• Smart Structures and Systems
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• 제22권4호
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• pp.441-457
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• 2018

Characteristic parameter values of seismic isolators deviate from their nominal design values due to uncertainties and/or errors in their material properties and element dimensions, etc. Deviations may increase over service life due to environmental effects and service conditions. For accurate evaluation of the seismic safety level, all such effects, which would result in deviations in the structural response, need to be taken into account. In this study, the sensitivity of the probability of failure of the structures equipped with nonlinear base isolation systems to the uncertainties in various isolation system characteristic parameters is investigated in terms of various isolation system and superstructure response parameters in the context of a realistic three-dimensional base-isolated building model via Monte Carlo Simulations. The inherent record-to-record variability nature of the earthquake ground motions is also taken into account by carrying out analyses for a large number of ground motion records which are classified as those with and without forward-directivity effects. Two levels of nominal isolation periods each with three different levels of uncertainty are considered. Comparative plots of cumulative distribution functions and related statistical evaluation presented here portray the potential extent of the deviation of the structural response parameters resulting from the uncertainties and the uncertainty levels considered, which is expected to be useful for practicing engineers in evaluating isolator test results for their projects.

• 전산구조공학
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• 제10권2호
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• pp.131-138
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• 1997

이 논문에서는, 균일한 횡방향 인장변형률이 작용하는 조건에서 강체모재들을 결합하고 있는 점탄성 접착재층의 계면모서리에 발생하는 응력 특이성을 조사하고있다. Williams방법을 응용하여 라플라스 변형공간에서 특성방정식을 구하였고, 주어진 점탄성 모델에 대해서 변형공간에서의 특성방정식을 시간공간으로 해석적으로 전환하였다. 시간 공간에서의 특이차수는 수치적으로 계산하였다. 계면을 따라 발생하는 응력의 특성을 조사하는데 시간영역 경계요소법을 적용하였다. 수치해석 결과에 의하면, 특이차수는 시간이 경과함에 따라 커지는 반면에, 자유모서리 응력확대계수는 시간에 따라 이완되는 특성을 보여주고 있다.

• 한국콘텐츠학회논문지
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• 제9권6호
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• pp.309-324
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• 2009

본 연구는 사회복지서비스 조직간 네트워크의 구조적인 특성과 이러한 특성에 미치는 영향요인을 알아보고자 하는데 그 목적이 있다. 또한 네트워크 내용별 특성과 중심적인 역할을 하는 기관이 어떠한 기관인지를 살펴보고자 하였다. 이를 통해 사회복지서비스 조직간 관계를 규명하고 클라이언트 중심의 효과적인 서비스 전달을 위한 조정과 통합의 방안을 제시하는데 있어 기초자료를 제공함에 있다. 분석결과, 내용별 네트워크의 상대적인 활발성 순서는 정보교환, 클라이언트의뢰, 자원교환의 순으로 나타났으며, 개별기관의 네트워크 성향에 미치는 요인들로는 선행 이론들 중 직위, 모임수, 조직유형, 네트워크 경험 등의 유의미한 영향력이 경험적으로 일부 인정 되었다.

• Advances in concrete construction
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• 제1권1호
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• pp.85-102
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• 2013

Prior concrete strength distributions can be updated by using direct information from test results as well as by taking into account indirect information due to conformity control. Due to the filtering effect of conformity control, the distribution of the material property in the accepted inspected lots will have lower fraction defectives in comparison to the distribution of the entire production (before or without inspection). A methodology is presented to quantify this influence in a Bayesian framework based on prior knowledge with respect to the hyperparameters of concrete strength distributions. An algorithm is presented in order to update prior distributions through numerical integration, taking into account the operating characteristic of the applied conformity criteria, calculated based on Monte Carlo simulations. Different examples are given to derive suitable hyperparameters for incoming strength distributions of concrete offered for conformity assessment, using updated available prior information, maximum-likelihood estimators or a bootstrap procedure. Furthermore, the updating procedure based on direct as well as indirect information obtained by conformity assessment is illustrated and used to quantify the filtering effect of conformity criteria on concrete strength distributions in case of a specific set of conformity criteria.

• Steel and Composite Structures
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• 제30권2호
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• pp.185-199
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• 2019

Modular construction is an emerging technology to accommodate the increasing restrictions in terms of construction period, energy efficiency and environmental impacts, since each structural module is prefabricated offsite beforehand and assembled onsite using industrialized techniques. However, some innate structural drawbacks of this innovative method are also distinct, such as connection tying inaccessibility, column instability and system robustness. This study aims to explore the theoretical and numerical stability analysis of a tenon-connected square hollow section (SHS) steel column to address the tying and stability issue in modular construction. Due to the excellent performance of composite structures in fire resistance and buckling prevention, concrete-filled steel tube (CFST) columns are also taken into account in the analysis to evaluate the feasibility of adopting composite sections in modular buildings. Characteristic equations with three variables, i.e., the length ratio, the bending stiffness ratio and the rotational stiffness ratio, are generated from the fourth-order governing differential equations. The rotational stiffness ratio is recognized as the most significant factor, with interval analysis conducted for its mechanical significance and domain. Numerical analysis using ABAQUS is conducted for validation of characteristic equations. Recommendations and instructions in predicting the buckling performance of both SHS and CFST columns are then proposed.

• 한국연소학회:학술대회논문집
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• 한국연소학회 1997년도 제15회 KOSCO SYMPOSIUM 논문집
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• pp.163-173
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• 1997

This article presents an application of a large-scale structural mixing model (Broadwell et al. 1984) to the blowout of turbulent reacting jets discharging perpendicularly into an unconfined cross air-flow. In an analysis of a common stability curve, a plausible explanation can be made that the phenomenon of blowout is related only to the mixing time scale of the two flows. The most notable observation is that the blowout distance is traced at fixed positions at all times according to the velocity ratio R. Measurements of the lower blowout limits in the liftable flame agree qualitatively with the blowout parameter ${\varepsilon}$, proposed by Broadwell et al. Good agreement between the results calculated by a modified blowout parameter ${\varepsilon}^'$ and experimental results confirms the important effect of a large-scale structure in specifying the stabilization feature of blowouts.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2004년도 봄 학술발표회 논문집
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• pp.151-160
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• 2004

Genetic algorithm is the theory of grafting the principle of survival of the fittest in genetics on to the computer algorithm and it is used to solve the optimization problems, especially the shape and size optimization of the structure in Architectural problems. In the size optimization problem discrete variables are used, but series variables have to be used in the shape optimization problem because of the incongruenty. The purpose of this study is to obtain the optimum shape of cable domes by using the real coding genetic algorithm. Generally, the structural performance of the cable domes is influenced very sensitively by pre-stress, geometry and length of the mast because of its flexible characteristic. So, it is very important to decide the optimum shape to get maximum stiffness of cable domes. We use the model to verify the usefulness of this algorithm for shape optimization and analyze the roof system of Seoul Olympic Gymnastic Arena as analytical model of a practical structures. It is confirmed lastly that the optimum shape domes have more stiffness than initial shape ones.

• 한국지능시스템학회논문지
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• 제25권1호
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• pp.85-90
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• 2015

본 논문은 중소기업의 CEO의 핵심역량 24개를 FSM을 이용하여 구조분석을 하고 5개의 그룹으로 분류하였다. 또한 CEO의 업무별로 CEO의 업무능력과 핵심역량과의 관련성을 파악하기 위해 회귀분석을 실시하였다. 본 논문의 특징은 중소기업 CEO의 역량에 대한 분류와 구조화를 통한 층별 상호간의 관계를 알 수 있고, CEO의 업무능력에 무슨 역량그룹이 영향을 주는지를 알 수 있게 해준다.

• 한국미생물·생명공학회지
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• 제23권4호
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• pp.416-424
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• 1995

Mechanism of the cyclodextrin (CD) production reaction by cyclodextrin glucanotransferase (CGTase) using swollen extrusion starch as substrate was investigated emphasizing the structural features of starch granule. The degree of gelatinization was identified to be the most representative structural characteristic of swollen starch. The most suitable degree of gelatinization of swollen starch for CD production was around 63.52%. The structural transformation of starch granule during enzyme reaction was also followed by measuring the changes of the degree of gelatinization, microcrystallinity, and accessible and inaccessible portion to CGTase action of residual swollen starch. The adsorption phenomenon of CGTase to swollen starch was also examined under various conditions. The inhibition mechanism of CGTase by various CDs was identified to be competitive, most severely by a-CD. The mechanism elucidated will be used for development of a kinetic model describes CD production reaction in heterogeneous enzyme reaction system utilizing swollen extrusion starch.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2005년도 춘계학술대회 논문집
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• pp.96-99
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• 2005

Fiber optic connector, ferrule, is a device to connect and align fiber optics cable on fiber-optic communication system. In this paper, Structural analysis was performed to analyze bed and frame structure of co-axial grinding machine. Deformation and modal analysis for natural frequency was performed using ANSYS Designspace program to analyze structural characteristics. New improved model of bed and frame structure was proposed based on initial basic model.