• Proceedings of the Computational Structural Engineering Institute Conference
• /
• 1992.10a
• /
• pp.7-19
• /
• 1992

An efficient approach to limit analysis is presented whereby a continuous perfectly plastic structure is replaced by a discrete mathematical model. It is formulated as a mathematical programming problem using the static theorem of plasticity. The discretization is accomplished by writing the governing equilibrium equations in finite difference form, and is combined with piecewise linearization of the nonlinear yield curve, thus converting the formulation into a linear programming exercise. Examples of reported cases involving plates and shells are solved to illustrate the ease of application of the present method, its flexibility and accuracy - features which it make attractive to practising engineers.

• Physical Therapy Korea
• /
• v.24 no.2
• /
• pp.9-18
• /
• 2017

Background: Limitation of hamstring extensibility is often associated with various musculoskeletal problems such as alterations in posture and walking patterns. Thus, certain appropriate strategies need to be established for its management. Objects: The aim of this study was to compare the effects of the neural mobilization technique and static stretching exercises on popliteal angle and hamstring compliance in young women with short hamstring syndrome (SHS). Methods: Thirty-three women with SHS were randomly assigned to either group-1 ($n_1=17$) that underwent the neural mobilization technique or group-2 ($n_2=16$) that underwent the static stretching exercises. Outcome measures included the active popliteal angle (APA) and a hamstring's electromyographic (EMG) activity at a maximum popliteal angle of the baseline. Intervention for each group was performed for a total time of 3-min (6 sets of a 30-sec application). Results: There were significant interactions between time and group in the APA [group-1 (pre-test to post-test): $69.70{\pm}8.14^{\circ}$ to $74.14{\pm}8.07^{\circ}$ and group-2: $68.66{\pm}7.42^{\circ}$ to $70.52{\pm}7.92^{\circ}$] (F1,31=6.678, p=.015) and the EMG activity of the hamstring (group-1: $1.12{\pm}.30{\mu}N$ to $.69{\pm}.31{\mu}V$ and group-2: $1.19{\pm}.49{\mu}V$ to $1.13{\pm}.47{\mu}V$)(F1,31=6.678, p=.015). Between-group comparison revealed that the EMG activity of the hamstring was significantly different at post-test between the groups (p<.05). Furthermore, in within-group comparison, group-1 appeared to be significantly different for both variables between pre- and post-test (p<.05); however, group-2 showed significant difference in only the APA between pre- and post-test (p<.05). Conclusion: These findings suggest that the neural mobilization technique and static stretching exercises may be advantageous to improve hamstring compliance in young women with SHS, resulting in a more favorable outcome in the neural mobilization technique.

• Journal of the Korea Convergence Society
• /
• v.12 no.12
• /
• pp.401-409
• /
• 2021

This study was conducted to investigate the effects of static recovery and dynamic recovery methods on heart rate, blood lactic acid concentration, and blood glucose during recovery after walking at the speed of 80bpm and 130+30bpm upon trekking of forest slopes in Taejo Mountain in Cheonan. 9 men in their 20s and 30s who had no abnormality in walking was subject to this experience. The result of through static recovery and dynamic recovery methods while trekking at the speed of 80bpm and 130+30bpm were analyzed by two-way repeated ANOVA. When there was a significant difference, the repeated method of contrast was applied to compare and analyze. The heart rate at 80bpm condition was significantly different depending on the method(p=.008) and time(p=.000) and there was no significant difference in blood lactic acid concentration for the recovery method(p=.401), but there was a significant difference depending on the time(p=.000). Blood glucose did not show significant difference according to the recovery method(p=.093), and there was significant difference depending on the time of static recovery method(p=.002). The heart rate in 130bpm + 30bpm condition was significantly different depending on to the method(p=.002) and time(p=.000), blood lactic acid concentration was significantly different depending on the method(p=.001) and time(p=.000), and blood glucose concentration was not significantly different between the time(p=090) and the method(p=.721).

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.12 no.3
• /
• pp.1244-1252
• /
• 2011

This study was to investigate the effect of intensive trunk-pelvic stabilizing training using sling exercise on trunk muscle activity and balance in patients with hemiplegia. Twenty hemiplegic patients(6 month ${\leq}$, 1 years >) participated were divided into two groups randomly. Control group(n=10) had only general rehabilitation training and experimental group(n=10) had both the general rehabilitation training and intensive trunk-pelvic stabilizing training using sling. They were treated for 30 min./5 times/4 week. I measured ability of trunk control, muscle activity, and balance which were done before and after the intensive training using sling. In significant difference after training, show a significant difference in TIS(p<.001), in particular static(p<.05), dynamic(p<.01), coordination(p<.05) and muscle activity of RA(p<.001), EO(p<.001), ES(p<.001), Multifidus(p<.05), FMA(Balance)(p<.01), and static(p<.001) & dynamic(p<.001) balance ability on MTD-Balance system. As this study proved effective therapeutic exercise of trunk muscle activity and balance ability on intensive trunk-pelvic stabilizing training using sling, it could identify importance of trunk-pelvic stabilizing and control on balance.

• Journal of the Korean Applied Science and Technology
• /
• v.38 no.2
• /
• pp.411-422
• /
• 2021

The purpose of this study was to examine the relationship between major satisfaction and university life adaptation according to the amount of physical activity for university students. This study implement survey to the 201 university students. Descriptive statistics, reliability analysis, one-way ANOVA and pearson's correlation analysis were conducted for data analyses. The results are as follows. First, university students' major satisfaction with the amount of physical activity is statistically significantly higher than that of low-intensity physical activity groups (p<.05). Second, university life adaptation according to the amount of physical activity was found to be statistically significantly higher in high-intensity physical activity groups than in medium-intensity physical activity groups and low-intensity physical activity groups (p<.05). Lastly, according to the relationship between physical activity, major satisfaction, and university life adaptation of university students, male students have a static correlation between physical activity, major satisfaction (general satisfaction), and university life adaptation (personal emotion adaptation) and female students have a static correlation between physical activity and university life adaptation(social adaptation) (p<.05). This study confirmed that the amount of physical activity of university students is related to their major satisfaction and adaptation to university life. Based on this conclusion, it is expected that university students will be able to manage their university life through physical activities.

• Korean Journal of Applied Biomechanics
• /
• v.26 no.2
• /
• pp.143-151
• /
• 2016

Objective: The purpose of this study was to investigate the effect of fatigue induction on ground reaction force (GRF) components, postural stability, and vertical jump performance in Taekwondo athletes. Method: Ten Taekwondo athletes (5 men, 5 women; mean age, $22.30{\pm}2.62years$; mean height, $174.21{\pm}9.20cm$; mean body weight, $67.28{\pm}12.56kg$) participated in this study. Fatigue was induced by a short period of strenuous exercise performed on a motorized treadmill. The analyzed variables included vertical jump performance, static stability (mediolateral [ML], center of pressure [COP], anteroposterior [AP] COP, ${\Delta}COPx$, ${\Delta}COPy$, and COP area), postural stability index values (ML stability index [MLSI], AP stability index [APSI], vertical stability index [VSI], dynamic postural stability index [DPSI]), and GRF components (ML force, AP force, peak vertical force [PVF], and loading rate). To analyze the variables measured in this study, PASW version 22.0 was used to calculate the mean and standard deviation, while a paired t-test was used to evaluate the pre- versus post-fatigue results. Pearson's correlation coefficients among variables were also analyzed. The statistical significance level was set at ${\alpha}$ = .05. Results: Vertical jump performance decreased significantly after the induction of fatigue, while AP COP, ${\Delta}COPx$, COP area, APSI, VSI, and DPSI increased significantly. PVF and loading rate increased significantly after the induction of fatigue, while the postural stability variables (AP COP, ${\Delta}COPy$, COP area, APSI, VSI, DPSI) were similarly correlated with GRF components (PVF, loading rate) after fatigue was achieved (r = .600, $R^2$ = 37%). Conclusion: These results suggest that the induction of fatigue can decrease postural stability and exercise performance of Taekwondo athletes during training and competition sessions.

• Journal of the Korean Society of Physical Medicine
• /
• v.12 no.4
• /
• pp.39-46
• /
• 2017

PURPOSE: The effectiveness of the stretching to increase the range of motion of the joint, reduce the risk of injury, enhance athletic performance or decrease post exercise muscle soreness. This study was to compare the effect of the stretching method applied on the shortened hamstring muscle for flexibility, strength, pressure pain threshold value and muscle tone. METHODS: This study is a two-group pretest- posttest design. Fifty-four healthy young adults were randomly assigned to a vibration-assisted stretching group (VASG, n=27) or a static stretching group (SSG, n=27). Participants performed each stretch in 4 sets of 30 seconds each. A 30-second break time was provided between the sets. The range of motion, strength, pressure pain threshold values and muscle tone of the hamstring muscle were measured to compare the effects of the stretching methods. RESULTS: Both the VASG and the SSG participants showed significant improvement in the range of motion and strength (p<.05); however, the increase in the VASG was significantly higher than that in the SSG (p<.05). The pressure pain threshold values and muscle tone were significantly decreased only in the VASG (p<.05). CONCLUSION: These findings indicate that vibration-supported stretching is an effective intervention for people with hamstring shortening, with high pain level and muscle tone decrease.

• Journal of the Korean Society of Physical Medicine
• /
• v.11 no.4
• /
• pp.127-137
• /
• 2016

PURPOSE: This study aimed to compare the effects of side-lying hip abduction exercise with and without vibration on pain, disability, strength and balance in individuals with low back pain. METHODS: 30 participants enrolled in this study were randomly assigned to an experimental group (EG, n=15) for side-lying hip abduction with vibration and a control group (CG, n=15) for side-lying hip abduction without vibration. Both groups were treated 3 times per week for 4 weeks. Pain (Numeric Rating Scale), disability (Korean Oswestry Disability Index), hip abductor muscle strength, and static balance were measured in both groups before and after the program. Results were analyzed using paired t-test for comparing the difference within the group and independent t-test for comparing the difference between two groups. RESULTS: Compared to the CG, the EG showed significantly greater reductions in pain and disability (p<.05). There was a significant difference in all balance categories of both the painful and non-painful sides within the EG (p<.05). Balance showed a significant decrease except the envelope area (ENV) on the non-painful side within the CG (p<.05). There was a significant increase in all balance categories except ENV of non-painful side between the two groups (p<.05). Balance increased on both the painful and non-painful sides in the EG. Balance improved on the painful side in the CG, but significantly decreased on the non-painful side (p<.05). CONCLUSION: Side-lying hip abduction exercise with vibration is considered an effective treatment for pain, disability and balance in individuals with low back pain.

• Korean Journal of Applied Biomechanics
• /
• v.25 no.3
• /
• pp.257-263
• /
• 2015

Objective : The purpose of this study was to investigate the effect of genu valgum on the body mass index, movement of lower limb joints, and ground reaction force. Methods : Gait patterns of 30 college students with genu valgum were analyzed and the static Q angle of the femur was measured for selecting genu valgum of the subjects. To analyze the kinetic changes during walking, the six-camera Vicon MX motion analysis system was used. The subjects were asked to walk 12 meters using the more comfortable walking method for walking. After they walked 12 meters more than 10 times, their most natural walking patterns were chosen three times and analyzed. Results : As a result of measuring a relationship between genu valgum and Q-angle, as the Q-angle increases, it showed a genu valgum also increased. Body Mass Index showed a significant difference between the groups was higher in the genu valgum group.(p<.001). The analysis result showed that genu valgum had a significant effect on the internal rotation moment in the hip joint(p<.05). Also, genu valgum had a significant effect on the internal rotation moment of the knee joint(p<.05). The comparative analysis of the Medial-Lateral ground reaction force in the genu valgum group showed a tendency to increase the medial ground reaction force(p<.05). The vertical ground reaction forces of the middle of the stance phase(Fz0) showed a significant increase in genu valgum group(p<.05), in particular the results showed a decrease in the early stance phase(p<.001). Conclusion : In conclusion, the change in body mass is considered to be made by proactive regular exercise for improvement of the genu valgum. In addition, the prevention of the deformation caused by secondary of the genu valgum in this study may be used as an indicator of the position alignment rehabilitation for structural and functional improvements. Applying a therapeutic exercise program for the next lap will require changes in posture alignment.

• The Journal of Korean Physical Therapy
• /
• v.26 no.6
• /
• pp.430-435
• /
• 2014

Purpose: The objective of this study was a virtual reality-based balance training program effective for improvement in physical function, examined the balance ability and fall efficacy of elderly women with experienced falls, intending to examine the program's usefulness as an exercise program to prevent the recurrence of a fall. Methods: The participants were 30 elderly women aged 65 or older who met the conditions. The participants were randomly assigned to either a balance training group (BT) or a virtual reality-based balance training group (VT) and received the training three times per week, 30 minutes per day, for six weeks. To measure static balance, the Tetrax Portable Multiple System (Tetrax Ltd, Israel) were used. To measure dynamic balance, the Berg Balance Scale (BBS) and functional reach test (FRT) was used, and regarding fall efficacy, the Korean Fall Efficacy Scale (K-FES) was used. Results: Tetrax significantly improved after the intervention in both the BT group and the VT group (p<0.05). The comparison between the two groups was not significantly. BBS and FRT result significantly improved after the intervention in both the BT and VT groups (p<0.001), while K-FES was significantly ameliorated in the VT group only (p<.05). Comparing the groups, there were more significant changes in the BBS (p<0.05) and FRT (p<0.01) result of the VT group than the BT group. Conclusion: A virtual reality-based balance training program is considered to be usable as an exercise program to prevent recurrence of falls in elderly women.