• The Korean Journal of Applied Statistics
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• v.29 no.6
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• pp.1095-1106
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• 2016

The quantile regression method proposed by Koenker et al. (1978) focuses on conditional quantiles given by independent variables, and analyzes the relationship between response variable and independent variables at the given quantile. Considering the linear programming used for the estimation of quantile regression coefficients, the model fitting job might be difficult when large data are introduced for analysis. Therefore, dimension reduction (or variable selection) could be a good solution for the quantile regression of large data sets. Regression tree methods are applied to a variable selection for quantile regression in this paper. Real data of Korea Baseball Organization (KBO) players are analyzed following the variable selection approach based on the regression tree. Analysis result shows that a few important variables are selected, which are also meaningful for the given quantiles of salary data of the baseball players.

• Journal of Digital Convergence
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• v.15 no.3
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• pp.405-411
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• 2017

The purpose of this study was to identify the color that you want the pitcher glove hit impact on the intensity of the other. The color of the glove pitcher was set to black, orange, beige three kinds analyzed the concentration of the batter accordingly. Subjects of this study were 15 people targeting high school baseball players in Daejeon, through a pre- test and vision test color blind players were selected with no visual problems. After the blow of the experiment was used to color the glove Nideffer is modified to fit and complement the six subscales B-TAIS. As a result, when wearing a colored glove that contrasts with the color of the ball, the batter's concentration was increased. Hopefully, research will take place using the ball skill and equipment of various pitchers.

• Korean Journal of Applied Biomechanics
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• v.14 no.3
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• pp.191-202
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• 2004

The batting performance in baseball is a repetitive movement. In order to make the stabilization of posture and the efficient shift of body weight, both the range of stance and stride are important. The previous studies explained that the consistent stride which included the amount of time, stance, and direction were needed. However, the batting performance is frequently changed according to the several speed of ball. Therefore, this study was to analyze the reaction time, the range of stance, the change of stride, and the change of GRF during the batting movement in three kinds of ball speed (120km/h, 130km/h, & 140km/h). Seven elite players are participated in this study. 1. The reaction time of the stride phase was short whereas the time of the swing phase was long according to the increasing ball speed. 2. The range of the stance was wide and the mediolateral direction of the stride was decreased according to the increasing ball speed. 3. In the three kinds of ball speed, the change of body weight was transferred to the center, the rear foot, and the front foot directions. The ball speed of 130km/h showed the high frequency of the suitable batting. At this ball speed, the movement of the body weight was shifted smoothly and the value of the Ground Reaction Force was large enough.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.12
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• pp.224-229
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• 2019

This study was undertaken to provide correct posture guidance and reference material for sports injury and injury prevention programs, by analyzing body alignment and plantar pressure distribution in high school baseball players. Totally, 32 subjects were enrolled for the study. Body alignment was measured from the trunk imbalance, kyphotic angle, lordotic angle, pelvic tilt, and pelvic torsion. Foot pressure was measured from the left maximum pressure, right maximum pressure, left weight, and right weight. The mean and standard deviation of the measured factors were calculated and tabulated, and the correlation between body alignment and foot pressure distribution was analyzed using Pearson's correlation analysis. All statistical significance levels were set at 0.05. Body alignment and foot pressure distribution show a positive correlation between the lordotic angle of lumbar spine and the left maximum pressure. There was no correlation between trunk imbalance, kyphotic angle, lordotic angle, pelvic tilt, pelvic torsion, and the left·right weight distribution and the left·right maximum pressure of each foot. Results of this study determined that the increase of the lordotic angle of lumbar spine results in more force on one side of the foot, thereby increasing the maximum pressure. We believe our data could be a reference for exercise programs on physical alignment and plantar pressure distribution of athletes.

• Journal of Korea Entertainment Industry Association
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• v.13 no.8
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• pp.425-434
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• 2019

The purpose of this study is to improve the academy sports field for the establishment of advanced sports culture. This study used qualitative research. The research participants were baseball players for 11 years and have been professional baseball players. Another study participant has been a soccer player for eight years. And he has been a football coach for 13 years. The results of this study are as follows. First, the act of entertaining was the form in which parents served sports leaders meals and alcohol. Parents' student athletes had increased chances of playing in the game and were able to receive faithful guidance. Second, the student athletes whose parents did not act of entertaining to the sports leader were discriminated against. The student athletes were harassed by their leaders, their positions changed, and their chances of playing were reduced. Third, parents' student athletes who did not act of entertaining to their leaders either stopped exercising or moved to another school because of discrimination. Eventually, the entertainment culture of academy sports acted as a mechanism to induce sports de-socialization of student athletes, and made students experience a negative aspect of sports culture. As a result, the entertainment culture of academy sports caused discriminatory treatment due to economic inequality. Therefore, the negative entertainment culture of academy sports should be eradicated for the establishment of advanced sports culture.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.26 no.1
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• pp.130-136
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• 2017

The three-wheel pitching machine is a device that throws balls automatically instead of a pitcher and is used chiefly to train baseball players. The machine is abundantly used by people in indoor baseball grounds for baseball games. However, in Korea, foreign products are more popular because the efficiency of domestic products is poor as compared to that of the foreign ones. Therefore, a miniature pitching machine was manufactured to analyze and solve the problems of the existing machine. We added a feeder device to insert the balls in the machine and developed a smart phone application. The machine is easily controlled by a smart phone with bluetooth. While manufacturing the miniature, the existing problems were mitigated and the machine was redesigned for mass production. This study attempted to render the pitching machine more convenient and safer as a substitute for foreign pitching machines.

• The Korean Journal of Applied Statistics
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• v.24 no.5
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• pp.915-930
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• 2011

There are a variety of methods to model game results and many methods exist for the case of paired comparison data. Among them, the Bradley-Terry model is the most widely used to derive a latent preference scale from paired comparison data. It has been applied in a variety of fields in psychology and related disciplines. We applied this model to the data of Korean Baseball League. It shows that the loglinear Bradley-Terry model of defensive rate and save is optimal in terms of AIC. Also some categorical characteristics, such as east team and west team, existence of golden glove winning players, team(s) with seasonal pitching leader, and team(s) with home advantage, influenced the game result significantly. As a result, the suggested models can be further utilized to predict future game results.

• 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 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 Internet Computing and Services
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• v.9 no.3
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• pp.79-90
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• 2008

This paper introduces how we have designed and implemented an efficient starting line-up system of professional baseball players, using the forward chaining technology which is an expert system technology. The knowledge base adopted holds 286 players and 148 evaluation Items. Each player's competitiveness is measured as a numerical value in points through 2 different phases. The 1st phase point represents the static information of the target player and the 2nd his dynamic information. This paper gets a representative value of the player, which is used as the basis on which an efficient line-up system in views of both game environments and counterparts is constructed.