• 한국전문물리치료학회지
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• 제12권1호
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• pp.63-70
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• 2005

To compare the effects of forward walking and backward walking on surface electromyographic analysis of quadriceps muscles at treadmill grades of 0%, 5% and 10%, subjects were randomized to eleven athletics (5 females, 6 males), with a mean age of 17.8 years, and a SD of 4.66 years. The values of the surface electromyographic (SEMG) activity of the rectus femoris (RF), vastus lateralis (VL) and vastus medialis oblique (VMO) were measured during forward walking and backward walking on a treadmill at grades of 0, 5 and 10%. The subjects walked for approximately 10 seconds at 4.0 km/h. The data were analyzed by repeated measuring of the two-way ANOVA and analyzed by a paired t-test between forward walking and backward walking. The SEMG activity levels of the RF, VL and VMO were the highest when both the forward walking and backward walking increased incrementally for treadmill grades of 0% to 10%, but the VMO/VL ratio had no significant changes. The SEMG activity levels of the RF, VL and VMO were significantly different between directions. However, SEMG activity levels of the RF, VL, VMO and VMO/VL ratio did not show significant difference among the treadmill grades. No statistically significant interactions were detected between the direction of walking and treadmill grade. Backward walking on the treadmill at 4 km/h and grades of 0%, 5%, 10% elicited a greater SEMG activity on the quadriceps muscles than did forward walking under the same conditions. The results suggest that the quadriceps may be effectively activated by performance at treadmill grades of 10%. This investigation confirms that backward walking up an incline may place additional muscular demands on individuals.

• 소음진동
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• 제6권6호
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• pp.819-825
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• 1996

Nonlinear dynamic characteristics of rubbing phenomenon in rotor dynamics are investigated experimentally and numerically. Rubbing phenomenon occurs when rotor contacts with stator during whirling and causes the large amplitude of vibration, high whirl frequencies, and possibly catastrophic failure. Rubbing has various types of forward whirl, backward rolling, backward slipping, and partial rub depending on the system parameters of rotating machinery and running speed. Experiments are performed for forward whirl and backward whirl. And numerical analysis are conducted to explain the changes between backward rolling and backward slipping. Experimental and numerical results show that the types of whirling motion depends on the friction coefficient between rotor and stator and the eccentricity of rotor.

• 한국전문물리치료학회지
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• 제27권3호
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• pp.185-190
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• 2020

Background: Backward walking exercise may offer some unique and potentially beneficial differences compared with forward walking exercise. There is still a lack of research on backward walking exercises and forward head posture. Objects: The purpose of this study was to determine the effect of backward walking exercise on college students forward head posture in their 20s. Methods: Twenty-one subjects participated in the experiment. The subjects were those with a craniovertebral angle (CVA) of 55 degrees or less who understood the purpose and method of this study and voluntarily agreed. A camera capable of taking pictures of the lateral plane was installed at a distance of 1.5 meters before exercising. Pictures were taken before walking backward, and after walking for 15 minutes on the treadmill, the images were taken in the same way. The composition of the backward walking exercise was walking at a rate of 1.0 for 5 minutes, and the remaining 10 minutes were walking at a rate of 1.5. Wilcoxon signed rank test was used to compare CVA and craniorotational angle (CRA) before and after exercise. Results: As a result of this study, there was a significant difference in CVA before and after exercise (p < 0.05). There was a significant difference in CRA before and after exercise (p < 0.05). Conclusion: The backward walking exercise and verbal command seems to have positively influenced the changes in CVA and CRA among college students in their 20s. It seems that studies to confirm balance or muscle activity as well as changes in forward head posture through the long-term intervention of the backward walking exercise should be conducted.

• 대한정형도수물리치료학회지
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• 제15권2호
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• pp.50-62
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• 2009

Purpose: to analyze and compare mucsle activity of Quadriceps femoris depending on the existence of taping while normal people walk forward and backward on treadmill when the slope and speed changes on treadmill. Method: Among 40 people who participated in this study, 20 experimenter who apply a taping walk forward and backward to 0%, 5%, 10% gradient per 2km/h and 4km/h using treadmill to give arbitrary walking behavior, 20 experimenter who doesn't apply a taping also walk forward and backward to 0%, 5%, 10% gradient per 2km/h and 4km/h using treadmill. To analyze muscle activity, We use an electromyography and Kinesio tape of good elasticity for obtained suffient effects in the experiment. Result: During backward walking in 2km/h, Vastus medialis and Vastus lateralis showed significant differences(p<0.05) when apply a taping. During backward walking in 2km/h, Vastus medialis and Rectus femoris, and Vastus lateralis all showed significant differences(p<0.05). During backward walking in 2km/h, Vastus medialis and Vastus lateralis showed significant differences in 10% gradient(p<0.05). During backward walking in 4km/h, Vastus medialis and Rectus femoris, and Vastus lateralis all showed significant differences(p<0.05). During backward walking in 4km/h, By the difference in slope, Vastus medialis and Vastus lateralis showed significant differences between 0% and 10% gradient(p<0.05). Conclusion: In comparison to muscle activity of Quadriceps femoris when apply a taping according to slope and speed during forward and backward walking on treadmill, when apply a taping and walk backward and 10% gradient on treadmill in 4km/h, maximum of muscle activity is shown.

• 한국운동역학회지
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• 제17권3호
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• pp.1-10
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• 2007

The purpose of this study was to examine the differences of lower limbs muscle activities depending on three walking speeds of 2.5km/h, 5.0km/h and 7.5km/h during forward walking and backward walking making 14 students the subjects of this study. To achieve this aim, surface electrodes for factor analysis of EMG were adhered to rectus femoris, biceps femoris, tibialis anterior and gastrocnemius medial head of right lower limbs. The conclusions through this study are as follows. 1) The muscle activity of rectus femoris was higher in backward walking group than in forward walking group and it was the highest at 7.5km/h walking speed. 2) The muscle activity of biceps femoris was higher in forward walking group than in backward walking group. It was the lowest at 5.0km/h walking speed and the highest at 7.5km/h walking speed. 3) The muscle activity of tibialis anterior was higher in backward walking group than in forward walking group. It was the lowest at 5.0km/h walking speed and the highest at 7.5km/h walking speed. 4) The muscle activity of gastrocnemius medial head was higher in backward walking group than in forward walking group except P2. It was the lowest at 5.0km/h walking speed and the highest at 7.5km/h walking speed.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2003년도 추계 학술대회논문집
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• pp.165-170
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• 2003

Centrifugal blowers are widely used for air handling units in industry applications. The blower has a centrifugal impeller and a scroll casing including a driving component such as an electric motor. The impeller takes forward or backward blades to induce flows into the blower. Comprehensive investigation according to the two kinds of blades is systematically carried out for a guidance of design. It is observed that flow rate of the blower with forward blades is larger than that of the system with backward blades. The reason is due to larger velocity from the rotating forward blades and the tendency is validated by a parallel experiment with a wind tunnel. Numerical analysis for the system shows detail information inside the blades and the casing. A series of figures to show the flow details offers deep understanding of a centrifugal blower with different blades.

• 대한물리치료과학회지
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• 제24권1호
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• pp.22-28
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• 2017

Purpose: The purpose of this study was to investigate the changes in the activity of the thigh muscle(rectus femoris, vastus medial/ lateralis, hamstring medial/lateralis) which are caused by the change cf lower extremity muscle activity to speed and inclination during forward and backward walking on the treadmill. Method: Twenty healthy young adults were recruited. The subjects were given a warm-up for 1 minute at the speed of 2.0km/h before exercise, and 2km/h to 4km/h from 10% to 4km/h in the frontal and backward walking. Result: In the present study, it was found that the muscle activity of the lateral broad and inward wide muscles increased when the treadmill was backward for 40 seconds without training. And the femur and the muscle were significantly different from 10% to 4km/h(p<.05). Conclusion: These findings suggest that in the treadmill, it is effective in increasing the leg strength in the backward walking than in the forward walking. And it was concluded that muscle activity increased at 4km/h when the speed was 2km/h when backward walking.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2003년도 The 8th Asian Symposium on Precision Forging ASPF
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• pp.162-166
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• 2003

In combined forward-backward extrusion with controlled forward speed by a counter punch, accurate parts with forward rod can be formed. As an extension of this method, reverse extrusion is proposed, in which the extruded forward rod is pushed back while the main punch is kept at the final position after the forward-backward extrusion process. The experiment is carried out using lead as a model material. With the reverse extrusion method, longer forward rods can be formed without under-filling defect than that by combined extrusion with controlling extrusion speed.

• 대한물리의학회지
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• 제11권3호
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• pp.1-9
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• 2016

PURPOSE: The purpose of this study was to identify the effects on flexibility of bridge and plank exercises using sling suspension on an unstable surface. METHODS: The subjects of this study were 20 healthy adults in their 20s (plank=10, bridge=10). Both types of exercise were performed three times per week for a period of four weeks. Each exercise was performed in the front and side direction. Exercise intensity was altered through the use of a sling, which was placed at the knee and ankle. Flexibility at trunk forward flexion and backward extension was measured. The trunk forward flexion was measured at sitting position. The trunk backward extension was measured at prone position. The data were analyzed by Two-way ANOVA. RESULTS: There were significant differences in the pre- and post-test for both the bridge and plank exercise groups. In the bridge exercise, significant differences were shown in the trunk forward flexion and the trunk backward extension (p<.05). In the plank exercise, a significant difference was shown in the trunk backward extension (p<.05). No significant differences were noted in interaction effect or the main effects in either group. CONCLUSION: Bridge and plank exercises on an unstable surface improve flexibility. The bridge exercise improves the flexibility of the forward and backward muscles of the trunk. The plank exercise improves the flexibility of the forward muscles of the trunk. This information would be useful in the development of exercise programs including bridge and plank exercises for improving flexibility and core stability.

• 대한치과교정학회지
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• 제14권1호
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• pp.161-172
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• 1984

This study was undertaken to evaluate the cephalometric changes of the soft tissue and skeletal profile subsequent 10 the rapid palatal expansion in 25 Angle's Class III cases, ranging in age from six to fifteen years, with cross-bite of the anterior teeth, underdevelopment of maxilla and facial disharmony Following results were obtained: 1. ANS moved downward, Point A presented forward & downward movement increasing SNA and Point B presented backward & downward movement decreasing SNB. 2. Mandible was rotated to backward & forward and maxilla moved forward & downward with the bite opening and improvement of anterior teeth cross-bite. 3. Soft tissue on mandible was rotated to backward & forward following hard tissue changes causing the decrease of facial convexity angle and backward & downward rotation of Point B', Pog'. 4. Response of the upper lip was more significant in downward than forward direction, and correlated with the upper central incisor and mandible rotation. 5. Response of the lower lip was more significant in downward than backward direction, and correlated with the mandible rotation. 6. There was a rather high degree of correlation between skeletal profile and soft-tissue profile, 1 : LS, $\bar{1}$:Pog', Pog:LS, Pog:LI, Pog:Pog' in horizontal measurements and $\bar{1}$:Pog', Pog:LI, Pog:Pog' in vertical measurements.