• Journal of the Korea Institute of Information and Communication Engineering
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• v.18 no.11
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• pp.2613-2620
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• 2014

In this paper, we consider a full duplexing (FD) wireless cellular network where a central base station (BS) works in the FD mode while the downlink (DL) and uplink (UL) users work in the time division duplexing (TDD) mode. Since this FD system induces the inter-user interference from UL user to DL user, the main challenge for maximizing the system performances is user scheduling that makes a pair of DL user and UL user to use the same radio resource simultaneously. We formulate an optimization problem for user pairing to maximize the cell capacity and propose a suboptimal user scheduling algorithm with low complexity. This scheduling algorithm is designed in a way where the DL user with a better signal quality has a higher priority to choose its UL user that causes less interference. Simulation results show that the FD system using the proposed user scheduling algorithm achieves the optimal performance and significantly outperforms the conventional TDD system in terms of the cell capacity.

• KIISE Transactions on Computing Practices
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• v.21 no.5
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• pp.379-386
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• 2015

We propose a novel user-perceived performance optimization framework for the Android platform that takes advantage of the user-centric response time analysis. To this end, we propose a new definition of response time, which we call the user-centric response time, as a metric for the quality of user-perceived performance of the smartphone application. In this paper, we describe the design and implementation of an on-line user-centric response time analyzer for Android-based smartphones, which provides smartphone application developers with valuable insight for user-perceived performance optimization. We implemented the user-centric response time analyzer on the Android platform, version 4.0.4 (ICS) running on a Galaxy Nexus smartphone. From our experimental results, the proposed user-centric response time analyzer accurately estimates user-centric response times with an accuracy of 92.0% compared to manually measured times with less than 1% performance penalty. In order to evaluate the efficiency of the proposed framework, we were able to reduce the user-centric response time of the target application by up to 16.4% based on the evaluation results by the proposed framework.

• Journal of Information Technology Applications and Management
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• v.31 no.1
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• pp.113-122
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• 2024

This comprehensive study delves into the analysis of user review data across various metaverse platforms, employing advanced text mining techniques such as TF-IDF and Word2Vec to gain insights into user perceptions. The primary objective is to uncover the factors that contribute to user satisfaction and dissatisfaction, thereby providing a nuanced understanding of user experiences in the metaverse. Through TF-IDF analysis, the research identifies key words and phrases frequently mentioned in user reviews, highlighting aspects that resonate positively with users, such as the ability to engage in creative activities and social interactions within these virtual environments. Word2Vec analysis further enriches this understanding by revealing the contextual relationships between words, offering a deeper insight into user sentiments and the specific features that enhance their engagement with the platforms. A significant finding of this study is the identification of common grievances among users, particularly related to the processes of refunds and login, which point to broader issues within payment systems and user interface designs across platforms. These insights are critical for developers and operators of metaverse platforms, suggesting a focused approach towards enhancing user experiences by amplifying positive aspects. The research underscores the importance of continuous improvement in user interface design and the transparency of payment systems to foster a loyal user base. By providing a comprehensive analysis of user reviews, this study offers valuable guidance for the strategic development and optimization of metaverse platforms, ensuring they remain responsive to user needs and continue to evolve as vibrant, engaging virtual environments.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.18 no.2
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• pp.397-419
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• 2024

Online learning has become a widespread practice for students and teachers in acquiring and delivering knowledge. Education platforms have become prominent in the 21st century with the evolution of technology and the accessibility to online learning. As a result, various learning management systems (LMSs) have been introduced to facilitate online interaction between users. For instance, communication between students and teachers at school. However, there is a need to emphasise user engagement in LMS to enhance the online learning experience amongst students since the design of LMS affects user engagement. This study utilised a systematic literature review (SLR) that examined 74 articles published between 2014 and 2023, focusing on cross-cultural design (CCD), user-centred design (UCD), and usability in LMS design. This study aimed to review CCD and its association with UCD, user interfaces (UI), and user experience (UX) in the context of LMS. CCD has been introduced as an approach to design that embraces different cultures, languages, and social contexts, while UCD plays a significant role in defining user engagement for LMS. All elements in CCD and UCD help create a better user experience for LMS. Besides, this study reviewed the usability of selected LMS to give insights to developers in creating a positive user engagement. An insight into cultural factors that influence the usability of LMS has revealed their value for LMS design, such as the UI/UX elements. Initially, this study may guide future researchers in improving education quality by emphasising CCD and LMS usability, which can enhance user engagement.

• The Journal of the Korea Contents Association
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• v.9 no.4
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• pp.95-102
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• 2009

Recently, remote user authentication scheme protecting user anonymity using smart card has been researched with interest increasing on user privacy. Although authentication scheme providing user anonymity using smart card had been proposed by Das et al, Chien et al. pointed out Das et al. scheme fail to provide user anonymity and proposed new scheme to overcome the problem. A remote system Kim et al. proposed a scheme which is traceable about malicious user with protecting user anonymity. In this paper, we point out that Kim et a1. scheme fail to provide user anonymity and propose a scheme for some problems Kim et al. scheme has. And then we analysis our scheme on cryptophic security and efficiency with Kim scheme.

• IE interfaces
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• v.22 no.1
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• pp.17-25
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• 2009

In mobile device's user interface, menu organization is very important as well as menu structure because small display of mobile device. Menu items should be organized based on user knowledge structure to design user-centered interface. Traditionally, MDS (Multidimensional Scaling) have been most often used to expose users' perceived organization of menu items. But, information that MDS reveals is just relative spatial location of concepts and not relevant to concepts connection. Unlike MDS, Trajectory Mapping explicitly finds users' cognitive links between perceived concepts. This study proposes a Trajectory Mapping technique for eliciting knowledge structure, especially a set of cognitive pathways linking menu items, from end user. With twelve participants, MDS and Trajectory Mapping were conducted using cellular phone's menu items. And user knowledge structure was analyzed through Visual Concept Map that combination of results of MDS and Trajectory Mapping. After then, menu items were organized according to users' perceived organization. Empirical usability test was also conducted. The results of usability test showed that usability, in terms of task performance time, number of errors, and satisfaction, for newly organized interface was significantly improved compare to original interface. The methodology of this study is expected to be applicable to design a user-centered interface. In other words, Trajectory Mapping technique can be used as a design tool of user interface for imposing user knowledge structure on the interface.

• Journal of the Ergonomics Society of Korea
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• v.34 no.5
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• pp.531-540
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• 2015

Objective: The objective of this research is to investigate the fundamentals of human computer interaction for wearable computers and derive technology requirements. Background: A wearable computer can be worn anytime with the support of unrestricted communications and a variety of services which provide maximum capability of information use. Key challenges in developing such wearable computers are the level of comfort that users do not feel what they wear, and easy and intuitive user interface. The research presented in this paper examines user interfaces for wearable computers. Method: In this research, we have classified the wearable user interface technologies and analyzed the advantages and disadvantages from the user's point of view. Based on this analysis, we issued a user interface technology to conduct research and development for commercialization. Results: Technology requirements are drawn to make wearable computers commercialized. Conclusion: The user interface technology for wearable system must start from the understanding of the ergonomic aspects of the end user, because users wear the system on their body. Developers do not try to develop a state-of-the-art technology without the requirement analysis of the end users. If people do not use the technology, it can't survive in the market. Currently, there is no dominant wearable user interface in the world. So, this area might try a new challenge for the technology beyond the traditional interface paradigm through various approaches and attempts. Application: The findings in this study are expected to be used for designing user interface for wearable systems, such as digital clothes and fashion apparel.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.14 no.3
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• pp.1363-1376
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• 2020

An improved clustering scheme based on user group is proposed. Every two users are grouped among N-users in the allowed system according to their link gain from large to small. Each user group is numbered sequentially. Two user clusters are obtained according to the principle of maximizing link gain difference for the users in the first and last user groups. The remaining user groups are added to the two existing user clusters according to the parity of the group number. The clustering should be clustered again among the users in either user cluster if the throughput summation of a user cluster in NOMA is less than that of these users in orthogonal multiple access. The simulation results show that the proposed clustering scheme can increase the system throughput by about 8% compared with the hybrid clustering scheme when the number of users requiring service is 12.

• Knowledge Management Research
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• v.17 no.1
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• pp.155-174
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• 2016

Recent years, a smartphone has been playing a role of searching, booking, and decision-makings in the tourism industry through tourists' user experiences and engagements. This study investigated the tourists' behavior toward smartphone usage regarding Chinese visitors who were ranked in Korea inbound tourism. This research model formulated two types of usage which identified explorlative use and exploitive use and the antecedent relationships of user empowerment including user competence, user impact, usage meaning, user trust. We analyzed SmartPLS2.0 for the hypotheses and found that first, user competence has a positive influence both of exploitative use and explorative use, second, user impact has a positive influence on exploitative use, but has not influenced on explorative use, third, usage meaning has not influence on exploitive use, but has a postitive influence on explorative use, and finally user trust has influence on both of exploitive and explorative use. Based on the results we found, we suggested Chinese tourists' smartphone usages' behaviors and theoretical and practical implications.

• Journal of Korean Library and Information Science Society
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• v.11
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• pp.19-43
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• 1984

There are two broad classes of user studies, in terms of their purposes or a n.0, pplications. One class might be termed basic studies, in which the purpose is to create or obtain knowledge regarding information needs and uses with no particular a n.0, pplication. The second type of study might be termed a n.0, pplied. The aim of second type is preparing standards to evaluate and improve existing information systems or to design new systems. The trends of user study tend toward basic research from a n.0, pplied ones. Furthermore, not only the broad-based studies change with special setting up and subdivided studies, but also the scopes of user study vary social scientist, human scientist, and even common users from limited natural scientists and technologists earlier. The aims of this paper is to summarize continuously pointed problems of user studies and to survey the state of the arts by reviewing the trends of user studies. The major problems of user studies are terminology, conceptualization, and methodology. These terms are essential to this study, and very important to decide the research fields and to select a method of survey, respectively. And in order to predict the user needs, studies of 'information needs' are inevitable instead those of 'information demands' which principally studied till nowadays. On the other hand, to reduce the problems of user studies, it is needed more qualitative studies ever than before and cooperation with other areas, for example, behavioral 'science, psychology, communication science and so forth.