• Journal of the Korea Convergence Society
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• v.8 no.12
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• pp.369-378
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• 2017

This study is devoted to investigating participation motivations of billiard players who join games through open-ended questionnaires, and identify the difference of participation motivations in the game according to age and experience. Thus, 696 original data on participation motivations was obtained from 267 billiard players in Gyeonggi-do based on open-ended questionnaires. Results from inductive analysis are as follows. First, their participation motivations included 10 general sectors such as interests, objective achievement motive, competition, interpersonal relationship, mental health, job, gambling, sport competence, suggestion by others, and university admission. Second, enjoyment showed the highest percents among participation motivations according to participants' age. Third, interest showed the highest percents among participation motivations in less than five years of their experiences. Objective achievement motive was the highest portion for more than five years. These outcomes will be used as a basic data to understand the relationship of billiard players who participate in the game and further create better billiard game culture.

• The Korean Journal of Applied Statistics
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• v.7 no.2
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• pp.263-268
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• 1994

Thomas Bayes assumed uniform prior for the location $\theta$ of a billiard ball W in his historic 1764 paper. In this study, following mathematical derivation of the uniform distribution from several assumptions that are plausible on te billiard table, it is argued that the probabilistic meaning of Bayes' uniform prior (especially in Billiard Problem) is not just sujective but logical.

• Bulletin of the Korean Mathematical Society
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• v.36 no.1
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• pp.147-159
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• 1999

Tabanov investigated the global symmetric perturbation of the integrable billiard mapping in the ellipse [3]. He showed the nonintegrability of the Birkhoff billiard in the perturbed domain by proving that the principal separatrices splitting angle is not zero.In this paper, using the exact separatrix map of an one-degree-of freedom Hamiltoniam system with time periodic perturbation, we show the existence the stochastic layer including the uniformly hyperbolic invariant set which implies the nonintegrability near the separatrices of a Birkhoff's billiard in the domain bounded by $C^2$ convex simple curve constructed by the generic global perturbation of the ellipse.

• Journal of Environmental Health Sciences
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• v.44 no.3
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• pp.267-274
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• 2018

Objectives: This study examined the impact of a smoke-free policy on indoor air quality at indoor recreation facilities by assessing $PM_{2.5}$ concentrations before and after the implementation of the new policy. Methods: Using real-time monitors, $PM_{2.5}$ concentrations were measured in 50 billiard rooms and 50 golf simulator rooms in Seoul, Korea. The characteristics of the indoor recreation facilities, smoking status, and atmospheric conditions were recorded at the same time.After the enforcement of a smoke-free policy, $PM_{2.5}$ concentrations, installation of smoking room, and smoking status were examined when the facilities were revisited. Results: Almost a half of the billiard rooms and over 80% of golf simulator rooms were located underground. Seventy percent of the billiard rooms and one hundred percent of the golf simulator rooms were equipped with a local exhaust ventilation system. After the implementation of the smoke-free policy, 46% of the billiard rooms and 20% of the golf simulator rooms newly installed a smoking room. In the billiard rooms with a newly-installed smoking room, the $PM_{2.5}$ concentrations decreased from 97.9 to $45.6{\mu}g/m^3$ after the implementation of the smoke-free policy. The same change of 29.0 to $ 26.3{\mu}g/m^3$ was not statistically significant in golf simulator rooms. Indoor $PM_{2.5}$ concentrations were correlated with outdoor $PM_{2.5}$ concentrations, number of smokers, and number of people in the room. Conclusions: The smoke-free policy for indoor recreation facilities was not effective at making the indoor spaces free from second hand smoke. Although a few billiard rooms installed a smoking room, indoor $PM_{2.5}$ concentrations were still higher than those of outdoor $PM_{2.5}$ or atmospheric $PM_{2.5}$. Stricter enforcement of the smoke-free policy should be achieved to prevent secondhand smoke exposure.

• Bulletin of the Korean Mathematical Society
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• v.12 no.1
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• pp.17-21
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• 1975

• Journal of Digital Convergence
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• v.14 no.11
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• pp.645-654
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• 2016

The purpose of this research is aimed at billiards experts and non-experts during the billiard stroke: a comparative analysis of concentration and muscle activity, identifying the differences between the two groups by the objective and scientific data is presented to propose the basis for effective and efficient training methods of billiards. The results of the study showed no significant differences in muscle activity and concentration between experts and non-experts. Therefore, the muscle activity and concentration between the experts and non-experts had no positive effect during the billiard stroke. These causes are thought to be as a lack of research subjects, being a one-time experiment, and not being able to control psychological and physiological experiments completely. In this regard, psychological and physiological experiments are considered to be controlled for further study to determine the principles more clearly.

• Journal of Practical Engineering Education
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• v.12 no.2
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• pp.309-319
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• 2020

Billiards is a fun and popular sport, but both route planning and cueing prevent beginners from becoming skillful. A beginner in billiards requires constant concentration and training to reach the right level, but without the right motivating factor, it is easy to lose interests. This study aims to induce interest in billiards and accelerate learning by utilizing billiard path prediction and visualization on a highly immersive augmented reality platform that combines a stereo camera and a VR headset. For implementation, the placement of billiard balls is recognized through the OpenCV image processing program, and physics simulation, path search, and visualization are performed in Unity Engine. As a result, accurate path prediction can be achieved. This made it possible for beginners to reduce the psychological burden of planning the path, focus only on accurate cueing, and gradually increase their billiard proficiency by getting used to the path suggested by the algorithm for a long time. We confirm that the proposed AR billiards is remarkably effective as a learning assistant tool.

• Journal of environmental and Sanitary engineering
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• v.21 no.1 s.59
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• pp.58-65
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• 2006

This study is measured in at ozone concentrated places in school and outside of school where places that use copy machine and the others do not use one. Library copy room, Search room, Y-Copy, J-copy, R-shop are the places using copy machines and Search room, K-apt, J-billiard hall are the opposite. The measurement was held three times a day-the morning, the afternoon and the evening-once for each at indoor and outdoor. 8 places were lower than domestic ozone concentration standard(0.06ppm). The indoor ozone concentration average was the highest in Search room of school and was the lowest in Library restroom. The outdoor ozone concentration average was the highest in J-billiard hall.

• Proceedings of the Korean Information Science Society Conference
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• 2007.10a
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• pp.215-216
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• 2007

• Journal of the Korean Society of Clothing and Textiles
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• v.16 no.1 s.41
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• pp.85-96
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• 1992

The puropse of this study is to find out that whether the juvenile delinquency could be decreased by the revival of school uniform for the high school students. For this purpose, the difference and frequency of juvenile delinquency between uniformed students and none·uniformed students were surveyed. In addition, the relation among the students, social classes, receiving attitude for the sub-culture, with juvenile delinquency were also surveyed. For this study, 728 high school students were' studied with a questionaire. They were 328 ' uniformed students from 6 schools and 400 none-uniformed students from other 6 schools. The conclusions of this study are as follow: 1. The order of juvenile delinquency is resistance to their parents and teachers, cunning in examination, drinking, watching shameful video tapes, possession of dirty books and pictures, gambling, entering to thea rooms, billiard rooms, the prohibited cinema houses aild drinking houses, and smoking. The students' delinquency was chiefly misdeed against the public order and social position and most of them were without any victims. And there were no misdeed such as drug addiction, robbrry and bodily harm. 2. The difference of juvenile delinquency between uniformed and non·uniformed schools was not found. 3. More nisdeed were occurred when they were without uniform; especially in cases of entering to shameful video shops, drinking houses, tea rooms and billiard rooms. 4.The logical propriety that the juvenile delinquency would be decreased by putting on uniform to all students is scarce, because Ell misdeed were occurred when they were without uniform after school. Uniform were worn only when they go to school. 5. A negative effect between student's affection toward their parents and schools, and juvenile deliquency was found. Much they love their parents and schools, less misdeed occurred. 6. Positive effect between sub·culture and juvenile delinquency was found. The friendship with delinquent students gives a great influence to juvenile delinquency.