• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.5
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• pp.3074-3078
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• 2014

We implemented a dual-band slot-coupled patch (SCP) antenna for the external access point (AP) of the wireless local area network (WLAN) band. The antennas consist of two radiators on three layers. The first radiator is a slotted bow tie antenna operating at the 2.4-2.483 GHz band. The second radiator is a patch antenna with parasitic elements operating at 4.095-5.845 GHz. The high gain and broad bandwidth is important element of wireless access. To enhance the bandwidth, a coupled feeding was used in the first radiator and a parasitic patch was used in the second radiator. We used a parasitic patch and chock to improve the directivity and isolation in both radiators. The porposed antenna was designed by EM simulation tool and measured. The S11 of the antenna was less than -11dB (VSWR 1.8:1) at operating frequency. The peak gain was more than 6 dBi in the first antenna and more than 8 dBi in the second antenna.

• Journal of the Korean Society for Library and Information Science
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• v.42 no.3
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• pp.365-382
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• 2008

What is the starting point of discussions for the open access of Korean journals? This study analyzed whether the serials crisis in Western societies are in academic libraries in Korea. The rising of prices of Korean electronic journals in academic libraries and recognition of librarians for it were surveyed. This study found that the subscription fees for web DBs of Korean journals have been increased from 1.3 times to 34 times during the last 10 years. But librarians in the universities did not think that the subscription fees are very high. And the 35% of respondents thought that the subscription fees for the web DBs in academic libraries will be increased to bring to a crisis to libraries. This study suggested that the leading groups of discussions for open access in Korea wilt be interested in the aspects of public goods and social justice, another values of open access.

• Journal of Korean Library and Information Science Society
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• v.52 no.4
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• pp.153-177
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• 2021

The revision of the Korean Cataloging Rules (KCR) is in progress in order to conform IFLA LRM conceptual model and to strengthen its internal stability. Religious works, along with musical works and legal works, have been treated as special and important in cataloging rules. This trend continues in the new cataloging rules that seek a bibliographic model that interconnects related materials. However since KCR2(1966), there are no rules for access points or specific rules on religious works. Under the circumstances, this study analyzed (1) the contents of religious works in the recently revised cataloging rules, (2) the access points and their functions for religious works implemented in online catalogs and authority system, and finally (3) the direction and scope of KCR revision. As a result of the study, this study suggested that it is necessary to prepare detailed rules for preferred title and authorized access points for various religious works in KCR. In conclusion, some issues for further discussion were summarized.

• ETRI Journal
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• v.30 no.2
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• pp.301-307
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• 2008

As broadband access is evolving from digital subscriber lines to optical access networks, Ethernet passive optical networks (EPONs) are considered a promising solution for next generation broadband access. The point-to-multipoint topology of EPONs requires a time-division multiple access MAC protocol for upstream transmission. In this paper, we propose a new enhanced dynamic bandwidth allocation algorithm with fairness called EFDBA for multiple services over EPONs. The proposed algorithm is composed of a fairness counter controller and a fairness system buffer in the optical line terminal. The EFDBA algorithm with fairness can provide increased capability and efficient resource allocation in an EPON system. In the proposed EFDBA algorithm, the optical line termination allocates bandwidth to the optical network units in proportion to the fairness weighting counter number associated with their class and queue length. The proposed algorithm provides efficient resource utilization by reducing the unused remaining bandwidth made by idle state optical network units.

• Journal of the Korean Society for information Management
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• v.17 no.2
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• pp.67-83
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• 2000

The tremendous growth in electronic journals made it clear that access would be one of the biggest issues confronting libraries seeking to adopt them. While users must be given the freedom to move seamlessly between electronic and paper journals, the most of university libraries in Korea have not provided a single point access to these yet. This study offers opportunities to improve the convenience which permits integrated access to the thousands of electronic and paper ones. It is suggested that the integrated catalog can be an appropriate solution that allows the one-stop shopping approach to library's entire collection.

• IEMEK Journal of Embedded Systems and Applications
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• v.15 no.3
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• pp.111-118
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• 2020

We investigate the optimization problem of transmit power control and MMSE Receiver filter for multi access points environment. Previous work showed that increasing the number of access points decreases the transmit power consumption. Accordingly, transmit power control algorithm was developed in such a way that the transmit power is minimized, while each terminal meets Signal to Interference and Noise Ratio Requirement. In this work, we further reduce the transmit power consumption by optimizing the transmit power level and the MMSE receiver filter together. We showed that the proposed joint optimization algorithm satisfies the necessary and sufficient conditions to be standard interference function, which guarantees convergence and minimum transmit power consumption. We observed that the proposed algorithm outperforms the algorithm which only optimizes the transmit power.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.8 no.12
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• pp.4293-4304
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• 2014

In order to ensure the wireless connectivity and seamless service to mobile users, the next generation network system will be an integration of multiple wireless access networks. In a heterogeneous wireless access system, bandwidth allocation becomes crucial for load balancing to avoid network congestion and improve system utilization efficiency. In this article, we propose a new dynamic bandwidth allocation scheme for hierarchical wireless network systems. First, we derive a multi-objective decision criterion for each access point. Second, a bargaining strategy selection algorithm is developed for the dynamic bandwidth re-allocation. Based on the intervenient Stackelberg game model, the proposed scheme effectively formulates the competitive interaction situation between several access points. The system performance of proposed scheme is evaluated by using extensive simulations. With a simulation study, it is confirmed that the proposed scheme can achieve better performance than other existing schemes under widely diverse network environments.

• Journal of the Institute of Convergence Signal Processing
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• v.16 no.3
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• pp.102-107
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• 2015

Personal information leakage is one of the great recent issues, which can be caused by hacking or censorship when a messenger program is used between user groups in Android-based smartphones, In order to solve these problems, companies generally apply complex security procedures inside the messenger, but which degrade the efficiency of work. This paper proposes a method which can improve work efficiency and strengthen security by allowing only the clients that can access a particular AP, and implementing a closed messenger group. The proposed method is validated by implementing on the Android-based smartphones.

• Journal of Korea Multimedia Society
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• v.12 no.11
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• pp.1521-1529
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• 2009

There is a serious unfairness problem between upstream and downstream flows of AP in IEEE 802.11 Wireless LAN. This problem is because Wireless LAN's DCF MAC protocol provides AP with equal channel access priority to mobile noded. Also, it makes this problem worse that the TCP's Data segment loss is more effective on throughput than the TCP's ACK segment. In this paper, we first make several simulations to analysis the unfairness in the various point of view and to find reasons of the unfairness. Also, this paper presents AP's scheduling scheme to alleviate the unfairness problem and evaluate the scheme through ns2 simulator.

• 한국정보통신설비학회:학술대회논문집
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• 2007.08a
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• pp.64-68
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• 2007

Commercial WiBro and 3G HSDPA services are launched last year in order to provide high speed wireless Internet access and multimedia service. Currently mobile communication service providers concentrate on the deployment of indoor mobile network since indoor traffic is remarkably increased. For fine indoor wireless communication, an installation of access point system via Public IP network which is called Femtocell is required. The development of indoor Femtocell system must be considered in the viewpoint of low hardware complexity, cost reduction, interlocking with WiBro/HSDPA network without change of network component and easy element management. In this paper, we review the implementation issue and technology of dual mode AP which provides WiBro and HSDPA signal to the user simultaneously. Especially, we describe on the HSDPA Femtocell standardization status and possible 3 types of HSDPA communication module development design. Furthermore we analyze the merits and demerits of each HSDPA Femtocell design type and propose a system which enables handover between indoor HSDPA Femtocell and outdoor commercial HSDPA mobile network.