• Journal of Internet Computing and Services
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• v.8 no.5
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• pp.21-33
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• 2007

An overlay network is a virtual network which is constructed on top of a physical computer network. A node in the overlay network is connected through virtual or logical links, where each link corresponds to a path of the links in the underlying physical network. Overlay networks are suitable for sharing heterogeneous resources in distributed environments, However, overlay networks are limited for achieving reliable communication that failure detection in overlay networks is a very important issue. In this paper, we review conditions of conventional failure detection and propose a new approach to failure detection and resilience which can be applied to HRing (Hierarchical Ring) overlay networks. The proposed method consists of the failure detection and the failure resilience phases. Because it utilizes the characteristics of the HRing overlay network for failure detection, it can reduce unnecessary network traffic and provide better scalability and flexibility. We also analyzed and evaluated the performance of the proposed approach through simulations.

• Convergence Security Journal
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• v.8 no.4
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• pp.51-56
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• 2008

A combination of VPNs and dial-up access, such as DSL and Cable, usually provides the cost-effective solution as the substitution of private networks on high-cost leased line. The business demand for high availability has increased with VPN spreading. This paper presents the schemes for a high availability of network access and a load balancing of network traffic in VPN gateways by using multiple links or multihoming capability based on active-active approach. The high availability and load balancing of network links can be achieved by duplicating external network access into multiple independent links. This can provide a continuous network connection to internal users even if one of the links is failed. Moreover, it can provide twice network bandwidth by distributing the traffic into the links. Static and dynamic algorithms are proposed as the load balancing algorithms.

• Proceedings of the Korea Information Processing Society Conference
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• 2019.10a
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• pp.697-700
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• 2019

무장데이터링크 시뮬레이션은 네트워크 기반 유도무기 모델링을 위하여 M&S 기술을 바탕으로 무장데이터링크의 운용성 및 정밀타격 성능을 검증하기 위한 시뮬레이션 소프트웨어다. 네트워크 기반 유도무기 모델은 원격임무통제를 위한 무장데이터링크망과 가상전장을 위한 시뮬레이션망이 연동하는 분산네트워크 환경에서 동작한다. 이때 유도탄모델 인터페이스는 다수의 프로토콜과 종속관계를 갖게 된다. 따라서 프로토콜이 수정될 때마다 유도탄모델 뿐만 아니라, 해당 인터페이스를 사용하는 다른 프로토콜도 수정되어야 한다. 또한 시뮬레이션 특성상 다양한 운용개념이 유도탄모델에 적용될 수 있다. 기존 고정표적 유도탄모델에 임무통제기능을 적용할 경우, 기존 모델이 훼손될 뿐만 아니라 기능 추가 및 삭제가 쉽지 않다는 문제가 있다. 본 논문은 서로 다른 프로토콜을 유도탄모델에 쉽게 적용하고 변경할 수 있는 프로토콜 변경용이성과 기 개발된 고정표적 유도탄모델을 변경하지 않고 무장데이터링크 운용 개념을 적용할 수 있는 유도탄모델 확장성을 위한 구조를 제안한다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.39B no.8
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• pp.491-498
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• 2014

Due to the ossification of current Internet, it is hard to accommodate new service requirements. One of the solutions to this problem is network virtualization. In this paper, we propose a heuristic virtual network embedding method for network virtualization. The proposed method checks whether the candidate substrate nodes in the substrate network have the possibility of satisfying virtual link requirements. It gives priority to the virtual nodes and the substrate nodes, and embeds the node with higher priority first. Also, the proposed method tries to cluster the mapped substrate nodes if possible. We evaluate the performance of the proposed method in terms of time complexity and virtual network acceptance rate.

• Journal of the Korean Institute of Telematics and Electronics S
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• v.36S no.3
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• pp.8-17
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• 1999

무선 ATM망에서 다수 연결채널로부터 발생되는 트래픽의 서비스 질을 보장하고 한정된 무선 자원을 효율적으로 사용하기 위해서는 다중접속제어 기술이 중요한 설계요소 중 하나이다. 본고에서는 ATM 프로토콜 특성을 무선 구간에 까지 확장한 동적다중슬롯할당(DMSA: Dynamic Multi-Slot Assignment)기법의 단점 중 하나인 연결채널별 지연 성능의 차이에 대해 분석하고, 이를 해결하기 위하여 이동국으로부터 각 연결채널에 대해 전달되는 정보를 이용하여 중앙제어국에 가상큐를 도입하는 방안을 제안한다. 중앙제어국에서는 구성된 가상큐룰 이용하여 상향링크의 다음 한 프레임내 모든 타임슬롯에 대한 연결채녈 할당을 수행한다. 다양한 트래픽 소스에 대한 시뮬레이션을 통해 가상큐-동적다중슬롯할당 알고리즘이 기존의 동적다중슬롯할당 알고리즘에 비해 중앙제어국에서의 단순한 제어 부하만으로도 다수의 연결채널에 대해 균등한 설비스 질을 보장하고 지연 변이 특성의 성능 향상을 나타냄을 입증한다. 이러한 연구결과는 동종 혹은 이종의 트래픽을 가진 각 연결 채널에 대해 무선 구간의 분산 환경으로 인해 발생할 수 있는 불평등성을 해결함으로써 무선 ATM의 개념을 우선 ATM과 유사한 환경으로 분석할 수 있는 계기를 마련한 것으로 판단된다.

• Journal of the Korean Society for information Management
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• v.34 no.3
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• pp.7-21
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• 2017

This study analyzed the methods for representing and linking personal information in the linked data of National Library of Korea and provided suggestions for expanding the scope of identifying and linking of the personal information. As a result, the personal information as a subject has been dealt with a concept, where the personal information as a contributor has been linked with a vocabulary of personal name. In addition, there have not been assured of including additional information except existing authority data in the process of building the linked data. Therefore, this study suggested that linking personal information as a subject and personal information as a contributor was essential for the quality of linked data. In addition, we proposed to provide additional information related to the person in linked data for expanding the scope of access points in information discovery.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.42 no.1
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• pp.77-87
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• 2017

Even though current LTE/LTE-A mobile networks provide enough high data rate and low latency to support conventional wireless services, to support ultra-low delay services, such as virtual reality and remote control, in the next generation mobile communication network, it is required to provide very low delay about several ms. However, in the uplink transmission of the LTE/LTE-A system, the process of scheduling grant is required to obtain uplink resources for uplink transmission from the eNB. The process of granting uplink resources from eNB brings additional fixed latency, which is one of the critical obstacles to achieve low delay in uplink transmissions. Thus, in this paper, we propose a novel uplink transmission scheme called Cut-in uplink transmission, to reduce uplink latency. We provide the performance of the proposed uplink transmission scheme through simulations and show the proposed uplink transmission scheme provides lower uplink transmission delay than conventional uplink transmission scheme in LTE/LTE-A mobile networks.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.38 no.6
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• pp.941-947
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• 2018

Station transfers for smart card based railway networks refer to transfer pedestrian movements that occur at the origin and destination nodes rather than at a middle station. To calculate the optimum path for the railway network, a penalty for transfer pedestrian movement must be included in addition to the cost of within-car transit time. However, the existing link label-based path searching method is constructed so that the station transfer penalty between two links is detected. As such, station transfer penalties that appear at the origin and destination stations are not adequately reflected, limiting the effectiveness of the model. A ghost node may be introduced to expand the network, to make up for the station transfer penalty, but has a pitfall in that the link label-based path algorithm will not hold up effectively. This research proposes an optimal path search algorithm to reflect station transfer penalties without resorting to enlargement of the existing network. To achieve this, a method for applying a directline transfer penalty by comparing Ticket Gate ID and the line of the link is proposed.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.41 no.12
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• pp.1793-1800
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• 2016

Network virtualization is considered as an enabling technology to accomodate recently introduced new services such as cloud services and data center networks on top of the existing network environment. In this paper, an efficient virtual network mapping method is proposed which takes account of the location and resource requirements of virtual nodes and the bandwidth requirements of virtual links. The proposed method sets bandwidth as the priority metric for network mapping, and searches for a set of substrate nodes and paths that houses the virtual nodes and virtual links. Through the simulation experiments, it is verified that the proposed method provides better cost to revenue ratio and fast experiment time without degrading success rate of virtual network mapping.

• Digital Contents
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• no.1 s.68
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• pp.52-58
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• 1999

지금까지 우리는 북극에 가상의 비행기를 띄우기 위해 컴튼의 대화식 백과사전의 일부인 Compton's Interactive World Atlas를 사용했다. 하이퍼 링크를 활용하고 버튼을 눌러 텍스트를 불러오고 전체적으로 변화무쌍한 방식으로 연구를 수행하면서, 우리는 폴리니나 디드로 같은 백과사전의 원조들이 최신의 화려한 멀티미디어 백과사전을 본다면 어떤 생각을 할 것인지 궁금해하지 않을 수가 없다.