• Earthquakes and Structures
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• 제7권5호
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• pp.647-665
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• 2014

Squat reinforced concrete walls require enough shear strength in order to promote flexural yielding, which creates the need for designers of an accurate method for strength prediction. In many cases, especially for existing buildings, strength estimates might be insufficient when more accurate analyses are needed, such as pushover analysis. In this case, estimates of load versus displacement are required for building modeling. A model is developed that predicts the shear load versus shear deformation of squat reinforced concrete walls by means of a panel formulation. In order to provide a simple, design-oriented tool, the formulation considers the wall as a single element, which presents an average strain and stress field for the entire wall. Simple material constitutive laws for concrete and steel are used. The developed models can be divided into two categories: (i) rotating-angle and (ii) fixed-angle models. In the first case, the principal stress/strain direction rotates for each drift increment. This situation is addressed by prescribing the average normal strain of the panel. The formation of a crack, which can be interpreted as a fixed principal strain direction is imposed on the second formulation via calibration of the principal stress/strain direction obtained from the rotating-angle model at a cracking stage. Two alternatives are selected for the cracking point: fcr and 0.5fcr (post-peak). In terms of shear capacity, the model results are compared with an experimental database indicating that the fixed-angle models yield good results. The overall response (load-displacement) is also reasonable well predicted for specimens with diagonal compression failure.

• 한국자동차공학회논문집
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• 제8권3호
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• pp.119-129
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• 2000

In order to show the efficiency and accuracy of an expert drawbead model, finite element simulations of auto-body panel stampings are carried out. For numerical modeling of the drawbead of a panel die, the drawbead restraining force and bead-exit thinning calculated by the expert model are imposed to a node nearest to the drawbead position as a boundary condition, Finite element simulations show that the expert model provides the accurate solution, guarantees the stable convergence, and has the merit in the computation time.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2007년도 7th International Meeting on Information Display 제7권1호
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• pp.33-36
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• 2007

We performed a discharge analysis on ac plasma display panel through the numerical simulation of the EF (Energy Fluid) model using the electron's energy equation. When it is compared to the results of commonly used LFA (Local Field Approximation) model, there is a clear difference in the spatiotemporal distribution of Xe excited species. In particular, the experimentally observed striation phenomena in the anode region could be observed in EF model and the occurrence of the striation was attributed to the ionization and excitation instability due to the streaming electrons in the anode region plasma.

• Communications for Statistical Applications and Methods
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• 제29권3호
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• pp.373-391
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• 2022

The distribution of observations in most econometric studies with spatial heterogeneity is skewed. Usually, a single transformation of the data is used to approximate normality and to model the transformed data with a normal assumption. This assumption is however not always appropriate due to the fact that panel data often exhibit non-normal characteristics. In this work, the normality assumption is relaxed in spatial mixed models, allowing for spatial heterogeneity. An inference procedure based on Bayesian mixed modeling is carried out with a multivariate skew-elliptical distribution, which includes the skew-t, skew-normal, student-t, and normal distributions as special cases. The methodology is illustrated through a simulation study and according to the empirical literature, we fit our models to non-life insurance consumption observed between 1998 and 2002 across a spatial panel of 103 Italian provinces in order to determine its determinants. Analyzing the posterior distribution of some parameters and comparing various model comparison criteria indicate the proposed model to be superior to conventional ones.

• 한국강구조학회 논문집
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• 제9권4호통권33호
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• pp.683-695
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• 1997

본 연구는 강제 라멘교각 접합부 panel zone의 전단거동특성에 대하여 검토한 것이다. 여기에서는 접합부 시험체 20개에 대한 재하실험 결과와 3가지의 FEM해석 모델에 대한 결과를 제시 하였다. 이와같은 실험및 해석결과를 비교 검토한 결과, panel zone의 강도와 변형 성능은 단면적비와 전단좌굴등에 의하여 감소하는 경향을 보이고 있음을 알 수 있었다. 따라서 본 연구에서는 이상의 결과를 기초로 panel zone의 강도와 변형성능에 대한 새로운 평가식을 제안하였으며, 또한 기존의 라멘교각 접합부에 대한 변형성능에 관해서 검토하였다.

• 한국공간구조학회논문집
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• 제12권1호
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• pp.51-58
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• 2012

압출성형 ECC 패널을 활용한 철근콘크리트 복합 슬래브 구조에 대한 비선형 휨 해석 모델을 새롭게 제시하였다. ECC 패널은 직접인장시험 결과로부터 균열 이후에 고인성 인장거동을 하는 재료로 모델링하였다. 개발 모델을 기존 철근콘크리트 슬래브 및 ECC 패널 철근콘크리트 복합슬래브 실험체의 휨 실험결과와 비교하였다. 예측결과는 실험결과와 잘 일치하였으며, ECC 패널 적용 철근콘크리트 복합슬래브는 균열제어, 휨내력 및 휨변형능력 개선에 장점이 있는 것으로 판단되었다.

• Smart Structures and Systems
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• 제20권5호
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• pp.595-605
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• 2017

The present article reported the thermal buckling strength of the sandwich shell panel structure and subsequent improvement of the same by embedding shape memory alloy (SMA) fibre via a general higher-order mathematical model in conjunction with finite element method. The geometrical distortion of the panel structure due to the temperature is included using Green-Lagrange strain-displacement relations. In addition, the material nonlinearity of SMA fibre due to the elevated thermal environment also incorporated in the current analysis through the marching technique. The final form of the equilibrium equation is obtained by minimising the total potential energy functional and solved computationally with the help of an original MATLAB code. The convergence and the accuracy of the developed model are demonstrated by solving similar kind of published numerical examples including the necessary input parameter. After the necessary establishment of the newly developed numerical solution, the model is extended further to examine the effect of the different structural parameters (side-to-thickness ratios, curvature ratios, core-to-face thickness ratios, volume fractions of SMA fibre and end conditions) on the buckling strength of the SMA embedded sandwich composite shell panel including the different geometrical configurations.

• The Journal of Asian Finance, Economics and Business
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• 제9권4호
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• pp.173-183
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• 2022

The objective of this research is to examine the influence of the COVID-19 pandemic on stock markets in a few developing and developed countries. This study uses daily data from January 2020 to May 2021 and obtained from World Health Organization and Thomson Reuters. The secondary data was evaluated through panel econometric methodology that includes different unit root tests, and to analyze the long-run relationship between variables, panel cointegration techniques were applied. The long-run causality among variables was examined through Panel Vector Error Correction Model. The overall findings of this study suggest a long-run association exists between several cases and death with the stock returns of the GCC and other stock markets. Furthermore, the VECM model also identified a long-run causality running from COVID cases and death towards the stock rerun of both sets of stock markets. However, a subsequent Wald test yielded mixed results, indicating no short-run causality between cases and deaths and stock returns in both groups; however, in the case of GCC, several COVID-19 cases are having a causal impact on stock markets, which is notable in light of the fact that the death rate in GCC is significantly lower than in many developed and developing countries.

• Earthquakes and Structures
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• 제11권4호
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• pp.723-740
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• 2016

Reinforced concrete corbels are generally used to transfer loads within a structural system, such as buildings, bridges, and facilities in general. They commonly present low aspect ratio, requiring an accurate model for shear strength prediction in order to promote flexural behavior. The model described here, originally developed for walls, was adapted for corbels. The model is based on a reinforced concrete panel, described by constitutive laws for concrete and steel and applied in a fixed direction. Equilibrium in the orthogonal direction to the shearing force allows for the estimation of the shear stress versus strain response. The original model yielded conservative results with important scatter, thus various modifications were implemented in order to improve strength predictions: 1) recalibration of the strut (crack) direction, capturing the absence of transverse reinforcement and axial load in most corbels, 2) inclusion of main (boundary) reinforcement in the equilibrium equation, capturing its participation in the mechanism, and 3) decrease in aspect ratio by considering the width of the loading plate in the formulation. To analyze the behavior of the theoretical model, a database of 109 specimens available in the literature was collected. The model yielded an average model-to-test shear strength ratio of 0.98 and a coefficient of variation of 0.16, showing also that most test variables are well captured with the model, and providing better results than the original model. The model strength prediction is compared with other models in the literature, resulting in one of the most accurate estimates.

• 한국지리정보학회지
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• 제26권2호
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• pp.20-41
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• 2023

최근 저출산·고령화에 따른 도시축소 현상과 지방도시의 쇠퇴는 빈집이라는 새로운 도시문제를 낳고 있다. 본 연구는 전국 시·군·구를 대상으로 2015년부터 2019년까지 수집한 공간 패널 데이터를 이용하여 빈집 분포를 살펴보고 시공간적 종속성을 고려한 공간패널모형을 이용하여 빈집발생의 요인을 추정하는 것이 목적이다. 분석 결과 빈집은 시공간적으로 종속성이 있었으며, OLS 모형에 비해 시공간적 종속성을 고려하여 빈집 발생 요인을 추정하는 것이 타당함을 확인하였다. 동적공간패널모형을 이용하여 분석한 결과 빈집발생의 가장 큰 영향요인은 주택관련요인인 것으로 나타났다. 이 결과는 빈집 발생의 관리를 위해서는 인구이동, 양호하지 못한 인프라 등 뿐만 아니라 주택 공급량에 대한 정책적 고려가 필요함을 시사한다.