• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2009.01a
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• pp.360-363
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• 2009

Variation of viewing position of the observer is one of factors of image distortion in the stereoscopic display. A rotation movement of the observer makes the stereoscopic image distortion and that is caused by different horizontal position of each eye of the observer. It is different from horizontal and depth directional movement of the observer. In this paper, we showed the numerical simulation result about the distortion analysis and the correction of the stereoscopic image in rotation movement of the observer.

• Physical Therapy Korea
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• v.19 no.4
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• pp.61-69
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• 2012

The purpose of this study was to identify the effects of tensor fasciae latae-iliotibial band (TFL-ITB) self-stretching exercise on the lumbopelvic movement patterns during active prone hip lateral rotation (HLR) in subjects with lumbar extension rotation syndrome accompanying TFL-ITB shortness. Eleven subjects (9 male and 2 female) were recruited for the two-week study. A three dimensional ultrasonic motion analysis system was used to measure the lumbopelvic movement patterns. The TFL-ITB length was measured using the modified Ober's test and was expressed as the hip horizontal adduction angle. The subjects were instructed how to perform TFL-ITB self-stretching exercise program at home. A paired t-test was performed to determine the significant difference in the angle of lumbopelvic rotation, movement onset time of lumbopelvic rotation, TFL-ITB length, and LBP intensity before and after the two-week period of performing the TFL-ITB self-stretching exercise. The results showed that after the intervention, the lumbopelvic rotation angle decreased significantly (p<.05), the movement onset time reduced significantly (p<.05), and LBP intensity decreased slightly but not significantly (p=.07). The hip horizontal adduction angle increased significantly (p<.05) after the intervention. These findings indicate that TFL-ITB stretching exercise increased TFL-ITB length, decreased lumbopelvic rotation angle, and delayed the movement onset time of lumbopelvic rotation after two-weeks. In conclusion, the TFL-ITB self-stretching exercise performed over a period of two weeks may be an effective approach for patients with lumbar extension rotation syndrome accompanying TFL-ITB shortness.

• Korean Journal of Applied Biomechanics
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• v.21 no.3
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• pp.269-279
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• 2011

This study was analyzed the characteristics on the stability of posture while conducting a through two and half rotation technic of pench$\acute{e}$ in rhythmic gymnastics. Two rhythmical gymnastics player(LKH and SSJ) who is a member of the national team were selected, and for obtain the kinematic and kinetic variables were used a ProReflex MCU 240 infrared camera(Qualisys, Sweden) and a Type9286A force platform(Kistler, Switzerland). The mechanical factors were computed by using Visual3D program and Matlab R2009a. During the landing and rotation phase the results showed following characteristics; 1) In medial-lateral and horizontal displacement of the support foot, LKH showed smaller movement than SSJ, but SSJ showed smaller movement than LKH in swing foot. LKH showed bigger movement in medial-lateral axis of COP and vertical axis of COG, but SSJ showed bigger movement in horizontal axis of COP and medial-lateral axis of COG. 2) SSJ showed bigger maximum horizontal and vertical velocity at P1 and P2 than LKH. 3) In the inclination angle of COP and COG, SSJ showed smaller change than LKH, but within medial-lateral tilt of the shoulder, LKH performed rotation motion in horizontal position than SSJ. There was no differences in each force components during rotation, but on landing phase, the results showed a characteristic that SSJ exerted bigger breaking force and vertical force than LKH.

• Physical Therapy Korea
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• v.31 no.1
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• pp.72-78
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• 2024

Background: Limitations of shoulder range of motion (ROM), particularly shoulder internal rotation (SIR), are commonly associated with musculoskeletal disorders in both the general population and athletes. The limitation can result in connective tissue lesions such as superior labrum tears and symptoms such as rotator cuff tears and shoulder impingement syndrome. Maintaining the center of rotation of the glenohumeral joint during SIR can be challenging due to the compensatory scapulothoracic movement and anterior displacement of the humeral head. Therefore, observing the path of the instantaneous center of rotation (PICR) using the olecranon as a marker during SIR may provide valuable insights into understanding the dynamics of the shoulder joint. Objects: The aim of the study was to compare the displacement of the olecranon to measure the rotation control of the humeral head during SIR in individuals with and without restricted SIR ROM. Methods: Twenty-four participants with and without restricted SIR ROM participated in this study. The displacement of olecranon was measured during the shoulder internal rotation control test (SIRCT) using a Kinovea (ver. 0.8.15, Kinovea), the 2-dimensional marker tracking analysis system. An independent t-test was used to compare the horizontal and vertical displacement of the olecranon marker between individuals with and without restricted SIR ROM. The statistical significance was set at p < 0.05. Results: Vertical displacement of the olecranon was significantly greater in the restricted SIR group than in the control group (p < 0.05). However, no significant difference was observed in the horizontal displacement of the olecranon (p > 0.05). Conclusion: The findings of this study indicated that individuals with restricted SIR ROM had significantly greater vertical displacement of the olecranon. The results suggest that the limitation of SIR ROM may lead to difficulty in rotation control of the humeral head.

• Korean Journal of Optics and Photonics
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• v.20 no.2
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• pp.87-93
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• 2009

Variation of the observer's viewing position is one of the major causes of image space distortion in the stereoscopic display. Especially, a large image distortion, which is caused by different depth direction positions of the observer's two eyes, is made by the observer's rotation movement in relation to the center of the screen. This is different from distortion of horizontal and depth directional movement of the observer. In this paper, we analyzed distortion of the image space due to the observer's rotation movement and showed the corrected result of distortion through simulation in the stereoscopic display. Finally, we showed that the distortion shape of the observer's rotation movement is different from horizontal and depth directional movement of the observer.

• The Journal of Advanced Prosthodontics
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• v.10 no.6
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• pp.401-407
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• 2018

PURPOSE. When performing an occlusal procedure, it is recommended that the patient should be sitting straight with the head in a natural position. An inappropriate mandibular position caused by an incorrect occlusal record registration or occlusal adjustment can result in damaged teeth and cause functional disorders in muscles and temporomandibular joints. The purpose of this study was to clarify the influence of horizontal cephalic rotation on mandibular position by investigating the three-dimensional positions of condylar and incisal points. MATERIALS AND METHODS. A three-dimensional jaw movement measurement device with six degrees of freedom (the WinJaw System) was used to measure condylar and incisal points. The subjects were asked to sit straight with the head in a natural position. The subjects were then instructed to rotate their head horizontally $0^{\circ}$, $10^{\circ}$, $20^{\circ}$, $30^{\circ}$, $40^{\circ}$, $50^{\circ}$and $60^{\circ}$ in the right or left direction. RESULTS. The results indicated that horizontal cephalic rotation made the condyle on the rotating side shift forward, downward, and toward the inside, and the condyle on the counter rotating side shift backward, upward, and toward the outside. Significant differences in deviations were found for angles of rotation higher than $20^{\circ}$. The incisal point shifted in the forward and counterrotating directions, and significant differences were found for angles of rotation higher than $20^{\circ}$. CONCLUSION. The mandibular position was altered by horizontal cephalic rotations of more than $20^{\circ}$. It is essential to consider the possibility of deviation of the mandibular position during occlusal procedures.

• Korean Journal of Applied Biomechanics
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• v.25 no.3
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• pp.293-300
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• 2015

Objective : The purpose of this study was to compare the kinematic data of the horizontal rotation movements of shoulder, hip, knee during two-handed backhand drive stroke according to two different ball directions. Methods : The kinematic variables were analyzed such as the joint angles of the lower body, horizontal rotation angles of the shoulder, hip, inter-knee segment, body twist angle and difference in angle of forward swing. Two-handed backhand drive stroke was analyzed through a three-dimensional motion analysis. The collected data were analyzed by a paired t-test, and the statistical significant value was set at ${\alpha}=.05$. Results : The findings of this study were as follows; First, there was no difference in the total angles of lower limb joints from the forward swing position to impact posterior. Second, there was no difference in the horizontal rotation angles of E1 shoulder, hip, and E2 shoulder but the horizontal rotation angles of E1 knee, E2 hip, knee, E3, and E4 shoulder, hip, and knee were different in all events. Third, there was no difference in the body twist angle of the maximum horizontal rotation. In addition, there was no difference in the angle of the body twist by the ball direction in the shoulder-hip, the hip-knee and the shoulder-knee. Conclusion : Horizontal rotation angle determines ball directions.

• Physical Therapy Korea
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• v.24 no.4
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• pp.77-83
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• 2017

Background: Shoulder external rotation exercises are commonly used to improve the stabilizing ability of the infraspinatus. Although the side-lying wiper exercise (SWE) is the most effective shoulder external rotation exercise to maximize infraspinatus activity, the effect of adduction force on the infraspinatus and posterior deltoid has not been demonstrated. Objects: This study was conducted to investigate whether horizontal adduction force increases infraspinatus activity and decreases posterior deltoid activity. Methods: Twenty-eight healthy subjects (male: 21, female: 7; $age=23.5{\pm}1.8years$; $height=170.1{\pm}7.4cm$; $weight=69.4{\pm}9.6kg$) were recruited. Subjects were asked to perform the SWE under two conditions: (1) general SWE and (2) SWE with adduction force using pressure biofeedback. Surface electromyography (EMG) signals of the infraspinatus and posterior deltoid were recorded during SWE. Paired t-tests were used to compare the EMG activity of the infraspinatus and posterior deltoid between the two conditions. Results: Posterior deltoid muscle activity was significantly decreased following SWE with adduction force ($7.53{\pm}4.52%$) relative to general SWE ($11.68{\pm}8.42%$) (p<.05). However, there was no significant difference in the infraspinatus muscle activity between the SWE with adduction force ($28.33{\pm}12.16%$) and the general SWE ($26.54{\pm}13.69%$) (p>.05). Conclusion: Horizontal adduction force while performing SWE is effective at decreasing posterior deltoid activity.

• The Journal of Internal Korean Medicine
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• v.13 no.2
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• pp.100-110
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• 1992

For an effective acupuncture treatment, the location of muscles around Sutaeumkyongkun and Suyangmyongkyongkun were researched and they were made contracted. The conclusion is as follows; 1. The contraction of muscles around Sutaeumkyongkun gives appearance of the postures ; free movement of thumb, abduction of extension of wrist, flexion and pronation of elbow, depression and abduction of girdle of superior limb, flexion, internal rotation and horizontal flexion of shoulder joint These postures all together consequently produces the action 'holding something in arms'. 2. The contraction of muscles around Suyangmyongkyongkun gives appearance of the postures; extension of metacarpophalangeal and interphalangeal joint of index finger extension and abduction of thumb, extension of wrist, extension and supination of elbow, adduction, elevation and upward rotation of girdle of superior limb, extension, abduction, adduction, internal rotation, external rotation, horizontal extension of shoulder joint, flexion and opposite rotation of neck. These postures all together consequently produces the action 'raising arms'.

• Korean Journal of Applied Biomechanics
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• v.20 no.4
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• pp.487-495
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• 2010

The purpose of this study was conducted to make a comparative biomechanical analysis of X-factor and X-factor stretch during driver and iron swing. The subjects were composed of 10 professional golfers with more than 10 years career. The result was as follows: First, the analysis of the back swing with driver and iron swing showed no differences statistically between both the timing in horizontal rotating of shoulder and hip, the time required for X-factor stretch also showed no differences statistically. Second, the back swing with a driver swing showed more maximum horizontal rotation of shoulder and hip joint than the back swing with an iron swing, but the twist of shoulder and hip that was X-factor stretch angle showed no difference. Third, the GRF of the max value for the left and right foot during shoulder and hip horizontal rotation of back swing showed no differences statistically in the movement of driver and iron swing during the back swing, and the GRF of X-factor stretch for the left and right foot showed no differences statistically in driver and iron swing. Therefore the result of this research showed that the operation of torso(X-factor stretch) and weight shifting were similar although the horizontal rotation of body was different during the driver and iron swing.