• Journal of information and communication convergence engineering
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• v.11 no.4
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• pp.223-228
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• 2013

Cognitive radio has been recently considered a promising technology to improve spectrum utilization by enabling secondary access to licensed bands that are not used by primary users temporarily or spatially. A prerequisite to this secondary access is the lack of interference to the primary system. This requirement makes spectrum sensing a key process for cognitive radio. In this study, we consider amplify and forward (AF)-based cooperative spectrum sensing for cognitive radio networks where multiple relay nodes are utilized to amplify and forward the primary user signal for better spectrum sensing, and maximum ratio combining is used for fusion detection by a cognitive coordinator. Further, the detection probability and the bit error rate of AF-based cooperative spectrum sensing are analyzed in fading multiple cognitive relay channels. The simulation results show that the AF-based cooperative spectrum sensing scheme outperforms the conventional scheme.

• Journal of Korean Institute of Industrial Engineers
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• v.37 no.3
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• pp.264-270
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• 2011

A new method for creating a logical data model is proposed. The logical data model developed by the method defines table, primary key, foreign key, and fields. The framework of the logical data model is constructed by modeling the relationships between events and their related entity types. The proposed method consists of a series of objective and quantitative decisions such as maximum cardinality of relationships and functional dependency between the primary key and attributes. Even beginners to database design can use the methology as long as they understand such basic concepts about relational databases as primary key, foreign key, relationship cardinality, parent-child relationship, and functional dependency. The simple and systematic approach minimizes decision errors made by a database designer. In practial database design the method creates a logical data model in Boyce-Codd normal form unless the user of the method makes a critical decision error, which is very unlikely.

• International journal of advanced smart convergence
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• v.13 no.2
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• pp.258-266
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• 2024

E-learning systems have proliferated in recent years, particularly in the wake of the global COVID-19 pandemic. For kids, there isn't a specific online learning platform available, though. To do this, new conceptual models of training and learning software that are adapted to the abilities and preferences of end users must be created. Young pupils: those in kindergarten, preschool, and elementary school are unique subjects with little research history. From the standpoint of software technology, young students who have never had access to a computer system are regarded as specific users with high expectations for the functionality and interface of the software, social network connectivity, and instantaneous Internet communication. In this study, we suggested creating an electronic learning management system that is web-based and appropriate for primary school pupils. User-centered design is the fundamental technique that was applied in the development of the system that we are proposing. Test findings have demonstrated that students who are using the digital environment for the first time are studying more effectively thanks to the online learning management system.

• The KIPS Transactions:PartC
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• v.17C no.4
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• pp.335-346
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• 2010

Mac OS X is the Computer Operating System that develop in Apple Inc. Mac OS X is the successor to Mac OS 9 Version which had been Apple's primary operating system since 1984. Recently, Mac OS X 10.6 (Snow Leopard) has been manufactured and is distributed to user. Apple's Mac OS X Operating System is occupying about 10% in the world Operating System market share. But, Forensic tools that is utilized on digital forensic investigation can not forensic analysis about Mac OS X properly. To do forensic investigation about Mac OS X, information connected with user's action and trace can become important digital evidence in Operating System. This paper presents way about user trace data acquisition methodology in Mac OS X.

• Journal of Information Technology Services
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• v.19 no.5
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• pp.125-136
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• 2020

The subject of this study is user experience analysis for OTT mobile app services. Application service quality was quantitatively measured by utilizing KS-eSQI evaluation model from a service quality perspective. The purpose of this analysis is to analyze how service reuse and other people's intention to recommend services are affected by service quality. In addition, further analysis of user experience will qualitatively look at what efforts are needed to improve OTT service quality and provide a user-friendly environment. According to the survey, the higher the level of KS-eSQI service quality, the higher the reuse of OTT services and recommendation of others. In particular, the dimensions of primary services and unexpected additional services had a higher impact on customer loyalty and recommendation of others than in other industries. Moreover, the following three implications were found to improve app services from a customer experience perspective. First, images and video thumbnails that highlight the strength of the content they provide should be actively utilized. Second, it is necessary to provide service companies with evidence for data-based work recommendations. Third, it should provide a viewing environment in which users can respond more intelligently to the various situations and conditions when they actually watch.

• Proceedings of the Korea Society of Design Studies Conference
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• 2001.10a
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• pp.54.1-54
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• 2001

• Journal of The Korea Institute of Healthcare Architecture
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• v.1 no.2
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• pp.39-51
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• 1996

Design scheme drawings of the two major corporate hospitals - Asan Medical Center and Samsung Medical Center - are analysed in the aspect of floor area distributions and their proportions for various users and user-functions. Primary users of hospitals are categorized into three ; patients, employees and others. Then, patient spaces are subdivided into patient private, patient/medical, patient/support staff, patient/nursing, patient/guardian, patient common ; employee spaces into doctors, trainees, doctors common, nurses, support staffs, non-medical staffs, employee common ; others spaces into subcontractors, general publics, non-living, and internal circulation. The purpose of this research is to develop a user-focused insight into hospital spaces and a new method of hospital programming and design.

• 한국디지털정책학회:학술대회논문집
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• 2004.11a
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• pp.405-421
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• 2004

The digital government is one of the most significant areas of study to emerge in information science in the past several years. The digital government is, in broad terms, a computerized system that allows a community of users to obtain a coherent means of access to an organized, electronically stored repository of information and knowledge. The information resources and technologies embodied by the World Wide Web are now accepted ad the primary example of the digital government. The need exists for a means to measure user success in the digital government. Because a digital government environment involves two broad functions?1) information search and retrieval and 2) interactivity with and through the medium-this research posits that measures of both of these functions will show positive correlation with user success.

• Journal of Information Processing Systems
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• v.13 no.2
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• pp.417-427
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• 2017

Power allocation is an important factor for cognitive radio networks to achieve higher communication capacity and faster equilibrium. This paper considers power allocation problem to each cognitive user to maximize capacity of the cognitive systems subject to the constraints on the total power of each cognitive user and the interference levels of the primary user. Since this power control problem can be formulated as a mixed-integer nonlinear programming (NP) equivalent to variational inequality (VI) problem in convex polyhedron which can be transformed into complementary problem (CP), we utilize modified projection method to solve this CP problem instead of finding NP solution and give a power control allocation algorithm with a subcarrier allocation scheme. Simulation results show that the proposed algorithm performs well and effectively reduces the system power consumption with almost maximum capacity while achieve Nash equilibrium.

• International Journal of Contents
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• v.12 no.1
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• pp.70-75
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• 2016

In this paper, we considered heterogeneous spectrum sharing system where the number of subcarriers of the primary user (PU) was twice as much as that of the secondary user (SU). In this case, due to non-orthogonality and inter-carrier interference (ICI) from SU to PU, it is difficult to satisfy the interference constraint of PU. In order to mitigate ICI and satisfy the interference constraint, we proposed a new transmission scheme of the SU with power allocation scheme. The proposed scheme will only generate subcarrier-by-subcarrier interference. Therefore, it can easily satisfy the interference constraint of the PR and enhance the capacity of the SU. In addition, we derived the ergodic capacity of the SU. Based on numerical results, we confirmed that the proposed schemes could guarantee SU with a reliable capacity while satisfying the interference constraint of the PU. In addition, the derived capacity well matched the numerical results.