• ETRI Journal
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• v.37 no.5
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• pp.877-887
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• 2015

This paper is a first-hand summary on our comprehensive live trial of cellular-assisted device-to-device (D2D) communications currently being ratified by the standards community for next-generation mobile broadband networks. In our test implementation, we employ a full-featured 3GPP LTE network deployment and augment it with all necessary support to provide realtime D2D connectivity over emerging Wi-Fi-Direct (WFD) technology. As a result, our LTE-assisted WFD D2D system enjoys the required flexibility while meeting the existing standards in every feasible detail. Further, this paper provides an account on the extensive measurement campaign conducted with our implementation. The resulting real-world measurements from this campaign quantify the numerical effects of D2D functionality on the resultant system performance. Consequently, they shed light on the general applicability of LTE-assisted WFD solutions and associated operational ranges.

• Journal of Advanced Marine Engineering and Technology
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• v.37 no.2
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• pp.199-204
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• 2013

Marine data communications still look for a novel data communication system at sea because of the restriction of bandwidths and costs of current carriers. In order to make the most efficient use of the broadband land carriers at sea, this paper proposes a routing scheme (MCS-NTC) at a marine MANET model. The routing scheme optimizes the route by choosing optimal nodes and carriers among the traditional and land carriers based on normalized transmission characteristics of applications and carriers. The performance is compared with the max-win method (OMH-MW) scheme considering the specific values of transmission characteristics. The result shows that our scheme derives more efficient routes than the previous one in terms of the transmission characteristics such as bandwidth, cost, delay, the number of hops and carriers.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.38B no.10
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• pp.851-860
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• 2013

To overcome a scarcity of radio resources to mobile broadband service, the usage of TV white space gains much attraction around the world. This paper carries out an interference analysis either by performing realistic experiments or by executing statistical Monte-Carlo simulation to exploit interference probability. The results obtained from experiments are compared to those from simulations in order to clarify the coexistence of utilization of TV band devices (TVBD) in indoor circumstances. Along the execution of our experiment in the presence of DTV receiver, we apply to a variety of transmission parameters proposed in FCC for TVBD. According to experimental and simulation works, the allowable transmission powers of TVBD systems are exploited for the plausible which are coexist on the first as well as the second adjacent frequency bands. Throughout results, it can conclude that TVBD systems can be coexisted via achieving proper transmission powers depending on the locations of themselves without showing harmful interference to DTV reception.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.23 no.7
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• pp.761-767
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• 2012

In this paper, a novel ultra-wideband planar monopole antenna for the UHF communications and Digital-TV reception is proposed. The proposed antenna fed by a coplanar waveguide(CPW) is based on a triangular patch that has a broadband characteristic. To further increase the bandwidth of the triangular patch antenna, the top side of the regular triangular patch is loaded with a notch cut and each oblique side with a step. In addition, a slope is given to the ground plane of the CPW structure. Experimental results show that the -10 dB return loss bandwidth of the proposed antenna is 2,320 MHz from 480~2,800 MHz(5.83:1 bandwidth), which covers all the frequency bands of the various wireless communication systems and Digital TV broadcasting in the UHF band. Within the entire operating frequency range, the measured antenna gain in y-z plane(E-plane) varies from 3.01 to 4.71 dBi.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2011.10a
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• pp.237-240
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• 2011

Voice over Internet Protocol calls using administrative agency to build a national information and communication service, 'C' group, providers, the KT, SK Broadband, LG U+, Samsung SDS, as there are four operators. To prepare for an attack on Voice over Internet Protocol for administrative agency, security is a need for research to support the model. In this paper, the Internet telephone business of Administrative Agency to investigate and analyze the specific security measures to respond. Should set priorities around confidentiality about five security threats from NIS to Study of Voice over Internet Protocol Security Response Model for Administrative Agency. (1) Illegal wiretapping, (2) call interception, (3) service misuse, (4) denial of service attacks, (5) spam attacks, write about and analyze attack scenarios. In this paper, an analysis of protection by security threats and security breaches through a step-by-step system to address the research study is a step-by-step development of the corresponding model.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.12
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• pp.5601-5613
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• 2011

The purpose of this paper is to better understand the socio-economic differentials of Internet access and use. Data from '2008 Korean Internet usage behavior' were used to conduct logistic regression analysis. The findings show that there are significant socio-economic(age, gender, educational attainment, employment situation, and Internet access type) disparity in Internet access(Internet access at home, broadband Internet access). Also socio-economic variables enter in as statistically significant in most specifications for Internet use intensity (Intensive internet use, frequent internet use, less frequent internet use). The gender, household income and education attainment explanations for large differential in Internet use intensity are generally very similar. It is shown that age, education attainment and household income level cause a large digital divide on Internet service use(information use, communication and community use, e-commerce use, Internet banking use).

• Journal of the Korea Institute of Information and Communication Engineering
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• v.14 no.8
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• pp.1783-1791
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• 2010

Mobile WiMAX system provides broadband wireless access with a variety of services such as voice, video and data communications and providing QoS for each of these services become an important issue. In Mobile WiMAX system, it is important to allocate resources appropriately in order to support the efficient utilization of resources among various real-time and non real-time services. Although many packet scheduling schemes for real-time services in OFDMA system have been proposed, it need to be modified to apply to Mobile WiMAX system. Since Mobile WiMAX supports five types of service classes, QoS constraints of each class should be taken into consideration. In this paper, we propose an efficient packet scheduling scheme to support various services by considering the QoS constraints of each class.

• KIPS Transactions on Computer and Communication Systems
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• v.2 no.8
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• pp.357-368
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• 2013

Our society has evolved into a fully connected society in a mixed reality environment enabling various knowledge sharing / management / control / creation due to the expansion of broadband ICT infrastructure, smart devices, cloud services and social media services. Therefore cyber threats have increased with the convenience. The society of the future can cause more complex and subtle problems, if you do not have an effective response to cyber threats, due to fusion of logical space and physical space, organic connection of the smart object and the universalization of fully connected society. In this paper, we propose the strategy to build knowledge-base as the basis to actively respond to new cyber threats caused by future various environmental changes and the universalization of fully connected society.

• The Transactions of the Korea Information Processing Society
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• v.6 no.2
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• pp.385-395
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• 1999

Video-On-demand system provides electronic video rental services from remote video servers on a broadband communication networks. When we assume some situation that serve the same video stream by batching, each time single video stream became available at server-end side, we face the problem that what video stream to be scheduled at what time instant. Hence, in order to manage the resource bandwidth which is different at each stream, the policy of channel allocation became important factor. In this work, we proposed three type of scheduling policies with queueing, as are cumulative Waiting Time(CWT), Mean Waiting Time(MWT) and Predictable Popular Factor(PPF). While CWT policy is good for popular video, MWT policy was good for non-popular video. Also, we know that PPT policy has some fairness for average wait time and reneging rate of user requests.

• Journal of KIISE:Information Networking
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• v.36 no.4
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• pp.360-368
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• 2009

Recently, broadband access networks have been competitively deployed all over the world with the development of various multimedia services for such a network. ETRI(Electronics and Telecommunications Research Institute) built the FTTH(Fiber-To-the-Home) service center to develop a next-generation equipment and a high-quality service/platform as well as to promote domestic industry in the field of optical communication. The FTTH service center has a variety of test equipments such as FTTH standard testbed for a BMT(bench mark test), a network operation center, and IPTV service equipments. Also, ETRI deployed a new type of commercial optical access networks cooperating with ISP(Internet Service Provider). This paper presents the performance evaluation of FTTH E-PON(Ethernet Passive Optical Network) system as a platform for TPS(Triple Play Service) based on QoS(Quality of Service) and QoE(Quality of Expericence) issues. This FTTH E-PON system is successfully demonstrated as an optical access network system by commercial network service provider and the FTTH service center of ETRI.