• Nuclear Engineering and Technology
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• 제53권2호
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• pp.357-367
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• 2021

In general, common cause failures (CCFs) have been modeled with the assumption that components within the same group are symmetric. This assumption reduces the number of parameters required for the CCF probability estimation and allows us to use a parametric model, such as the alpha factor model. Although there are various asymmetric conditions in nuclear power plants (NPPs) to be addressed, the traditional CCF models are limited to symmetric conditions. Therefore, this paper proposes the copulabased CCF model to deal with asymmetric as well as symmetric CCFs. Once a joint distribution between the components is constructed using copulas, the proposed model is able to provide the probability of common cause basic events (CCBEs) by formulating a system of equations without symmetry assumptions. In addition, Bayesian inferences for the parameters of the marginal and copula distributions are introduced and Markov Chain Monte Carlo (MCMC) algorithms are employed to sample from the posterior distribution. Three example cases using simulated data, including asymmetry conditions in total failure probabilities and/or dependencies, are illustrated. Consequently, the copula-based CCF model provides appropriate estimates of CCFs for asymmetric conditions. This paper also discusses the limitations and notes on the proposed method.

• Journal of Power Electronics
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• 제15권3호
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• pp.712-720
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• 2015

A model predictive current control (MPCC) method that does not employ a cost function is proposed. The MPCC method can decrease common-mode voltages in loads fed by three-phase voltage-source inverters. Only non-zero-voltage vectors are considered as finite control elements to regulate load currents and decrease common-mode voltages. Furthermore, the three-phase future reference voltage vector is calculated on the basis of an inverse dynamics model, and the location of the one-step future voltage vector is determined at every sampling period. Given this location, a non-zero optimal future voltage vector is directly determined without repeatedly calculating the cost values obtained by each voltage vector through a cost function. Without utilizing the zero-voltage vectors, the proposed MPCC method can restrict the common-mode voltage within ± V_dc/6, whereas the common-mode voltages of the conventional MPCC method vary within ± V_dc/2. The performance of the proposed method with the reduced common-mode voltage and no cost function is evaluated in terms of the total harmonic distortions and current errors of the load currents. Simulation and experimental results are presented to verify the effectiveness of the proposed method operated without a cost function, which can reduce the common-mode voltage.

• 대한교통학회지
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• 제18권2호
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• pp.63-71
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• 2000

로짓경로선택모형의 문제점으로 지적되고 있는 순환교통류(cyclic flow)와 경로중복(path overlapping)은 노드중복(common nodes)과 링크중복(common links)문제로 해석할 수 있다. 노드중복은 최단경로 보장문제 및 균형배정시 효율성 문제와, 링크중복은 비관련대안의 독립성 문제와 관련된다. 최근 위 문제들에 대한 연구가 각각 이루어지고 있으나, 두 가지 문제를 모두 고려한 연구나 이런 경우 로짓모형의 속성을 비교한 연구는 없었다. 이 글에서는 노드중복과 링크중복을 고려한 경우와 그렇지 않은 경우의 선택확률을 비교하여 현재 이용되고 있는 로짓경로선택모형의 문제점과 한계를 살펴보았다. 이를 위하여 본 연구에서는 노드중복문제와 링크중복문제를 동시에 고려한 로짓경로선택모형을 제시하였다. 이는 기존의 링크중복개념을 특정링크를 기준으로 통행기점에서 특정링크의 초기노드가지의 링크중복과 특정링크 종점노드부터 통행종점가지의 링크중복으로 세분화한 것이라고 할 수 있다. 제시된 모형을 이용하여 가상네트워크에서 경로 및 링크선택확률을 계산한 결과, 노드 중복과 링크중복을 고려함으로써 선택대안들간의 차별성을 고려하면서 특정경로 또는 특정링크의 선택확률이 과소 또는 과대추정되는 문제를 감소시킬 수 있었다. 이러한 결과를 통해 중복경로와 순환경로를 배제한 다중경로를 보다 효과적으로 도출할 수 있을 것으로 기대된다.

• 한국IT서비스학회지
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• 제12권3호
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• pp.311-321
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• 2013

In the community of software engineering, diverse modeling languages are used for representing all relevant information in the form of models. Also many different models such as business model, business process model, product models, interface models etc. are generated through software life cycles. In this situation, models need to be integrated for enterprise integration and enhancement of software productivity. Researchers propose rebuilding models by a specific modeling language, using a intemediate modeling language and using common reference for model integration. However, in the current approach it requires a lot of cost and time to integrate models. Also it is difficult to identify common objects from several models and to update objects in the repository of common model objects. This paper proposes software model integration using metadata model based on Linked data. We verify the effectiveness of the proposed approach through a case study.

• Journal of the Korean Data and Information Science Society
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• 제16권4호
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• pp.791-799
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• 2005

We consider two components parallel system in which the lifetimes have the bivariate Pareto model with bivariate random censored data. We assume that bivariate Pareto model is affected by common stress which is independent of the lifetimes of the components. We obtain estimators for the system reliability based on likelihood function and relative frequency. Also we construct approximated confidence intervals for the reliability based on maximum likelihood estimator and relative frequency estimator, respectively. Finally we present a numerical study.

• 한국컴퓨터정보학회논문지
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• 제21권1호
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• pp.115-123
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• 2016

In this study, we collect various side effect pairs which are appeared frequently at many drugs, and select side effect pairs that have higher severity. For every selected side effect pair, we extract common genetic networks which are shared by side effects' genes and drugs' target genes based on PPI(Protein-Protein Interaction) network. For this work, firstly, we gather drug related data, side effect data and PPI data. Secondly, for extracting common genetic network, we find shortest paths between drug target genes and side effect genes based on PPI network, and integrate these shortest paths. Thirdly, we develop a classification model which uses this common genetic network as a classifier. We calculate similarity score between the common genetic network and genetic network of a drug for classifying the drug. Lastly, we validate our classification model by means of AUC(Area Under the Curve) value.

• 한국추진공학회지
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• 제24권5호
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• pp.56-64
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• 2020

29.7% 축소 NASA 표준 연구 모형에 대하여 소형 저속 풍동에서 시험을 수행하였다. 풍동시험 모형은 NASA Langley 연구소와 AIAA 항력추정 워크숍 위원회의 지침에 따라 알루미늄으로 제작하였다. 풍동의 능력 한계 등으로 상대적으로 낮은 레이놀즈수인 0.3 × 10⁶ 에서 정적 힘과 모멘트를 측정하였다. 세 가지 타입(핀 스팅, 블레이드 스팅, 벨리 스팅) 모형지지부에 대하여 피칭모멘트를 비교하였다. 보정된 벨리 스팅과 핀 스팅에 의한 피칭모멘트 보정량은 비슷하였으며 블레이드 스팅에 의한 피칭모멘트 값이 가장 적었다.

• Journal of information and communication convergence engineering
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• 제9권6호
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• pp.712-720
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• 2011

Radio frequency identification (RFID) is an established technology and has the potential, in a variety of applications, to significantly reduce cost and improve performance. As RFID-enabled applications will fulfill similar tasks across a range of processes adapted to use the data gained from RFID tags, they can be considered as software products derived from a common infrastructure and assets that capture specific ions in the domain. This paper discusses a framework that supports the development of RFID-enabled applications based on a business process family model (BPFM), explicitly representing both commonalities and variabilities. To develop this framework, common activities are identified from RFID-enabled applications and the variabilities in the common activities are analyzed in detail using variation point concepts. Through this framework, RFID data is preprocessed, and thus, RFID-enabled applications can be developed without having to process RFID data. Sharing a common model and reusing assets to deploy recurrent services may be considered an advantage in terms of economic significance and the overall product quality afforded.

• 한국소음진동공학회논문집
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• 제19권5호
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• pp.499-508
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• 2009

This paper focuses on the modelling of common rail diesel injector using the AMESim code and shows the appropriateness of the developed model. For the developed injector model, simulations are carried out to analyze the behavior characteristics of the injector for the variations of injector model parameters such as orifice diameters, rail pressures, and energizing times. Simulation results show that the diameters of inlet and outlet orifices have close relation with injection quantity. Increment of rail pressure and energizing time provides increment of injection quantity, and simulated energizing time map shows injection characteristics of the common rail injector.

• 제어로봇시스템학회논문지
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• 제17권9호
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• pp.851-856
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• 2011

In this paper, the fuzzy output-feedback controller is addressed for a discrete-time nonlinear interconnected systems with common input. The nonlinear interconnected system is represented by a T-S (Takagi-Sugeno) fuzzy model. Based on T-S fuzzy interconnected system, the fuzzy output-feedback controller is designed with common input. The stability condition of the closed-loop system is represented to the LMI (Linear Matrix Inequality) form. PEMFC model is given to show the verification of the controller discussed throughout the paper.