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User behavior modeling in online games using machine learning techniques : focused on malicious user detection and churn prediction

초록/요약

Recently, machine learning has been widely used in various fields. Online game company also is trying to apply machine learning techniques to solve the problems that arise during the development and operation of online games. While these attempts are mainly focused on suggesting machine learning algorithms for efficient learning, there are other important issues that need to be addressed to apply machine learning in practice: Constructing training data, feature engineering, designing appropriate evaluation schemes, and maintaining the predictive model. This thesis proposes methodologies for solving the four problems described above when building a service based on a machine learning model in an online game. The methodologies was applied to live games which are serviced in NCSOFT. However, it still has some limitations. Recently, advances in machine learning have led to alternatives to overcome these limitations. Online games are a great platform to observe the behavior of various users in the virtual-world. In the virtual-world, a wide range of data is generated, ranging from activities performed by users, social relationships, economic systems, and even text data via chat between users. In other words, almost all forms of data that can be handled in the field of machine learning are generated with massive amounts. However, there is a few researches because of the lack of interchange between industry and academia. In this thesis, various issues and solutions are discussed to apply machine learning to live services in online games. I hope this study contributes a little to overcome the obstacles mentioned above.

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목차

Chapter 1. Introduction . 1
Chapter 2. Game bot detection using self-similarity . 4
2.1. Introduction 4
2.2. Related works 6
2.3. Back ground . 8
A. Terminology . 8
B. Ecology of game world in MMORPGs . 10
C. Game bots and RMT 11
2.4. Game bot characteristics . 12
A. Exploratory data analysis 12
B. Feature review 19
2.5. Methodology 21
A. Feature extraction and selection . 21
B. Modeling and evaluation . 23
C. Monitoring and retraining detection model . 24
2.6. Experiments . 26
A. Data preprocessing . 26
B. Ground truth construction . 27
C. Modeling and evaluation . 29
D. Automated model maintenance . 31
2.7. Real-world deployment 33
A. Generality . 34
B. Ground truth and model maintenance 35
C. Extreme cases and anomalies 35
D. Hacks detection 37
E. False positive issue 37
F. Individuals using bots 37
2.8. Conclusion 38
Chapter 3. Gold farming group detection using network analysis 40
3.1. Introduction . 40
3.2. Related works . 42
3.3. How RMT works 43
3.4. Dataset . 44
3.5. Trade network analysis for RMT detection . 45
A. Construction of a virtual goods trading network and community detection 45
B. Community grouping by network structure 47
C. User grouping by play style 49
D. RMT group detection . 51
E. RMT estimation . 55
3.6. Measurement study of RMT 57
A. Volume of RMT . 57
B. Monopoly of RMT market 59
C. RMT network in other games 61
3.7. Conclusion 62
Chapter 4. Profit optimizing churn analysis 64
4.1. Introduction . 64
4.2. Related works . 66
4.3. Dataset . 68
A. Time unit for data aggregation . 69
B. Churn definition 69
4.4. Methodology 70
A. Prediction target selection . 70
B. Feature engineering 75
C. Profit evaluation 78
4.5. Exploratory data analysis 81
A. Trends and variations in gaming activities . 81
B. Party activity . 82
C. Legion 84
4.6. Experiments . 86
A. Total churner prediction vs. loyal churner prediction . 86
B. Threshold optimization 89
4.7. Discussions . 90
A. Limitation of a binary classifier . 90
B. Cost optimization . 92
4.8. Conclusion 93
Chapter 5. Limitations, alternatives and future works 95
5.1. Limitations 95
5.2. Alternatives 96
A. Weak supervision . 96
B. Feature embedding . 96
C. Expected profit function 99
5.3. Future works 100
Chapter 6. Conclusion . 101
References . 103
Acknowledgements . 112

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