• Korean Journal of Applied Biomechanics
• /
• v.28 no.2
• /
• pp.109-117
• /
• 2018

Objective: To compare head and hand movement patterns during squash forehand motions between experts and less-skilled squash players. Method: Four experts and four less-skilled squash players participated in this study. They performed squash forehand swings and a VICON motion analysis system was used to obtain displacement and velocity data of the head and right hand during the movement. Mann-Whitney U-tests were performed to compare head and hand range of motion and peak velocity, and cross-correlation was performed to analyze the head-hand coordination pattern between groups in three movement directions. Results: In terms of head and hand kinematic data, experts had greater head range of motion during down swings than less-skilled squash players. Experts seemed to reach peak hand velocity at impact by reaching peak head velocity followed by hand peak velocity within a given temporal sequence. In terms of head-hand coordination patterns, both groups revealed high positive correlations in the medial-lateral direction, indicating a dominant allocentric coordination pattern. However, experts had uncoupled coordination patterns in the vertical direction and less-skilled squash players had high positive correlations. These results indicate that the head-hand movement pattern likely an important factor squash forehand movement. Conclusion: Analysis of head and hand movement patterns could be a key variable in squash training to reach expert-level performance.

• Korean Journal of Applied Biomechanics
• /
• v.17 no.4
• /
• pp.169-179
• /
• 2007

The purpose of this study was to investigate the relations between the segments of the body and to qualitatively analyze coordination pattern of joints and segments during Sweep Shot movement in Ice Hockey, by utilizing coordination variables was angle vs. angle plots. By the utilization the three dimensional anatomical angle cinematography, the angles of individual joint and segment according to sweep shot in ice hockey. The subjects of this study were five professional ice hockey players. The reflective makers were attached on anatomical boundary line of body. For the movement analysis three dimensional cinematographical method(APAS) was used and for the calculation of the kinematic variables a self developed program was used with the LabVIEW 6.1 graphical programming(Johnson, 1999) program. By using Eular's equations the three dimensional anatomical Cardan angles of the joint and ice hockey stick were defined. The three dimensional anatomical angular displacement and coordination pattern of trunk and Upper limb(shoulder-elbow, elbow-wrist linked system) showed important role of sweep shot in ice hockey. As the result of this paper, for the successful movement of sweep shot in ice hockey, it is most important role of coordination pattern of trunk-shoulder, shoulder-elbow and elbow-wrist. specially turnk movememt as a proximal segment. Coordination pattern of Upper Limb(upperarm-forearm-hand) of Sweep Shot movement in Ice Hockey that utilizes coordination variables seems to be one of useful research direction to understand basic control mechanisms of Ice hockey sweep shooting linked system skill. this study result showed flexion-extension, adduction-abduction and internal-external rotation of trunk are important role of power and shooting direction coordination pattern of upper Limb of Sweep Shot movement in Ice Hockey.

• Korean Journal of Applied Biomechanics
• /
• v.24 no.3
• /
• pp.229-238
• /
• 2014

This study comparatively analyzed the speed and segment coordination characteristics of Taekwondo hand techniques, while different attention focusing strategies were utilized. Ten elite Taekwondo poomsae athletes participated, and three different strategies (no focus, target focus, body focus) were utilized in random order. The hand velocity and upper body segment coordination characteristics were analyzed, with the following results. First, the maximum magnitudes of the hand velocity differed between the focus conditions for the Araenaereomakgi and Momtongjireugi techniques. Second, the angular velocity and kinetic energy transfer patterns of the segments differed between the focus conditions, and in the case of the body focus condition, the movement was more correct according to the theory. Third, the shoulder and elbow joint coordination patterns differed between the focus conditions, with more efficient movement shown with the body focus condition. In conclusion, we confirmed the potential of effectively using an attention focusing strategy in a taekwondo teaching situation. However, the effect on the movement coordination and results of the movement could be changed by a difference in the cue provided or the type of the task. In addition, depending on the task, the attention focusing strategy could affect the efficiency of the movement. Therefore, coaches and masters of Taekwondo will have to constitute determine the appropriate attention focusing cues based on the task.

• Journal of Biomedical Engineering Research
• /
• v.28 no.3
• /
• pp.417-422
• /
• 2007

In this study, we investigated spatio-temporal eye-hand coordination by the "Global effect paradigm", a target-distracter configuration Global effect is observed a variety of visual tasks, for example, during rapid automatic tracking, scanning for target detail, and the comparison of target configurations. Global effect used to investigate eye-hand coordination with a task that presents a target close to a distracter. Eight young subjects participated in the experiments. The experiments consist of using a distracter less eccentric than the targe1 and using a distracter more eccentric than target. Each experiment consist of tasks which are making reference, pointing the target with watching visual stimulation(saccade) and pointing the target. The subject's task was to move towards the target as quickly as possible. We measured the eye movement by using EOG and the hand movement by using NDI Optotrak system. This study shows that eye and hand movement exists for global effect paradigm in spatio-temporal coordination.

• Korean Journal of Applied Biomechanics
• /
• v.31 no.4
• /
• pp.259-269
• /
• 2021

Objective: The purpose of this systematic review and meta-analysis was to investigate age-related bimanual coordination functions in older adults. Method: Thirteen studies that compared bimanual coordination functions in older adults with those in healthy young adults qualified for this meta-analysis. We additionally categorized 21 total comparisons from the 13 qualified studies into two types of task-related moderator variables: (1) kinematic versus kinetic movements and (2) symmetry versus asymmetry movements. Results: Random effects model meta-analysis found that older adults revealed significant bimanual coordination impairments as compared with young adults (Hedges's g = -0.771; p < .0001; I² = 74.437%). We additionally confirmed specific bimanual coordination deficits using two moderator variables: 1) kinematic (Hedges's g = -0.884; p < .0001; I² = 0.000%) and kinetic (Hedges's g = -0.666; p = .023; I² = 86.170%). 2) symmetry (Hedges's g = -0.712; p = .001; I² = 74.291%) and asymmetry (Hedges's g = -0.817; p < .0001; I² = 76.322%). The moderator variable analysis indicated older adults indicated bimanual coordination deficits in the upper extremities than healthy young adults while performing kinematic bimanual coordination tasks and asymmetry coordination tasks. Conclusion: These findings suggest that developing motor rehabilitation programs based on asymmetric bimanual movement task for enhancing interlimb coordination functions of older adults may be crucial for increasing their independence in everyday activities. Given that elderly revealed the deficits in lower extremities coordination when older adults perform gait, posture, and balance, future studies should estimate lower limb coordination functions in elderly people.

• Korean Journal of Applied Biomechanics
• /
• v.17 no.4
• /
• pp.73-82
• /
• 2007

The purpose of this study was to qualitatively analyze coordination pattern of joints and segments during Dwichagi in Taekwondo and present a point of difference as compared with the previous study on Dolryeochagi in Taekwondo. By the utilization of three-dimensional cinematography, the angles of individual joints and segments of six male Taekwondo experts during Dwichagi were calculated by using Euler's angle. The used coordination variables were angle vs. angle plots between adjacent joints and segments and angle vs. angular velocity plots of individual joints and segments, respectively. It was observed during Dwichagi that in-phase coordination and spring-like rotational control mechanism of the lower and upper trunk were transferred into straight spring-like control mechanism of lower leg passing through flexion-extension and the fixation of degree-of-freedom of lower trunk and hip joint alternatively. This comparative study that coordination variables were used seems to be more useful research direction to deeply understand basic control mechanisms of Taekwondo kicking techniques when compared with the previous studies that defined Dwichagi as a thrust movement pattern merely based on biomechanical variables of a kicking leg.

• Journal of the Ergonomics Society of Korea
• /
• v.26 no.2
• /
• pp.149-155
• /
• 2007

Recently, various devices requiring text input such as mobile phone IPTV, PDA and UMPC are emerging. The frequency of text entry for them is also increasing. This study was focused on the evaluation of Korean text entry interface. Various models to evaluate text entry interfaces have been proposed. Most of models were based on human cognitive process for text input. The cognitive process was divided into two components; visual scanning process and finger movement process. The time spent for visual scanning process was modeled as Hick-Hyman law, while the time for finger movement was determined as Fitts' law. There are three questions on the model-based evaluation of text entry interface. Firstly, are human cognitive processes (visual scanning and finger movement) during the entry of text sequentially occurring as the models. Secondly, is it possible to predict real text input time by previous models. Thirdly, does the human cognitive process for text input vary according to users' text entry speed. There was time gap between the real measured text input time and predicted time. The time gap was larger in the case of participants with high speed to enter text. The reason was found out investigating Eye-Hand Coordination during text input process. Differently from an assumption that visual scan on the keyboard is followed by a finger movement, the experienced group performed both visual scanning and finger movement simultaneously. Arrival Lead Time was investigated to measure the extent of time overlapping between two processes. 'Arrival Lead Time' is the interval between the eye fixation on the target button and the button click. In addition to the arrival lead time, it was revealed that the experienced group uses the less number of fixations during text entry than the novice group. This result will contribute to the improvement of evaluation model for text entry interface.

• Journal of Biomedical Engineering Research
• /
• v.15 no.1
• /
• pp.77-82
• /
• 1994

We investigated the characteristic of the sensory motor coordination by measuring the hand point ins and the gaze movement to the visual and sound stimulation. Our results showed that the gaze vol ocity to sound stimulation did not depend on stimulation direction, but lagged behind 0.2 sec toward the pheriperal direction to the visual stimulation. Our data showed that to both visual and sound stimulation, the error of hand pointing value increased with an increasement of eccentricity.

• Journal of the Ergonomics Society of Korea
• /
• v.30 no.2
• /
• pp.365-373
• /
• 2011

The existing GOMS model overestimates the performance time of mouse activities because it describes them in a serial sequence. However, parallel movements of eye and hand(eye-hand coordination) have been dominant in mouse activities and this eye-hand coordination is the main factor for the overestimation of performance time. In this study, therefore, the revised CGOMSL model was developed to implement eye-hand coordination to the mouse activity to overcome one of the limitations of GOMS model, the lack of capability for parallel processing. The suggested revised CGOMSL model for drag activity, as an example for one of mouse activities in this study, begins visual search processing before a hand movement but ends the visual search processing with the hand movement in the same time. The results show that the revised CGOMSL model made the prediction of human performance more accurately than the existing GOMS model. In other words, one of the limitations of GOMS model, the incapability of parallel processing, could be overcome with the revised CGOMSL model so that the performance time should be more accurately predicted.

• Journal of the Ergonomics Society of Korea
• /
• v.16 no.1
• /
• pp.63-71
• /
• 1997

This paper presented an experiment which examined eye and hand movement characteristics of novice and experienced workers in the press operation. Continuous recordings of eye and hand movements were made on five novice operators and five experienced operators in press operation. Significant difference between the novice and the experienced operators was observed in eye fixation time, eye movement patterns, hand dwell time, and eye-hand coordination. Also, differences were observed in spatial distribution of eye fixations during the die-closing portion of a stroke. There were no significant differences between the novice and the experiencedoperators in the eye and the hand movement time. The results could be used to establish a guide determining the method and training period to train the novice operators.