• Physical Therapy Korea
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• v.13 no.4
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• pp.79-86
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• 2006

The purpose of the current experiment was to describe interlimb coordination when swing limb conditions are being manipulated by constraining step length or by adding a 5 or 10 pound weight to the swing limb distally. Subjects were asked to begin walking with the right limb to land on the primary target (normal step length) that is 10 cm in diameter. However, if, during movement, the light was illuminated, then the subject had to step on one of the secondary targets (long and short step length). These three step length conditions were repeated while wearing a 5 pound ankle weight and then when wearing a 10 pound ankle weight. Ground reaction force (GRF) data indicated that there were changes in the forces and slopes of the swing and stance Fx GRFs. Long stepping subjects had to increase the propulsive force required to increase step length. Consequently, swing and stance toe-off greatly increased in the long step length condition. Short step length subjects had to adequately adjust step length, which decreased the speed of gait initiation. Loading the swing limb decreased the force and slope of the swing limb. Swing and stance toe-off was longest for the long step length condition, but there was a small difference of temporal events between no weight and weight condition. It appears that subjects modulated GRFs and temporal events differently to achieve the peak acceleration force of the swing and stance limb in response to different tasks. The findings from the current study provide preliminary data, which can be used to further investigate how we modulate forces during voluntary movement from a quiet stance. This information may be important if we are to use this or a similar task to evaluate gait patterns of the elderly and patient populations.

• Korean Journal of Applied Biomechanics
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• v.25 no.3
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• pp.249-256
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• 2015

Objective : The purposes of this study was to perform a kinematical analysis on age and walkway types in elderly women subjects. Method : Forty subjects participated in the experiment (A1 group - age: $67.30{\pm}1.49yrs$, height: $153.81{\pm}4.47cm$, weight: $61.80{\pm}5.24kg$, A2 group - age: $71.70{\pm}1.10yrs$, height: $152.01{\pm}2.84cm$, weight: $59.69{\pm}7.34kg$, A3 group - age: $76.80{\pm}0.98yrs$, height: $150.16{\pm}6.08cm$, weight: $57.27{\pm}6.42kg$, A4 group - age: $81.80{\pm}0.60yrs$, height: $152.18{\pm}4.77cm$, weight: $55.80{\pm}7.78kg$). The study method adopted was the 3D analysis with six cameras. Ground type were classifed as gait pattern on flat, ascent and descent ramp. For the statistical analysis, the SPSS 21.0 was used to perform Repeated measured Two-way ANOVA. Results : In velocity of CM, there was faster movement on flat ground. When it came to the velocity of right toe, there was no significance in early mid-swing of right foot, but A4 was the slowest in late mid-swing of right foot on flat ground. In joint angle in left foot strike, the left hip joint and knee joint were more flexed in descent ramp, In addition left and right ankle joints were more plantarflexed in descent ramp, and left ankle joint was more plantarflexed in the over 75 yrs age groups. Conclusion : The higher age group were more flexed in lower body joints during descent ramp.

• Korean Journal of Applied Biomechanics
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• v.27 no.1
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• pp.19-23
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• 2017

Objective: The aim of this study was to investigate the relationship between the ball velocity and the upper extremity kinematics for both dominant and non-dominant side in inexperienced participants about an overarm throwing task. Method: Seven women who are inexperienced in overarm throwing participated in this study (Age: $25.1{\pm}2.4years$, Height: $160.8{\pm}3.5$; Weight $56.5{\pm}7.8$). Participants visit the laboratory for three days with one day rest between test sessions. Whole body 3-dimensional (3D) motion capture was recorded during the overarm throwing trials with ten cameras Vicon motion analysis system (T-10, T40, Oxford Metrics Ltd, UK). Total 45 overarm throwing were recorded for each side for each test session. Ball speed also was measured 3 meters away behind the subjects and recorded for every trial. Results: Mean ball velocity was higher for dominant hand compared to non-dominant hand (p <.05). Trunk segment variables (maximum angles and angular velocities) showed the most consistent relationship with the ball velocity. Conclusion: The importance of the trunk segment during the throwing activities can be seen in some individuals. But inconsistent results between subjects emphasize the importance of the individuals' movement patterns especially for bilateral sports. The future studies should be conduct about the sequence of segments, kinetic variables and effect of training.

• Proceeding of EDISON Challenge
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• 2016.03a
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• pp.455-462
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• 2016

Recently, followed by rapid growth of robotics field, multi-linkage mechanism which can even pass by rough road is getting lots of attention. In this paper, I focused on Jansen mechanism. It's a kinematics object which is named after Dutch artist Theo jansen. Jansen mechanism embraces structure and mechanism which creates locomotion with the combination of the power and simple structure. Theo jansen suggests a 'Holy number'. It's an ideal ratio of leg components length. However, if there's desired gait locomotion, you have to adjust the ratio and the length. But even slight change of the length could cause a big change at the end-point. To solve this problem, I suggest a reverse engineering method to get a ratio of each links by nonlinear optimization with pre-set desired trajectory. First, we converted a movement of the joint of Jansen mechanism to vectors by kinematics analysis of multi-linkage structure. And we showed the trajectory at the end-point. After that, we set desired trajectory which we found most ideal. Then we got the length of the leg components which draws a trajectory as same as trajectory we set, using Multi-objective genetic algorithm toolbox in MATLAB. Result is verified by Edison designer and mSketch. And we analyzed if it could pass through the obstruction which is set dynamically.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.17 no.5
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• pp.1070-1075
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• 2013

In this research, we describe a security robot system and ongoing research results to control human's wrong direction in order to forbid human to enter security zone. Proposed robot system surveils a security area with equipped laserscanner sensor usually. When it detect walking human who is for the area, robot calculates his velocity vector, plans own path to forestall and interrupts him who want to head restricted area and starts to move along the estimated trajectory. The walking human is assumed to be a point-object and projected onto an scanning plane to form a geometrical constraint equation that provides position data of the human based on the kinematics of the mobile robot. While moving the robot continues these processes for adapting change of situation. After arriving at an opposite position human's walking direction, the robot advises him not to be headed more and change his course. The experimental results of estimating and tracking of the human in the wrong direction with the mobile robot are presented.

• Korean Journal of Applied Biomechanics
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• v.15 no.3
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• pp.79-94
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• 2005

Because the golf swing is very complex movement, it is varied in different gender, skill level, and club. This study measured kinematic variables in golf swing regarding gender, skill level, and club types using FasTrak electromagnetic tracking system. Golf swing kinematics including time variables, linear and angular displacement variables, angular velocity variables were analyzed and compared through three-way ANOVA The results were as follows: 1. In time variables, Female and driver showed longer backswing time than male and iron. Downswing time was longer in female and nonexperts than male and experts. Backswing time over downswing time was longer in experts than nonexperts. Uncocking time was longer in male and experts than female and nonexperts. The differences were statistically significant (p<.05). 2. In displacement variables, Female and nonexperts showed greater backswing head lift than male and experts. Impact head lift was greater in female, nonexperts, and iron than male, experts, and driver. The differences were statistically significant (p<.05). Experts and driver showed greater top hip rotation angle than nonexperts and iron. Top shoulder rotation angle was greater in male, experts and driver than female, nonexperts, and iron. X-factor was greater in male, experts, and driver than female, nonexperts, and iron. Male and experts showed greater backswing hip sway than female and nonexperts. Impact hip sway was greater in male and iron than female and driver. The differences were statistically significant (p<.05). 3. In velocity variables, Experts displayed higher impact hip rotation velocity than nonexperts. Impact shoulder rotation velocity was greater in male and iron than female and driver (p<.05).

• Korean Journal of Applied Biomechanics
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• v.31 no.3
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• pp.155-161
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• 2021

Objective: There is a lack of studies using the 3D-2D image registration techniques on the mechanism of a shoulder injury for ice hockey players. This study aimed to analyze in vivo 3D glenohumeral joint arthrokinematics in collegiate ice hockey athletes and compare shoulder scaption with or without a hockey stick using the 3D-2D image registration technique. Method: We recruited 12 male elite ice hockey players (age, 19.88 ± 0.65 years). For arthrokinematic analysis of the common shoulder abduction movements of the injury pathogenesis of ice hockey players, participants abducted their dominant arm along the scapular plane and then grabbed a stick using the same motion under C-arm fluoroscopy with 16 frames per second. Computed tomography (CT) scans of the shoulder complex were obtained with a 0.6-mm slice pitch. Data from the humerus translation distances, scapula upward rotation, anterior-posterior tilt, internal to external rotation angles, and scapulohumeral rhythm (SHR) ratio on glenohumeral (GH) joint kinematics were outputted using a MATLAB customized code. Results: The humeral translation in the stick hand compared to the bare hand moved more anterior and more superior until the abduction angle reached 40°. When the GH joint in the stick hand was at the maximal abduction of the scapula, the scapula was externally rotated 2~5° relative to 0°. The SHR ratio relative to the abduction along the scapular plane at 40° indicated a statistically significant difference between the two groups (p < 0.05). Conclusion: With arm loading with the stick, the humeral and scapular kinematics showed a significant correlation in the initial section of the SHR. Although these correlations might be difficult in clinical settings, ice hockey athletes can lead to the movement difference of the scapulohumeral joints with inherent instability.

• KIPS Transactions on Software and Data Engineering
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• v.11 no.5
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• pp.221-228
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• 2022

With the application of artificial intelligence technology, robots can provide efficient services in real life. Unlike industrial manipulators that do simple repetitive work, this study presented design methods of 6 degree of freedom robot arm and intelligent object search and movement methods for use alone or in collaboration with no place restrictions in the service robot field and verified performance. Using a depth camera and deep learning in the ROS environment of the embedded board included in the robot arm, the robot arm detects objects and moves to the object area through inverse kinematics analysis. In addition, when contacting an object, it was possible to accurately hold and move the object through the analysis of the force sensor value. To verify the performance of the manufactured robot arm, experiments were conducted on accurate positioning of objects through deep learning and image processing, motor control, and object separation, and finally robot arm was tested to separate various cups commonly used in cafes to check whether they actually operate.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.9 no.1
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• pp.1-8
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• 2008

We propose how to program the off-line buffing robot path along shoes' outsole shape in the footwear buffing process by a 5-axis microscribe system like robot mechanism. The microscribe system we developed consists of a 5-axis robot link with a turn table, a signal processing unit, PC and an application software program. Itmakes a robot path on the shoes' upper in accordance with the movement of a microscribe with many joints. The developed system calculates the encoder pulse values for the microscribe arm's rotation and transmits the angle pulse values to the PC through a processing unit. Denavit-Hartenberg's(D-H) direct kinematics is used to make the global coordinate from microscribe joint one. Problems with the microscribe's kinematics can be solved efficiently and systematically by D-H representation. With the coordinate values calculated by D-H equation, our system can draw a buffing gauge-line on the upper sole. We obtain shoes' outline points, which are 2 outlines coupled with the points and the normal vector based on the points. By applying the system to the buffing robot in a flexible manufacturing system, it can be used effectively to program the path of a real buffing robot.

• Korean Journal of Applied Biomechanics
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• v.18 no.1
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• pp.147-158
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• 2008

The purpose of this study was to analyze the kinematical variables involved in two types of service motion in tennis pinpoint and platform stance, to find the fastest serving method. Seven skilled high school tennis players participated, and the kinematics were recorded by the Vicon motion analysis system. For the gathering and analysis of the data workstation, bodybuilder and polygon were used. During the back swing for the pinpoint stance, as the back leg moves forward the COM and the racquet moves more, thus taking 0.04 seconds longer than the platform stance. The body of the subject takes a bow-shape as the subject's foot moves back and their hip moves forward. This movement enables the subject to create more power during the backswing to impact. It also increases the spread of the COM racquet and the serve speed is increase. As there is no forward movement of the foot during the backswing of the platform stance, the COM and the racquet move less and thus the time required is shorter than that for the pinpoint stance by 0.04seconds. Similarly, the time spent creating the power for the serve is shortened, the COM racquet is narrower and the speed is lessened. However, the advantage of this serve is that it increases the stability.