• Journal of the Korean Society of Safety
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• v.29 no.4
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• pp.153-159
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• 2014

Low back pain is one of major issues in musculoskeletal diseases mainly caused by MMH (Manual Material Handling) tasks. In Korea, the standards of NIOSH(National Institute for Occupational Safety and Health) Lift Equations in U. S. A. have been most widely used. However, there is no standard in case the height of one feet is higher than that of another one. Moreover, since the standards are developed in U. S. A., there are many limitations for the applicability of Korean workers. In this study, MVC(Maximum Voluntary Contraction) for four postures are measured and an empirical model based on SVR(Support Vector Regression) is constructed. Constructing SVR model, PSO(Particle Swarm Optimization) is employed to investigate the optimal parameters of SVR. The results show that the performance of this empirical model is approximately accurate, even if the deviation of experimental values is large due to the individual differences. This empirical model may contribute to establish the standards of MMH tasks in Korea.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.66 no.12
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• pp.1815-1820
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• 2017

In this paper, a study was conducted to estimate the maximum muscle strength which is a standard for selecting exercise intensity in weight training. We designed a device that estimates the muscle fatigue from the EMG signal, expecting to show a correlation between peak muscle strength and fatigue. Curl - Dumbbell was performed using a 4 kg dumbbell and the frequency change of the EMG was observed. At this time, the designed device acquires the signal using the MCU and finally Matlab was used to confirm the change in the center frequency value. The results of 10 subjects were analyzed using SPSS regression analysis. The statistical results showed a correlation of $R^2$ 0.583 and Significant probability of 0.010, and the relation of Y = 8.144-2.097 (slope (MDF)) was obtained. In conclusion, if the wearable device is manufactured in the form of a wearable device and the user can recommend the exercise intensity, the system will be able to retry the more efficient exercise.

• Korean Journal of Applied Biomechanics
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• v.23 no.2
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• pp.149-157
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• 2013

In the present study, we aimed to elucidate how muscle strength and activity are affected by movement pattern(bilateral [BLM] & unilateral movement [ULM]) and movement velocity($0^{\circ}$/s, $60^{\circ}$/s, $120^{\circ}$/s) at maximum effort, and to elucidate the relationship between a left/right asymmetry and bilateral deficit. A total of 18 healthy males participated in the study. Each participant performed maximum knee extension bilaterally and unilaterally while the EMG and moment were recorded, and then the relationships between the asymmetry and bilateral deficit were analyzed. The peak moments for the isokinetic motion at $60^{\circ}$/s and $120^{\circ}$/s and overall muscle activities of lower extremity were significantly reduced for the BLM in comparison to the ULM. And though the asymmetry in ULM were maintained during BLM at all velocities, the bilateral deficits at the velocity of $0^{\circ}\acute{y}$/s and $120^{\circ}\acute{y}$/s were significantly correlated with increased asymmetries of muscle strength in ULM. In conclusion, the reduction in the muscle strength exhibited in bilateral knee extension was shown to arise partially from a reduction in muscle activity, and left/right asymmetry was found to be associated with mechanical reduction in bilateral movement. These findings suggest that training aimed at increasing muscle strength must involve methods and strategies intended to reduce left/right asymmetry.

• Journal of the Korean Society of Physical Medicine
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• v.16 no.1
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• pp.73-81
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• 2021

PURPOSE: This study examined effects of the untact trunk stabilization exercise program on muscle thickness, trunk strength, maximal expiratory flow, and static balance. METHODS: The subjects were 20 normal adults divided into 10 in the contact exercise group and 10 in the untact exercise group. The trunk stabilization exercise program was conducted for four weeks. The muscle thickness was measured using ultrasound. The maximal expiratory flow was measured using Personal Best Full Range Peak Flow Meter. The static balance was measured through Bio-rescue; and the trunk muscle strength was measured by bending the upper body forward and measuring the time for maintaining the posture. RESULTS: Both contact and untact exercise groups showed significant differences in muscle thickness, muscle strength, maximal expiratory flow, and static balance (p < .05). A significant difference in muscle thickness on ultrasound was observed between the contact and untact exercise groups (p < .05). CONCLUSION: Activation of the transverse abdominal muscle requires accurate instructions of the contact exercise, but despite environmental constraints, the untact exercise program is as effective as the contact exercise for improving muscle strength, maximum expiratory flow, and static balance.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.10
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• pp.506-514
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• 2018

This study was conducted to investigate the relationship between hand grip strength and cardiopulmonary fitness in patients with myocardial infarction. In this retrospective study, 67 patients who experienced myocardial infarction for 10 months were analyzed. Hand grip strength was measured using a handheld dynamometer. Dynapenia was diagnosed based on a dominant hand grip strength of less than 30 kg for males and 20 kg for females. A cardiopulmonary exercise test was performed using a treadmill. Physical activity status was also evaluated. Cardiorespiratory fitness parameters were analyzed using a t-test and a Mann-Whitney test. VO2max, METmax, and exercise time significantly decreased in the dynapenia group compared with the non-dynapenia group. Correlation analysis revealed that dominant handgrip strength was significantly related to cardiorespiratory fitness parameters. Moreover, VO2max, METmax, and exercise time were significantly increased in patients with vigorous activity compared with the sedentary group. These findings indicate that handgrip strength could potentially be used as a marker of cardiorespiratory functions. Accordingly, patients with myocardial infarction should be evaluated for grip strength and physical activity, and we can encourage patients to participate actively in cardiac rehabilitation.

• Journal of Internet Computing and Services
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• v.14 no.6
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• pp.33-39
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• 2013

When the eldery with limited mobility and disabled use a wheelchairs to move, it can cause decreased exercise ability like decline muscular strength in upper limb and lower extremities. The disabled people suffers with spinal cord injuries or post stroke hemiplegia are easily exposed to secondary problems due to limited mobility. In this paper, We designed intelligent wheelchair robot system for upper limb and lower extremities exercise/rehabilitation considering the characteristics of these severely disabled person. The system consists of an electric wheelchair, biometrics module for Identification characteristics of users, upper limb and lower extremities rehabilitation. In this paper, describes the design and configurations and of developed robot. Also, In order to verify the system function, conduct performance evaluation targeting non-disabled about risk context analysis with biomedical signal change and upper limb and lower extremities rehabilitation over wheelchair robot move. Consequently, it indicate sufficient tracking performance for rehabilitation as at about 86.7% average accuracy for risk context analysis and upper limb angle of 2.5 and lower extremities angle of 2.3 degrees maximum error range of joint angle.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.33 no.2
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• pp.146-156
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• 1988

This study was carried out to investigate the change of endosperm substance and seedling growth in rice seedlings for machine transplanting with use of two rice varieties, which Samgangbyeo (Indica${\times}$Japonica) and Dogjinbyeo (Japonica) were sown on May 8 with five levels of seeding density. 1. The total dry matter weight, leaf area, length of the longest root, number and length of new roots were negatively correlated with seeding density, and the plant height had the similar tendency to them from 20 days after sowing(DAS). 2. The rooting ability was negatively correlated with seeding density and decreased from 35 DAS in Dongjinbyeo. 3. The endosperm substance were exhausted at 25 to 30 DAS in Samgangbyeo and at 25 DAS in Dongjinbyeo. 4. The leaf area was more useful than the ratio of plant height to dry matter weight for judging the constitution of seedlings. 5. The reducing sugar contents in the endosperm were the greatest among parts of rice seedlings followed by leaf and root. The contents in leaf, root and endosperm reached maximal at 10 DAS, and varied with plant parts, seedling growth and varieties in different levels of seeding density. 6. The protein contents in leaf and root of rice seedlings became decreased with seedling growth., and were minimal values at 15 DAS. The content in endosperm was decreased soon after seeding, and minimal at 4 DAS with showing some fluctuation of protein content after then.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.8
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• pp.190-199
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• 2017

The purpose of this study is to propose the standard of health-related fitness evaluation according to the working styles of male manufacturing workers. The subjects were 15,329 male manufacturing workers aged from 40 to 59 years old who had taken a health-related fitness test by K Institution. Health-related fitness components are cardiorespiratory endurance, muscular strength, muscular endurance, flexibility and body composition. We measured Vo2max, grip strength, sit-up, trunk flexion forward, and body fat percentage to ascertain each component. Data were analyzed with Two-way ANOVA, T-test, One-way ANOVA(Scheffe) and Percentile using SPSS version 18.0 program. The analysis results are as follows. First, the health-related fitness of manufacturing workers varied significantly according to their working styles(maximum oxygen uptake : F=88.67(p<.001), grip strength : F=20.09(p<.001), sit-up : F=42.06(p<.001), trunk flexion forward : F=69.44(p<.001), body fat percentage : F=136.75(p<.001)).Therefore, the evaluation standard was set based on the percentile of health fitness items. Second, the average Vo2max, grip strength, and trunk flexion forward of blue-collar workers were higher than those of white-collar workers at all ages. On the other hand, the average sit-up and body fat percentage of white-collar workers were higher than those of blue-collar workers at all ages. Third, these evaluation criteria differed greatly when compared with the results of the National Physical Fitness Survey. Therefore, we have confirmed that the evaluation criteria should be applied differently according to the working style of a worker when evaluating his health-related fitness.

• Korean Journal of Applied Biomechanics
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• v.19 no.3
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• pp.539-547
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• 2009

The purpose of this study was to investigate the changes of kinetic and kinematic parameters in obstacle gaits after 12 weeks of an aquatic exercise program. Eight female elders walked in four different heights of obstacles(0, 2.5, 5.1, & 15.2cm) on their self-selected speed. The ROM of hip was significantly increased after the aquatic exercise program. Swing and Stance duration were decreased. The step length was significantly increased and the step width was decreased. After the exercise program the clearance between the right foot and the top of obstacle(except 15.2cm) increased and the crossing speed was increased. The braking force, propulsive force, braking impulse, and propulsive impulse were significantly changed after the aquatic exercise program. The 12 weeks of the aquatic exercise program resulted in lower body strength and balance gains in female elders. The improvements were associated with changes in kinetic and kinematic parameters leading to an obstacle-crossing speed and a safer lower-limb control. The aquatic exercise program is suggested as an effective intervention to promote gait ability and prevent fall-related to the injuries.

• Journal of the Korean Society of Physical Medicine
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• v.10 no.4
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• pp.101-106
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• 2015

PURPOSE: Application of an oscillating program for the lower extremities is an effective training method for increasing muscle strength. However, no oscillatory program has yet been identified to confirm the effectiveness of oscillation for balance ability and maximum muscle strength. We investigated the effects of an 8-week vibration exercise program on the maximum muscle strength and balance of the lower extremities. METHODS: Research subjects participating in the study were 22 male and female college students with no past history of diseases of the nervous or musculoskeletal systems. All subjects were randomly divided into two groups and performed their assigned experimental treatment 3 times a week over a period of 20 min for 8 weeks. Maximum strength of the quadriceps extension, flexion, and balance ability were measured using Biodex System 4 and Biodex balance systems. RESULTS: The 8-week oscillation program resulted in a significant increase in quadriceps extension and flexion strength in both male and female participants (p<.05). The balance ability also showed a significant improvement after the oscillation program (p<.05). The balance value was higher for male 17% than for female 21% (p<.05) participants. CONCLUSION: An 8-week oscillation program led to an increase in the strength of knee flexion and extension. The balance ability also improved significantly. This positive effect on balance ability was higher in female than in male subjects.