• Journal of the Korean Applied Science and Technology
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• v.38 no.1
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• pp.1-8
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• 2021

The purpose of this study was to analyze relationship between biomechancal factors and diver's distance during golf driver swing. Fifteen professional golfers were participated in as subject. Eight motion capture cameras(250 Hz), 2 force plates(1000 Hz), and Trackman were used to collect kinematic and kinetic datas. It was performed Pearson's correlation analysis using SPSS 24.0. The level of significance was at .05. Ball speed, club head speed, X-Factor, and ground reaction force were correlated on driving distance, However, smash factor and knee moment were not correlated on driving distnace. Ball speed, club head speed, X-Factor, and ground reaction force were effected to driving distance, but smash factor and knee moment were not effected to driving distance.

• The Journal of the Convergence on Culture Technology
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• v.7 no.3
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• pp.571-576
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• 2021

This study was carried out to overcome the problems of the existing fitness business and to build a fitness system that can meet the increased demand in the Corona situation. As a platform technology for non-face-to-face fitness edutainment service, it is a next-generation fitness exercise device that can use various body parts and synchronize network-type information. By synchronizing the exercise information of the fitness equipment, it was composed of learning contents through MR-based avatars. A quantified result was derived from examining the applicability of the customized evaluation system through momentum analysis with A.I analysis applying the LSTM-based algorithm according to the cumulative exercise effect of the user. It is a motion capture and 3D visualization fitness program for the application of systematic exercise techniques through academic experts, and it is judged that it will contribute to the improvement of the user's fitness knowledge and exercise ability.

• Proceedings of the Korea Information Processing Society Conference
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• 2011.04a
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• pp.544-546
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• 2011

Due to the explosive growth of online social network users, large numbers of users discover these social network sites are a place where they can be able to spend their spare time, share feelings, ideas freely, and to search for new friends or partners. These web sites give an opportunity for its users to socialize with new people and to keep in touch or reconnect with current or old friends and families across disperse continents via these web sites, which traditionally replace the traditional methods. These social network web sites need careful investigations and findings on the usability for effective interactivity and more usability. However, little research might have previously invested on the usability of these on social network web sites. Therefore, we propose a new framework to study the usability of these social network sites. We namely call our framework "Interactivity". This framework will enable us to assess the usability of the social network sites. It will provide an overview of the user's behavior while interacting in these social network web sites. Measurement of the interactivity will be measured using Camtasia software. This software will entirely capture the interactivity of users including the screen and the movements, which the screen and the motion of the user action will undergo to analysis at the end of our research.

• Korean Journal of Applied Biomechanics
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• v.34 no.1
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• pp.34-44
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• 2024

Objective: This study aimed to investigate how the movements occurring during the follow-through phase after releasing an arrow among elite compound archers, are associated with the arrow impact points on the target. Method: Nine elite archers performed consecutive compound archery shooting under conditions identical to actual competitions using their own bows and equipment. Motion capture system and force platform were utilized to record the changes in joint positions and center of pressure, respectively. Principal component analysis was employed to identify the patterns in which multidimensional joint positions and COP changes were organized with horizontal and vertical coordinates of arrow impact points. Subsequently, correlation analysis quantified the relationship between individual variables and the coordinates of arrow impacts on the target. Results: We found a common organizational pattern in which the two axes of the impact point coordinates were grouped into the first two principal components. The movements of the upper and lower limbs following release exhibited opposite patterns in the anterior-posterior axis, with significant correlations observed between the arrow impact points of the horizontal axis and the left shoulder, right elbow, left hip, and both knees. Additionally, the lateral movements induced by the reaction force upon arrow release showed significant associations with the vertical coordinates of the impact points. Particularly, the correlations between the movements of the left shoulder and elbow, as well as the bilateral hip and right knee, were consistently observed among all participants. Conclusion: These findings implied that the post-release movements could significantly influence the trajectory and impact points of the arrows in compound archery. We suggest that a consistent and controlled movement during the follow-through phase may be more beneficial for optimizing shooting accuracy and precision rather than minimizing movements.

• Korean Journal of Applied Biomechanics
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• v.25 no.1
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• pp.29-37
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• 2015

Objective : The purpose of this study was to investigate the biomechanical properties of shock absorption strategy and postural stability during the drop landing for each types. Methods : The motions were captured with Vicon Motion Capture System, with the fourteen infra-red cameras (100Hz) and synchronized with GRF(ground reaction force) data(1000Hz). Ten male soccer players performed a drop landing with single-leg and bi-legs on the 30cm height box. Dependent variables were the CoM trajectory and the Joint Moment. Statistical computations were performed using the paired t-test and ANOVA with Turkey HSD as post-hoc. Results : The dominant leg was confirmed to show a significant difference between the left leg and right leg as the inverted pendulum model during Drop Landing(Phase 1 & Phase 2). One-leg drop landing type had the higher CoM displacement, the peak of joint moment with the shock absorption than Bi-leg landing type. As a lower extremity joint kinetics analysis, the knee joint showed a function of shock absorption in the anterior-posterior, and the hip joint showed a function of the stability and shock absorption in the medial-lateral directions. Conclusion : These findings indicate that the instant equilibrium of posture balance(phase 1) was assessed by the passive phase as Class 1 leverage on the effect of the stability of shock absorption(phase 2) assessed by the active phase on the effect of Class 2 leverage. Application : This study shows that the cause of musculo-skeletal injuries estimated to be focused on the passive phase of landing and this findings could help the prevention of lower damage from loads involving landing related to the game of sports.

• Korean Journal of Applied Biomechanics
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• v.25 no.2
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• pp.149-155
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• 2015

Purpose : Recently, many researchers and golf coachers demonstrated that X-factor and X-factor stretch had a co-relationship with driving distance. However, its relationship is still controversial and ambiguous. Thus, the aim of this study was to examine the relationship among X-factor, X-factor stretch and swing-related factors, including driving distance in elite golfers. Method : Seventeen male elite golfers (handicap: ${\leq}4$) with no history of musculo-skeletal injuries participated in the study. Thirty spherical retro-reflective markers were placed on including the middle point of PSIS, the right/left ASIS, the right/left lateral acromion of the scapula, driver head and shaft grip. All motion capture data was collected at 100Hz using 6 infrared cameras. Carry distance, club speed, ball speed, smash factor, launch angle, and spin rate were collected from radar-based device, TrackMan. Results : Pearson's correlation coefficient method was used to find the correlations among X-factor, X-factor stretch and swing-related factors. Positive correlations between driving distance and other swing-related factors which include club speed(r=.798, p<.001), and ball speed(r=.948, p<.001) were observed. In contrast to the swing-related factors, X-factor and X-factor stretch had no relationship to driving distance. Conclusion : These results indicate that X-factor and X-factor stretch are not key regulators in driving distance.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.41 no.3
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• pp.153-160
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• 2017

Gait analysis has been conducted in various environments, but the biomechanics during the transition from uphill walking to downhill walking have not been reported. The purpose of this study is to investigate the knee and ankle joint kinematics and kinetics during walking on a triangle-shaped slope compared with those during level walking. Kinematic and kinetic data of eighteen participants were obtained using a force plate and motion capture system. The greater peak ankle dorsiflexion angle and moment and the peak knee extension moment were observed (p<0.05) during both uphill and downhill walking on the triangle-shaped slope. In summary, uphill walking on a triangle-shaped slope, which showed a peak knee flexion of more than $50^{\circ}$ with greater peak knee extension moment, could increase the risk of patellofemoral pain syndrome. Downhill walking on a triangle-shaped slope, which involved greater ankle dorsiflexion excursion and peak ankle dorsiflexion, could cause gastrocnemius muscle strain and Achilles tendon overuse injury.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.5
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• pp.2339-2345
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• 2011

Gait recognition is the method to identify the person who walks in front of camera using characteristics of individuals by a sequence of images of walking people. The accuracy of biometric such as fingerprint or iris is very high; however, to provide information needs downsides which allow users to direct contact or close-up, etc. There have been many studies in gait recognition because it could capture images and analysis characteristics far from a person. In order to recognize the gait of person needs a continuous sequence of walking which can be distinguished from the individuals should be extracted features rather than an single image. Therefore, this paper proposes a method of gait recognition that the motion of objects in sequence is described the characteristics of a shape sequence descriptor, and through a variety of experiments can show possibility as a recognition technique.

• Computers and Concrete
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• v.26 no.1
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• pp.75-94
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• 2020

The aim of this research is to investigate free vibration of a novel five layer Timoshenko microbeam which consists of a transversely flexible porous core made of Al-foam, two graphen platelets (GPL) nanocomposite reinforced layers to enhance the mechanical behavior of the structure as well as two piezo-magneto-electric face sheets layers. This microbeam is subjected to a thermal load and resting on Pasternak's foundation. To accomplish the analysis, constitutive equations of each layer are derived by means of nonlocal strain gradient theory (NSGT) to capture size dependent effects. Then, the Hamilton's principle is employed to obtain the equations of motion for five layer Timoshenko microbeam. They are subsequently solved analytically by applying Navier's method so that discretized governing equations are determined in form of dynamic matrix giving the possibility to gain the natural frequencies of the Timoshenko microbeam. Eventually, after a validation study, the numerical results are presented to study and discuss the influences of various parameters such as nonlocal parameter, strain gradient parameter, aspect ratio, porosity, various volume fraction and distributions of graphene platelets, temperature change and elastic foundation coefficients on natural frequencies of the sandwich microbeam.

• Korean Journal of Applied Biomechanics
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• v.17 no.1
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• pp.111-119
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• 2007

The purpose of this study was to investigate muscle activity and gait pattern in lower limb depending on the outsole of heel rockers. Fifteen healthy men volunteered for this experiment. Each subject performed totally three trails with two pairs of different heel rocker shoes and a pair of normal running shoes at speed of 1.33m/s for 1 minute during walking on a treadmill. Kinematic data gathered in 100Hz was recorded and analyzed by using the 3D motion capture system to measure the trunk tilt and joint angle of the right lower limb. And the lower extremity muscle activities were simultaneously recorded in 1000Hz and assessed by using EMG. The statistical analysis was the one-way ANOVA with the repeated measures to compare among the three kinds of shoes. The level of statistical significance for all tests was 0.05. Joint angle of lower limb was showed statistically significant different in MST(hip joint), LHS(ankle joint), and RTO(knee and ankle joint). Muscle activity of rectus femoris and biceps femoris was statistically increased in both heel rocker shoes during gait cycle on treadmill. The maximum peak time of tibialis anterior in the negative heel rocker showed the delay of approximately 23.8%time than normal shoes. Gait pattern variability of the negative heel rocker was increased in the first half of the stance phase and the variability of the positive heel rocker was increased in the terminal stance phase. In Conclusion, stability was decreased in between joints of lower limb on positive heel rocker than negative heel rocker. This study found that there were different joint angle, muscle activity, gait pattern and coordinate system of the lower limb in each kind of shoes. These unstability affected the lower extremity and the whole body. A further study has to be continued with study of rehabilitation and exercise for a long-term.