 29 patients were selected as research subjects; all of them understood the purpose and contents of this research and agreed to participate in the experiment. The research subjects were divided into a visual control and unstable supporting ground dual-task(VUDT) group(10 patients), a visual control dual-task(VDT) group(10 patients), and an unstable supporting ground dual-task(UDT) group(9 patients); all of the subjects received 30-minute trainings, three times a week for a total of four weeks. A Timed-Up-and-Go(TUG) test was performed to investigate the change of walking function among the subjects, and a 10m walking test was conducted to measure their walking speed. According to the study results, all three groups showed significant differences after dual-task training; the dual-task training group under the condition of visual control and unstable supporting ground showed the most prominent change. This study confirmed that dual-task training using visual control and unstable supporting ground has a positive impact on the walking ability of patients with stroke. Through the study results, we found that implementing dual-task training under the condition of visual control and unstable supporting ground can more effectively improve the walking ability of patients with stroke, rather than performing visual control dual-task training or unstable supporting ground dual-task training only.

• Proceedings of the Korea Concrete Institute Conference
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• 1996.10a
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• pp.459-465
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• 1996

This paper is about unstable behavior in concrete during the localized deformation and the crack growths in concrete. By modeling the strain localization phenomenon of concrete, the stability condition of the localization is obtained and analyzed. And the stability and bifurcation condition of crack growths in two parallel cracks under different loading conditions are derived and discussed.

• The Journal of Korean Physical Therapy
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• v.28 no.3
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• pp.195-200
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• 2016

Purpose: This study was designed to evaluate the effects of the different condition of leg support surface on the upper extremity and core muscle activity during the push-up exercise. Methods: Fifteen healthy subjects that were practicable push-ups were recruited in this study. Subjects were instructed the push-up exercise in the different condition of the leg support surface. Each condition of support surface was set to the high and lower, and the unstable and stable condition. Muscle activation was measured by using the surface electromyography (EMG), and recorded from the triceps brachii, serratus anterior, latissimus dorsi, rectus abdominis, abdominal external oblique, and erector spinea muscle. Results: In the results of experiments, there was no significant difference of muscle activation in upper extremity between the high unstable and high stable support surface. By contrast, muscle activation of the rectus abdominis and abdominal external oblique was significantly higher in the low unstable support surface, compared with those of the low stable support surface. It is well known that the core muscle was important to stabilization of trunk stability. Conclusion: This result demonstrates that the low and unstable support surface for the lower extremity was suited for training of core muscle for trunk stabilization during the push-up exercise.

• Physical Therapy Korea
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• v.19 no.1
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• pp.28-36
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• 2012

This study used an unstable platform to change the support surface type and position of both lower limbs in order to determine changes in weight distribution and muscle including the vastus medialis, tibialis anterior, lateral hamstring, and lateral gastrocnemius of both lower limbs were evaluated during knee joint flexing and extending in a semi-squat movement in 32 hemiplegic patients. The support surface conditions applied to the lower limbs were divided into four categories: condition 1 had a stable platform for both lower limbs; condition 2 had an unstable platform for the non-hemiplegic side and a stable platform for the hemiplegic side; condition 3 had a stable platform for the non-hemiplegic side and an unstable platform for the hemiplegic side; and condition 4 had an unstable platform for both sides. The normalized EMG activity levels of muscles and weight bearing ratio of both sides in the four surface conditions were compared using repeated measures ANOVA. A significant increase was found in the weight support distribution for the hemiplegic side in flexing and extending sessions in condition 2 compared to the other conditions (p<.05). A statistically significant decrease in significant decrease in asymmetrical weight bearing in flexing and extending sessions was observed for condition 2 compared to the other conditions (p<.05). A similar significant decrease was found in differences in muscular activity for both lower limbs in condition 2 (p<.05). The muscular activity of the hemiplegic side, based on the support surface for each muscle showed a significantly greater increase in condition 2 (p<.05). An unstable platform for the non-hemiplegic side and a stable platform for the hemiplegic side therefore increased symmetry in terms of the weight support distribution rate and muscle activity of lower limbs in hemiplegic patients. The problem of postural control due to asymmetry in hemiplegic patients should be further studied with the aim of developing continuous effects of functional training based on the type and position of the support surfaces and functional improvement.

• Journal of Korean Physical Therapy Science
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• v.15 no.1
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• pp.67-74
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• 2008

A decrease in the ability to maintain static and dynamic balance after stroke could be related to the inability to select reliable sensory information in producing relative motor action needed to maintain postural stability. The purpose of this study was to compare the effects of two different types of surface conditions on the balancing ability of subjects with stroke. Eighteen hemiparetic subjects were assigned to an experimental and control group participating in a six－week rehabilitative therapeutic exercise program focusing on balance and mobility. Exercises were performed 3 to 5 times per week in a stable surface condition by the control group, and in an unstable surface condition by the experimental group. Pre－ and post test assessments involved the measurement of the static balance and dynamic balance, respectively by 7－item Berg Balance Scale－3P and by Pro－3 Balance System. Results showed that under the unstable surface condition, static balance in the experimental group showed more improvement than that of the control group.(Statistically, not very significant.) All the aspects of dynamic balance and mediolateral sway(balance) improved significantly than those of the control group. However, there were no significant differences between two groups. Overall, it can be concluded that under the unstable surface condition, the rehabilitative therapeutic exercise programs are effective in improving the dynamic balance of stroke subjects. The results suggest that the adaptation of the unstable surface in the rehabilitative therapeutic exercises could be effective for the patients with hemiplegia in balance. Further studies are needed to confirm the effectiveness of the unstable surface on improving balance and postural stability of hemiplegics.

• International Journal of Railway
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• v.9 no.2
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• pp.46-49
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• 2016

In this study a new detection technique based on WAK is introduced that can be used for identifying unstable concrete sleeper installed in ballast by triggering activated wave on the sleeper surface. If a gap exists immediately below the concrete sleeper, static stiffness can be lower than stable case's stiffness. The concrete sleeper is assumed as a single degree of freedom system (SDOF). The static stiffness K can be obtained by iteratively calculated mass (m), stiffness (k) and damping coefficient (c) of SDOF system. Those coefficients are used to specify the ballast condition such as a gap between the sleeper and ballast. Typical test results using a small sleeper model test are summarized and explained for proof of effectiveness of the WAK test for checking unstable condition of the sleeper.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.20 no.2
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• pp.616-623
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• 1996

This paper investigates the linear stability of reacting mixing layers with special emphasis on the existence of multiple unstable modes. The governing equations for laminar flows are from two-dimensional compressible boundary-layer equations. The chemistry is a finite rate single step irreversible reaction with Arrhenius kinetics. For the incompressible reacintg mixing layer with variable density. A necessary condition for instability has been derived. The condition requires that the angular momentum, not the vorticity, to have a maximum in the flow domain. New inflectional modes of instability are found to exist in the outer part of the mixing layer. For the compressible reacting mixing layer, supersonic unstable modes may exist in the abscence of a generalized inflection point. The outer modes at high Mach numbers in the reacting mixing layer are continuations of the inflectional modes of low Mach number flows. However, the generalized inflection point is less important at supersonic flows.

• Journal of information and communication convergence engineering
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• v.15 no.4
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• pp.244-249
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• 2017

Wearable sensor-based gait analysis has been widely conducted to analyze various aspects of human ambulation abilities under the free-living condition. However, there have been few research efforts on using wearable sensors to analyze human walking on an unstable surface such as on a ship during a sea voyage. Since the motion of a ship on the unstable sea surface imposes significant differences in walking strategies, investigation is suggested to find better performing wearable sensor-based gait analysis algorithms on this unstable environment. This study aimed to compare two representative gait event algorithms including time domain and frequency domain analyses for detecting heel strike on an unstable platform. As results, although two methods did not miss any heel strike, the frequency domain analysis method perform better when comparing heel strike timing. The finding suggests that the frequency analysis is recommended to efficiently detect gait event in the unstable walking environment.