• International Journal of Contents
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• v.11 no.4
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• pp.38-43
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• 2015

Non-orthogonal multiple access (NOMA) where all users share the entire time and frequency resource has paid attention as one of the key technologies to enhance the spectral efficiency and the total throughput. Nevertheless, as the number of users and SIC error increase, the inter-user interference and the residual interference due to the SIC error also increase, resulting in performance degradation. In order to mitigate the performance degradation, we propose grouping-based NOMA system. In the proposed scheme, all users are divided into two groups based on the distance between the BS and each user, where one utilizes the first half of the bandwidth and the other utilizes the rest in the orthogonal manner. On the other hand, users in each group share the spectrum in the non-orthogonal manner. Grouping users can reduce both the inter-user interference and residual interference due to the SIC error, so it can outperform conventional NOMA system, especially in case that the number of users and the SIC error increase. Based on that, we also present the hybrid operation of the conventional and the proposed NOMA systems. In numerical results, the total throughput of the proposed NOMA systems is compared with that of the conventional NOMA systems with regard to the number of users and SIC error. It is confirmed that the proposed NOMA system outperforms the conventional NOMA system as the number of users and the SIC error increase.

• Journal of the Ergonomics Society of Korea
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• v.29 no.3
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• pp.287-296
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• 2010

The purpose of this research is to analyze priority of the elderly user interface (UI) evaluation criteria based on user's lifestyle. Since the elderly population will occupy over 20% of the all Korean population in the near future, we need to know older users' needs and information because elderly users will be main customers in the super-aged society. This paper investigated the definition of elderly users and characteristics demographically, socio-economically, and physically/cognitively. A total of 238 questionnaires from older users were analyzed based on a segmentation table for the elderly developed by the previous study. According to factor analysis and cluster analysis, 6 types of lifestyle and 4 groups of the elderly users were classified, respectively. The priority of UI evaluation criteria for large electronic home appliances and mobile products was analyzed by analyses of variance (ANOVAs). The results indicated that the priority of (physical, emotional, and cognitive) UI criteria was significantly different among elderly users' lifestyles for both home appliances and mobile products. Consequently, the results of this study may help the company develop some competitive silver products and give higher satisfaction to the elderly users by suggesting different priority of UI evaluation criteria according to the target elderly group. The results may also contribute to revitalize national economy by significantly increasing senior market shares.

• Journal of the Korean Society of Costume
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• v.50 no.8
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• pp.17-28
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• 2000

The purposes of this study were to determine dimension of apparel expectations, performances and service quality of discount store and thereby, to analyze effect of apparel commodities dimension (expectations, performances, disconfirmation and satisfaction) and service dimension(service quality and satisfaction ) on repurchase intention. The subject were 363 women in the age of twenty to sixty years old who live in Seoul and the suburban of Seoul. The results of this study could be summarized as follows : It was found that discount score consumers' expectation and performance with apparel commodities were classified 2 factors of the function and expression. On the other hand, the dimensions of service quality were found to have such 4 factors as reliability, VMD, convenience, and facilities. 2. It was found that consumers' intention of repurchase of discount store were affected by such variables as disconfirmation and service quality. While less frequent users were affected by expectations and disconfirmation with apparel commodities, more frequent users were affected by such variables as disconfirmation, service quality and service satisfaction. Meanwhile, discount store users were found to be affected by disconfirmation, and off-price store users were affected by disconfirmation: and service quality. 3. More frequent users of discount store scored more on average than less frequent users in terms of expectation, performance, disconfirmation, and satisfaction with apparel commodities and intention of repurchase. On the other hand, off-price store users scored more on average than discount users in terms of expectation and performance with apparel commodities and Intention of repurchase.

• Journal of Korea Multimedia Society
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• v.17 no.11
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• pp.1307-1312
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• 2014

Online games are virtual space where it connects individual users through network connection to offer enjoyment of play games and game developer who service online games have to develop new contents and provide them to users to extend life of their service. Typically, in order to update new contents, all service companies have maintenance schedule to stop the game service for a while to update both server and client applications. Usually this process takes quite amount of time and users do not have any other choice but disconnected from server and wait until it is over. The purpose of this thesis is to describe the advantages of new design system which will allows users to continue to play the game even during the update. The main focus of this design is to make users feel more convenience in online gaming experience by move client from previous server to new server while users are still playing. If they can to connect current client with new server without any certificate validation process while users information from the client can automatically pass through to the new server, users may not need to experience maintenance for new contents update.

• Journal of Information Science Theory and Practice
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• v.5 no.4
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• pp.6-25
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• 2017

In this paper, a large-scale study on users' understanding of search-based advertising is presented. It is based on (1) a survey, (2) a task-based user study, and (3) an online experiment. Data were collected from 1,000 users representative of the German online population. Findings show that users generally lack an understanding of Google's business model and the workings of search-based advertising. 42% of users self-report that they either do not know that it is possible to pay Google for preferred listings for one's company on the SERPs or do not know how to distinguish between organic results and ads. In the task-based user study, we found that only 1.3 percent of participants were able to mark all areas correctly. 9.6 percent had all their identifications correct but did not mark all results they were required to mark. For none of the screenshots given were more than 35% of users able to mark all areas correctly. In the experiment, we found that users who are not able to distinguish between the two results types choose ads around twice as often as users who can recognize the ads. The implications are that models of search engine advertising and of information seeking need to be amended, and that there is a severe need for regulating search-based advertising.

• Journal of the East Asian Society of Dietary Life
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• v.10 no.1
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• pp.89-97
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• 2000

The goal of this study was to fine the way of reduction on food waste in the university cafeteria. A survey was conducted on the 500 faculty members using Yeungnam University cafeteria , and if illustrate the faculty's use and perception for the reduction of food waste. Its results can be summarized as follows ; 32.0 % of the total users use the university cafeteria everyday, also 56.6% of the users preferred Korean style dish. Female users left more food than the male users resulting in more food wastes. The male users resulting in more food waste and the most leaving food was Kimchi than the other types of foods. The most favorite stew and side dish turned out to be Yukgaejang and Bulgogi respectively, also Kimchibokkumbab was the preffered dish. But they disliked Sunjiguk , Ginger, Jellyfish and Mackerel pike. The preception of male users on the reduction of food waste was lower than that of female users. The best way of food waste treatment recognized by the users were utilizing the waste food as fodder for animals or fertilizer.

• ETRI Journal
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• v.32 no.4
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• pp.512-519
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• 2010

A cooperative model is presented to enable sharing of the spectrum with secondary users. Compared with the optimal model and competitive model, the cooperative model could reach the maximum total profit for secondary users with better fairness. The cooperative model is built based on the Nash equilibrium. Then a conceding factor is introduced so that the total spectrum required from secondary users will decrease. It also results in a decrease in cost which the primary user charges to the secondary users. The optimum solution, which is the maximum total profit for the secondary users, is called the collusion state. It is possible that secondary users may leave the collusion state to pursue the maximum of individual profit. The stability of the algorithm is discussed by introducing a vindictive factor to inhabit the motive of deviation. In practice, the number of secondary users may change. Adaptive methods have been used to deal with the changing number of secondary users. Both the total profit and fairness are considered in the spectrum allocating. The shared spectrum is 11.3893 with a total profit of 65.2378 in the competitive model. In the cooperative model, the shared spectrum is 8.5856 with the total profit of 73.4963. The numerical results reveal the effectiveness of the cooperative model.

• Journal of the Korean Institute of Intelligent Systems
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• v.15 no.5
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• pp.538-544
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• 2005

The service supporting structure for users in ubiquitous computing environment requires technology that divides efficiently resources shared around users according to users context. So, needs research that analyze service items and resources that is offered according to users context information and divide adaptively necessary service and resources. Therefore, in this paper we proposes an intelligent P2P mobile agent that recognizes users context using portable mobile devices and is available for intelligent service by sharing serviced item according to users' context. The proposed structure removes monopoly for specific resources, and supports effective users context-awareness and service.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.15 no.6
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• pp.2069-2085
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• 2021

A Social Networking Service (SNS) platform provides digital footprints to discover users' interests and track the social diffusion of product adoptions. How to identify a small set of seed users in a SNS who is potential to adopt a new promoting product with high probability, is a key question in social networks. Existing works approached this as a social influence maximization problem. However, these approaches relied heavily on text information for topic modeling and neglected the impact of seed users' relation in the model. To this end, in this paper, we first develop a general product adoption function integrating both users' interest and social influence, where the user interest model relies on historical user behavior and the seed users' evaluations without any text information. Accordingly, we formulate a product adoption maximization problem and prove NP-hardness of this problem. We then design an efficient algorithm to solve this problem. We further devise a method to automatically learn the parameter in the proposed adoption function from users' past behaviors. Finally, experimental results show the soundness of our proposed adoption decision function and the effectiveness of the proposed seed selection method for product adoption maximization.

• Journal of Multimedia Information System
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• v.9 no.3
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• pp.201-208
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• 2022

Customized service is a vital and mandatory element for apps in improving their technical performance and app customer analysis. While apps require users' consent for their data extraction and usage, many of the terms and agreement forms are written intricately, making it harder for users to fully understand the whole concept of users' data collection for customized services. Ever since the Facebook-Cambridge Analytica scandal, personal data privacy has been re-examined, forcing many app companies to reinforce a reliable solution to data privacy issues. However, there has not been a secured solution, which worries many people about the future advanced issues when metaverse platforms are actively used in daily apps. The research aims to collect the reactions and behaviors of everyday app users who utilize apps with customized services to understand the nature of privacy data issues and the users' opinions about the future implementation of metaverse platforms. The method of the research was an online questionnaire that targeted university students. The study revealed many fearful and anxious reactions about personal data and further metaverse issues where most app users were uneducated about how current apps collect and utilize users' private data.