• 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 Communications and Networks
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• v.12 no.1
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• pp.30-42
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• 2010

In this work we consider the problem of downlink resource allocation for proportional fairness of long term received rates of data users and quality of service for real time sessions in an OFDMA-based wireless system. The base station allocates available power and subchannels to individual users based on long term average received rates, quality of service (QoS) based rate constraints and channel conditions. We formulate and solve a joint bandwidth and power optimization problem, solving which provides a performance improvement with respect to existing resource allocation algorithms. We propose schemes for flat as well as frequency selective fading cases. Numerical evaluation results show that the proposed method provides better QoS to voice and video sessions while providing more and fair rates to data users in comparison with existing schemes.

• Journal of Korea Society of Digital Industry and Information Management
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• v.16 no.4
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• pp.67-74
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• 2020

As the information age develops, Online education and Non-face-to-face work are becoming common. Telecommuting such as tele-education and video conferencing through the application of information technology is also becoming common due to the COVID-19. Unexpected information leakage can occur online when the company conducts work remotely or holds meetings. A system to authenticate users is needed to reduce information leakage. In this study, there are various ways to authenticate remote access users. By applying burn authentication using a biometric system, a method to identify users is proposed. The method used in the study was studied the main component analysis method, which recognizes several characteristics in facial recognition and processes interrelationships. It proposed a method that can be easily utilized without additional devices by utilizing a camera connected to a computer by authenticating the user using the shape and characteristics of the face by using the PCA method.

• Fashion & Textile Research Journal
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• v.16 no.4
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• pp.625-634
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• 2014

This study develops a sizing system of mass-customized male suits for wheelchair users. One hundred and three male wheelchair users' 21 anthropometric dimensions were measured to identify body shapes and develop a sizing system. The measured wheelchair users' body sizes were compared with the average body sizes of Korean males from the $6^{th}$ Korean Body Size Survey to understand the body size differences between two groups. As a result of body shape classification using the KS's Drop method, wheelchair user body shapes were classified into four shapes for upper-body (A: 32%, B: 26%, BB: 24%, and Y: 18%), and two shapes for lower-body (B: 70% and A: 30%). The upper-body of wheelchair users was relatively developed than Korean males; however, the lower-body was relatively stunted. The key dimensions of a sizing system were selected as chest circumference, waist circumference, and trunk length, outside leg length based on the correlation analysis between anthropometric measures. The top sizes were determined considering chest and waist circumferences for horizontal sizes, and additionally the trunk length was divided into short, medium, and long groups for vertical sizes. The bottom sizes were selected considering the waist and hip circumferences for horizontal sizes, and additionally their outside leg length was divided into short, medium, and long groups for vertical sizes.

• Korean journal of communication and information
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• v.30
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• pp.143-174
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• 2005

This study aims at applying Chaffee & McLeod's co-orientation model to Internet portal news providers and users to find out their mutual understanding toward various features of online news. Included in those features are interactivity, expansion of user role, larger choices(user characteristics), real time update of news, limitless quantity, contextualized contents through hypertext, data base service, and multimedia contents(contents characteristics). To test the level of agreement, accuracy and congruency between the parties, a survey was conducted among 105 portal news providers from 11 online news media, and 105 portal news users between ages 20 and 40. The result indicated that both portal news providers and users showed agreement for user characteristics, but by and large displayed either ignorance or partial congruency toward contents characteristics. Communication between portal news providers and users are thus exported to increase until it reaches the point where the internet's newly born identity as a news medium gets finally stabilized.

• 한국경영정보학회:학술대회논문집
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• 2008.06a
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• pp.400-410
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• 2008

As the number of blog users has been increasing significantly, a lot of studies have been carried out to find out what makes people use a blog or feel satisfied with it. However, most of the previous studies assumed that dissatisfaction is the opposite of satisfaction and a person who is dissatisfied with a blog does not use it, failing to explain about blog users who do not feel satisfied with their blogs but use them continually. In addition, the studies found out just blog users' motives and satisfying factors in using blogs, and did not suggest any way to improve and promote blog services. Against this backdrop, this study conducted a survey of blog users in order to examine how the satisfying factors of a blog selected through a prior study affect both satisfaction and dissatisfaction of a user. The survey results showed that the satisfying factors are divided into two groups: group A which affect satisfaction and dissatisfaction equally, and group B which affect them differently. Based on the results, this study subdivides group A into high involvement factors and low involvement ones, and group B into motivators, which strongly affect satisfaction, and hygiene factors, which strongly affect dissatisfaction. According to characteristics of each group, this study suggests ways to improve and promote blog services.

• The Journal of the Korea Contents Association
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• v.6 no.9
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• pp.108-115
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• 2006

This paper will study the influence of comedic elements of the game on the gaming choice by the game users, and focus its goal on establishing the foundation for the various game production environments. Within the game, the comedic elements are categorized as one of actively expressive elements and enhance the game's entertainment together with its sound qualities of graphics, scenario, sounds and level designs. Although the comedic elements are generally acknowledged as necessities, the research on how the users actually perceive those elements has been insufficient. Therefore this paper will investigate characteristics, compositions and techniques of the comedy used in the game and will analyze the influence that those comedic elements have on the users' recognition, satisfaction and royalty to the game.

• Journal of KIISE:Computing Practices and Letters
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• v.14 no.3
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• pp.306-310
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• 2008

Since the preference for information recommendation service can change according to the context, we should know the user context before providing information recommendation. This paper proposes recommender system that considers multi-user preference in mobile environment and attempted to apply it to restaurant recommendation. To model the preference of individual users in mobile environment, we have used Bayesian network, and restaurant recommendation mostly should consider not an individual user but several users, so this paper has used AHP of multi-criteria decision making process to obtain the preference of several users based on one of individual users. For experiments, we conducted recommendation in 10 different situations, and finally, we confirmed that the proposed system was evaluated as a good one using a usability test of SUS.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.9 no.2
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• pp.73-82
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• 1999

In an open network computing environment a host cannot to identity its users correctly to network services. In order to prevent this thing we present the design of a authentication scheme 솟 using the notion of rth -residuosity problem and discrete logarithm problem which is proposed by S. J. Park et al. The proposed scheme described here is efficient method for mutual authentication without leakage of users identity in mobile communication system that ensure user anonymity and untraceability.

• Journal of the Ergonomics Society of Korea
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• v.31 no.5
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• pp.695-704
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• 2012

Objective: The purpose of this study was to investigate major factors influencing adoption of smartphone to promote its use by older adults. Background: Despite increasing proportion of elderly people and elderly market, the proportion of elderly smartphone user is still relatively small compared to whole smartphone users. Thus, we need to find out major factors influencing adoption of smartphone to increase proportion of elderly smartphone users. Method: Seven major factors were extracted from 36 survey questions using factor analysis. Regression analysis was also applied to determine specific factors affecting intention of use based on user versus non-user of smartphone, age, gender, and educational background. Results: As results of factor analysis and regression analysis, major factors influencing adoption of smartphone for elderly users were significantly different according to gender, age, educational background based on smartphone users or non-users. Conclusion: The result of this study identified major factors influencing adoption of smartphone for the elderly and provided basic information related to adoption of smartphone according to elderly people's characteristics. Consequently, we can expect to reduce the information gap and to improve quality of life for the elderly. Application: The development and marketing strategy could be applied differently based on the factors influencing adoption of smartphone. It is also possible to develop a prediction model for smartphone adoption according to elderly users' characteristics.