• Advances in biomechanics and applications
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• v.1 no.2
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• pp.85-93
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• 2014

In this paper, two procedures of enumerating the axial rotation are proposed using the unit sphere of the spherical rotation coordinate system specifying 3D rotation. If the trajectory of the movement is known, the integration of the axial component of the angular velocity plus the geometric effect equal to the enclosed area subtended by the geodesic path on the surface of the unit sphere. If the postures of the initial and final positions are known, the axial rotation is determined by the angular difference from the parallel transport along the geodesic path. The path dependency of the axial rotation of the three dimensional rigid body motion is due to the geometric effect corresponding to the closed loop discontinuity. Firstly, the closed loop discontinuity is examined for the infinitesimal region. The general closed loop discontinuity can be evaluated by the summation of those discontinuities of the infinitesimal regions forming the whole loop. This general loop discontinuity is equal to the surface area enclosed by the closed loop on the surface of the unit sphere. Using this quantification of the closed loop discontinuity of the axial rotation, the geometric effect is determined in enumerating the axial rotation. As an example, the axial rotation of the arm by the Codman's movement is evaluated, which other methods of enumerating the axial rotations failed.

• Korean Journal of Applied Biomechanics
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• v.20 no.3
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• pp.293-301
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• 2010

The purpose of this study was to investigate the kinematic difference between skilled and less skilled group for the forward walk at dance sports rumba. Six female players(skilled group: 3, less skilled group: 3) were participated as the subjects. To obtain the three-dimensional location coordinates in the joints and segments, it shot with 100Hz/s using 8 video cameras. Step length, shoulder rotation angle, orientation angle and angular velocity of pelvis were analyzed for each trail. The skilled group showed a bigger movement than the less skilled group at the shoulder rotation angle and ROM. The skilled group showed a bigger movement than the less skilled group at the up/down obliquity and internal/external rotation movement for pelvis. And the skilled group showed a bigger movement than the less skilled group at Maximum angle (down obliquity) of P2 and Maximum angle (up obliquity) of P3 to pelvis ROM. The skilled group showed a faster angular velocity than the less skilled group at P2 (+ direction, posterior) of anterior & posterior tilt, P2 & P3 (- direction, up) of up & down obliquity, and P2 (+ direction, external) of internal & external rotation.

• The Korean Journal of Physiology
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• v.24 no.1
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• pp.103-113
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• 1990

The role of cervical proprioceptors in the control of body posture was studied in bilaterally labyrinth-ectomized, decerebrate cats. The animals were suspended on hip pins with the neck extended horizontally. With this placement the EMG activities of extensor and flexor muscles of the upper extremities were observed by means of sinusoidal head rotator. The rotator can induce two kinds of neck movement: The one is 'pitch' which describes a rotatory neck motion to transverse axis of the body and mainly occurs at skull-C1 (atlantooccipital) joint and the other is 'roll', side-to-side relation of the neck to longitudinal axis, whose center is C1-C2 (atlanto-axial) joint. The following results were obtained. 1) Responses of EMG activity were closely dependent on the rotatory range of the neck. And the EMG activity was not changed during sustained neck torsion, eliciting a typical tonic neck reflex. 2) On pitching movement, the head-up rotation produced the excitation of bilateral triceps muscles, whereas the head-down rotation produced the inhibition. And the response of bilateral biceps muscles was the opposite to that of triceps. 3) On rolling movement, the side-up rotation of the head produced the excitation of ipsilateral triceps muscles and the inhibition of contralateral ones. And the response of biceps muscles was the opposite to that of triceps. 4) The minimum requirement of motion to evoke EMG activities in the upper extremities was $3.2^{\circ}{\sim}12.5^{\circ}$. These results have shown that the cervical proprioceptors produce tonic discharge on the upper brachial muscles, regulate the EMG activities of those muscles, and are very sensitive to neck rotation. And it can be stated that the cervical proprioceptors may play an important role in the control of body posture and movement.

• Korean Journal of Applied Biomechanics
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• v.26 no.4
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• pp.369-375
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• 2016

Objective: The purpose of this study was to investigate the possibility of injuries and the types of movement related to damage by body parts, and to prepare for prevention of injuries and development of a training program. Method: For this study, the experiment was conducted according to levels of 60 percentages (ST) and 85 percentages (MA) and 10 subjects from the Korean elite national weightlifting team were included. Furthermore, we analyzed joint moment and muscle activation pattern with three-dimensional video analysis. Ground reaction force and EMG analyses were performed to measure the factors related to injuries and motion. Results: Knee reinjuries such as anterior cruciate ligament damage caused by deterioration of the control ability for the forward movement function of the tibia based on the movement of the biceps femoris when the rectus femoris is activated with the powerful last-pull movement. In particular, athletes with previous or current injuries should perceive a careful contiguity of the ratio of the biceps femoris to the rectus femoris. This shows that athletes can exert five times greater force than the injury threshold in contrast to the inversion moment of the ankle, which is actively performed for a powerful last pull motion and is positively considered in terms of intentional motion. It is activated by excessive adduction and internal rotation moment to avoid excessive abduction and external rotation of the knee at lockout motion. It is an injury risk to muscles and ligaments, causing large adduction moment and internal rotation moment at the knee. Adduction moment in the elbow joint increased to higher than the injury threshold at ST (60% level) in the lockout phase. Hence, all athletes are indicated to be at a high risk of injury of the elbow adductor muscle. Lockout motion is similar to the "high five" posture, and repetitive training in this motion increases the likelihood of injuries because of occurrence of strong internal rotation and adduction of the shoulder. Training volume of lockout motion has to be considered when developing a training program. Conclusion: The important factors related to injury at snatch include B/R rate, muscles to activate the adduction moment and internal rotation moment at the elbow joint in the lockout phase, and muscles to activate the internal rotation moment at the shoulder joint in the lockout phase.

• Physical Therapy Korea
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• v.26 no.1
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• pp.67-74
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• 2019

Background: Uncontrolled lumbopelvic movement leads to asymmetric symptoms and causes pain in the lumbar and pelvic regions. So many patients have uncontrolled lumbopelvic movement. Passive support devices are used for unstable lumbopelvic patient. So, we need to understand that influence of passive support on lumbopelvic stability. It is important to examine that using the pelvic belt on abdominal muscle activity, pelvic rotation and pelvic tilt. Objects: This study observed abdominal muscle activity, pelvic rotation and tilt angles were compared during active straight leg raise (ASLR) with and without pelvic compression belt. Methods: Sixteen healthy women were participated in this study. ASRL with and without pelvic compression belt was performed for 5 sec, until their leg touched the target bar that was set 20 cm above the base. Surface electromyography was recorded from rectus abdominis (RA), internal oblique abdominis (IO), and external oblique abdominis (EO) bilaterally. And pelvic rotation and tilt angles were measured by motion capture system. Results: There were significantly less activities of left EO (p=.042), right EO (p=.031), left IO (p=.039), right IO (p=.019), left RA (p=.044), and right RA (p=.042) and a greater right pelvic rotation angle (p=.008) and anterior pelvic tilt angle (p<.001) during ASLR with pelvic compression belt. Conclusion: These results showed that abdominal activity was reduced while the right pelvic rotation angle and anterior pelvic tilt angle were increased during ASLR with a pelvic compression belt. In other words, although pelvic compression belt could support abdominal muscle activity, it would be difficult to control pelvic movement. So pelvic belt would not be useful for controlled ASLR.

• The Journal of Korean Physical Therapy
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• v.7 no.1
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• pp.21-31
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• 1995

This study was described the movement patterns when rising from supine to erect stance. Two hundred eighty seven subjects, ranging in age from 6 year to 28 were filmed while rising from a supine position. Movement Patterns were classified using categorical descriptions of the action of three body regions-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. The incidence of each movement pattern was calculated and graphed with respect to age level and sex. The most common form of rising for subject in the 6, 7 year mate group usually involved push and reach pattern with upper extremity, half kneel pattern with lower extremity, partial rotation pattern with head-trunk. In the 6, 7 year female group usually involved symmetrical push pattern with upper extremity, symmetrical squat with balance step pattern with lower extremity, symmetrical interrupted by rotation pattern with head - trunk. In the teenage and twenties both sex group usually involved symmetrical push pattern with upper extremity, symmetrical squat pattern with lower extremity, partial rotation pattern with head-trunk.

• The Journal of Korean Physical Therapy
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• v.16 no.3
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• pp.86-96
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• 2004

A clinical study about painful manifestation on lumbar with regard to movement change of trunk The purpose of this study is to present the basis of low back pain therapy which is close examined of back muscle that is the main reason for that case of back pain when trunk rotation, flexion and extension. Therefore this study, which is based on literature review and clinical experience, has tried to figure out that back pain which is considered to be significant for the most increasing time, posture, motion, painful area, involved muscle have any influence on trunk rotation, flexion and extension This study has done with the patients in oriental rehabilitation clinic, K-oriental hospital, from Jan, 2003 to Dec, 2003. Total cases were 145(male:$39\%$-52 patients, female:$64.1\%$-93 patients) those who complained lumbosacral pain with radiating that makes patient unable to bending or extending the trunk. And they were surveyed retrospect way, checking the medical record and that of therapist. Results are as followings. 1. For sprain patient, $34.5\%$ complained pain on extension, and among them, the most remarkably, patients who did right rotation extension pattern were $20\%$. Herniated disc patient shows greater limit on flexion when trunk moves bending route, but right rotation with extension pattern shows the most limitation on flexion-extension according to the rotation of trunk 2. Cases of morning back pain($60.5\%$) showed high value on right rotation extension pattern($18.6\%$), right rotation flexion pattern($16.3\%$) but did not show big difference on left flexion and extension pattern 3. Patients those who complain pain on sitting position showed highest value each left, right $14.6\%$ of left and right rotation extension pattern 4. Among extension painful patient, there showed highest value of each $32.5\%$ on right rotation extension pattern, and $20.0\%$ on right rotation flexion pattern. 5. Tenderness distribution of quadratus lumborum showed $34.5\%$ on right rotation extension pattern, $20.7\%$ on left rotation extension pattern, and that of iliopsoas muscle at right rotation flexion pattern showed right muscle $20.0\%$, left $50.0\%$ Derived from the results of survey above, for sprain and HIVD patient showed greatest pain on right rotation pattern, for pain plus patient on right rotation extension among those who has extreme pain on sitting in the morning described tenderness on right quadratus lumborum, and those who complain pain on left rotation extension described tenderness on left lumborum the most Decisively, it is possible to figure out the problem muscle that involved when I found the time, position, motion that aggravating and painful area. Therefore this study would be expected to be able to be a useful clinical materials on diagnosis and therapy of low back pain.

• Journal of the Korean Society of Earth Science Education
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• v.5 no.1
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• pp.20-30
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• 2012

The purpose of this study is to find how elementary students who have different spatial ability affects their understandings on the concept of the rotation of the earth. In order to perform this study, four 5th grade students were picked out of 85 students in Seoul. They had the same conceptual achievement on the movement of celestial bodies but had different spatial abilities. The results of this study were as follows : Regardless of their spatial ability, they understand how day and night are performed, and understand the fact that diurnal motions of moon are related to the rotation of the earth. Also, the students who had higher spatial abilities showed better understanding on the concept of the rotation of the earth and understood the reconstructed concepts in stereoscopic space. But the students who had lower spatial abilities did not fully understand the concept of the rotation of the earth and just memorized them as fragmentary concepts. As for the gender differences, the boy students who had higher spatial ability explained the concept clearly and the others who had lower spatial ability had difficulty in understanding the rotation direction of the earth related with the diurnal movement of celestial bodies. In the same manner, the girl students who had higher spatial ability explained the concepts concretely and the others who had lower spatial ability had difficulty in explaining the concepts by operating them stereoscopically. Therefore, developing teaching methods and studying data and so on, for the girl students, they should be trained to operate the stereoscopic space directly, and for the boy students, they should learn to think over objects with multi-viewpoints. And then the spatial ability on the movement of celestial bodies would be expected to be improved.

• 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.

• Korean Journal of Applied Biomechanics
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• v.24 no.1
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• pp.1-9
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• 2014

The purpose of this study was to investigate the muscle mechanical properties of the pelvic axial pre-rotational movement for the Jireugi in the Taekwondo Juchumseogi stance. Eleven elite Taekwondo Poomsae athletes participated. Each participant performed 5 right hand Jireugi in Juchumseogi stance as fast and strong as possible while their motion was recorded by a 3D motion analysis system and the ground reaction forces by two force plates. The power and work of the muscular group surrounding the waist were analyzed to verify the effect of the stretch-shortening cycle (SSC) theory. The cause of the greater power seems to be the application of the SSC by the muscles surrounding the waist during the preparation phase of the pre-rotation group. For the none pre-rotation group, they only used the concentric contraction of the muscles surrounding the waist. Because the pre-rotation group used the SSC theory, they had the effect of shortening of the range of movement, creating a fast and more powerful rotation, thus anticipating the increase the magnitude of impact.