• Journal of IKEEE
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• v.23 no.3
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• pp.941-946
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• 2019

In this paper, the author analyzed the PCI (Physical Cell Identification) allocation methods in the LTE (Long Term Evolution) SON (Self Organization Network) environment. A variety of techniques have been proposed for how to allocate PCI, and the LTE standard fundamentally explained that collision between a cell and neighbor cells arise while a cell assign the PCI. Therefore, in this paper, the author examined the scenarios of PCI collision, weak collision, and confusion proposed by LTE specification. In addition, the cell central approach and the distributed approach were discussed as solutions for each scenario. In this paper, the author reviewed the approach of graphic coloring technique which was studied recently and explained the strategy of central approach.

• Korean Management Science Review
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• v.26 no.1
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• pp.161-169
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• 2009

A traffic analysis on the Internet has an advantage for obtaining the characteristics of transferred packets. There were many studies to understand the characteristics of the Internet traffic with mathematical statistical approach. The approach of this study is different from previous studies. We first introduced a virtual network concept to present the Internet as a simplified mathematical model. It also represents each traffic flowing on the Internet as a parallel Gaussian channel on the virtual network. We suggest the optimal capacity of each parallel Gaussian channel using some related studies on the Gaussian channel model.

• ETRI Journal
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• v.29 no.2
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• pp.249-251
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• 2007

A novel idea is presented to locate intersections in a video sequence captured from a moving vehicle. More specifically, we propose a Bayesian network approach to combine evidence extracted from a video sequence and evidence from a database, maximizing evidence from various sensors in a systematic manner and locating intersections robustly.

• Journal of Internet Computing and Services
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• v.9 no.2
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• pp.61-68
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• 2008

Authentication for inter-NEMO rooming is on important issue for achieving the seamless mobile networking. In this proposal, the technical challenge lies in the fact that a visited network does not initially have the authentication credentials of a roaming mobile router. This paper proposes an efficient approach for providing AAA service in NEMO environment. This approach uses localized authentication based on the roaming agreement between ISPs. A public key certificate structure is proposed, tailored to the business model of wireless internet Service Providers (ISPs). In this approach, the mutual authentication between a visited network and a roaming user can be performed locally without any control with user's home network. In conclusion, our protocol shown that communication delay can be reduced by overuse 45% overhead in communication delay than the previous AAA approach.

• Journal of The Korean Association For Science Education
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• v.12 no.1
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• pp.93-101
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• 1992

The purposes of this study were; 1) to apply the network analysis to evaluation of students' laboratory reports, 2) to test the applicability of the systematic network analysis. For this purposes, 7th grade 88 students from 22 middle schools in Inchon city of Korea were selected and their laboratory reports were evaluated by a evaluation criterion network developed in this study. The evaluation criterion consisted of 4 categories and 10 subcategories. The results of this study suggested that the network analysis approach was suitable one for the evaluation of students' laboratory reports. This was supported by total score distribution, means/weight, Cronbach's ${\alpha}$ coefficient(0.70), and the subcategories' reliabilities. The resluts of the factor analysis indicated that the evaluation criterion network of this study had two factors.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.14 no.11
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• pp.4483-4501
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• 2020

Recent findings identified the scatter and shape of MFD (macroscopic fundamental diagram) is heavily influenced by the spatial distribution of link density in a road network. This implies that the concept of MFD can be utilized to divide a heterogeneous road network with different degrees of congestion into multiple homogeneous subnetworks. Considering the actual traffic data is usually incomplete and inaccurate while most traffic partition algorithms rely on the completeness of the data, we proposed a three-step partitioned algorithm called Iso-MB (Isoperimetric algorithm - Merging - Boundary adjustment) permitting of incompletely input data in this paper. The proposed algorithm was implemented and verified in a simulated urban transportation network. The existence of well-defined MFD in each subnetwork was revealed and discussed and the selection of stop parameter in the isoperimetric algorithm was explained and dissected. The effectiveness of the approach to the missing input data was also demonstrated and elaborated.

• Journal of Communications and Networks
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• v.12 no.1
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• pp.86-94
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• 2010

In this paper, we present a decentralized algorithm to find minimum cost quality of service (QoS) flow subgraphs in network coded multicast schemes. The main objective is to find minimum cost subgraphs that also satisfy user-specified QoS constraints, specifically with respect to rate and delay demands. We consider networks with multiple multicast sessions. Although earlier network coding algorithms in this area have demonstrated performance improvements in terms of QoS parameters, the proposed QoS network coding approach provides a framework that guarantees QoS constraints are actually met over the network.

• Journal of Satellite, Information and Communications
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• v.2 no.2
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• pp.85-91
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• 2007

The satellite networks provide global coverage. The integration of terrestrial networks with a satellite network is the most attractive approach to develop a global communication system. The IP Multimedia Subsystem (IMS) is intended to be the system that will merge the internet with the telecom world. A user with a dual-mode terminal can access both the satellite network and terrestrial network. The seamless handoff between two networks and a user's QoS level is the major issue concerning this integration. In this paper, we propose IMS-based satellite/terrestrial integrated network architecture for a global communication system. Based on the proposed architecture, an inter-network handoff and end-to-end soft QoS procedure is discussed. Our proposed soft QoS scheme is also analyzed to calculate the number of rejected calls.

• Journal of the Korean Geographical Society
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• v.44 no.2
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• pp.187-205
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• 2009

Failures on network components of a public transportation system can give rise to the severe degradation of entire system functionality. This paper aims at exploring how potential failures can affect the system flows and reliability of subway network systems in Metropolitan Seoul. To evaluate the range of impacts of disruptions, this research employs a probabilistic approach, network reliability. Network reliability measures the network resiliency and probability of flow loss under a variety of simulated disruptions of critical network components, transfer stations in subway system. By identifying the best and worst scenarios associated with geographical impact, as well as evaluating the criticality of transfer stations, this research presents some insights for protecting current subways systems.

• Management Science and Financial Engineering
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• v.6 no.2
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• pp.29-45
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• 2000

We consider the design of a two-level telecommunication network having logical full-mesh/star topology, with the implementation of conduit systems taken together. The design problem is then viewed as consisting of three subproblems: locating hub facilities, placing a conduit network, and installing cables therein to configure the logical full-mesh/star network. Without partitioning into subproblems as done in the conventional approach, the whole problem is directly dealt with in a single integrated framework, inspired by some recent successes with the approach. We successfully formulate the problem as a variant of the classical multicommodity flow model for the fixed charge network design problem, aided by network augmentation, judicious commodity definition, and some flow restrictions. With our optimal model, we solve some randomly generated sample problems by using CPLEX MIP program. From the computational experiments, it seems that our model can be applied to the practical problem effectively.