• Journal of the Korean Mathematical Society
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• v.50 no.4
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• pp.879-897
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• 2013

Shannon entropy is one of the widely used randomness measures especially for cryptographic applications. However, the conventional entropy tests are less sensitive to the inter-bit dependency in random samples. In this paper, we propose new online randomness test schemes for true random number generators (TRNGs) based on the mutual information between consecutive ${\kappa}$-bit output blocks for testing of inter-bit dependency in random samples. By estimating the block entropies of distinct lengths at the same time, it is possible to measure the mutual information, which is closely related to the amount of the statistical dependency between two consecutive data blocks. In addition, we propose a new estimation method for entropies, which accumulates intermediate values of the number of frequencies. The proposed method can estimate entropy with less samples than Maurer-Coron type entropy test can. By numerical simulations, it is shown that the new proposed scheme can be used as a reliable online entropy estimator for TRNGs used by cryptographic modules.

• Knowledge Management Research
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• v.21 no.2
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• pp.101-118
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• 2020

The usage of emoticons used in the online environment continues to increase, and also the market for emoticons is growing rapidly. Emoticons go beyond simply conveying the meaning of a message and play various roles such as smooth communication, pursuit of fun, and intimacy. In this study, we first identify the factors that motivate users to use emoticons in an online messenger service, and then determine whether the derived factors have a significant effect on emoticon usage. Furthermore, based on Regulatory Focus Theory, we will distinguish between the group of promotion focus and the group of prevention focus to see how the influence of motives on emoticon usage differs.

• International Journal of Control, Automation, and Systems
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• v.6 no.2
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• pp.282-287
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• 2008

In distributed mobile robot systems, autonomous robots accomplish complicated tasks through intelligent cooperation with each other. This paper presents behavior learning and online distributed evolution for cooperative behavior of a group of autonomous robots. Learning and evolution capabilities are essential for a group of autonomous robots to adapt to unstructured environments. Behavior learning finds an optimal state-action mapping of a robot for a given operating condition. In behavior learning, a Q-learning algorithm is modified to handle delayed rewards in the distributed robot systems. A group of robots implements cooperative behaviors through communication with other robots. Individual robots improve the state-action mapping through online evolution with the crossover operator based on the Q-values and their update frequencies. A cooperative material search problem demonstrated the effectiveness of the proposed behavior learning and online distributed evolution method for implementing cooperative behavior of a group of autonomous mobile robots.

• Journal of Information Processing Systems
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• v.6 no.1
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• pp.43-52
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• 2010

In the secure communication areas, three-party authenticated key exchange protocol is an important cryptographic technique. In this protocol, two clients will share a human-memorable password with a trusted server, in which two users can generate a secure session key. On the other hand the protocol should resist all types of password guessing attacks. Recently, STPKE' protocol has been proposed by Kim and Choi. An undetectable online password guessing attack on STPKE' protocol is presented in the current study. An alternative protocol to overcome undetectable online password guessing attacks is proposed. The results show that the proposed protocol can resist undetectable online password guessing attacks. Additionally, it achieves the same security level with reduced random numbers and without XOR operations. The computational efficiency is improved by $\approx$ 30% for problems of size $\approx$ 2048 bits. The proposed protocol is achieving better performance efficiency and withstands password guessing attacks. The results show that the proposed protocol is secure, efficient and practical.

• International journal of advanced smart convergence
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• v.9 no.4
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• pp.179-183
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• 2020

The online education platform market is developing rapidly after the coronavirus infection-19 pandemic. As school classes at various levels are converted to non-face-to-face classes, interest in non-face-to-face online education is increasing more than ever. However, the majority of online platforms currently used are limited to the fragmentary functions of simply delivering images, voice and messages, and there are limitations to online hands-on training. Indeed, digital transformation is a traditional business method for increasing coding education and a corporate approach to service operation innovation strategy computing thinking power and platform model. There are many ways to evaluate a computer programmer's ability. Generally, piecemeal evaluation methods are used to evaluate results in time through coding tests. In this study, the purpose of this study is to propose a comprehensive evaluation of not only the results of writing, but also the execution process of the results, etc., and to evaluate the programmer's propensity habits based on the programmer's coding experience to evaluate the programmer's ability and productivity.

• Journal of KIISE
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• v.44 no.3
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• pp.314-322
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• 2017

In MMORPG (Massively Multiplayer Online Role-Playing Game), users advance their own characters to get to the maximum (max) level by performing given tasks in the game scenario. Although it is crucial to retain users with high levels for running online games successfully, little efforts have been paid to investigate them. In this study, by analyzing approximately 60 million in-game logs of over 50,000 users, we aimed to investigate the process through which users achieve the max level and churn of such users since the moment of achieving the max level, and determine possible indicators related to churn after the max level. Based on the result, we can predict churn of the max level users by employing behavioral patterns before the max level. Moreover, we found users who are socially active and communicate with many people before the max level are less likely to leave the service (p<0.05). This study supports that communication patterns are important factors for persistent usage of the users who achieve the max level, which has practical implications to guide elite users on enjoying online games in the long run.

• Journal of Korea Game Society
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• v.15 no.6
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• pp.97-106
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• 2015

In an Unity engine for multi-player online games, the main thread processing game logic must be separated from the network thread that is responsible for network packet communication. Packet communication between the network threads needs to drop packets that overlap in order to improve the rendering speed. In this paper, the packet discard policy of network thread is proposed for an Unity engine for multi-player online games. The proposed method is the hybrid method of both Partial Packet Discard and Periodic Packet Discard methods to improve the rendering speed by periodically discarding overlapped network packets managed by the queue. The rendering speed of the proposed method is analyzed and its effectiveness is verified by various packet generating simulations of the Unity engine for multi-player online games.

• Fashion & Textile Research Journal
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• v.22 no.5
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• pp.617-627
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• 2020

This study investigates the apparel sizing communication presented in online retail websites focusing on women's ready-to-wear tailored jackets and to analyze the meaning of these information as the actual product size guide factor. A total of 34 retail websites were selected based on the highest growth fashion companies list and the best fashion brands list. We collected size information in two types: size specifications including sizing code, body measurements, garment measurements, and size references including customized size guide tools, size information in customer reviews, model size information, and others. Most websites prefer to present garment measurements rather than body measurements that are recommended notations under Korean standards and related regulations. In addition, there was the absence of consistency in presenting measurements list and terms that can confuse consumers in size communication. This study found that the stature measurement was a key factor in size reference despite that it did not represent a proper garment size. The obsolete Korean numbering sizing code such as '55 and '66 was still used in many ways such as idiomatic expressions for body shape. It also implied that we can take advantage of the old sizing code for accessible size information. The finding of this study gives an in-depth diagnosis of current online sizing information problems and suggests useful basic data for developing online apparel size standards and marketing strategies.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.41 no.4
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• pp.228-237
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• 2018

The importance of eWOM (electronic word-of-mouth) communication through online communities is increasing on a daily basis. This study analyzed how the relationship between eWOM (electronic Word-Of-Mouth) factor and eWOM communication depends on the cultural orientation of users in the online community. The research model was developed based on four cultural orientations of individual affect Social tie and usefulness. The model consists of variables such as social tie and perceived usefulness as predecessors of eWOM, four dimensions of cultural orientation (Horizontal Individualism, Horizontal Collectivism, Vertical Individualism, Vertical Collectivism), and eWOM. The model was tested empirically using the PLS (partial least squares) structure equation model. Survey was conducted for online community users in South Korea. Data was statistically validated whether fits on research model. The study results reveal that Social Tie have a positive effect on Perceived Usefulness. Social Tie and Perceived Usefulness have a positive effect on eWOM. 3 of cultural orientations (HC, VI, VC) have a positive effect on Social Tie. Only one of cultural orientations (HC) have an negative effect on Perceived Usefulness. Especially, horizontal collectivism (HC) shows strong correlation with perceived usefulness, whereas vertical collectivism (VC) shows weak correlation with perceived usefulness andvertical individualism (VI) shows strongly correlation with social tie, whereas horizontal individualism (HI) shows weak correlation with social tie. Based on the study results, customized service strategy could be formulated according to the different vertical styles and various eWOM factors.

• The Journal of the Korea institute of electronic communication sciences
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• v.19 no.1
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• pp.257-266
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• 2024

This study explored the determinants that influence purchase intention in online shopping based on augmented reality applications. The main results are discussed focusing on hypotheses as follows. First, interactivity had a positive effect on psychological ownership. Second, interactivity had a positive effect on decision comfort. Third, psychological ownership had a positive effect on decision comfort. Fourth, psychological ownership had a positive effect on purchase intention. Fifth, decision comfort had a positive effect on purchase intention. Therefore, in online shopping based on augmented reality applications, interaction determines psychological ownership and decision comfort, and psychological ownership and decision comfort can be evaluated as key factors that promote product purchase intention in online shopping. In order to increase purchase intention in online shopping, a marketing strategy is required to increase interactivity, psychological ownership, and decision comfort through augmented reality applications.