• Korean Management Science Review
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• v.29 no.2
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• pp.65-77
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• 2012

With the explosivley increasing demand in wireless telecommunication service, the shortage of radio spectrum has been worsen. The traditional approach of the current fixed spectrum allocation leads to spectrum underutilization. Recently, CR (Cognitive Radio) technologies are proposed to enhance the spectrum utilization by allocating dynamically radio resources to CR Networks. In this study, we consider a radio resource(power, subcarrier) allocation problem for OFDMA-based CRN in which a base station supports a variety of CUs (CRN Users) while avoiding the radio interference to PRN (Primary Radio Network). The problem is mathematically formulated as a general 0-1 IP problem. The optimal solution method for the IP problem requires an unrealistic execution time due to its complexity. Therefore, we propose an heuristic that gives an approximate solution within a reasonable execution time.

• Journal of Korean Library and Information Science Society
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• v.33 no.4
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• pp.331-348
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• 2002

The Journals of medical libraries an the primary resources of medical library collections, and the majority of them are foreign journals. Recently, medical libraries have some difficulties in purchasing materials due to the rapidly increasing journal Vices and the curtailment in the budget. A proposal for the establishment of an information center for controlling Korean medical bibliographies was suggested. This system will be expected to contribute to the users for acquiring materials more effectively.

• International Journal of Knowledge Content Development & Technology
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• v.10 no.1
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• pp.47-70
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• 2020

This article examines the utilization of e-resources Modibbo Adama University of Technology, (MAUTech) Yola under the auspices of the central library, the Ibrahim Babangida Library. Academics and students are primary users of information resources of any library, hence, their responses towards the utilization of e-resources in the institution have been critically considered in this study. A Mixed method research Design was adopted for the study. A case study approach was employed. The Technology Acceptance Model (TAM) and Diffusion of Innovation (DoI) theories were used to develop the conceptual framework of this paper. Questionnaires were used as data gathering tools. Academics and students acted as participants. Major findings are lack of sufficient Internet access for academics and students and lack of training and awareness campaigns. Conclusion has shown that e-resources did not impact research and teaching of academics in MAUTech, Yola.

• Proceedings of the Korea Database Society Conference
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• 2010.06a
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• pp.299-308
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• 2010

The primary objective of this paper is to examine of post acceptance behavior model in VCC services. Based on the relevant literature reviews, this study posits six characteristics, that is, expectation confirmation, perceived usefulness, perceived enjoyment, satisfaction, and continuance intention as key variables to describe the post acceptance behavior model in VCC services. And then we constructed a research model and hypotheses about relationship between these variables. A total 286 usable survey responses of CCC service users have been employed in the analysis. The empirical results of this study are summarized as follows. Firstly, expectation confirmation has a positive effect on the perceived usefulness, perceived enjoyment, and satisfaction. Secondly. perceived enjoyment has a positive effect on the satisfaction. Lastly, perceived usefulness, perceived enjoyment, and satisfaction have a positive effect on the continuance intention. These results will be helpful for the UCC services sector to further develop a service delivery strategies for strengthening the ongoing relationship with customers. Finally, some possible limits of the present research and future directions for such research were discussed.

• Asia pacific journal of information systems
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• v.26 no.1
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• pp.143-162
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• 2016

Social media marketing has gained attention from marketers because of the growing number of social media users. Considering the unique context of each company or organization behind the marketing is necessary when choosing and applying various social media marketing strategies to ensure achievement of better business performance. However, previous studies have focused on context-specific marketing strategies. Accordingly, this study aims to develop context-specific social media marketing strategies. In this study, we first develop a conceptual framework with two items, namely, brand awareness and business orientation of an organization, as criteria, and classify the framework into four contexts. We then propose context-specific social media marketing strategies for each of the contexts. We examine the framework and proposed social media marketing strategies based on multiple case studies. The primary contribution of this study is our context-specific social media marketing strategies.

• Proceedings of the Korean Society of Marine Engineers Conference
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• 2005.11a
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• pp.57-58
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• 2005

Recently the telematics system is used widely. Users want to high quality communications. Since the primary advantage of using an array is to enhance a desired signal and reject jamming interferences, array signal processing is essential to satisfy unmet demand of user. In general, beamforming is a spatial filtering operation performed on the data received by an array of sensors. So we propose the beamformer design that use FPGA for real time processing. And we use zero-padding interpolation for high resolution data.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2017.11a
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• pp.21-23
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• 2017

본 논문에서는 스펙트럼 감지 무선 인지 네트워크에서 동기화 에러가 존재하는 환경을 고려한다. 동기화에러가 존재 할 때 주어지는 오검출 확률(miss detection probability)을 이용하여 일차 사용자와 이차 사용자들 간의 충돌 확률(collision probabliyt)를 유도한다. 유도된 수식을 몬테 카를로 모의실험(Monte Carlo simulation)을 통해 확인한다.

• Asia pacific journal of information systems
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• v.6 no.1
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• pp.75-108
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• 1996

Expert Systems (ES) have been successfully applied to bank loan decisions. However, with regard to bank loan decisions, most loan officers approach the acquisition of an ES with apprehension, which implies that organizational resources devoted to the development and implementation of ES may have been wasted or misused. Because the primary cause of the users resistance to use ES are more significantly related to the behavioral elements rather than technical elements, applying appropriate behavioral theory to the well representative sample group of the whole bank loan officers in the United States with a very accurate measurement tool can provide some clues for developing successful ES for bank loan officers. In this study : 1) Vroom's (1964) expectancy theory was selected to explain bank loan managers' motivation to use an ES ; and 2) the ANN model's prediction power to estimate bank loan officers' motivation levels of using an ES was examined.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.9 no.1
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• pp.260-279
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• 2015

In this paper, we investigate physical layer security for multiple decode-and-forward (DF) relaying underlay cognitive radio networks (CRNs) with fixed transmit power at the secondary network against passive eavesdropping attacks. We propose a simple relay selection scheme to improve wireless transmission security based on the instantaneous channel information of all legitimate users and the statistical information about the eavesdropper channels. The closed-form expressions of the probability of non-zero secrecy capacity and the secrecy outage probability (SOP) are derived over independent and non-identically distributed Rayleigh fading environments. Furthermore, we conduct the asymptotic analysis to evaluate the secrecy diversity order performance and prove that full diversity is achieved by using the proposed relay selection. Finally, numerical results are presented to verify the theoretical analysis and depict that primary interference constrain has a significant impact on the secure performance and a proper transmit power for the second transmitters is preferred to be energy-efficient and improve the secure performance.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.8 no.7
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• pp.2350-2364
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• 2014

This paper addresses the problem of resource allocation in amplify-and-forward (AF) relayed OFDM based cognitive radio networks (CRNs). The purpose of resource allocation is to maximize the overall throughput, while satisfying the constraints on the individual power and the interference induced to the primary users (PUs). Additionally, different from the conventional resource allocation problem, the rate-guarantee constraints of the subcarriers are considered. We formulate the problem as a mixed integer programming task and adopt the dual decomposition technique to obtain an asymptotically optimal power allocation, subcarrier pairing and relay selection. Moreover, we further design a suboptimal algorithm that sacrifices little on performance but could significantly reduce computational complexity. Numerical simulation results confirm the optimality of the proposed algorithms and demonstrate the impact of the different constraints.