• Journal of the Korean Society of Industry Convergence
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• v.22 no.4
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• pp.435-445
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• 2019

Ball screw drives are widely used in industry, and many studies have been devoted on precise, fast and robust control of ball screw drives. In this study, a novel position control algorithm for ball screw drives is proposed, which consist of a PD controller, a friction feedforward and a disturbance observer. The dynamics and the position error of such controller are analyzed to establish an error model, which can be used to predict the resulting position error of the given desired trajectory. Using the proposed error model, the desired trajectory can be modified so that the predicted position error can be compensated in a feedforward manner. The proposed algorithm does not require the model of the system for the error prediction, and thus can be easily applied to conventional control systems. The performance of the system is verified through simulations and experiments.

• Journal of Powder Materials
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• v.28 no.6
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• pp.462-469
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• 2021

Tin/graphite composites are prepared as anode materials for Li-ion batteries using a dry ball-milling process. The main experimental variables in this work are the ball milling time (0-8 h) and composition ratio (tin:graphite=5:95, 15:85, and 30:70 w/w) of graphite and tin powder. For comparison, a tin/graphite composite is prepared using wet ball milling. The morphology and structure of the different tin/graphite composites are investigated using X-ray diffraction, Raman spectroscopy, energy-dispersive X-ray spectroscopy, and scanning and transmission electron microscopy. The electrochemical properties of the samples are also examined. The optimal dry ball milling time for the uniform mixing of graphite and tin is 6 h in a graphite-30wt.%Sn sample. The electrode prepared from the composite that is dry-ball-milled for 6 h exhibits the best cycle performance (discharge capacity after 50^th cycle: 308 mAh/g and capacity retention: 46%). The discharge capacity after the 50^th cycle is approximately 112 mAh/g, higher than that when the electrode is composed of only graphite (196 mAh/g after 50^th cycle). This result indicates that it is possible to manufacture a tin/graphite composite anode material that can effectively buffer the volume change that occurs during cycling, even using a simple dry ball-milling process.

• Journal of the Korean Society of Industry Convergence
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• v.11 no.4
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• pp.209-216
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• 2008

The ball screw position control system driven by a pneumatic motor using continuous sliding mode is proposed. The design and performance of proposed servo system are presented by means of examples tested under practical service conditions. Results of experimental implementation on the proposed system illustrate the effectiveness of the ball screw position control system driven by a pneumatic motor using continuous sliding mode as a servo pneumatic actuator driven by a pneumatic motor.

• Journal of Sport and Applied Science
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• v.3 no.2
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• pp.11-16
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• 2019

Purpose: New sports is a modified physical activity which is developed for participants to easily learn and play. This study is to analyze distribution channels and related strategies of Korea new sports and to discuss strategies for promoting Korea new sports, especially for two-two ball. Research design, data, and methodology: The study reviewed literatures including documents of Dae-Han two-two-ball association and new sports related research articles. Results: First, Dae-Han two-two-ball association has introduced two two ball to consumers via educational organizations such as schools and youth education sectors. Second, Dae-Han two-two-ball association has introducted two two ball to school teachers by teacher training sessions. Third, Dae-Han two-two-ball association has educated future instructors and provided certificates to them. Fourth, Dae-Han two two ball association has applied governmental projects and sought to promote domestic new sports. Finally, Dae-Han two two ball association has hosted national events every year for facilitating Korea new sports across nation. Conclusions: In conclusion, Korea new sports shoud be spread out by school teachers and educational organizations. Two-two ball association needs to develop a systematic educational and managerial process for training instructors. Finally, Two-two ball association needs to make opportunities of teacher training sessions. Future directions were discussed.

• Applied Chemistry for Engineering
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• v.25 no.1
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• pp.72-77
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• 2014

Microstructure and thermal stability of mechanically ball milled $FeS_2$ were investigated. The average particle size and distribution of $FeS_2$ powder were changed in two steps with the increased ball milling time. The average particle size drastically decreased from $98.4{\mu}m$ to 1.01 and $0.89{\mu}m$ after ball milling of 10 h and 30 h, respectively. However, the distribution was broad and a shoulder appeared at $2{\mu}m$ because the pulverization was still in process at 10 h ball milling. After 60 h ball milling, the distribution became narrower. After ball milling of 120 h, the average particle size increased because of $FeS_2$ particle agglomeration. Therefore, the particle size distribution became broaden again. Finally, after ball milling of 170 h, $FeS_2$ with the narrowest size distribution can be obtained. Thermal stability of $FeS_2$ was unstable as the $FeS_2$ particle was pulverized. Therefore, the activation energy of the fine size particles is 27% lower than that of the as-received $FeS_2$.

• International journal of advanced smart convergence
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• v.10 no.1
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• pp.134-141
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• 2021

The purpose of this study is to investigate the effect of the elderly's motivation to participate in ball games on social support and subjective feelings of happiness. The subjects of this study were elderly people aged 65 or older who lived in Gwangju in 2020 and participated in the ball game movement. Besides, 150 males, 150 females, and 300 total subjects were selected using the convenient sampling method. The survey tool focuses on the motivation for participation in ball game movement, social support, and subjective happiness, and the data collected using this are used for the SPSS 20.0 version, and use statistics are processed according to the purpose of analysis. The results obtained through this research process are as follows. First, it was found that the elderly's motivation to participate in ball game exercise partially affected social support. Second, it was found that the elderly's motivation to participate in ball game exercises had a partial effect on subjective happiness. Third, it was found that the elderly's social support partially affected the subjective feelings of happiness.

• Journal of the Korean Society of Industry Convergence
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• v.8 no.4
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• pp.227-234
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• 2005

In this study an experimental investigation was conducted to assesment of cutting ability for CBN ball end-milling, STD11 and NAK80 materials. The cutting force and surface roughness of the work-pieces were obtained in machining center. The assessment of CBN tools were inspected through the tool dynamotor and SEM. When $30^{\circ}$ negative rake angle, the wear and cutting force were good, surface roughness was better at cutting fluid during CBN cutting.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.13 no.11
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• pp.5512-5526
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• 2019

In sports video games, especially ball games, motion capture techniques are used to reproduce the ball-driven performances. The amount of motion data needed to create different situations in which athletes exchange balls is bound to increase exponentially with resolution. This paper proposes how avatars in virtual worlds can not only imitate professional athletes in ball games, but also create and edit their actions effectively. First, various ball-handling movements are recorded using motion sensors. We do not really have to control an actual ball; imitating the motions is enough. Next, motion is created by specifying what to pass the ball through, and then making motion to handle the ball in front of the motion sensor. The ball's occupant then passes the ball to the user-specified target through a motion that imitates the user's, and the process is repeated. The method proposed can be used as a convenient user interface for motion based games for players who handle balls.

• Journal of Digital Convergence
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• v.14 no.12
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• pp.525-535
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• 2016

The purpose of this study was to evaluate the effect of thoracic dynamic stretching with elastic band on the ROM and ball speed for baseball player. For this purpose, 11 baseball players of the I city high school and university performed thoracic dynamic stretching with elastic band before throwing a ball. After stretching, we measured the ROM and ball speed and compared. The results were as follows. First, ROM after stretching showed a significant increase immediately compared with before stretching. Second, the speed of the ball was significantly increased after stretching compared with before. These results indicated that thoracic dynamic stretching with elastic band for baseball players might have a positive effect on ball speed as well as ROM.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.59 no.8
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• pp.1444-1448
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• 2010

The ball and beam system is one of the most popular models for studying control systems because of its nonlinearity and several control techniques have been proposed. Sliding mode control is a popular robust control method which rejects the external disturbance. In this paper, we propose a robust controller using the ${\epsilon}$-sliding surface. On the ${\epsilon}$-sliding surface, the system robustness and convergence can be manipulated via a use of ${\epsilon}$. We show the stability analysis and convergence analysis on the ${\epsilon}$-sliding surface. In addition, the experimental results show the validity of the proposed controller.