• Korean Journal of Applied Biomechanics
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• v.12 no.2
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• pp.109-130
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• 2002

The purpose of this paper was to make a comparative analysis for the difference of the various kinematic variation which is occurred in the each situation when pitchers throw a straight and a curve ball. Four pitchers, who are two national team players and two high level pitchers, were selected among the right over hand pitchers of D university in the Busan for this paper. The data were analyzed by using 3D equipment. The results of the analysis which was about the elapsed time of the pitching, the movement of the body center-point, the highest height of the left knee, stride length, knee joint angle, shoulder joint angle, elbow joint angle and wrist joint angle in the each section(ST, LKU, HBP, LCF, MCP, BRP) were as follows : 1. Pitching time in the each section and step in the pitching for straight and curve ball was similar. The total elapsed time of the straight and curve ball was 1.78${\pm}$0.07sec and 1.77${\pm}$0.11sec in the order. 2. The position change of the body center to the Z(above below) direction did not show significant difference in the each situation of the section and step between pitching for the straight and curve ball. 3. Height of the left knee did not show significant difference as 125.38${\pm}$11.85cm and 124.95${\pm}$11.63m in the each pitching motion for straight and curve ball. The rate(%H) between height and stride length showed 68.42${\pm}$5.53(%H), 68.40${\pm}$5.45(%H) in the each pitching motion. 4. Pitching for curve ball showed longer stride length than pitching for straight ball that as the stride length was 140.35${\pm}$4.96cm and 144.8${\pm}$1.69cm. The rate(%H) between height and stride length showed 76.9${\pm}$3.77(%H), 79.39${\pm}$2.23(%H) in the each pitching motion. 5. Left knee joint angle did not show significant difference in the ST, LKU and HBP section in the each pitching motion. However, it was shown that knee joint angle was flexed much more in the LFC, MCP and BRP section in the pitching for curve ball. 6. Right shoulder joint angle did not show significant difference in the ST, LKU and HSP section. However, when pitches threw a curve ball in the LKU section. In the LFC section, the right shoulder joint angle was extended much more in the pitching for curve ball, and the angle was extended much in the MCP and BRP section in the pitching for curve ball than straight ball. 7. Right elbow joint angle did not show significant difference in the ST, LKU and HRP section in the two pitching motion. The angle had more flexion in the LFC and MCP section in the pitching for curve ball than the pitching for straight ball. The angle in the each pitching motion for straight ball and curve ball were extended by a narrow margin in the BRP section. 8. Right wrist joint angle was extended much more in the LFC and MCP section in the pitching for curve ball. In the BRP section, the angle was extended much more in the pitching for straight ball than curve ball.

• The Journal of Korean Academy of Prosthodontics
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• v.55 no.3
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• pp.311-318
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• 2017

Several types of attachments have been used for implant supported and/or retained overdentures. Locator is one of the stud type attachments and it has been generally used. However, the colored matrix is resilient and vulnerable to wear, so frequent post-insertion maintenance is needed. To solve this problem, it is necessary to introduce innovative attachment system. Overdentures using Air Gap attachment (AGA) has improved masticatory function and facial esthetics. AGA is made of metal, so it could be more resistant to wear or friction than the other resilient attachments. Nevertheless, AGA plays a role in stress breakers because it allows movement during denture movement with predetermined gap. In addition, both pre-existing implants and natural teeth were successfully used for connection of AGA. AGA could replace other unsplinted type of attachments. Overdentures using AGA could provide satisfactory result in terms of function, esthetics and retention. However, long term follow up is needed.

• Korean Journal of Applied Biomechanics
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• v.19 no.2
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• pp.287-296
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• 2009

This is written to present basic shot information among iron clubs and information of weight shift, because previous study conducted on all clubs was rut enough. This article is about shot analysis of iron club 3,4,5,6,7,8,9 and weight movement, conducted on four skilled golf players and four students who major in golf and are less than three years. The analysis of long and short irons showed statistically meaningful different results for all the participants but iron clubs of 3,4,5 didn't in head speed and ball speed. The skilled group showed better results in head speed, ball speed and direction, Launch angle than the unskilled group. In weight shift movement analysis, the unskilled group moved, on back swing top, their more weight(65.36%) but the skilled group was on their left foot (70.21%)when clubs were on impact moment. It shows that the skilled group put on power more efficiently by moving weight.

• Korean Journal of Applied Biomechanics
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• v.17 no.1
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• pp.81-90
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• 2007

The effort identifying positioning information of the moving object in real time has been a issue not only in sport biomechanics but also other academic areas. In order to solve this issue, this study tried to track the movement of a pitched ball that might provide an easier prediction because of a clear focus and simple movement of the object. Machine learning has been leading the research of extracting information from continuous images such as object tracking. Though the rule-based methods in artificial intelligence prevailed for decades, it has evolved into the methods of statistical approach that finds the maximum a posterior location in the image. The development of machine learning, accompanied by the development of recording technology and computational power of computer, made it possible to extract the trajectory of pitched baseball from recorded images. We present a method of baseball tracking, based on object tracking methods in machine learning. We introduce three state-of-the-art researches regarding the object tracking and show how we can combine these researches to yield a novel engine that finds trajectory from continuous pitching images. The first research is about mean shift method which finds the mode of a supposed continuous distribution from a set of data. The second research is about the research that explains how we can find the mode and object region effectively when we are given the previous image's location of object and the region. The third is about the research of representing data into features that we can deal with. From those features, we can establish a distribution to generate a set of data for mean shift. In this paper, we combine three works to track baseball's location in the continuous image frames. From the information of locations from two sets of images, we can reconstruct the real 3-D trajectory of pitched ball. We show how this works in real pitching images.

• Therapeutic Science for Rehabilitation
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• v.12 no.1
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• pp.23-35
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• 2023

Objective : This study is to examine the practical use of clinical observational evaluation of sensory integration therapy and the difficulty and importance of measuring results for each sub-item, and through this, to confirm the usefulness of the application of Artificial Intelligence measurement technology in clinical observational measurement and the need for application. Methods : The questionnaire consisted of the actual use of the sensory integration evaluation tool, the difficulty of measurement for each detailed item of clinical observation, the usefulness of AI measurement technology, the importance of evaluation for each detailed item, and the need for developing AI measurement technology. Results : The detailed items that were difficult to measure during clinical observation were the Finger-to-Nose Test and Postural control (71.0%), followed by Eye movement and Protective Extension Test (67.7%). 83.9% of the study subjects answered that it would be useful to apply AI measurement technology when observing images. Postural control (on the ball) (90.3%) was the highest item that answered that AI measurement technology was needed, followed by Eye movement (83.9%), and Prone Extension and Protective Extension Test (77.4%). Conclusion : The results confirmed the desire of therapists that clinical observation is an important evaluation tool in the field of child occupational therapy in Korea.

• Proceedings of the KIEE Conference
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• 2007.10a
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• pp.315-316
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• 2007

This paper presents a new methodology to improve movement database for a humanoid robot. The database is initially full of human motions so that the kinetics characteristics of human movement are immanent in it. then, the database is updated to the pseudo-optimal motions for the humanoid robot to perform more natural motions, which contain the kinetics characteristics of robot. for this, we use the evolutionary algorithm. the methodology consists of two processes : (1) the offline imitation learning of human movement and (2) the online generation of natural motion. The offline process improve the initial human motion database using the evolutionary algorithm and inverse dynamics-based optimization. The optimization procedure generate new motions using the movement primitive database, minimizing the joint torque. This learning process produces a new database that can endow the humanoid robot with natural motions, which requires minimal torques. In online process, using the linear combination of the motion primitive in this updated database, the humanoid robot can generate the natural motions in real time. The proposed framework gives a systematic methodology for a humanoid robot to learn natural motions from human motions considering dynamics of the robot. The experiment of catching a ball thrown by a man is performed to show the feasibility of the proposed framework.

• Korean Journal of Applied Biomechanics
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• v.29 no.2
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• pp.43-51
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• 2019

Objective: This study aims to propose an efficient technical model through a kinematic analysis of field hockey drag flick shooting motion in laboratory situations and game situations and to build up the basic data on drag flick shooting technique through a comparative analysis of a Korean specialized shooter and specialized shooters of competing Asian countries. Method: This study selected one Korean female national specialized shooter and seven specialized shooters of competing countries, China, Japan, India, and Malaysia, who participated in the 2018 Asian Hockey Champions Trophy as research subjects. In exercise situations, a 3-D motion analysis utilizing an infrared camera was conducted, while in game situations, an image-based 3-D motion analysis utilizing a digital camera was conducted. Results: The Korean specialized shooter had smaller changes in the angles of the trunk and the stick in game situations than in exercise situations. She had a high angular velocity of the trunk and the stick head, and the maximum speed of the ball was high. The Korean specialized shooter had the maximum angular velocity of the trunk higher than the specialized shooters of the competing countries did, and the angular velocity of the stick head and the maximum speed of the ball were in the average level. Conclusion: As for drag flick shooting in game situations, changes in the angle of the trunk and the stick were small, and the angular velocity was high due to the pressure that the shooters should perform the motion fast with the defenders' interruptions, and this high angular velocity of the trunk and the stick head affected the movement of the ball. Thus, the maximum speed of the ball was higher in game situations than in exercise situations. The Korean specialized shooter had the maximum angular velocity higher than the specialized shooters of the competing countries did; however, the maximum speed of the ball was average, and it turned out that the maximum speed of the ball was associated with the angular velocity of the stick head in P3. Therefore, Korean specialized shooters need complementary training for a change to the torque of the stick head, using the strong torque of the trunk.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.12 no.3
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• pp.590-595
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• 2008

A new adaptive TMS variable area flow meter that is used to the environment measuring equipment is proposed. This system is consist of a ball moving within the tube line which corresponds to gas flow and photo sensor array which monitoring the movement of ball. This system can monitoring the position of bali in case of the very few gas flow in various levels. And it can automatically adjust the gas flow at the highest and the lowest level to prevent the tube line blockage.

• The Journal of the Korea institute of electronic communication sciences
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• v.19 no.1
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• pp.157-164
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• 2024

In this paper, we would like to develop a system that selects the drink you want with an application made with an app inventory for the person who manufactures the drink and manufactures the drink. After combining the drinks to be mixed with the dispenser, the actuator was controlled to accurately move the ball screw to the location of the dispenser by controlling the step motor through Arduino. According to the actuator movement control and the number of times the dispenser is pressed, the amount of drinks to be mixed is extracted in proportion to each other. Finally, we establish a system to replace the labor force of cafes and further suggest directions that the system can be used everywhere.

• Journal of the Korea Convergence Society
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• v.11 no.11
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• pp.239-247
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• 2020

This study is about design and verification of stress reduction of bearings for wind turbines. In a slewing bearing having a typical four-contact structure, the contact point moves to the end of the raceway due to a large moment load, resulting in a stress concentration. A bearing was designed to reduce such contact point movement. The deformation behavior of typical ball bearings and newly designed bearings was calculated through finite element analysis under ultimate load by replacing the ball with a spring element. The contact stress between the ball and the raceway was calculated by finite element analysis by inputting the deformation behavior analysis result as a boundary condition. The effectiveness of the bearing stress analysis method using spring elements was verified through comparison of the contact stress according to the bearing structure.