• 한국시뮬레이션학회논문지
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• 제10권2호
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• pp.61-74
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• 2001

The reliability evaluation of the large scale network becomes very complicate according to the growing size of network. Moreover if the reliability is not constant but follows probability distribution function, it is almost impossible to compute them in theory. This paper studies the network evaluation methods in order to overcome such difficulties. For this an efficient path set algorithm which seeks the path set connecting the start and terminal nodes efficiently is developed. Also, various variance reduction techniques are applied to compute the system reliability to enhance the simulation performance. As a numerical example, a large scale network is given. The comparisons of the path set algorithm and the variance reduction techniques are discussed.

• 디지털콘텐츠학회 논문지
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• 제6권1호
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• pp.7-12
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• 2005

논문은 IEEE 표준인 SCI(Scalable Coherent Interface)에 근거한 degree 2의 ICR(Interleaved Cyclic Ring) 네트워크의 신뢰도를 연구하였고 대표적인 링 네트워크들과 비교하였다. ICR 네트워크의 신뢰도 연구에 있어서 두 노드가 동시에 통신 할 수 있는 신뢰도를 계산하였다. ICR 네트워크의 신뢰도 연구에서 실패율(failure rate)의 변화에 신뢰도의 반응을 연구하였고 적은 노드에 대하여 정확한 신뢰도를 구하고 노드 수가 증가한 경우에는 최대 최소 경계를 계산하여 평균치 일반식을 구하였다. ICR 네트워크의 사이클의 변화에 따라 ICR 네트워크의 신뢰도를 다른 링 네트워크와 비교하였다.

• 품질경영학회지
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• 제10권2호
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• pp.18-24
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• 1982

This paper estimates the reliability & mean time to failure (MTIF) of a cyclic or acyclic network system by the Monte-Carlo simulation method. Estimates of MTTF and Reliability become difficult as the complexity of a system increases. The method in this paper finds all simple paths from the given network, and then simulates the reliability of the required time and MTFF by using these paths. Life-times of the components in a network follow some probability distributions (Exponential, Weibull, Normal, Lognormal, etc.). The method, written in Level II. Basic Language, is validated for some simple examples and then estimates the reliability and MTFF of some cyclic network system.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제10권8호
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• pp.3602-3620
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• 2016

Dynamic topology is one of the main influence factors on network performability. However, it was always ignored by the traditional network performability assessment methods when analyzing large-scale mobile ad hoc networks (MANETs) because of the state explosion problem. In this paper, we address this problem from the perspective of complex network. A two-layer hierarchical modeling approach is proposed for MANETs performability assessment, which can take both the dynamic topology and multi-state nodes into consideration. The lower level is described by Markov reward chains (MRC) to capture the multiple states of the nodes. The upper level is modeled as a small-world network to capture the characteristic path length based on different mobility and propagation models. The hierarchical model can promote the MRC of nodes into a state matrix of the whole network, which can avoid the state explosion in large-scale networks assessment from the perspective of complex network. Through the contrast experiments with OPNET simulation based on specific cases, the method proposed in this paper shows satisfactory performance on accuracy and efficiency.

• 한국측량학회지
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• 제28권6호
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• pp.587-594
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• 2010

측지망은 측량작업과 조정계산의 기준으로써 그 구성이 측량성과의 품질에 많은 영향을 미침에도 불구하고 대부분의 측지망 설계는 경험적 또는 단순한 기하학적 강도만을 기준으로 설계되어진다. 본 논문은 해석적 기법에 의한 측지망의 최적화 설계를 위하여 측지망의 품질을 평가하기 위한 다양한 기준을 분석하고 제시하기 위한 것으로써 측지망 품질평가 기준으로 정밀도(오자타원, 2DRMS, CEP), 신뢰성(내적신뢰성) 및 견인성(최대전단변형률, 주변형률, 면적변형률)을 제시하고 이를 실제 측지망의 설계에 적용함으로써 그 효용성을 평가하였다. 기관측된 실제 측지망에 8가지 품질평가 인자를 적용하여 측지망 최적화 설계의 효용성을 평가한 결과, 최적화 설계 전 후 품질평가 인자는 평균값에 있어서 정밀도는 2%, 신뢰성은 3%, 견인성은 3,001%로 향상되었으며, 최대값에 있어서 정밀도는 5% 신뢰성은 7%, 견인성은 16,957% 향상된 것으로 분석되었다.

• 한국건축시공학회지
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• 제14권1호
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• pp.102-109
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• 2014

The purpose of this study is to analyze collaborative relationship between members of a building construction organization. For the analysis of collaborative relationship, this researcher collected data by conducting a questionnaire survey with members of three large building construction organizations for apartment housing. The analyzed contents of collaborative relationship were the 'frequency of communication between organizational members' and their 'reliability'. According to the analysis of communication network, construction managers had low frequency of communication, whereas those responsible for each area, like construction deputy managers, had high frequency of communication. It indicates that middle managers are at the center of communication related to construction work in construction organizations. According to the analysis of reliability network, construction managers showed highest reliability, and employees at the top level in an organizational map also showed high reliability. Since they generally have a lot of experience, are some older of age, and assume responsibility for work, they are considered to receive reliability from other organizational members. This study proved that it was possible to numerically express reliability of organizational members, which is an abstract concept, and analyze it. Therefore, it is expected that the analysis result will highly be likely to be used in the area of construction management.

• ETRI Journal
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• 제41권2호
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• pp.207-223
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• 2019

Network function virtualization can significantly improve the flexibility and effectiveness of network appliances via a mapping process called service function chaining. However, the failure of any single virtualized network function causes the breakdown of the entire chain, which results in resource wastage, delays, and significant data loss. Redundancy can be used to protect network appliances; however, when failures occur, it may significantly degrade network efficiency. In addition, it is difficult to efficiently map the primary and backups to optimize the management cost and service reliability without violating the capacity, delay, and reliability constraints, which is referred to as the reliability-aware service chaining mapping problem. In this paper, a mixed integer linear programming formulation is provided to address this problem along with a novel online algorithm that adopts the joint protection redundancy model and novel backup selection scheme. The results show that the proposed algorithm can significantly improve the request acceptance ratio and reduce the consumption of physical resources compared to existing backup algorithms.

• ETRI Journal
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• 제44권1호
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• pp.155-167
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• 2022

The Internet of Things (IoT) is a new paradigm that connects physical and virtual objects from various domains such as home automation, industrial processes, human health, and monitoring. IoT sensors receive information from their environment and forward it to their neighboring nodes. However, the large amounts of exchanged data are vulnerable to attacks that reduce the network performance. Most of the previous security methods for IoT have neglected the energy consumption of IoT, thereby affecting the performance and reducing the network lifetime. This paper presents a new multistep routing protocol based on cellular learning automata. The network lifetime is improved by a performance-based adaptive reward and fine parameters. Nodes can vote on the reliability of their neighbors, achieving network reliability and a reasonable level of security. Overall, the proposed method balances the security and reliability with the energy consumption of the network.

• 한국전자통신학회논문지
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• 제9권6호
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• pp.657-664
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• 2014

본 연구는 SNS 이용자들을 대상으로 이용동기를 분석하여, 각 이용동기의 중간값을 기준으로 상, 중, 하로 구분하고, 정보교류, 네트워크 밀도, 정보신뢰도, 유대인식의 차이를 알아보았다. 소셜 네트워크 이용 동기는 정보추구 동기, 사회적 영향동기, 오락적 동기, 네트워크 형성동기로 나타났다. 이러한 이용동기 수준에 따라 종속변인으로 설정한 정보교류 정도, 네트워크 밀도, 정보신뢰도, 유대인식에 차이가 나타났다. 특히 정보교류 정도와 정보의 신뢰성은 4가지 동기 수준에 따라 차이가 나타났으며, 네트워크 밀도와 유대인식의 차이는 사회적 영향 동기 수준에 따라 차이가 나타났다.

• 한국지진공학회:학술대회논문집
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• 한국지진공학회 2003년도 추계 학술발표회논문집
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• pp.66-73
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• 2003

The technique for the seismic reliability evaluation of the electric power network is presented. In the previous study, the state of the substations was represented by the bi-state which is classified as failure or survival. However, the hi-state model can result in oversimplified analysis, because substations are worked by the parallel operating system. In this paper, Considering the characteristics of the parallel operating system, the damage of the substation is expressed by the multi-state for the more realistic seismic reliability evaluation. Using Monte-Carlo simulation method, the seismic reliability for Korean 345㎸ electric power network is evaluated. Analysis results show that reliability levels of the network by the multi-state analysis is higher than that by the hi-state analysis and the electric power network in southeastern area of the Korean Peninsular may be vulnerable to earthquakes.