• Communications for Statistical Applications and Methods
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• 제27권5호
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• pp.523-533
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• 2020

This paper suggests three available methods for finding nonnegative estimates of variance components of the random effects in mixed models. The three proposed methods based on the concepts of projections are called projection method I, II, and III. Each method derives sums of squares uniquely based on its own method of projections. All the sums of squares in quadratic forms are calculated as the squared lengths of projections of an observation vector; therefore, there is discussion on the decomposition of the observation vector into the sum of orthogonal projections for establishing a projection model. The projection model in matrix form is constructed by ascertaining the orthogonal projections defined on vector subspaces. Nonnegative estimates are then obtained by the projection model where all the coefficient matrices of the effects in the model are orthogonal to each other. Each method provides its own system of linear equations in a different way for the estimation of variance components; however, the estimates are given as the same regardless of the methods, whichever is used. Hartley's synthesis is used as a method for finding the coefficients of variance components.

• 한국정보과학회논문지:소프트웨어및응용
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• 제30권5_6호
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• pp.414-429
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• 2003

시스템 개발 시 복잡성을 감소시키고 개발 비용과 기간을 단축하기 위하여 컴포넌트 기반 개발(CBD)이 산업계에서 보편화 되고 있다. 그러나, 현재 대표적인 CBD는 한 회사나 하나의 어플리케이tus에 의존적인 컴포넌트를 개발하고 있다[1,2]. 따라서 어떤 도메인의 여러 패밀리에서 컴포넌트를 재사용하기 위한 컴포넌트 가변성이 강조 되고 있다. 하지만, 컴포넌트 가변성의 정의나 유형에 대해 구체적으로 제시된 연구가 미흡하여, 컴포넌트의 주 목적인 재사용 측면보다. 유지보수 목적의 컴포넌트가 개발되고 있다[3]. 본 논문에서는 컴포넌트의 재사용성을 높이기 위하여, 컴포넌트 특징을 반영한 컴포넌트 가변성을 정형적으로 정의한다. 또한, 기존의 컴포넌트 가변성으로 인식된 논리 가변성을 명확하게 정의하고, 추가로 3가지 가변성 유형을 제시함으로써, 컴포넌트에서 존재하는 모든 가변성 유형을 제시한다. 컴포넌트 커스터마이제이션시에 가변성의 경우의 수를 예측, 확인 할 수 있는 컴포넌트 가변성 Scope를 제시한다. 컴포넌트 개발에 있어서 이러한 기법을 적용함으로써, 여러 패밀리 멤버에서 재사용 할 수 있는 고품질의 컴포넌트 개발을 지원 할 수 있다.

• Journal of the Korean Data and Information Science Society
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• 제6권2호
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• pp.1-7
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• 1995

This paper considers the reliability estimation of a two-component shared-load system based on Freund model. Maximum likelihood estimator, order restricted maximum likelihood estimator and uniformly minimum variance unbiased estimator of the reliability function for the system are obtained. Performance of three estimators for moderate sample sizes is studied by simulation.

• 대한인간공학회지
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• 제19권3호
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• pp.23-37
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• 2000

Usability is one of the most important factors that affect customers' decision to purchase a product. Several studies have been conducted to model the relationship between the product design variables and the product usability. Since there could be hundreds of design variables to be considered in the model, a variable screening method is required. Traditional variable screening methods are based on expert opinions (Expert screening) in most Kansei engineering studies. Suggested in this study are statistical methods for screening important design variables by using the principal component regression(PCR), cluster analysis, and partial least squares(PLS) method. Product variables with high effect (PCR screening and PLS screening) or representative variables (Cluster screening) can be used to model the usability. Proposed variable screening methods are used to model the usability for 36 audio/visual products. The three analysis methods (PCR, Cluster, and PLS) show better model performance than the Expert screening in terms of $R^2$, the number of variables in the model, and PRESS. It is expected that these methods can be used for screening the product design variables efficiently.

• Structural Engineering and Mechanics
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• 제89권1호
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• pp.77-91
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• 2024

During strong seismic events, inelastic shear deformation occurs in beam-column joints. To capture inelastic shear deformation, an analytical model for beam-column joint in reinforced concrete (RC) frame structures has been proposed in this study. The proposed model has been developed using a rotational spring and rigid links. The stiffness properties of the rotational spring element have been assigned in terms of a moment rotation curve developed from the shear stress-strain backbone curve. The inelastic rotation behavior of joint has been categorized in three stages viz. cracking, yielding and ultimate. The joint shear stress and strain values at these stages have been estimated using analytical models and experimental database respectively. The stiffness properties of joint rotational spring have been modified by incorporating a geometry factor based on dimensions of adjoining beam and column members. The hysteretic response of the joint rotational spring has been defined by a pivot hysteresis model. The response of the proposed analytical model has been verified initially at the component level and later at the structural level with the two actually tested RC frame structures. The proposed joint model effectively emulates the inelastic behavior precisely with the experimental results at component as well as at structural levels.

• 한국과학교육학회지
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• 제29권8호
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• pp.990-1010
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• 2009

이 연구에서는 뇌기반 진화적 교육 원리를 도출하기 위하여, 인간 뇌의 구조적 기능적 특징, 개체간과 개체내에서 일어나는 생물학적 진화, 뇌내에서 일어나는 진화적 과정, 과학 자체와 개별 과학자의 과학적 활동에 내재된 진화적 속성에 관한 연구물을 리뷰하였다. 이렇게 하여 도출된 인간 뇌의 주요 특징과 생성-선택-파지를 핵심 요소로 하는 보편 다윈주의 혹은 보편 선택주의를 토대로, 뇌기반 진화적 과학 교수 학습 모형을 개발하였다. 이 모형은 세 가지 요소와 세 가지 단계 및 평가로 이루어진다. 세 가지 요소는 정의적, 행동적, 인지적 요소이고, 각 요소를 구성하는 세 단계는 다양화 $\rightarrow$ 비교 선택 $\rightarrow$ 확장 적용(ABC-DEF; Affective, Behavioral, Cognitive components - Diversifying$\rightarrow$Emulating, Estimating, Evaluating $\rightarrow$ Furthering steps)이다. 이 모형에서 정의적 요소 (A)는 인간 뇌에서 감성을 관장하는 대뇌변연계에 토대를 두고 자연 사물과 현상에 대한 학습자의 흥미 호기심과 관련된다. 행동적 요소(B)는 시각 정보를 처리하는 후두엽, 언어 정보의 이해.생성과 관련된 측두엽, 감각운동 정보를 처리하는 감각운동령을 수반하고 과학적 활동의 직접 해보기와 관련된다. 인지적 요소(C)는 사고, 계획, 판단, 문제해결과 관련된 전두엽합령에 토대를 둔다. 이 모형은 이러한 측면에서 '뇌기반(brain-based)'이다. 이 모형의 세 가지 각 요소를 구성하는 세 단계에서, 다양화 단계(D)는 각 요소에서 다양한 변이체를 생성하는 과정이고, 가치나 유용성에 비추어 비교.선택하는 단계(E)는 변이체들 중 유용하거나 가치 있는 것을 검증하여 선택하는 과정이며, 확장.적용 단계(F)는 선택된 것을 유사한 상황으로 확장하거나 적용하는 단계이다. 이 모형은 이러한 측면에서 '진화적(evolutionary)'이다. ABC 세 요소에 대해, 과학적 활동에서 감성적 요인이 출발점으로 갖는 중요성과 뇌에서 사고 기능과 관련되는 신피질에 비해 감성을 관장하는 대뇌변연계의 우세한 역할을 반영하여 DARWIN (Driving Affective Realm for Whole Intellectual Network) 접근법을 강조한다. 이 모형은 학교 현장에서 다루는 과학 주제와 학생의 특징에 따라 다양한 형태와 수준으로 융통성 있게 실행될 수 있다.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2010년도 춘계학술대회 논문집
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• pp.74-75
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• 2010

Inflow broadband noise is generated when turbulence in the rotor wakes impinges on the downstream stator vanes. In this paper a three-dimensional model is developed to investigate the broadband noise due to turbulence-cascade interaction. In the newly-developed model, we consider the effects of incident turbulent gust component in span-wise direction on the inflow broadband noise. The quasi-three-dimensional theory is deduced based on the tonal analytic theory of Smith (1972) and two-dimensional broadband noise generalization by Cheong et al. (2006; 2009). Extending the modified LINSUB code, quasi-three-dimensional computational results are presented. Finally, we compare these computational results with time-domain results to validate the theory.

• Smart Structures and Systems
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• 제15권4호
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• pp.1139-1158
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• 2015

This paper proposes an efficient system identification method for modeling nonlinear behavior of civil structures. This method is developed by integrating three different methodologies: principal component analysis (PCA), artificial neural networks, and fuzzy logic theory, hence named PANFIS (PCA-based adaptive neuro-fuzzy inference system). To evaluate this model, a 3-story building equipped with a magnetorheological (MR) damper subjected to a variety of earthquakes is investigated. To train the input-output function of the PANFIS model, an artificial earthquake is generated that contains a variety of characteristics of recorded earthquakes. The trained model is also validated using the1940 El-Centro, Kobe, Northridge, and Hachinohe earthquakes. The adaptive neuro-fuzzy inference system (ANFIS) is used as a baseline. It is demonstrated from the training and validation processes that the proposed PANFIS model is effective in modeling complex behavior of the smart building. It is also shown that the proposed PANFIS produces similar performance with the benchmark ANFIS model with significant reduction of computational loads.

• Wind and Structures
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• 제12권3호
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• pp.259-279
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• 2009

The paper is concerned with the numerical study of the cross-wind response of the 295 m-tall six-flue industrial chimney, located in the power station of Belchatow, Poland. The response of the chimney due to turbulent wind flow is caused by the lateral turbulence component and vortex excitation with taking into account motion-induced wind forces. The cross-wind response has been estimated by means of the random vibration approach. Three power spectral density functions suggested by Kaimal, Tieleman and Solari for the evaluation of the lateral turbulence component response are taken into account. The vortex excitation response has been calculated by means of the Vickery and Basu's model including some complements. Motion-induced wind forces acting on a vibrating chimney have been modeled as a nonlinear aerodynamic damping force. The influence of three components mentioned above on the total cross-wind response of the chimney has been investigated. Moreover, the influence of damping ratios, evaluated by Multi-mode Random Decrement Technique, and number of mode shapes of the chimney have been examined. Computer programmes have been developed to obtain responses of the chimney. The numerical results and their comparison are presented.

• 대한안전경영과학회지
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• 제13권1호
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• pp.195-202
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• 2011

The study interprets each of three classification models based on Bath-Tub Failure Rate (BTFR), Extreme Value Distribution (EVD) and Conjugate Bayesian Distribution (CBD). The classification model based on BTFR is analyzed by three failure patterns of decreasing, constant, or increasing which utilize systematic management strategies for reliability of time. Distribution model based on BTFR is identified using individual factors for each of three corresponding cases. First, in case of using shape parameter, the distribution based on BTFR is analyzed with a factor of component or part number. In case of using scale parameter, the distribution model based on BTFR is analyzed with a factor of time precision. Meanwhile, in case of using location parameter, the distribution model based on BTFR is analyzed with a factor of guarantee time. The classification model based on EVD is assorted into long-tailed distribution, medium-tailed distribution, and short-tailed distribution by the length of right-tail in distribution, and depended on asymptotic reliability property which signifies skewness and kurtosis of distribution curve. Furthermore, the classification model based on CBD is relied upon conjugate distribution relations between prior function, likelihood function and posterior function for dimension reduction and easy tractability under the occasion of Bayesian posterior updating.