• The Korean Journal of Applied Statistics
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• v.37 no.4
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• pp.525-539
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• 2024

Massive multiplayer online role playing game (MMORPG) is a common type of game these days. Predicting user churn in MMORPG is a crucial task. The retention rate of users is deeply associated with the lifespan and revenue of the service. If the churn of a specific user can be predicted in advance, targeted promotions can be used to encourage their stay. Therefore, not only the accuracy of churn prediction but also the speed at which signs of churn can be detected is important. In this paper, we propose methods to identify early signs of churn by utilizing the daily predicted user retention probabilities. We train various deep learning and machine learning models using log data and estimate user retention probabilities. By analyzing the change patterns in these probabilities, we provide empirical rules for early identification of users at high risk of churn. Performance evaluations confirm that our methodology is more effective at detecting high risk users than existing methods based on login days. Finally, we suggest novel methods for customized marketing strategies. For this purpose, we provide guidelines of the percentage of accessed users who are at risk of churn.

• Journal of Korea Game Society
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• v.11 no.4
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• pp.27-35
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• 2011

Concentration is one of the most important factor in learning ability. It is important to improve concentration for learning ability. Most digital kids have been accustomed to addictive media like games since childhood, so traditional methods of teaching and learning has been difficult to give interests for them. Therefore introducing a new teaching methods was inevitable for students with low concentration. This is an experiment to prove the hypothesis that the concentration training by certain serious game would be helpful for improving students' concentration. Not only some serious games but also meditation by music was effective to improve concentration in the experiment. Average people is hard to immerge in meditation. but some serious games involve fun factors like curiosity, challenges, competitions and rewards. Games are not more negative to young people, will be helpful to society in various forms.

• 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.

• Journal of Korea Game Society
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• v.12 no.6
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• pp.59-70
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• 2012

There are many methods to buy and sell online items. But A lot of people use item trade sites when they want to sell or buy their items. This article analyzes the price structure of item trade, and finds why gamers use item trade sites in spite of the brokerage. We analyze the difference of item prices between in the market of item trade sites and in the market of other trade methods. And we find that the prices of item trade sites is higher than those of other markets. Buyers pay about 6% higher prices to seller. The higher prices are for the safe trading what item trade sites supply. And sellers take about 0.7% higher prices than in other markets. There is a sufficient motive when gamers use item trade sites in spite of their high prices.

• Physical Therapy Rehabilitation Science
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• v.9 no.3
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• pp.209-214
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• 2020

Objective: Using biofeedback in instructing pelvic floor muscle (PFM) activation is a great method to provide information on muscle contraction. This study aimed to determine the immediate effectiveness of a mobile game-based instruction with an extracorporeal biofeedback device (EBD) to improve PFM contraction in healthy subjects. Design: Cross-sectional study. Methods: Sixteen healthy subjects (4 men and 12 nulliparous women; age, 31±5 years) were enrolled. The subjects were randomly categorized into two groups, those who were to receive instructions on how to contract the PFM by using the EBD (n=7) and those who were to undergo a transabdominal ultrasonography (TAUS; n=9) with biofeedback. PFM function was measured as the displacement (mm) of PFM elevation by using the TAUS before and after the instructions in each group. Results: The EBD and TAUS groups showed a significant increase in the displacement of PFM elevation after the instructions from 5.93±4.03 mm to 7.62±3.77 mm and from 5.27±3.39 mm to 7.47±2.79 mm, respectively (p<0.05). No significant differences were found between the two groups. Conclusions: The results of this study indicated that instructions for PFM contraction using the EBD and TAUS showed an immediate effect; however, no significant difference in effectiveness was observed between the two instruction methods. Therefore, not only can the TAUS method be used but the EBD method can also be used as a PFM instruction method for noninvasive procedures. However, further studies are needed to demonstrate the effectiveness of training and exercise on larger sample sizes that includes patient populations with PFM dysfunction.

• Journal of Korea Game Society
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• v.14 no.2
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• pp.67-76
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• 2014

Recently there have been many interests on tangible sport games that can recognize the motions of players. In this paper, we propose essential technologies required for tangible games, which are methods for swing motion recognition and the calculation of shuttle cock's trajectory. When a user carries out a badminton swing while holding a smartphone with his hand, the motion signal generated by smartphone-embedded acceleration sensors is transformed into a feature vector through a Daubechies filter, and then its swing type is recognized using a k-NN based method. The method for swing motion presented herein provides an advantage in a way that a player can enjoy tangible games without purchasing a commercial motion controller. Since a badminton shuttle cock has a particular flight trajectory due to the nature of its shape, it is not easy to calculate the trajectory of the shuttle cock using simple physics rules about force and velocity. In this paper, we propose a method for calculating the flight trajectory of a badminton shuttle cock in which the wind effect is considered.

• Journal of Korea Game Society
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• v.18 no.5
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• pp.123-132
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• 2018

Various methods have been proposed to efficiently animate the motion of soft objects in realtime. In order to maintain the topology between the elements of the objects, it is required to employ constraint forces, which limit the size of the time steps for the numerical integration and reduce the efficiency. To tackle this, an implicit method with larger steps was proposed. However, the method is, in essence, a linear system with a large matrix, of which solution requires heavy computations. Several approximate methods have been proposed, but the approximation is obtained with an increased damping and the loss of accuracy. In this paper, new integration method based on harmonic oscillation with better stability was proposed, and it was further stabilized with the hybridization with approximate implicit method. GPU parallelism can be easily implemented for the method, and large-scale soft objects can be simulated in realtime.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.28 no.4
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• pp.951-962
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• 2018

In order to strengthen the information security of the organization, it is important to invest in the information security facility, but the information security awareness of the organization members is also very important. Effective education is needed to raise awareness of this information security. However, the method of collective education utilized by most organizations is not very effective. Educational methods using serious games can be a good alternative. Educational methods using serious games have already proved effective through various cases and researches and are used in many fields. In this paper, we design and implement a game program to improve the awareness of individual information security policy importance. The training was conducted for the members of the organization and the change of awareness about the importance of individual information security policy was examined through analysis of evaluation data before and after the training.

• KIPS Transactions on Computer and Communication Systems
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• v.2 no.4
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• pp.163-176
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• 2013

Cloud-based streaming game service has numerous merits, but it may suffer from presentation latency in a thin-client. It is an important issue especially for game service which needs instantaneous response to user inputs. This research proposes the methods for reducing the presentation latency between the server unit and the thin-client unit. The approaches proposed to be employed with server unit include the source/sync video format equalization, encoding format configuration according to the media type, and the S/W implementation for transmitting clock periodically. The methods for the thin-client unit include the decreasing the number of instructions, use of light encryption algorithm, and improvement on H/W decoding. The proposed schemes are tested with a commercialized streaming service platform, which reveals the reduction of presentation latency as large as a few hundred milliseconds and reaches the acceptable level (about 100 milliseconds).

• The Journal of the Korea Contents Association
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• v.9 no.9
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• pp.151-162
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• 2009

As the aging population has increased, the silver generation is getting to account for the considerable percent of economic activities and becomes the main body of production and consumption. Although the economic activity of silver generation is increased, the development of silver contents for the leisure activities is still not revitalized. The serious silver contents and the easy-to-use interface are very important because the silver generation is relatively weaker than young people in perception, studying, and exercise, and is fragile in mobility and vitality. This paper suggests methods to develop sensory bicycle, gate ball, and mole game contents haying lower body exercise effects for the silver generation to utilize leisure and maintain health. Along with fun as games, functional design factors suitable to the cognitive ability and bodily activity ability of the silver generation were considered and through sensory intefaces that are easy for the silver generation to use and customized progressing methods complying with individual characteristics, it was attempted to induce continued interests and lower body exercise effects.