• International journal of advanced smart convergence
• /
• v.10 no.3
• /
• pp.17-25
• /
• 2021

As a new paradigm in non-orthogonal multiple access (NOMA), correlated superposition coding (CSC) has gained an attention in the literature of NOMA, in contrast to standard independent superposition coding (ISC). In the conventional 3-user CSC scheme, it has been reported that the average allocated power can be reduced, owing to an introduced correlation between transmitted signals. Thus, this paper proposes a 3-user cross CSC scheme with purely-imaginary correlation coefficients. First, we derive the achievable data rates of the proposed 3-user cross CSC scheme, for each of the three users. Then, simulations demonstrate that for the proposed 3-user cross CSC scheme, the achievable data rates of the first and second users increase greatly and slightly, respectively, whereas the achievable data rate of the third user decreases little, compared to those of the conventional 3-user CSC scheme. In addition, we also show that the sum rate of the three users of the proposed 3-user cross CSC scheme is much larger than that of the three users of the conventional 3-user CSC scheme. As a result, the proposed 3-user cross CSC scheme could be a solution to the problem of the reduction of the average allocated total power in the conventional 3-user CSC scheme toward the fifth-generation (5G) NOMA mobile networks.

• Journal of the Korea Society of Computer and Information
• /
• v.22 no.3
• /
• pp.53-60
• /
• 2017

The purpose of this study is to provide empirical and quantitative analysis on user's perceived privacy, security, and user satisfaction when providing visualization information about objects and service provider behaviors that users can not perceive in internet service process. Through previous research, we have examined the importance of privacy and security factors as a key factor to be considered for the characteristics of the Internet of things and the Internet of things. In addition, service blueprint, which is one of the service design methodologies to examine the flow of service usage in providing Internet service of things, was examined. In the flow of things internet service utilization, it is found that the things that are out of the user's cognitive area and the behavior of the service provider take up a large part. Therefore, the hypothesis that the trust of the Internet service security and the satisfaction of the user experience can be improved by providing the security visualization information about the behavior of the object and the invisible service provider in the non-contact aspect of the user and the object. In order to verify the hypothesis, we conducted experiments and questionnaires on the use of virtual objects' internet environment and conducted statistical analysis based on them. As a result, it was analyzed that visual information feedback on non - contact and invisible objects and service provider's behaviors had a positive effect on user's perceived privacy, security, and satisfaction. In addition, we conclude that it can be used as a service design evaluation tool to eliminate psychological anxiety about security and to improve satisfaction in internet service design. We hope that this research will be a great help for the research on application method of service design method in Internet environment of objects.

• Journal of the Korea Institute of Information Security & Cryptology
• /
• v.27 no.6
• /
• pp.1419-1429
• /
• 2017

Recently, environment based authentication technique had proposed reinforced authentication, which generating statistical model per user after user login history classifies into account takeover or legitimate login. But reinforced authentication is likely to be attacked if user was not attacked in past. To improve this problem in this paper, we propose unconsciousness authentication technique that generates 2-Class user model, which trains user's environmental information and others' one using machine learning algorithms. To evaluate performance of proposed technique, we performed evasion attacks: non-knowledge attacker that does not know any information about user, and sophisticated attacker that only knows one information about user. Experimental results against non-knowledge attacker show that precision and recall of Class 0 were measured as 1.0 and 0.998 respectively, and experimental results against sophisticated attacker show that precision and recall of Class 0 were measured as 0.948 and 0.998 respectively.

• Journal of Information Technology Services
• /
• v.20 no.5
• /
• pp.137-146
• /
• 2021

Recently, public participation in government policy design has been further expanded and public services perceived by users are expanding. At this time, the role of the digital government and the direction of the service to be pursued are user-centered, and above all, it is necessary to focus on the keywords of pre-emptive, preventive, and customized. In order to propose service quality improvement in the public sector, service user-centered classification and monitoring are integrated and the usability of government documents is improved. It is necessary to identify the needs of whether to provide a path for public participation. In the post-corona era, people are accessing quarantine information from the digital government every day. The government should proactively respond to the acceleration of digital transformation and the non-face-to-face demands of the people who experience non-face-to-face daily life. In order to evolve into a smart organization along with the innovation promotion plan and to provide customized services, it is necessary to use existing guides for institutional and technical improvement, along with new technology and data-based analysis, to strive for change management. The government should seek counter-measures that have advanced one step ahead by incorporating new high-tech IT with user-centered necessary services. This study aims to derive improvement plans to provide user-centered digital government service design when designing public services and collecting public opinions. Based on the e-government development model research and the existing research on user-centered service design in the public sector, institutional and technical measures are provided for the improvement of digital government service design.

• Proceedings of the IEEK Conference
• /
• 2002.07c
• /
• pp.1886-1888
• /
• 2002

Non-verbal information plays an important role not only in human-to-human communications but also in human computer interaction. In this paper, we examine effects of human-like agent's primitive movements on user's impression, where the human-like agent's primitive movements include eye, mouth, and head. SD (Semantic Differential) method was used for evaluation, and two factors were extracted as a result of the factor analysis. It is found that the first factor influenced the user's impression particularly.

• Journal of the Korean Society for Library and Information Science
• /
• v.19
• /
• pp.151-188
• /
• 1990

The aims of automation efforts in libraries are the rationalization of interval work and improvement of user services. After a period of exclusive internal computer utilization, later voluntary contact with the computer (e.g., circulation control with self services), patrons of American libraries now have to go to a computer terminal if they want certain information. Online public access catalogs(OPAC) have been used in American libraries since the end of the seventies. But OP AC are accepted by patron only if they have a useful and flexible user interface. This paper briefly describes the use of online catalogs in different type of libraries, categories of user (user, non-user), aspect of catalog use in context with computer experience etc. The disscussion then focuses on the characteristics of the final report of online catalog use study of Council on Library Resources and user problems in searching, as reported in many other catalog use studies.

• Journal of the Korean Institute of Educational Facilities
• /
• v.21 no.1
• /
• pp.33-42
• /
• 2014

The purpose of this study is to suggest a basis for exterior space improving in university campus in terms of upgrading the quality of university education environment by analysing user's cognition and physical feature about campus exterior space. For this, this study was survey six major university students in Busan city about perception of campus exterior space, and analyzes the user's cognition by using natural-language vocabulary analysis for qualitative approach. Next, this study analyzes the physical feature of campus exterior space by investigating user's intensive using spaces and preferred, non-preferred spaces in their universities, then propose the improved direction of campus exterior space by comparing the analyzed data of user's cognition and physical feature. A SPSS20 program is used for the data analysis and the sample sizes are 171 college students.

• The Transactions of the Korean Institute of Electrical Engineers P
• /
• v.58 no.1
• /
• pp.1-8
• /
• 2009

Recently, application of non-linear load is gradually increased. Non-linear load produces harmonic components of current during the energy conversion transition. Passive filter is used for reducing of harmonics in the user power systems. This filter, which is composed of capacitor and reactor, frequently get out of order by electrical stress. There are voltage and current increase when capacitor and reactor are applied in the user's filter systems. If increased voltage and current is above stipulated values, they have severely an influences on the life of capacitor and reactor. This paper describes that the voltage and current of capacitor used for filter is within the limits of allowable values, but reactor is beyond the limits and reveals spike voltage. Therefore this phenomenon brings about premature fault of reactor and capacitor.

• Journal of the Korea Society of Computer and Information
• /
• v.23 no.3
• /
• pp.25-31
• /
• 2018

In this paper, we consider the game theoretic approach to investigate the transmit power optimization problem where D2D users share the uplink of the cellular system. Especially, we formulate the transmit power optimization problem as a non cooperative power control game. In the user wide sense, each user may try to select its transmit power level so as to maximize its utility in a selfish way. In the system wide, the transmit power levels of all users eventually converge to the unique point, called Nash Equilibrium. We first formulate the transmit power optimization problem as a non cooperative power control game. Next, we examine the existence of Nash Equilibrium. Finally, we present the numerical example that shows the convergence to the unique transmit power level.

• Journal of Korean Society for Quality Management
• /
• v.23 no.2
• /
• pp.1-9
• /
• 1995

Two user groups, expert and non-expert, are sampled to measure the image quality of G3 facsimile. A ITU-TS tset chart No. 2 has been transmitted among some selected cities and evaluated by user groups. Their subjective evaluation to the image quality is quantified by Mean Opinion Score method. There is highly significant difference in the image quality between expert and non-expert. From modified logit model, it is concluded that there is no significance in two considered factors, the effects of the number of links and transmission time. The derived percent curves show that 80% of non-experts(90% of expert) is considering the image quality of G3 facsimile "fair, good, or excellent".