• Journal of the Korean Society of Physical Medicine
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• v.11 no.3
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• pp.133-139
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• 2016

PURPOSE: The purpose of this study is to examine the impact of balance training on a three-dimensional balance trainer that provides the up-and-down vertical movement of the knee joint and left-and-right horizontal movement, along with visual feedback on the functional ability of children with spastic cerebral palsy (CPs). METHODS: 8 CPs participated in this study. The experiment was implemented for 40 minutes, three times a week for a total of six weeks. The subjects received general physiotherapy for 15 minutes in each session focused on balance and walking, as based on the neuro-developmental treatment theory. Balance training was performed for 20 minutes on a three-dimensional balance trainer where knee joint movement providing visual feedback is applied. The evaluations were conducted before and after the test, and posture sway was measured using 10 Meter Walking Test (10MWT), Timed Up & Go Test (TUG), and the Good Balance System to evaluate the functional ability and balance of the subjects RESULTS: 10MWT was not statistically significant (p>.05). On the contrary, TUG and postural sway indicate static balance showed a statistically significant decrease (p<.05). In a static balance test using the Good Balance System, the average moving speed statistically significantly decreased in the AP and ML directions (p<.05), and the mean velocity moment also significantly decreased (p<.05). CONCLUSION: These findings suggested that balance training using the three-dimensional balance trainer, with the features of visual feedback and up-and-down knee joint movement effects on increasing dynamic and static balance.

• Korean Journal of Applied Biomechanics
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• v.21 no.2
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• pp.173-179
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• 2011

This study aims to analyse difference in biomechanical factors between dominant legs and recessive ones according to muscular imbalance during drop landing targeting talented children in sports. The subjects of the study were ten primary students who are attending to Sports Program for Talented Children organized by C university (age: $12.28{\pm}0.70$ year, height: $1.52{\pm}0.11$ m, and weight: $45.2{\pm}4.9$ kg). Strength legs were classified into dominant side and strengthless legs were classified into non-dominant legs. For three-dimensional analyses of the data collected, 6 video cameras(MotionMaster200, Visol, Korea) were used. To analyse ground reaction force, two force platforms(AMTI ORG-6, MA) were used and to analyse electromyograghy a 8-channeled wireless Noraxon Myoresearch made in USA was used at 1000 Hz for sampling. As a result, it was discovered that the dominants legs controlled knee bending motions more stably than strengthless legs as the maximum vertical ground reaction force was significantly high in dominant legs(p<.05), and joint moment of knee joints of the dominant legs was high(p<.05). Therefore, this study suggested that injury prevention program focusing on muscular balance as well as the existing sports programs for talented children should be developed based on results of the study and it is expected that the results will be useful for improvement of sports programs for talented children.

• Journal of Oral Medicine and Pain
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• v.15 no.1
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• pp.105-115
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• 1991

The purpose of the study was to evaluate the occlusal stability at the moment of dynamic occlusal tooth contact and to investigate the correlation between the occlusal stability and the masticatory muscle activities. It also evaluated the effect of short-term use of occlusal splints on the occlusal stability and the masticatory muscle activities in patients with temporomandibular disorders during maximum voluntary clenching by synchondronized with temporomandibular disorders during maximum voluntary clenching by synchronized use of the T-Scan system(Tekscan, Inc, USA) and K6-Diagnostic system(Myo-tronics Research, Inc, USA) The author measured its distance from retruded contact position(RCP) to intercuspal position(IP), average of contact intervals(ACI), total left-right statistics(TLR), average muscle activities of masseter and anterior temporal muscles during maximum voluntary clenching in 20 patients with temporomandibular disorders and 22 dental students as a control group. The data were compared between two groups and investigated for any correlations between the parameters. The results were as follows : 1. Both of the mean average of contact intervals and the mean absolute value of total left-right statistics during maximum voluntary clenching were increased in the patient group when compared with the control group. 2. Muscular disharmony of anterior temporal muscles of patient group is significantly greater than that of control group. However, muscular disharmony of masseter muscles of patient group is not significantly greater than that of control group. 3. There were significant correlations between muscular disharmony of anterior temporal muscles and average of contact intervals as well as total left-right statistics, and also between muscular disharmony of masseter muscles and total left-right statistics. 4. There were not any significant correlations between distance from RCP to IP and any other parameters. 5. There were a significant decrease in total left-right statistics and muscular disharmony of anterior temporal muscles during maximum voluntary clenching after a 1week use of occlusal splint in the patient group.

• Journal of Biosystems Engineering
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• v.35 no.5
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• pp.357-365
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• 2010

Workers in the agricultural industry have been exposed to many work-related musculoskeletal disorders. So, our objectives in this study were to measure and analyze worker's physiological bio-information to reduce musculoskeletal disorders in relation to agricultural works. We investigated worker's bio-information of physiological signals during the repeated lifting work such as body temperature, heart rate, blood pressure, physical activity, and heart rate variability. Moreover, we analyzed the workloads of lumbar spine during the repeated lifting work using the 3-axis acceleration and angular velocity sensors. The changes of body temperature was not significant, but the mean heart rate increased from 90/min to 116/min significantly during 30 min of repeated lifting work (p<0.05). The average worker's physical activity(energy consumption rate) was 206 kcal/70kg/h during the repeated lifting work. The workers' acute stress index was more than 80, which indicated a stressful work. Also, the maximum shear force on the disk (L5/S1) of a worker's lumbar spine in static state was 500N, and the maximum inertia moment was 139 $N{\cdot}m$ in dynamic state.

• Journal of Biomedical Engineering Research
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• v.24 no.1
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• pp.15-21
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• 2003

In this study, for a safetv assessment of light weight wheelchair occupant in frontal crash, we tested a dynamic sled impact test. we carried out total 6 times test and impact speed was 20g/48 km/h. By using Hybrid III 50%ile male dummy, head injury criteria(HIC), neck flexion moment, neck axial tension force, neck shear force. chest acceleration, head, wheelchair and knee excursion were measured, we evaluated light weight wheelchair occupant safety by motion criteria(MC) which proposed in SAE J2249 and combined injury criteria(CIC) which is a voluntary standard(GM-IARV) of General Motors Co.. when we assumed that the maximum injury value in frontal crash was 100%, the result of motion criteria(MC) of wheelchair occupant was 52%, occupant upper body injury index(CIC) was 60.1%.

• Earthquakes and Structures
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• v.9 no.4
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• pp.789-830
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• 2015

The recent re-assessment of the seismic hazard in Europe led for many regions of low to moderate seismicity to an increase in the seismic demand. As a consequence, several modern unreinforced masonry (URM) buildings, constructed with reinforced concrete (RC) slabs that provide an efficient rigid diaphragm action, no longer satisfy the seismic design check and have been retrofitted by adding or replacing URM walls with RC walls. Of late, also several new construction projects have been conceived directly as buildings with both RC and URM walls. Despite the widespread use of such construction technique, very little is known about the seismic behaviour of mixed RC-URM wall structures and codes do not provide adequate support to designers. The aim of the paper is therefore to propose a displacement-based design methodology for the design of mixed RC-URM edifices and the retrofit of URM buildings by replacing or adding selected URM walls with RC ones. The article describes also two tools developed for estimating important quantities relevant for the displacement-based design of structures with both RC and URM walls. The tools are (i) a mechanical model based on the shear-flexure interaction between URM and RC walls and (ii) an elastic model for estimating the contribution of the RC slabs to the overturning moment capacity of the system. In the last part of the article the proposed design method is verified through nonlinear dynamic analyses of several case studies. These results show that the proposed design approach has the ability of controlling the displacement profile of the designed structures, avoiding concentration of deformations in one single storey, a typical feature of URM wall structures.

• Earthquakes and Structures
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• v.10 no.4
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• pp.939-963
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• 2016

According to the new directives about the rational and efficient use of energy, thermal bridges in buildings have to be avoided, and the thermal insulation (TI) layer should run without interruptions all around the building - even under its foundations. The paper deals with the seismic response of multi-storeyed reinforced concrete (RC) frame building structures founded on an extruded polystyrene (XPS) layer placed beneath the foundation slab. The purpose of the paper is to elucidate the problem of buildings founded on a TI layer from the seismic resistance point of view, to assess the seismic behaviour of such buildings, and to search for the critical parameters which can affect the structural and XPS layer response. Nonlinear dynamic and static analyses were performed, and the seismic response of fixed-base (FB) and thermally insulated (TI) variants of nonlinear RC building models were compared. Soil-structure interaction was also taken into account for different types of soil. The results showed that the use of a TI layer beneath the foundation slab of a superstructure generally induces a higher peak response compared to that of a corresponding system without TI beneath the foundation slab. In the case of stiff structures located on firm soil, amplification of the response might be substantial and could result in exceedance of the superstructure's moment-rotation plastic hinge capacities or allowable lateral roof and interstorey drift displacements. In the case of heavier, slenderer, and higher buildings subjected to stronger seismic excitations, the overall response is governed by the rocking mode of oscillation, and as a consequence the compressive strength of the XPS could be insufficient. On the other hand, in the case of low-rise and light-weight buildings, the friction capacity between the layers of the applied TI foundation set might be exceeded so that sliding could occur.

• Earthquakes and Structures
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• v.10 no.5
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• pp.1143-1179
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• 2016

Offshore wind turbines are considered as a fundamental part to develop substantial, alternative energy sources. In this highly flexible structures, monopiles are usually used as support foundations. Since the monopiles are large diameter (3.5 to 7 m) deep foundations, they result in extremely stiff short monopiles where the slenderness (length to diameter) may range between 5 and 10. Consequently, their elastic deformation patterns under lateral loading differ from those of small diameter monopiles usually employed for supporting structures in offshore oil and gas industry. For this reason, design recommendations (API and DNV) are not appropriate for designing foundations for offshore wind turbine structures as they have been established on the basis of full-scale load tests on long, slender and flexible piles. Furthermore, as these facilities are very sensitive to rotations and dynamic changes in the soil-pile system, the accurate prediction of monopile head displacement and rotation constitutes a design criterion of paramount importance. In this paper, the Fourier Series Aided Finite Element Method (FSAFEM) is employed for the determination of static impedance functions of monopiles for OWT subjected to horizontal force and/or to an overturning moment, where a non-homogeneous soil profile has been considered. On the basis of an extensive parametric study, and in order to address the problem of head stiffness of short monopiles, approximate analytical formulae are obtained for lateral stiffness $K_L$, rotational stiffness $K_R$ and cross coupling stiffness $K_{LR}$ for both rough and smooth interfaces. Theses expressions which depend only on the values of the monopile slenderness $L/D_p$ rather than the relative soil/monopile rigidity $E_p/E_s$ usually found in the offshore platforms designing codes (DNV code for example) have been incorporated in the expressions of the OWT natural frequency of four wind farm sites. Excellent agreement has been found between the computed and the measured natural frequencies.

• Journal of Biosystems Engineering
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• v.27 no.3
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• pp.185-194
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• 2002

The objective of this study was to analyze a stability of sideways overturning of a forwarder developed by the Forestry Research Institute. The stability analysis was conducted using a multibody dynamic analysis program. VisualNastran Desktop. A solid model of the forwarder was constructed and its physical properties such as mass, mass center and mass moment of inertia were determined on 3D CAD modeler of the Solid Edge 8.0. 3D simulations of sideways overturning of the forwarder were also performed on the Visual Nastran using the solid model when it traveled across the slope and traversed over an up-hill side obstacle. Stability comparison between a bogie-wheeled and a 6-wheeled forwarders was also made and found that the bogie-wheeled forwarder was more stable than the 6-wheeled one on slopes. The safety speeds of the forwarder predicted by the simulation under various conditions can be used as a guideline for safe operations of forwarders in mountainous area. The technique of using a solid model for the sability analysis can also be applied successfully to other vehicles like agricultural tractors, loaders and construction equipments.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.31 no.9
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• pp.82-87
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• 2003

This research is concerned with ground experiments for satellite solar array deployment as well as the validation of theoretical modeling technique presented in the previous paper. We carried out the experiments on the strain energy hinge with stopper to investigate he buckling characteristics of the SEH, which affects the shape and the speed of the solar array deployment. The moment-angle diagram obtained from the experiments was later combined with the theoretical deployment model. This paper also presents the details of the ground experiments performed at the Korea Aerospace Research Institute(KARI) . It was found that the ground experimental results were in good agreement with the theoretical predictions thus validating the dynamic modeling technique.