• Korean Journal of Applied Biomechanics
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• v.19 no.2
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• pp.297-309
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• 2009

The study analyzed the mechanism of plantar foot pressure distribution during pitching wedge swinging on a flat, an up hill lie and a down hill lie to provide the fundamental information regarding biomechanical motion data by using plantar foot pressure measuring instrument. In the results, time factor spanning according to slope differences, plantar foot pressure factor and swing motion on the slope could have negative effect on the coiling of lower limbs during back swing, as well as the blocking of the lower limbs to minimize the dispersion of the weight and the release of the lower limbs after the impact during the down swing process. Moreover, since slope is one of many external factors affecting swing motion, address motion on an up hill lie limits the lower limbs movement, therefore, a relatively narrow stance is better on a down hill lie. It is estimated that a relatively wide stance would be better in order to limit the bigger activation of the lower limbs. Not only for the address motion but also during the down swing on an up hill lie it is concluded that the weight should be on the left foot in order to keep the body balance.

• Korean Journal of Applied Biomechanics
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• v.31 no.1
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• pp.50-58
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• 2021

Objective: This study aimed to determine the effect of wrist and trunk weight loading using sandbags in stroke patients in order to provide the quantitative data for enhancement of gait movement. Method: Twelve stroke patients, who have been diagnosed with hemiplegia over a year ago, were participated in this study. All subjects were asked to perform normal walking [N], wrist sandbag walking [W], wrist & trunk sandbag walking [WT], and both wrist sandbag walking [B] and both wrist & trunk sandbag walking [BT], respectively. Eight infrared cameras were used to collect the raw data. Gait parameters, arm swing, shoulder-pelvic kinematics, and lower extremity joint angle were calculated to examine the differences during walking. Results: As a result, there were no significant differences in the gait parameters, shoulder-pelvis, and lower extremities joint angles, but significant differences were found in the range of motion and the anteversion in arm swing. Conclusion: Wrist and trunk weight loading using sandbags affected the movement of the upper extremities only while it did not affect the movement of the lower extremities. It implies that it can reduce the risk of falling caused by a sudden movement change in lower extremities. In addition, the wrist and trunk weight loading using sandbags can induce changes in movement of the upper extremities independently and contribute to functional rehabilitation through resistance training.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2000.11a
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• pp.159-167
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• 2000

During the operation of crane system in the container yard, it is necessary to control the crane trolley position so that the swing of the hanging container is minimized. Recently an automatic control system with high speed and rapid transportation is required. Therefore, we designed a controller to control the crane system with disturbances and weight change. In this paper, we present the neural network two degree of freedom PID controller to control the swing motion and trolley position. Then we executed the computer simulation to verify the performance of the proposed controller and compared the performance of the neural network PID controller with our proposed controller in terms of the rope swing and the precision of position control. Computer simulation results show that the proposed controller has better performances than neural network PID with disturbances.

• Korean Journal of Applied Biomechanics
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• v.17 no.2
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• pp.227-237
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• 2007

The purpose of this study was to examine the effect of precision that kinematics had when short approach shots were taken. In this study, the subjects chosen were 5 skilled and 5 unskilled subjects, who were allowed to shoot 10 rounds of shots at target distances of 1m, 2m, 4m, and 8m. Three dimensional analysis was used as methods to obtain kinematics of each shots. In order to verify the statistical significance of the kinematic factors followed by the results of different skills and target distances, we used the two-way repeated ANOVA. The study was experimented within the level of p<.05. The results obtained were as follows: 1) the difference of shots of the forward and backward variations were larger than those of the left and right variations, the unskilled subjects' shot distances greatly got larger than that of the skilled subjects as the distance of the target increased, 2) not being affected by the target distance variations, the skilled subjects' rate of down-swing was shorter than the back-swing on short approach shots, 3) the skilled subjects' center of body weight tended to move more naturally towards the target when doing the down-swing to finish than that of the unskilled subjects on short approach shots, 4) the skilled subjects' right hand angle of cocking were narrower and tended to be kept much more consistent than that of the unskilled subjects on short approach shots, 5) the unskilled subjects when doing their back-swings, their right hips swayed towards the back, their trunk-flexion angles were shown to be lower than that of the skilled subjects on short approach shots, 6) the skilled subjects`body weight tended to move more naturally towards the left foot when doing the down-swing to finish than that of the unskilled subjects on short approach shots.

• Korean Journal of Applied Biomechanics
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• v.22 no.3
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• pp.277-284
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• 2012

The purpose of this study was to find out the changes in beginners' batting movements after taking undergraduate baseball lectures, by comparing and analyzing the speed of bat, the angle of body and its segments, the angular velocity and so on. For this purpose, the author picked up five undergraduates who had not taken baseball lectures, and conducted three-dimension computerized tomography twice on them, that is, before and after taking baseball classes, with eight infrared cameras and two force platforms. The conclusions are, first, the time required for swing was shortened after taking the classes. Second, the maximum velocity of the bat-end was increased. Third, at the time of impact, while the rotation angles of the pelvis and the tip of left foot were increased, the left elbow had more flexion after the classes. Fourth, the size of ground reaction force was increased at the point of swing where the ground reaction force of left foot became maximized. As we can infer from these conclusions, beginners' hitting movements before taking baseball classes tended to swing only with the arms, without waist rotation and weight shift of the lower body, but after the classes, their movements were proved to be corrected into the swing using the lower body. For the future studies, the author expects a research in a close to real environment by using pitching machine.

• Journal of the Korean Academy of Clinical Electrophysiology
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• v.10 no.2
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• pp.31-35
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• 2012

Purpose : The purpose of this study was to investigate the effect of kinematic variables by analysis of a gait in older. Methods : This study selected nine in older adults with osteoarthritis. The Kinematic variables during walk were compared analyzed using motion analysis. Results : The findings of this study are as follows. Stance time showed significant difference within-subject groups and interaction within-subjects and time. The swing and stride time showed a no significant interaction within-subjects and time. Swing time showed a no significant difference according to time and within-subjects. Stride time showed a significant difference according to time. But, stride time showed a no significant difference according to within-subjects. Conclusion : These findings of this study indicate that when the patients with total knee arthroplasty decreased stability. Therefore, stance and stride time showed increase when walking, because to decrease the weight bearing that is delivered to knee. And swing time showed decrease.

• Asia pacific journal of information systems
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• v.18 no.3
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• pp.1-20
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• 2008

Based on the multi-attribute utility theory (MAUT), we present a survey method to measure consumer preferences. The multi-attribute utility theory has been used to make decisions in OR/MS field; however, we show that the method can be effectively used to estimate the demand for new services by measuring individual level utility function. Because conjoint method has been widely used to measure consumer preferences for new products and services, we compare the pros and cons of two consumer preference survey methods. Further, we illustrate how swing weighing method can be effectively used to elicit customer preferences especially for new telecommunications services, Multi-attribute utility theory is a compositional approach for modeling customer preference, in which researchers calculate overall service utility by summing up the evaluation results for each attribute. On the contrary, conjoint method is a decompositional approach, which requires holistic evaluations for profiles. Partworth for each attribute is derived or estimated based on the evaluation, and finally consumer preferences for each profile are calculated. However, if the profiles are quite new and unfamiliar to the survey respondents, they will find it very difficult to accurately evaluate the profiles. We believe that the multi-attribute utility theory-based survey method is more appropriate than the conjoint method, because respondents only need to assess attribute level preferences and not holistic assessment. We chose swing weighting method among many weight assessment methods in multi-attribute utility theory, because it is designed to perform in a simple and fast manner. As illustrated in Clemen and Reilly (2001), to assess swing weights, the first step is to create the worst possible outcome as a benchmark by setting the worst level on each of the attributes. Then, each of the succeeding rows "swings" one of the attributes from worst to best. Upon constructing the swing table, respondents rank order the outcomes (rows). The next step is to rate the outcomes in which the rating for the benchmark is set to be 0 and the rating for the best outcome to be 100, and the ratings for other outcomes are determined in the ranges between 0 and 100. In calculating weight for each attribute, ratings are normalized by the total sum of all ratings. To demonstrate the applicability of the approach, we elicited and analyzed individual-level customer preference for new telecommunication services-WiBro and HSDPA. We began with a randomly selected 800 interviewees, and reduced them to 432 because other remaining ones were related to the people who did not show strong intention for subscription to new telecommunications services. For each combination of content and handset, number of responses which favored WiBro and HSDPA were counted, respectively. It was assumed that interviewee favors a specific service when expected utility is greater than that of competing service(s). Then, the market share of each service was calculated by normalizing the total number of responses which preferred each service. Holistic evaluation of new and unfamiliar service is a tough challenge for survey respondents. We have developed a simple and easy method to assess individual level preference by estimating weight of each attribute. Swing method was applied for this purpose. We believe that estimating individual level preference will be quite flexibly used to predict market performance of new services in many different business environments.

• Korean Journal of Applied Biomechanics
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• v.27 no.2
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• pp.141-147
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• 2017

Objective: We obtained force-displacement curves for countermovement jumps of multiple heights and examined the effect of an arm swing on changes in vertical jumping strategy. Countermovement jumps with hands on hips (Condition 1) and with an arm swing (Condition 2) were evaluated to investigate the mechanical effect of the arm movement on standing vertical jumps. We hypothesized that the ground reaction force (GRF) and/or center of mass (CoM) motion resulting from the countermovement action would significantly change depending on the use of an arm swing. Method: Eight healthy young subjects jumped straight up to five different levels ranging from approximately 10% (~25 cm) to 35% (~55 cm) of their body heights. Each subject performed five sets of jumps to five randomly ordered vertical elevations in each condition. For comparison of the two jumping strategies, the characteristics of the boundary point on the force-displacement curve, corresponding to the vertical GRF and the CoM displacement at the end of the countermovement action, were investigated to understand the role of arm movement. Results: Based on the comparison between the two conditions (with and without an arm swing), the subjects were grouped into type A and type B depending on the change observed in the boundary point across the five different jump heights. For both types (type A and type B) of vertical jumps, the initial vertical force at the start of push-off significantly changed when the subjects employed arm movement. Conclusion: The findings may imply that the jumping strategy does change with the inclusion of an arm swing, predominantly to modulate the vertical force advantage (i.e., the difference between the vertical force at the start of push-off and the body weight).

• Journal of rehabilitation welfare engineering & assistive technology
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• v.6 no.2
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• pp.23-30
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• 2012

In this study, we developed a wireless rehabilitation auditory feedback gait training system for symmetrical weight-bearing in patient with CVA. The device consists of an instantaneous shoe equipped with two load-cell sensors. Auditory feedback can be applied according to the weight-bearing. For gait patterns analysis, cadence, walking velocity, stance/swing phase ratio and gait cycle were examined. The clinical test with six healthy volunteers and two hemiplegic patients was performed applying the auditory feedback system. Both normal subjects and hemiplegic patients were increased strength on weight-bearing in affected limb, walking velocity, and cadence after biofeedback device. Also, the stance time with weight-bearing was increased while the swing time was decreased in gait phase. It can be expected that by using the feedback system, the patient with lower limb disorder will be able to reach a better quality of weight-bearing during gait.

• Korean Journal of Applied Biomechanics
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• v.12 no.2
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• pp.33-49
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• 2002

This study was intended to provide basic materials for golf coaching by somatotype by analyzing and comparing the kinematic factors found in each somatotype at the time of golf swing. For this purpose, the somatotype was divided into endomorph, mesomorph and ectomorph in reference to the weight, height and upper arm circumference of each of nine professional golfers. Each of their swing motions was videotaped with the camcorder and their swing motion was analyzed by dividing it into 8 sections. The time required for the swing motion, the displacement of the center of the human body and the rotation angle of the upper body were calculated through the three-dimensional image analysis based on the DLT(Direct Linear Transformation). Based on the findings of this study, the following conclusion was drawn: The endomorphic golfers showed the longest required golf swing time, followed by the mesomorphic golfer and then the endomorphic golfer. The displacement of left-to-right movement was largest in the mesomorphic golfers, followed by the endomorphic golfers the up-to-down displacement was upward at the time of impact and that the endomorphic and mesomorphic golfers raised the sense of stability by maintaining an almost uniform height at the time of impact. As for the rotational angle of the upper body and the rotational angle of the thigh, the upper body and the thigh took a form of rotating earlier in the ectomorphic golfers at the time of impact, who showed a somewhat different characteristics compared to the endomorphic and mesomorphic golfers. It is necessary to investigate the movement of more fundamental forces in presenting the theory related to the kinematic characteristics of this swing by somatotype. Accordingly, it is thought that it is necessary to analyze the center of pressure(COP) using the ground counterforce in the future study.