• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2008.05a
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• pp.873-875
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• 2008

In sensor network, the elimination of NLOS information is a necessity to improve the accuracy of the localization. For this reason, we proposed an algorithm iteratively eliminating the NLOS information to enhance the accuracy of the localization of a tag location, and simulated the proposed algorithm to confirm the performance. The proposed algorithm can estimate the location of the error distance within 3.5m when it has 10 LOS coordinates with LOS information. In addition, it can enhance the accuracy according to decreasing NLOS coordinates.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.9 no.3
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• pp.1057-1073
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• 2015

In this paper, we consider cooperative D2D communications in cellular networks. More precisely, a cellular user leases part of its spectrum to facilitate the D2D communication with a goal of improving the energy efficiency of a D2D pair. However the D2D pair is untrusted to the cellular user, such resource sharing may result in the information of this cellular user unsecured. In order to motivate the cellular user's generosity, this D2D pair needs to help the cellular user maintain a target secrecy rate. To address this issue, we formulate a joint spectrum and power allocation problem to maximize the energy efficiency of the D2D communication while guaranteeing the physical layer security of the cellular user. Then, a theorem is proved to indicate the best resource allocation strategy, and accordingly, an algorithm is proposed to find the best solution to this resource allocation problem. Numerical results are finally presented to verify the validity and effectiveness of the proposed algorithm.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.15 no.1
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• pp.105-110
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• 2015

In cognitive radio networks, when the signal-to-noise ratio (SNR) of the link between a primary transmitter and receiver is sufficiently high, the primary transmission does not frequently demand cooperation because direct transmission of the primary communication is usually successful. Therefore, there are few opportunities for a secondary transmitter to cooperate with the primary user system in exchange for an opportunity to share the spectrum. This article proposes a scheme in which the secondary system can deliberately degrade the SNR of the primary transmission, making it so that the primary system needs cooperation from the secondary nodes, and thereby increases opportunities for spectrum sharing.

• Journal of Advanced Navigation Technology
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• v.14 no.1
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• pp.41-48
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• 2010

Intrusion detection forms a vital component of internet security. To keep pace with the growing trends, there is a critical need to replace single layer detection technology with multi layer detection. Different types of Denial of Service (DoS) attacks thwart authorized users from gaining access to the networks and we tried to detect as well as alleviate some of those attacks. We have proposed a novel cross layer intrusion detection architecture to discover the malicious nodes. The information available across different layers of protocol stack are exploited in order to improve the accuracy of detection. We have used cooperative and distributive anomaly intrusion detection with data mining technique to enhance the proposed architecture. The simulation of the proposed architecture is done in OPNET simulator and the results are analyzed.

• Journal of Internet Computing and Services
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• v.10 no.1
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• pp.159-173
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• 2009

Locations of positioned nodes as well as gathered data from nodes are very important because generally multiple nodes are deployed randomly and data are gathered in wireless sensor network. Since the nodes composing wireless sensor network are low cost and low performance devices, it is very difficult to add specially designed devices for positioning into the nodes. Therefore in wireless sensor network, technology positioning nodes precisely using low cost is very important and valuable. This research proposes Cooperative Positioning System, which raises accuracy of location positioning and also can find positions on multiple sensors within limited times. And this research verifies this technology is excellent in terms of performance, accuracy, and scalability through simulation.

• Journal of Korean Library and Information Science Society
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• v.40 no.1
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• pp.363-384
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• 2009

School library programs are a specific strategy connecting user to resources. Accordingly in order to strengthen school libraries, it is necessary for teacher librarians to develop partnerships that can form relationships between internal and external resources. As a result of analyses of partnerships appeared in current middle school library programs, its most programs are based on the internal reading events. In addition to, classroom teachers and external human resources rarely participate in the program. To improve these problems, it is essential to develop teacher librarians' leadership and collaborative networks fostering educational presence of school libraries in a learning community.

• Journal of the Korea Computer Industry Society
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• v.6 no.5
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• pp.749-756
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• 2005

In the near future, we can access the information whenever we want, wherever we use because almost devices in ubiquitous environment are connected by either wired or wirelss networks. Especially, u-Learning which emphasizes on pedagogical property is enable to improve learning abilities. As researches of the previous u-Learning, there have been learning by mobile devices such as PDAs as well as the smart classroom which makes the remote students participate in the existing class. However, these researches have not satisfied pedagogical, cooperative and ubiquitous properties yet. Thus we suggest the framework for both local and mobile classroom, which can make the properties easy to satisfy.

• The Journal of Asian Finance, Economics and Business
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• v.7 no.1
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• pp.239-247
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• 2020

Technological convergence is yielding new values and affecting various fields not by single technology but by convergence between technologies. This study aims to analyze the IT -BT-NT convergence and differences between technologies in respect of collaboration within (inventor) and between (assignee) organizations. Among the main technologies leading the technological convergence, IT is the most active of converging with other fields. BT is knowledge-intensive and strong cooperative networks are important in this area. NT is applied in various industrial fields upon the basic technology. Using the data on applied and granted patents by Korean applicants in the U.S., this study conducted quantitative analysis and ANOVA to gain the following results. First, the degree of convergence in between IT-BT-NT is continuously increasing since 2002. Second, BT is where the collaboration within and between organizations is the most active among IT-BT-NT. Third, there were certain differences in the degree of convergence according to the years and the fields of technologies in all the IT-BT-NT. Organizations cooperate with other institutions to sustain their competitiveness with limited internal resources. Companies in these fields are recommended to perform diverse strategies to pursue further collaboration with the outside.

• The Journal of Asian Finance, Economics and Business
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• v.5 no.2
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• pp.119-128
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• 2018

A primary goal of transnationals is to offer their vision for selling products or services so that they are relevant to local cultures. The purpose of this study is to provide a solution for how transnational companies face various environments and how they can utilize and overcome them and survive strategically. This study will present strategic recommendations for transnational organizations. First, transnational organizations should identify the core areas where organizational can invest or allocate its precious resources to get full advantage of the attractive opportunities form the market and focus on building strong networks with the key stakeholders. Second, they should manage the knowledge flows and provide strategic direction in cooperative venture for the long term successful future and ensure that every department has an effective coordination with other departments in order to bring about the organizational change. Lastly, they should overcome the challenges managers face in a transnational business environment when companies expand their operations into international markets. The managers need to assess the organization's strengths and weaknesses and evaluate different forces which are present in the external environment. And then, Managers have to ensure that the company has sufficient resources, core competencies and capabilities.

• The KIPS Transactions:PartC
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• v.13C no.6 s.109
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• pp.749-756
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• 2006

Broadcast nature of wireless medium and path-loss reduction create a favourable condition for collaborative communications (CC) among single-antenna users to gain the powerful benefits of multi-antenna system without the demand for physical arrays. This paper proposes a CC strategy adapting to the propagation environment changes by optimizing the transmit signal amplification factors to simplify the structure of maximum likelihood (ML) detector and to obtain the minimum error probability as well. The closed-form BER expression was also derived and compared to the simulation results to evaluate the performance of the suggested solution. A variety of numerical results revealed the cooperation significantly outperforms non-cooperative counterpart under flat Rayleigh fading channel plus AWGN (Additive White Gaussian Noise).