• 한국운동역학회지
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• 제17권2호
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• pp.217-226
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• 2007

Putting score counts about 43 % of the golf score. The dominant idea of the putting motion to amateur golfers as well as to many professional golfers is a pendulum-like motion. If a golfer's putting stroke motion is a pendulum-like motion, the putting motion should be straight-back-and-through, the same backswing, downswing, and follow through length and period, and a swing with a fixed hinge joint. If the putting motions of the human are different from the pendulum motion, there could be confusion in understanding and teaching golf putting. The purpose of this study was to examine the center of rotation(COR) of the putter head to reveal whether professional golfers really putt like a pendulum. Thirteen male professional golfers were recruited for the study. Each golfers executed 10.94 m putts six times on an artificial grass mat. Putter head position data were collected through a 60 Hz three-dimensional motion analysis system and low pass filtered with cut-off frequency of 6 Hz. COR of the putter head was mathematically acquired. Each golfer's last five putting motions were considered. The results show that the COR of the putter head was neither fixed nor located inside of the golfer. The medio-lateral directional component of the COR of the putter head fluctuated in the range of 10 cm during downswing and follow through. The anterior-posterior directional component of the COR of the putter head was fixed from the beginning of the downswing through impact. Just after impact, however, it moved to the target up to 60 cm. The superior-inferior directional component of COR of the putter head moved in a superior direction with the beginning of the downswing and showed peak height just prior to impact. During the follow through, it moved back in an inferior direction. The height-normalized peak value of the COR of the putter head was $1.4{\pm}0.3$ height. Technically speaking, male professional golfers' 10.94 m putting motion is not a pendulum-like motion. The dominating idea of a pendulum-like motion in putting might come from the image of the flawless, smooth motion of a pendulum.

• 한국군사과학기술학회지
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• 제13권5호
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• pp.717-724
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• 2010

The initial trajectory of a spheroid configuration bobbin for precision guidance has been investigated by analyzing its aerodynamic load and six-degree-of-freedom motion. The effects of changes in the spheroidal head configuration, flow angle and lateral center-of-gravity offset are numerically studied using the commercial software "FLUENT". A wind tunnel test is also conducted to validate the numerical scheme and to examine effect of the Reynolds number on the flow around the bobbin. It is shown that the size of the separation bubble formed on the surface decreases significantly when the Reynolds number is varied between 110,000 and 140,000. At a zero flow angle, an oblate spheroidal head shows relatively moderate rotation while a prolate spheroidal head shows rapid rotation. The bobbin with a spherical head shape has little effect on the flow direction; however, the oblate bobbin is sensitive to the flow angle. The roll motion of the bobbin is greatly influenced by the lateral center-of-gravity offset and maximum dispersion is observed at half of the radius.

• 한국운동역학회지
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• 제32권4호
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• pp.147-152
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• 2022

Objective: The purpose of this study was to analyze the effects of club head and golf ball kinematics and body alignment according to the swing plane during golf driver swing. Method: Sixteen college golfers participated in this study. Kinematic data of the club head and golf ball were collected using golf swing analysis system (Trackman Ver. 3e). The body alignment variables were collected using 8 motion capture system. An Independent samples t-test was used for comparison between the Out-to-In group and In-to-Out group, and the statistical significance level was set at .05. Results: For the club head related variables, club path and club face angle showed higher values in Out-to-In swing plane than In-to-Out swing plane. For the kinematic variables of the golf ball, the total distance showed a higher value in the In-to-Out swing plane than that of the Out-to-In swing plane. For the body alignment, the In-to-Out swing plane showed higher values than the Out-to-In swing plane for the pelvis rotation angle and trunk rotation angle. Conclusion: This study suggest that it would be more effective to use the In-to-Out swing plane for increasing the total distance during the golf driver swing.

• 한국운동역학회지
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• 제15권3호
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• pp.153-159
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• 2005

The purpose of this study was to investigate the Effective X-Factor in golf swing. The term X-Factor means the relative rotation of shoulders with respect to hips during the golf swing. To ascertain the Effective X-Factor that resulted in a high club head speed at impact six golfers' swing motions were videotaped and analyzed using three-dimensional techniques. The results can be summarized as follows. The standard deviations of the professionals' average club head speeds were higher than the amateurs'. This means that the professionals' swing skills were better than amateurs' in driving accuracy and consistency. As the club head speeds were increased gradually the X-Factors and the club head speeds had reached to the subjects' average club head speeds, but the X-Factors and the club head speeds were not increased above the subjects' average club head speeds. The X-Factor Stretch early in the down swing was existed and Professional stretched values were higher than the amateurs. In conclusion my research results suggested that the increase in Effective X-Factors had no relationship to the increase in club head speeds.

• The Journal of Korean Physical Therapy
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• 제8권1호
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• pp.65-78
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• 1996

This study wan described the movement patterns when rising from supine to erect stance in the third through eighth decades. Two hundred fifty six subjects, ranging in age from 30 year to 89 were filmed while rising from a supine position. Movement patterns were classified using categorical descriptions of the action of the upper and lower extremity, head-trunk region. This study was designed to determine whether within the rising task the movement patterns of different regions of the body vary with age level and sex, to describe time by subjects to perform this task. The incidence of each movement pattern was calculated and graphed wi th respect to age level and sex. Erect standing time was increased by age increasing in beth sex group. The most common form of rising for subject in the third through fifth decades both sex usually involved symmeytrical push with upper extremity, symmetrical squat pattern with lower extremity, partial rotation pattern wi th head-trunk and symmetrical push to push and reach pattern with upper extremity, symmetri cal squat pattern with lower extremity. partial rotation with head-trunk. In the sixth through eighth decades usually involved symmetrical push to push and reach pattern with upper extremity, symmetrical squat pattern with lower extremity, partial rotation pattern with head-trunk in both sex group.

• 대한치과교정학회지
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• 제43권6호
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• pp.263-270
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• 2013

Objective: To evaluate condylar head remodeling after mandibular set-back sagittal split ramus osteotomy (SSRO) with rigid fixation in skeletal class III deformities. The correlation between condylar head remodeling and condylar axis changes was determined using cone-beam computed tomography (CBCT) superimposition. Methods: The CBCT data of 22 subjects (9 men and 13 women) who had undergone mandibular set-back SSRO with rigid fixation were analyzed. Changes in the condylar head measurements and the distribution of the signs of condylar head remodeling were evaluated by CBCT superimposition. Results: The subjects showed inward rotation of the axial condylar angle; reduced condylar heights on the sagittal and coronal planes; and resorptive remodeling in the anterior and superior areas on the sagittal plane, superior and lateral areas on the coronal plane, and anterior-middle and anterior-lateral areas on the axial plane (p < 0.05). Conclusions: The CBCT superimposition method showed condylar head remodeling after mandibular set-back SSRO with rigid fixation. In skeletal class III patients, SSRO with rigid fixation resulted in rotation, diminution, and remodeling of the condylar head. However, these changes did not produce clinical signs or symptoms of temporomandibular disorders.

• The Journal of Korean Physical Therapy
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• 제13권3호
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• pp.769-776
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• 2001

This study were to review of muscle imbalance of head, cervical and shoulder region. Head, cervical and shoulder region is a complicated mechanical unit. interconnected by numerous soft tissue links. These links, or articulation are functionaly and reflexly interdependent on one another. The line of gravity falls anterior to the transverse axis of rotation for flexion and extension of the head and creates a flexion moment. which tends to tut the head forward, is counteracted by tension in the tectorial membrane, and ligamentum nuchae, and by activity of the neck extensors. Therefore, the flexion moment equilibrate with the extension moment. Changing of the equilibrium will make mid cervical straight. It will make forward head posture(FHP) also. FHP makes imbalance of suboccipital muscles, suprahyoid muscles and infrahyoid muscles. It has some relationship with temporomandibular joint, spine and equilibrium of pelvis.

• 대한물리의학회지
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• 제11권4호
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• pp.1-9
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• 2016

PURPOSE: The aim of this study was to examine the effects of abdominal breathing and thoracic expansion exercises on craniovertebral and cranial rotation angles in patients with rotator cuff injury. METHODS: This study enrolled 19 patients with rotator cuff injury, and ten and nine of the patients were randomly placed in abdominal breathing and thoracic expansion exercise groups, respectively. After pain treatment in each group, breathing exercise was conducted thrice a week for four weeks. The patients were recorded by using a digital camera and Image J (version 1.46, National Institutes of Health, USA), an angle measurement program, was used to analyze changes in the craniovertebral angle, cranial rotation angle, and sagittal shoulder posture. RESULTS: Statistically significant differences in the craniovertebral angle were found in both the abdominal breathing and thoracic expansion exercise groups (p<.05). A significant difference in cranial rotation angle was found in the thoracic expansion exercise group only (p<.05). No statistically significant differences in sagittal shoulder posture were found in both groups (p>.05). CONCLUSION: Although abdominal breathing and thoracic expansion exercises did not effectively change sagittal shoulder posture, the exercises were effective in improving craniovertebral and cranial rotation angles. Therefore, abdominal breathing and thoracic expansion exercises are suggested as effective exercise programs for forward head posture.

• 한국자동차공학회논문집
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• 제12권6호
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• pp.1-8
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• 2004

In this paper we present the effects that valve train design parameters and operating conditions have on the valve rotation properties of a diesel engine. Rotation of intake and exhaust valves are very closely related to the long term durability of diesel engines. of the valves do not rotate even at a rated engine speed, it causes the uneven wear of the valve seat and valve head contact area, which eventually shortens the engine life. Because the rated speed of a diesel engine is relatively lower than that of a gasoline engine, the operating condition of a diesel engine produces tough environment for valve rotation. Therefore, the valve rotation is an important problem which should be solved in the early stage of engine development. In this study, we developed a new technique to measure the valve rotation and shaking motion simultaneously using three proximity sensors. Valve train rotating properties of a diesel engine were measured under various engine operating conditions.

• 대한정형도수물리치료학회지
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• 제19권2호
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• pp.11-18
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• 2013

Background: The objective of this study was to compare the efficacies of thoracic self-mobilization and strengthening exercise in young adults with thoracic hyperkyphosis. Methods: The subjects were 30 young adults (11 males, 19 females) with thoracic hyperkyphosis. They were randomly assigned to one of three groups: thoracic self-mobilization, thoracic strengthening exercise, and control group. The thoracic self-mobilization group performed active dynamic exercises, which included thoracic extension and rotation in supine and standing positions. The strengthening exercise group performed resistance exercises involving the back extensor muscle, with an elastic band and dumbbells. The outcome measures were the thoracic kyphosis angle and forward head posture (craniovertebral angle [CVA] and cranial rotation angle [CRA]). Results: Compared with the baseline values, the thoracic kyphosis angle had decreased while the CVA had increased in both training groups (p<.05), but the CRA was significantly decreased in only the strengthening exercise group. Thoracic self mobilization reduced kyphosis and improved CVA, while thoracic strengthening exercise reduced kyphosis and improved CVA and CRA. Conclusion: This study suggests a promising exercise intervention that can improve posture in young adults with thoracic hyperkyphosis.