• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.9
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• pp.6305-6314
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• 2015

This study presents numerical simulations of mean flow and turbulence structure of an open channel with submerged vegetation. Filtered Navier-Stokes equations are solved using large-eddy simulation (LES). The immersed boundary method (IBM) is employed based on a Cartesian grid. The numerical result is compared with experimental data of Liu et al. (2008) and shows that simulated results coincided reasonably with experimental data within the average error of 10%. Strong vortices are generated at the interface between vegetated and non-vegetated regions with spanwise extent. The generation of turbulence induced by shear at the interface is interfered with wake turbulence, resulting turbulence intensity maximum. Turbulence produced by shear affects the flow in vegetated region and the penetration depth increases with an increase in the submergence ratio. This result can be used to understand sediment transport mechanisms in the vegetated region.

• Journal of the Korea Society of Computer and Information
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• v.6 no.4
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• pp.74-84
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• 2001

In the current Internet, InteServ model based on Resource reSerVation Protocol (RSVP), DiffServ Model based on service differentiation according to per hope behavior(PHB) and traffic engineering policy, and two-tire model of above mentioned two models which are adapted differently as the target network status for providing the end-to-end QoS Path are suggested. But, when we integrated this internet QoS into the ATM based network, differences of the connection setup procedure, name/address translation methods, and QoS provisioning mechanisms for end-to-end path setup procedures are introduced. In this paper, we propose the method of shortcut based QoS path setup procedure to solve these problems, and to guarantee the integration and scalability of Next Generation Internet(NGI) names/address in Integrated IP network into ATM based network. This network should support the engineering differentiated into the multiple service classes, which depend on established by this path is designed suitably into the target router and host step by step. In the near future, this function which provide the QoS guaranteed path based on end-to-end shortcut between the configuration devices are extended into the NGI target network.

• The Journal of the Korea Contents Association
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• v.11 no.12
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• pp.570-577
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• 2011

In this paper, Policy-based QoS in 3GPP service network management techniques are not applied to the DiffServ technology is applied to the first interpretation. The next PBNM and DiffServ associated technologies by applying QoS performance improvement is verified. In this case that PBNM and DiffServ technology is applied, the amount of voice traffic reduced about 1 msec while best-effort traffic occurs 75 percent of the output link capacity. Also, video traffic which is the same as data traffic showed a decreased $0\sim10^{-4}$ packet loss rate than the case that DiffServ technology is applied. We apply the appropriate policy PBNM and DiffServ QoS mechanisms of the existing set of policies is not affected, just by using the appropriate 3GPP Service QoS level to suit the network operation, management can do that was found. This analytical method based on the University of California at Berkeley through NS-2 DiffServ technology into existing systems and next-generation networks mandated PBNM and DiffServ technology is applied to performance evaluation for the case.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.5B
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• pp.378-389
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• 2006

An IP address lookup scheme has become a critical issue increasingly for high-speed networking techniques due to the advent of IPv6 based on 128bit. In this paper, a novel global IPv6 unicast address lookup scheme is proposed for next generation internet routers. The proposed scheme perform a variable multiple hashing based on prefix grouping. Accordingly, it should not only minimize overflows with the proper number of memory modules, but also reduce a memory size required to organize forwarding tables. It has the fast building and searching mechanisms for forwarding tables during only a single memory access. Besides, it is easy to update forwarding tables incrementally. In the simulation using CERNET routing data as a 6bone test phase, we compared the proposed scheme with a similar scheme using a uniform multiple hashing. As a result, we verified that the number of overflows is reduced by 50% and the size of memory for forwarding tables is shrunken by 15% with 8 tables.

• Journal of Internet Computing and Services
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• v.7 no.1
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• pp.121-130
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• 2006

In next generation wireless networks, an application must be capable of rating service information in real-time and prior to initiation of the service it is necessary to check whether the end user's account provides coverage for the requested service. However, to provide prepaid services effectively, credit-control should have minimal latency. In an endeavor to support real-time credit-control for Mobile IPv6 (MIPv6), we design an implementation architecture model of credit-control authorization. The proposed integrated model combines a typical credit-control authorization procedure into the MIPv6 authentication procedure. We implement it on a single server for minimal latency. Thus, the server can perform credit-control authorization and MIPv6 authentication simultaneously. Implementation details are described as software blocks and units. In order to verify the feasibility of the proposed model. latency of credit-control authorization is measured according to various Extensible Authentication Protocol (EAP) authentication mechanisms. The performance results indicate that the proposed approach has considerably low latency compared with the existing separated models, in which credit-control authorization is separated from the MIPv6 authentication.

• Economic and Environmental Geology
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• v.45 no.2
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• pp.195-204
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• 2012

Biomineralization has been explored for geochemical cycles and microbial tolerance mechanisms to metal toxicity. Here, we are introducing NanoFermentation which enables economic, environmentally friendly, requiring low input energy, and scalable manufacturing of nano-dimensioned magnetite. We are also focusing on controlling factors of crystallite size which can determine superparamagnetism and ferrimagnetism. Controlling factors are such as microbial species, temperature, incubation time, medium composition, substituted elements and their concentration, precursor type, reaction volume, precursor concentration density and their combinations. Crystallite size distribution of biomagnetite depends on the balance between nuclei generation and crystal growth. Biomineralization will elucidate elemental cycles on earth crust and microbial ecology as well as it will be applied to material sciences and devices via massive production of nanomaterials.

• Journal of Korea Multimedia Society
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• v.8 no.7
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• pp.974-987
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• 2005

As the ad hoc networks have been received a great deal of attention to not only the military but also the industry applications, some security mechanisms are required for implementing a practical ad hoc application. In this paper, we propose a security architecture in ad hoc networks for the purpose of supporting ID-based public key cryptosystems because of the advantage that ID-based schemes require less complex infrastructure compared with the traditional public key cryptosystems. We assume a trusted key generation center which only issues a private key derived from IDs of every nodes in the system setup phase, and use NIL(Node ID List) and NRL(Node Revocation List) in order to distribute the information about IDs used as public keys in our system. Furthermore, we propose a collaborative status checking mechanism that is performed by nodes themselves not by a central server in ad-hoc network to check the validity of the IDs.

• Journal of KIISE:Computing Practices and Letters
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• v.12 no.3
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• pp.183-191
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• 2006

As genetic research is getting more active, data construction of genes are needed in the field of biology. Therefore, Gene Ontology Consortium has constructed genetic information by OWL, which is Ontology description language published by W3C. However, previous browsers for Gene Ontology only support simple searching mechanisms based on keyword, tree, and graph, but it is not able to search high quality information considering various relationships. In this paper, we suggest browsing technique which integratesvarious searching methods to support researchers who are doing actually experiment in biology field. Also, instead of typing a query, we propose querv generation technique which constructs query while browsing and query translation technique which translate generated query into SeRQL query It is convenient for user and enables user to obtain high quality information. And by this GO Guide browser, it has been shown that the information of Gene Ontology could be used efficiently.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.7A
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• pp.659-665
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• 2006

When using the Mobile IP which is the representative technology to secure the mobility in general IP networks, the packet loss during the handover is inescapable. To remedy the packet loss problem, the smooth handover was introduced. However, the smooth handover causes the packets sequence disruption during the packet forwarding procedure and it may result in the degradation of the network performance. The same problem also occurs in the WiBro (High-speed Portable Internet) system that is the next generation portable IP service system. The WiBro system, which provides the high speed data service just like xDSL and leased line in wired internet, aims to guarantee the portability, mobility, and the differentiated service based on IEEE 802.16. So, the handover mechanisms that solve the problems of packet loss and packet sequence distribution are required in the WiBro system. In this paper, we propose the handover mechanism and the packet sequence control algorithm that provide the reliability and the differentiated service for the unicast service in the WiBro system.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.9
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• pp.4492-4497
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• 2013

An important features of next-generation wireless networks will be heterogeneous environment in which a mobile terminal will be able to connect to multiple radio access networks and network selection mechanisms play an important role in ensuring QoS for users in this environment. In this paper, our study is concerned with an extension of the well known AHP to the group decision making methods. The users requested specific QoS divide into a group and the access networks with similar characteristics split into a group. Between each group, the one group is selected and within that group, the best access networks will be assigned according to priority order by network selection algorithm. The experimental results of MATLAB simulation show that the every user in each services can select the same network with decision value as large as 0.9. Consequently, the proposed network selection mechanism is more effective than conventional one in integrated UMTS and WLAN networks.