• Steel and Composite Structures
• /
• v.28 no.4
• /
• pp.427-438
• /
• 2018

Static stability is a decisive factor in the design of domes. Stability-related external factors, such as load and supports, are incorporated into structural vulnerability theory by the definition of a relative rate of joint well-formedness ($r_r$). Hence, the instability mechanism of domes can be revealed. To improve stability, an optimization model against instability, which takes the maximization of the lowest $r_r$ ($r_{r,min}$) as the objective and the discrete member sections as the variables, is established with constraints on the design requirements and steel consumption. Optimizations are performed on two real-life Kiewitt-6 model domes with a span of 23.4 m and rise of 11.7 m, which are initially constructed for shaking table collapse test. Well-formedness analyses and stability calculation (via arc-length method) of the models throughout the optimization history demonstrate that this proposed method can effectively enhance $r_{r,min}$ and optimize the static stability of shell-like structures. Additionally, seismic performance of the optimum models subjected to the same earthquake as in the shaking table test is checked. The supplemental simulations prove that the optimum models are superior to the original models under earthquake load as well.

• Clinics in Shoulder and Elbow
• /
• v.11 no.1
• /
• pp.1-5
• /
• 2008

Shoulder instability is generally diagnosed from a detailed history, physical examination and various radiological studies. Although, a physical examination is essential for making a diagnosis, it is quite difficult. For a precise physical examination, a thorough anatomical knowledge and a great deal of experience is needed. In addition, normal translation and pathologic laxity should be differentiated. An anatomical and biomechanical understanding of a stable and unstable shoulder joint and a precise physical examination are needed to determine the direction and extent of the instability as well as to diagnose the associated lesions and improve the surgical results.

• The Journal of Korean Physical Therapy
• /
• v.28 no.6
• /
• pp.376-380
• /
• 2016

Purpose: This study was to investigate the short-term effects of spiral taping (ST) on performance on the star excursion balance test (SEBT) in individuals with unilateral chronic ankle instability (CAI). Methods: This study was single-group pre - post measures experimental design. The subjects with CAI were 39 (range, 20-31 years; male 16, females 23) were enrolled in the study. The discomfort had in unilateral ankle and Cumberland ankle instability score was 19.56 (${\pm}3.29$). Spiral tape (a width of 3 mm) was applied $3{\times}4$ cross shape on medial malleolus, lateral malleolus and dorsal of talocural joint of unstable ankle. SEBT was measured baseline and 30 min later in stable ankle and unstable ankle. Results: SEBT showed significantly improved after applying the ST (p<0.05, ES=0.74) on unstable ankle. In comparison the difference of stable and unstable ankle, between the pretest and posttest were significant differences (p<0.01, ES=1.88). Conclusion: These results indicated that ST improves performance on the SEBT. Therefore, it suggests that ST may be a suitable intervention to dynamic balance in patients with CAI.

• The Journal of Korean Physical Therapy
• /
• v.29 no.5
• /
• pp.234-240
• /
• 2017

Purpose: The aim of this study was to determine the effectiveness of breathing exercises and lumbar segmental exercises on the segmental stability of patients with chronic back pain. Methods: Fifty-nine patients, who suffered from chronic low back pain, were enrolled in this examination. They were divided randomly into three groups: experiment group 1 underwent breathing and segmental stabilization exercises (n=20), experiment group 2 experienced segmental stabilization exercises (n=20), and the control group was given the modality treatment (n=19). The measurements were assessed through an Oswestry disability questionnaire (ODQ), as well as a lumbar segmental instability test (LSIT). Results: The ODQ results for experimental groups 1 and 2 were similar (p<0.05), both before and after six weeks of exercise, but different among the three groups (p>0.05). The differences in segmental instability of each of the three groups were similar (p<0.05), and also similar among the three groups (p<0.05). Conclusion: These findings suggest that lumbar segmental stabilization exercises are efficient in increasing the segmental stability and alleviating pain in patients with chronic back pain. Additional studies on this subject will be needed to improve the clinical applications in the future.

• Journal of Digital Convergence
• /
• v.10 no.11
• /
• pp.551-558
• /
• 2012

Objectives: The purpose of this study was to determine whether the sacrooccipital category II blocking technique may improve abdominal muscle endurance and alleviate shoulder pain caused by pelvic tilting. Methods: A total of 50 subjects diagnosed with category II sacroiliac joint instability and lower back pain were randomly assigned to the control or treatment group. The sacrooccipital technique category II blocking procedure (2-min duration) was performed 3 times a week until the category II indicator of joint instability had subsided. The control subjects were subjected to a sham procedure of equal duration and frequency. We assessed abdominal muscle endurance using the partial curl-up test and shoulder pain using a visual analogue scale, before and immediately after the intervention and 2 weeks after the intervention. Results: On two-way analysis of variance with repeated measures on time factor, significant treatment and interaction effects on muscle endurance were found. A significant interaction effect, but not treatment effect, was found for shoulder pain. Post hoc test showed that the shoulder pain was reduced immediately after intervention (treated group) and 2weeks (control and treated group) after the intervention as compared to before the intervention. Conclusions: This study suggests that sacrooccipital category II blocking can be used to alleviate shoulder pain caused by pelvic instability. The mechanisms behind the long-term benefits may include an increase in abdominal muscle endurance.

• Clinics in Shoulder and Elbow
• /
• v.12 no.2
• /
• pp.264-270
• /
• 2009

Purpose: The elbow joint is one of the most stable joints. Dislocation and fracture can occur in elbow joint most commonly next to shoulder joint. Various injuries can occur according to generated mechanism, age of patient and impact. Despite proper treatment, various complications can occur. Materials and Methods: We describe etiology and treatment of these complications after elbow trauma such as stiffness, instability and heterotopic ossification. Results and Conclusion: Malunion, nonunion and traumatic arthritis are addressed as a possible complication after fracture around elbow joint.

• Journal of the Korean Society of Physical Medicine
• /
• v.14 no.3
• /
• pp.21-27
• /
• 2019

PURPOSE: This study examined the changes in the kinematic variables during walking on a downhill ramp according to the shoe heel height. METHODS: The subjects were 10 adult women with no history of musculoskeletal disorders who agreed to participate in the study. Data were collected using a motion analysis system (VICON) consisting of six infrared cameras. The slope was 120 cm in width, 200 cm in length, and 15 in inclination. To confirm the change in gait parameters (stride length, gait speed) and lower extremity joint angle according to the heel heights of the shoes, flat, 5 cm, and 10 cm heel shoes were prepared and walked alternately. RESULTS: As a result, both the stride length and walking speed showed significant differences according to the heel height between flat and 10 cm (p<.05). In the sagittal plane, there was no significant difference in the hip joint and knee joint, but a significant difference was observed in all events in the ankle joint on all heel heights (p<.05). In particular, the heel strike and mid stance events showed significant differences among all height conditions (p<.05). No significant difference was observed in any of the joint angle changes in the frontal plane (p>.05). CONCLUSION: As the shoe heel height increased, the instability increased and efforts to secure the stability were made, leading to a shortened stride length, walking speed, and angle of the ankle joint.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.40 no.1
• /
• pp.33-39
• /
• 2016

This study investigated the dynamic instability of a ceramic-on-ceramic artificial hip joint system through complex eigenvalue analysis. We examined the mode-coupling mechanism through eigenvalue sensitivity analysis with the variation of system parameters. In addition, we constructed a finite element model including the negative slope of friction curve for investigating the negative-slope mechanism in the hip squeak problem. The numerical results show that the torsion-dominant mode becomes unstable due to the presence of the negative slope while the axial load is the important factor influencing the negative-slope type instability.

• Economic and Environmental Geology
• /
• v.33 no.2
• /
• pp.117-128
• /
• 2000

Regional evaluations of slope stability by the failure criterion and by environmental geological factors were conducted. The failure criterion is the general conditions for plane failure which consider the geometrical conditions between geological discontinuities and topographical slope planes. The factor focused in this condiction is dip and dip direction. Geostatics, named semivariogram was used for establishing structural domains in slope stability evaluation by the failure criterion. The influential range was calculated to 6 km in the case of dip direction of dominant joint set and 7 km in the case of dip of the same dominant joint set. Then applying this failure criterion to the study area produced a slope stability map using the established domains and slopes generated by TIN module of ARC/INFO GIS. This study considered another regional slope stability analysis. 5 failure-driven factors 9the unstable slope map, geology, engineering soil, groundwater, and lineament density) were selected and used as data coverages for regional slope stability evaluation by geoenvironmental factors. These factors were weighted and overlayed in GIS. From the graph of cumulatave area (%) and instability index, finding critical points classified the instability indices. The most unstable slopes are located in the southern area of Mt. Eorae, Dabul-ri, and the eastern area of Junkok-ri in the first area is plane failure. Also, the expected orientations of failure are 59/338 and 86/090 (dip/dip direction).

• Korean Journal of Applied Biomechanics
• /
• v.31 no.2
• /
• pp.79-86
• /
• 2021

Objective: The purpose of this study was to identify the effect of reduced plantar cutaneous sensation on gait kinematics during walking with and without CAI. Method: A total of 20 subjects involved in this study and ten healthy subjects and 10 CAI subjects participated underwent ice-immersion of the plantar aspect of the feet before walking test in this study. The gait kinematics were measured before and after ice-immersion. Results: We observed a before ice-immersion on plantar cutaneous sensation, CAI subject were found to reduced ankle dorsiflexion, knee external rotation, hip adduction, and internal rotation compared to control subject. After ice-immersion, CAI subjects were found to reduce knee external rotation, hip adduction. However, no significant ankle joint kinematics. Conclusion: While walking, gait pattern differences were perceived between groups with and without plantar cutaneous sensation. The results of the study may explain the abductions in the hip angle movements in CAI patients at initial contact compared to healthy subjects in the control group when plantar cutaneous sensation was reduced. A change in proximal joint kinematics may be a conservative strategy to promote normal gait patterns in CAI patients.