• Korean Journal of Applied Biomechanics
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• v.28 no.2
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• pp.87-92
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• 2018

Objective: The purpose of this study was to investigate the factors affecting two kinds of bat swing behavior through kinematic analysis. Method: A total of 32 high school baseball players participated in this study. The ball was placed on the tee-ball in a position where the subject could easily swing and the standard bat swing was performed as quickly and as accurately as possible using aluminum bats and wooden bats. Results: The aluminum bat showed a rapid swing speed of about 1.79 m/sec compared to the wooden bat. The speed of the batted ball was found to be significantly greater for the aluminum bat than for the wooden bat. In addition, although the difference between the shoulder-pelvis rotation angle according to the type of bat was not indicated, there was a statistically significant difference between the aluminum bat and the wooden bat in terms of the rotational angular velocity. Conclusion: Even though the results can explain the difference between the bat swing speed and the speed of the batted ball depending on the bat's material, it is difficult to explain the difference depending on the type of bat at the shoulder-pelvis rotation angle. However, shoulder-pelvic rotation angular velocity appears to be higher for the aluminum bat, and the differences in the type of bat is considered to be related to the batting swing factor.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.6
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• pp.239-244
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• 2019

The purpose of this study was to determine the correlation between upper limb muscle power and bat swing speed in elementary school baseball players. This study subjects were 32 subjects. Upper extremity muscle strength was measured in the Both Shoulder joints extensor flexor abductor adductor, Both elbow joints extensor flexor and bat swing speed. The correlation between upper extremity muscle strength and bat swing speed was analyzed using pearson's correlation analysis. There was a significant correlation between dominant upper extremity muscle strength and bat swing speed in the order of shoulder adductor, shoulder abductor, elbow flexor, and shoulder flexor and in correlation between non-dominant upper extremity muscle strength and bat swing speed in the order of shoulder adductor, elbow flexor, shoulder abductor, shoulder extensor, elbow extensor, and shoulder flexor. From these results, it can be seen that the stronger the upper extremity muscle strength, the bat swing speed is the more positive correlation.

• Archives of Plastic Surgery
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• v.46 no.3
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• pp.198-203
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• 2019

Background Professional affiliation between medical centers and professional sports teams can be mutually beneficial in the provision of healthcare and marketing strategy. Anecdotal evidence suggests a link between trauma volume and sporting events; however, there is limited data. This study aims to characterize the incidence of operative hand and facial trauma during professional baseball home games. Methods A retrospective review of surgical cases for traumatic hand or facial injuries at a level 1 center between 1999 and 2012 was performed. Demographic information including date of injury, admission status, and operative repair were collected. Patients were grouped based on whether their trauma occurred on the date of a home game. Results Operative hand and facial trauma occurred at a rate of 33.4 injuries per 100 days with home games, compared to 22.2 injuries per 100 days (incidence rate ratios, 1.50; 95% confidence interval, 1.34-1.69). When home games were played, patients were more likely to present as a result of motorcycle accidents (3.1% vs. 1.5%; P=0.04) or bicycle accidents (5.0% vs. 2.6%; P=0.01). Other mechanisms of trauma were not statistically different. There was an increase incidence of injuries during home games in August; weekly variability showed an increased incidence during the weekends. Conclusions There was an increased rate of operative hand and facial injuries on dates with professional home games. The incidence of injuries during home games was higher in the late summer and on the weekends. Further analysis may allow improved resource allocation and strategies for injury prevention and treatment.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.24 no.8
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• pp.978-984
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• 2020

In this study, the correlation between sports records and weather data was analyzed using the big data analysis method. To this end, data was collected by API and crawling, data was processed, statistics were performed, and data visualization was performed. The subject of this study was a player who entered the regular at-bat among outfielders in the 2019 KBO League. In addition, meteorological data were analyzed by using the unpleasant index and above 70 and below 70. As a result of the study, in the various hitting indicators, which are the records that pitchers intervene, the higher the unpleasant index, the better the outfielder's record, but pitchers, walks, pitches, pitching success rates, pitches per turn, pitches per game From the records of the back, it was found that the outfielder made the pitcher difficult. It is expected that this study will help the development of the sports data industry and the performance of baseball players, baseball teams, and coaching staff.

• Journal of the Korea Convergence Society
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• v.12 no.8
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• pp.61-66
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• 2021

The purpose of this study was to investigate the relationship between vertical jump and lower extremity muscle strength of elementary school baseball players. This study subjects were conducted with a total of 40 subjects. Vertical jump was measured using a vertical jump gauge, and a hand held dynamometer was used to measure lower extremity muscle strength. For the measurement of lower extremity muscle strength, flexion·extension·adduction·abduction·internal rotaiton·external rotation of both hip joint, flexion·extension of both knee joint, dorsi flexion·plantar flexion of both ankle joint were measured. pearson's correlation analysis was used to analyze the correlation between vertical jump and lower extremity muscle strength. From these results, it was found that the stronger the leg muscles except for the plantar flexion, the higher the vertical jump was, indicating a positive correlation. In future studies, follow-up studies on the relationship between batting ability and vertical jump & lower extremity muscle strength are needed.

• Journal of The Korean Association of Information Education
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• v.26 no.4
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• pp.273-284
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• 2022

The goal of this paper is to propose the use of machine learning platforms in education to train learners to recognize data biases. Learners can cultivate the ability to recognize when learners deal with AI data and systems when they want to prevent damage caused by data bias. Specifically, this paper presents a method of data bias education using MachineLearningforKids, focusing on the case of AI baseball referee. Learners take the steps of selecting a specific topic, reviewing prior research, inputting biased/unbiased data on a machine learning platform, composing test data, comparing the results of machine learning, and present implications. Learners can learn that AI data bias should be minimized and the impact of data collection and selection on society. This learning method has the significance of promoting the ease of problem-based self-directed learning, the possibility of combining with coding education, and the combination of humanities and social topics with artificial intelligence literacy.

• The Journal of the Korea Contents Association
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• v.22 no.5
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• pp.48-56
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• 2022

The importance of data analysis in baseball has been increasing after the success of MLB's Oakland which applied Billy Beane's money ball theory, and the 2020 KBO winner NC Dinos. Various studies using data in baseball has been conducted not only in the United States but also in Korea, In particular, the models using deep learning and machine learning has been suggested. However, in the previous studies using deep learning and machine learning, the focus is only on predicting the win or loss of the game, and there is a limitation in that it is difficult to interpret the results of which factors have an important influence on the game. In this paper, to investigate which factors is important by position, the prediction model for the Golden Glove award which is given for the best player by position is developed. To develop the prediction model, XGBoost which is one of boosting method is used, which also provide the feature importance which can be used to interpret the factors for prediction results. From the analysis, the important factors by position are identified.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.17 no.7 s.110
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• pp.605-614
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• 2006

In this paper, a 3D structure skimmer-shaped circular microstrip antenna is designed, the ends of whose both sides are made as DC(Depressed Carving part) applying perturbation effect to reduce the patch size of microstrip antenna operating at design frequency 1.575 GHz. The result shows its return loss, - 10 dB bandwidth, gain, - 3 dB beamwidth E, H-plane are -26.59 dB, 65 MHz(4.13 %), 4.66 dBd, $79^{\circ},\;87^{\circ}$ respectively. The diameter of the antenna is 85 mm, which is 12.4 % reduced compared to the size(97 mm) of general microstrip patch antenna. Therefore its area reduction is 23.2 %. Furthermore, a linear and circular polarized baseball-shaped circular microstrip antenna is designed to minimize the patch size of the antenna. This structure of antenna operating at the design frequency 1.575 GHz is applied with the optimum RC(Raised Carving part) & DC ratio and an asymptotic line angle. In case of linear polarized baseball-shaped circular microstrip antenna, the patch size of the antenna is 74 mm, which is 41.8 % area reduction compared to general microstrip patch antenna. In case of circular polarized baseball-shaped circular microstrip antenna, the diameter of patch is 82 mm, which is 28.5 % area reduction compare to general microstrip patch antenna linear polarized. We have verified that the perturbation effect can be applied to minimize the circular microstrip antenna.

• The Journal of Korean Orthopaedic Ultrasound Society
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• v.7 no.2
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• pp.89-97
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• 2014

Purpose: To evaluate the ultrasonographic findings of the elbows on group screening of middle school baseball players. Materials and Methods: Ninety-three players (age: 12-15, mean 13.5 years) of four middle school baseball team were evaluated with bilateral elbow ultrasonographies in the field regardless of elbow pain. Medial and anterolateral ultrasound examination of the both elbow were performed in the field to detect any abnormalities including medial epicondylar separation or fragmentation and capitellar osteochondritis dissecans respectively. We analyzed the relationship among elbow pain, physical findings and sonographic abnormalities and the differences of sonographic abnormalities between pitchers and fielders. Results: Thirty-six of 93 (39%) players had sonographic abnormalities of elbow in dominant arm, 30 with medial epicondylar apophyseal separation or fragmentation, 2 with osteochondritis dissecans, 4 with both lesions. Twenty-nine of 37 (78%) players with elbow pain had sonographic abnormalities. On physical examination, players with medial epicondylar abnormalities had medial epicondylar tenderness (59%) and pain on valgus stress test (52%), and 5 of 6 (83%) players with osteochondritis dissecans showed flexion contracture more than $5^{\circ}$. The incidence of medial epicondylar abnormalities between pitchers and fielders was statistically not significant but osteochondritis dissecans was more prevalent in pitchers (p<0.05). Conclusion: Elbow sonography is a simple and useful screening tool in the field and also effective for early detection of medial epicondylar abnormalities or osteochondritis dissecans that could be the main causes of elbow pain in adolescent baseball players.

• Journal of Digital Convergence
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• v.16 no.1
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• pp.409-420
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• 2018

This is a convergence study to investigate the factors affecting the psychological happiness of leisure sports participants(social baseball club) and to present a strategy for effective program development. The subjects of this study were 151 participants of social baseball clubs in J-do area and collected data by self-reported questionnaire. Data were analyzed by descriptive statistics, t-test, ANOVA, correlation analysis and stepwise multiple regression analysis. The results of this study were the explanatory power was 54.1% with psychological happiness, quality of life, self-efficacy. As a result, it was confirmed that strengthening interpersonal relationship ability, positive reinforcement of self-efficacy, and quality of life were important for improvement of psychological happiness. and in the future, it is necessary to study repeatedly to confirm the influence of psychological through objective measurement.