• 한국운동역학회지
• /
• 제21권1호
• /
• pp.47-55
• /
• 2011

The purpose of this study was to perform a kinematic analysis of Harai-goshi(hip throw) in superior female judo players. From our analysis, it appeared desirable for the player to shorten the duration of the technique for maximum results. It was also desirable for the player to draw the opponent backward while simultaneously maneuvering her close to her own body. A turning movement of the body toward the left side was found to be required for the technique, during which the player must lower the position of the center of gravity. During the subsequent angular change of the elbow, the player winds the elbow and, by moving the left shoulder, pulls the opponent toward her. The player lowers the body center by bending the left knee and letting the right knee extend, while turning the upper body and bending the hip joint. The player then draws the opponent in, contacts the opponent closely, turns, and stretches the right knee and hip joint rapidly and concisely, completing the move; it was also found to be desirable for the angular velocity to be increased for maximum efficacy.

• 대한정형도수물리치료학회지
• /
• 제18권2호
• /
• pp.23-29
• /
• 2012

Background: The present study was conducted with 30 adult males in order to examine the muscle activity of the trunk and the lower extremities at diverse initial bending angles of the hip joint during bridge exercise on a stable surfaces and on an unstable surface that is widely performed for stabilization. Methods: The initial angles of the hip joint used were $0^{\circ}$, $45^{\circ}$ and $90^{\circ}$ and the subjects were divided into a matt experimental group and a balance training group. Results: In maximum values of muscle activity at different exercise methods and angles, the matt experimental group showed statistically significant differences in the muscle activity values of the rectus abdominis muscle, the erector spinae muscle, the rectus femoris muscle and the peroneus muscles between different angles while the balance training group showed significant differences only in the muscle activity values of the erector spinae muscle between different initial angles of the hip joint. The matt experimental group showed significant differences in muscle activity between initial angles $0^{\circ}$ and $90^{\circ}$, between $45^{\circ}$ and $90^{\circ}$ in the rectus abdominis muscle, between $0^{\circ}$ and $90^{\circ}$ in the erector spinae muscle, between $45^{\circ}$ and $90^{\circ}$ in the rectus femoris muscle and between $0^{\circ}$ and $90^{\circ}$ in the peroneus muscles while the balance training group showed significant differences between $0^{\circ}$ and $90^{\circ}$ in the erector spinae muscle. Conclusions: Therefore, it is thought that bridge exercises should be applied to patients using diverse methods.

• 한국운동역학회지
• /
• 제13권2호
• /
• pp.49-63
• /
• 2003

For this study, four male university Taekwondo players were randomly chosen, between the weight categories of 60Kg and 80Kg. Their side kicks (yeop chagi), which are part of foot techniques, were kinematically analyzed in terms of the time, angle, and angular velocity factors involved with the kicks through the three-dimensional imaging. The results of the analysis are as fellows. 1. Time factor The first phase(preparation) was 0.48sec on average, accounting for 60% of the entire time spent; the second phase(the minimum angle of the knee joint) was 0.21sec on average, taking up 26% of the whole time spent; and the third phase(hitting) was 0.11sec on average, representing 14% of the entire time spent. 2. Angle factor In the first phase(preparation), rotating their bodies along the long axis, the players bended their hip and knee joints a lot, by moving fast in the vertical and horizontal directions, in the second phase(the minimum angle of the knee joint), the players continued to extend their bodies along the vertical axis, while pronating their lower legs and bending their hip and knee joints a lot to reduce the radius of gyration, and in the third phase(hitting), they extended their knee joints greatly so that the angle movements of their lower bodies shifted to circle movements. 3. Angular velocity factor In the first phase(preparation), the angular velocity of the hip and knee joints increased. while moving horizontally and rotating the body along the long axis; in the second phase(the minimum angle of the knee joint), the angular velocity increased by bending the hip and knee joints fast to reduce the rotation radios; and in the third phase(hitting), the angular velocity was found to have increased, by rotating the body along the long axis to increase the angular velocity and shifting the angular momentum of the pronated knee joint to the circular momentum.

• PNF and Movement
• /
• 제21권3호
• /
• pp.281-289
• /
• 2023

Purpose: This study investigated the effects of the non-elastic taping method for controlling internal hip joint rotation on internal and external hip rotator muscle activity in healthy people. Methods: In this study, 18 healthy volunteers were instructed to perform the small knee bending (SKB) test. All participants completed the test following two methods (using non-elastic taping and not using taping). Muscle activation during the two methods was measured using a surface electromyography (EMG) device. Surface EMG data were collected from the gluteus medius, gluteus maximus, and tensor fasciae femoris muscles while performing the SKB test with and without non-elastic taping. Results: Muscle activity in the gluteus maximus was significantly higher during the SKB test with non-elastic taping than during the conventional SKB test with taping (p < 0.05). Tensor fasciae latae muscle activity was lower during the SKB test with non-elastic taping than during the conventional SKB test (p < 0.05). Conclusion: The findings suggest that the non-elastic taping method for controlling internal hip joint rotation effectively activates the hip's external rotator muscles and minimizes unwanted internal rotator muscle use during the SKB test. Therefore, the non-elastic taping method for controlling internal hip joint rotation could be an effective intervention for those who cannot control the internal rotation of their hips.

• 한국복합재료학회:학술대회논문집
• /
• 한국복합재료학회 1999년도 추계학술발표대회 논문집
• /
• pp.234-238
• /
• 1999

This study suggests the design of the functionally gradient composite, [0/90/0/core]$_s$ cross-ply laminate, to prevent stress concentration induced from the difference of rigidity between the bone and the artificial hip joint and to reinforce the wear property of the surface and the expectation of their mechanical properties. First, the four-point bending test is done about wet bones and dry bones to know the mechanical properties of the cortical bones. In result, the wet bone shows the viscoelastic behavior and the dry bone shows the elastic behavior. Moreover, we expect the properties of the proposed gradient composites as a function of carbon fiber volume fraction in each layer to apply Halpin-Tsai equation, CLPT(classical laminate plate theory), and Bernoulli beam theory etc. and decide the thickness ratio of each lamina in order to match Young's modulus of the anisotropic cortical bone with the proposed gradient composites.

• KEPCO Journal on Electric Power and Energy
• /
• 제7권2호
• /
• pp.269-275
• /
• 2021

The turbine rotor, one of the main facilities in a power plant, it generates electricity while rotating at 3600 RPM. Because it rotates at high speed, it requires careful management because high vibration occurs even if it is deformed by only 0.1mm. However, bending occurs due to various causes during turbine operating. If turbine rotor bending occurs, the power plant must be stopped and repaired. In the past, straightening was carried out using a heating torch and furnace in the field. In case of straightening in this way, it is impossible to proceed systematically, so damage to the turbine rotor may occur and take long period for maintenance. Long maintenance period causes excessive cost, so it is necessary to straighten the rotor by minimizing damage to the rotor in a short period of time. To solve this problem, we developed a turbine rotor straightening equipment using high-frequency induction heating equipment. A straightening was validated for 500MW HIP rotor, and the optimal parameters for straightening were selected. In addition, based on the experimental results, finite element analysis was performed to build a database. Using the database, a straightening amount prediction model available for rotor straightening was developed. Using the developed straightening equipment and straightening prediction model, it is possible to straightening the rotor with minimized damage to the rotor in a short period of time.

• 대한기계학회:학술대회논문집
• /
• 대한기계학회 2001년도 춘계학술대회논문집A
• /
• pp.932-938
• /
• 2001

This study is concerned with the shape optimization of stem for the artificial hip prosthesis with unbonded cement mantle. The artificial hip prosthesis with unbonded cement mantle allows a stem to slip on cement mantle because of polished stem surface. Unbonded cement mantle type has several advantages compared with bonded cement mantle type, for example, small micro motion, preventing stress shielding and so on. In this study, 2-dimensional axisymmetric model was developed with considering characteristics of unbonded cement mantle. Moreover, optimal shape of stem was obtained by using feasible direction method. The objective of this optimization is maximizing supported vertical loading. The slip motion and stresses of stem, cement mantle and bone is used for constraints. The optimal shape which obtained by this study has slope of 0.15 in proximal part and maintains the width about 5mm in distal part In addition, simplified 3-dimensional analysis which applying optimal shape is carried out. The result of 3-dimensional analysis showed that optimal shape has some advantages for cement mantle stress. However, more realistic 3-dimensional analysis which including bending effect, complex geometries etc. is needed in further research.

• Physical Therapy Rehabilitation Science
• /
• 제11권2호
• /
• pp.259-268
• /
• 2022

Objective: The purpose of this study was to measure the immediate effect of hip hinge exercise stretching on hamstring flexibility, pelvic tilting angle, proprioception, and dynamic balance in individual with tightness of the hamstring. Design: A randomized controlled trial. Methods: A total of 35 healthy young adults (27 males, 8 females) volunteered for this study and randomly divided into three groups (Hip hinge exercise stretching group, passive stretching group, and PNF stretching group). The hamstring flexibility, pelvic tilting angle, knee joint proprioception, dynamic balance was conducted for 3 times. In order to evaluate the hamstring flexibility, the active knee extension test was performed. Forward bending test was performed to examine pelvic tilting angle.The proprioception was tested by the joint position sense test and dynamic balance was evaluated by Y balance test. Results: The hamstring flexibility, pelvic tilting angle and dynamic balance were significantly improved between three groups before and after intervention (p<0.05). Dynamic balance was significantly difference between the three groups in the posterolateral direction (p<0.05). Conclusions: This study result showed that hip hinge exercise stretching was the most effective method for increasing hamstring flexibility, pelvic tilting angle and dynamic balance. In addition, it is necessary to study whether hamstring stretching is effective in low back pain patient with hamstrings tightness.

• 국제물리치료학회지
• /
• 제7권2호
• /
• pp.1051-1055
• /
• 2016

The purpose of this study was to investigate the effect of the screen size of smart devices on the bending angle of the cervical spine. The subjects of this study were 30 healthy adults(15 men and 15 women) who used smartphones and tablet PC(personal computer). The changes in the bending angle of the upper and lower cervical spine were measured in the subjects after they had used a smartphone and a tablet PC for 300 seconds each. To make sure that all subjects began in the same starting position, an angle-measuring instrument was used to set the angles of the ankle, knee, hip, and arm joints to 90 degree. The subjects were asked to keep the trunk straight. They were asked to hold a smartphone in their hand and to bend their neck so that they could look down at the screen. Once they began using the smartphone in this manner, they were free to change their posture. We used a paired t-test to compare the bending angle of the cervical spine on subjects who used smartphones and tablet PC in the long-term and short-term there production error of cervical and the significance level was cervical. The results showed that, when using a smartphone and a tablet PC for 300 seconds, there was no significant difference in the bending angle of the upper cervical spine(p>.05), although there was a significant difference in the bending angle of the lower cervical spine(p<.05).

• 대한정형도수물리치료학회지
• /
• 제15권2호
• /
• pp.63-68
• /
• 2009

Purpose : The purpose of this study was to investigate the effect of tensor fasciae latae length on the rotation of pelvis during one leg stance. Methods : 41 healthy adults participated in this study. The movement of the pelvis and trunk was measured using 3-dimensional motion analyzer, during one leg stance. The movement of the pelvis and trunk was collected lateral shift, rotation, side bending, and flexion-extension. Tensor fasciae latae length of subjects was measured in sidelying positon with neutral position of hip joint and flexion $90^{\circ}$ of knee. Also, the range of motion of hip exteral and interal rotaion were measured in prone position wih lexion $90^{\circ}$ of knee. The subjects were separated 2 groups that more pelvic rotation group(n=15) and less pelvic rotation group(n=15) according to the degree of pelvic rotation. Results : The more pelvic rotation group was showed significantly higher in the ROM of hip external rotation than less pelvic rotation group(p<0.05). The difference of tensor fasciae latae length not showed significant difference between groups. During one leg stance, The movement of the shifting and flexion-extension of trunk and pelvis were not showed significant difference. But the side bending and the rotation of pelvis and trunk showed significant difference between groups. Conclusion : The difference of tensor fasciae latae length not showed significantly in more pelvic rotation group and less pelvic rotation group. But, this study suggests that the pelvis instability brings the instability of the trunk during one leg stance.