• Advances in Computational Design
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• 제1권3호
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• pp.275-296
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• 2016

This article presents an adaptive directional differential evolution (ADDE) algorithm and its application in solving discrete sizing truss optimization problems. The algorithm is featured by a new self-adaptation approach and a simple directional strategy. In the adaptation approach, the mutation operator is adjusted in accordance with the change of population diversity, which can well balance between global exploration and local exploitation as well as locate the promising solutions. The directional strategy is based on the order relation between two difference solutions chosen for mutation and can bias the search direction for increasing the possibility of finding improved solutions. In addition, a new scaling factor is introduced as a vector of uniform random variables to maintain the diversity without crossover operation. Numerical results show that the optimal solutions of ADDE are as good as or better than those from some modern metaheuristics in the literature, while ADDE often uses fewer structural analyses.

• Structural Engineering and Mechanics
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• 제27권4호
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• pp.409-424
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• 2007

In this paper, an identification method of impact force is proposed for composite structures. In this method, the relation between force histories and strain responses is first formulated. The transfer matrix, which relates the strain responses of sensors and impact force information, is constructed from the finite element method (FEM). Based on this relation, an optimization model to minimize the difference between the measured strain responses and numerically evaluated strain responses is built up to obtain the impact force history. The identification of force history is performed by a modified least-squares method that imposes the penalty on the first-order derivative of the force history. Moreover, from the relation of strain responses and force history, an error vector indicating the force location is defined and used for the force location identification. The above theory has also been extended into the cases when using acceleration information instead of strain information. The validity of the present method has been verified through two experimental examples. The obtained results demonstrate that the present approach works very well, even when the internal damages in composites happen due to impact events. Moreover, this method can be used for the real-time health monitoring of composite structures.

• Computers and Concrete
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• 제14권6호
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• pp.695-710
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• 2014

This paper presents a theoretical and computational approach to solve inelastic structures subjected to overloads. Current practice in structural design is based on elastic analysis followed by limit strength design. Whereas this approach typically results in safe strength design, it does not always guarantee satisfactory performance at the service level because the internal stiffness distribution of the structure changes from the service to the ultimate strength state. A significant variation of relative stiffnesses between the two states may result in unwanted cracking at the service level with expensive repairs, while, under certain circumstances, early failure may occur due to unexpected internal moment reversals. To address these concerns, a new inelastic model is presented here that is based on the nonlinear material response and the interaction relation between axial forces and bending moments of a beam-column element. The model is simple, reasonably accurate, and computationally efficient. It is easy to implement in standard structural analysis codes, and avoids the complexities of expensive alternative analyses based on 2D and 3D finite-element computations using solid elements.

• 한국시스템다이내믹스학회:학술대회논문집
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• 한국시스템다이내믹스학회 2007년도 춘계학술대회 발표논문집
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• pp.93-111
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• 2007

Even though place-marketingstrategies geared towards upgrading regional competitiveness have been brought to the forefront, due attention has not given to how to set up practical and viable strategies. Based on Geoff Coyle's ACTIFELD method, this study aims at formulating a series of implementation strategies of Jeungpyeong Place-Marketing. As the ACTIFELD technique contains intrinsic devices which would facilitate structural and systematic approach, it can easily encompass both qualitative and quantitative factors in reinterpreting complicated social phenomena and providing feasible alternatives. Furthermore, the study carries out additional public opinion surveys and expert brainstorming methods, as specific means to overcome relative weak points within the proposed ACTIFELD approach. The followings are major research findings. Firstly, in terms of maximizing existing strategies, Jeungpyeong should develop commercial items focused on Korean Ginseng and its byproducts. Secondly, among various festivals, Jeungpyeong should devise concrete processes to concurrently concentrate its support on Pork (Samgyupsal) and Korean Ginseng Festivals. Thirdly, as the majority of Jeungpyeong people prefers both do-it-your-self and traditional types, Jeungpyeong should prepare appropriate governance systems to deal with these issues. Fourthly, in order to contribute regional vitality, Jeungpyeong should strengthen public relation activities including guest-staying facilities. Lastly, Jeungpyeong should constantly improve the aggregate value of County Identity (CI)-based brands and it should also pursue production and public relation strategies actively applying the elderly.

• Structural Engineering and Mechanics
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• 제75권5호
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• pp.585-594
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• 2020

Detecting the damage of indeterminate trusses is of major importance in the literature. This paper proposes a quick approach in this regard, utilizing a precise mathematical approach based on Finite Element Method. Different to a general two-step method defined in the literature essentially based on optimization approach, this method consists of three steps including Damage-Suspected Element Identification step, Imminent Damaged Element Identification step, and finally, Damage Severity Detection step and does not need any optimizing algorithm. The first step focuses on the identification of damage-suspected elements using an index based on modal residual force vector. In the second step, imminent damage elements are identified among the damage-suspected elements detected in the previous step using a specific technique. Ultimately, in the third step, a novel relation is derived to calculate the damage severity of each imminent damaged element. To show the efficiency and quick function of the proposed method, three examples including a 25-bar planar truss, a 31-bar planar truss, and a 52-bar space truss are studied; results of which indicate that the method is innovatively capable of suitably detecting, for indeterminate trusses, not only damaged elements but also their individual damage severity by carrying out solely one analysis.

• 한국항만경제학회지
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• 제39권4호
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• pp.255-268
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• 2023

본 연구는 기존의 비선형 추정에 기초한 구조 단절/변화를 검정하기 위한 모형을 선형 회귀 분석으로 일반화한 모형으로 효율적 추정이 가능함을 제시하고자 한다. 특히, 효율적인 추정을 위해 인공지능, 머신러닝 등 분야와 관련해 구조 단절/변화 모니터링에 대한 관심이 높아지는 최근 이슈에 대해 선형회귀에 근거한 본 연구의 실증분석 결과는 구조 단절을 명확하게 추정하였으며, 글로벌 시황을 나타내는 대표적인 건화물선 운임 지수(발틱 드라이 벌크 지수, BDI)에 대한 적용 결과는 기존 연구와 일치하는 추정 결과를 제시한다. 이상의 선형 회귀에 근거한 분석은 CUSUM, MOSUM, F-통계 기반 프로세스 등 경험적 변동 프로세스의 피팅, 시각화 및 평가를 위한 다양한 유형의 추정에서 통계적으로 유의한 것으로 나타났다. 추가적으로 기존 연구에서 제시한 PELT(pruned exact linear time)를 적용한 추정에서도 유사한 추정 결과를 각각 나타낸다.

• International Journal of Computer Science & Network Security
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• 제21권11호
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• pp.199-206
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• 2021

Rhetorical relations between two text fragments are essential information and support natural language processing applications such as Question - Answering (QA) system and automatic text summarization to produce an effective outcome. Question - Answering (QA) system facilitates users to retrieve a meaningful response. There is a demand for rhetorical relation based datasets to develop such a system to interpret and respond to user requests. There are a limited number of datasets for developing an Arabic QA system. Thus, there is a lack of an effective QA system in the Arabic language. Recent research works reveal that unsupervised learning can support the QA system to reply to users queries. In this study, researchers intend to develop a rhetorical relation based dataset for implementing unsupervised learning applications. A web crawler is developed to crawl Arabic content from the web. A discourse-annotated corpus is generated using the rhetorical structural theory. A Naïve Bayes based QA system is developed to evaluate the performance of datasets. The outcome shows that the performance of the QA system is improved with proposed dataset and able to answer user queries with an appropriate response. In addition, the results on fine-grained and coarse-grained relations reveal that the dataset is highly reliable.

• Structural Engineering and Mechanics
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• 제13권2호
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• pp.135-154
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• 2002

This paper presents the convected material frame approach to study the nonlinear behavior of inelastic frame structures. The convected material frame approach is a modification of the co-rotational approximation by incorporating an adaptive convected material frame in the basic definition of the displacement vector and strain tensor. In the formulation, each discrete element is associated with a local coordinate system that rotates and translates with the element. For each load increment, the corresponding strain-displacement and nodal force-stress relationships are defined in the updated local coordinates, and based on the updated element geometry. The rigid body motion and deformation displacements are decoupled for each increment. This modified approach incorporates the geometrical nonlinearities through the continuous updating of the material frame geometry. A generalized nonlinear function is used to derive the inelastic constitutive relation and the kinematic hardening is considered. The equation of motion is integrated by an explicit procedure and it involves only vector assemblage and vector storage in the analysis by assuming a lumped mass matrix of diagonal form. Several numerical examples are demonstrated in close agreement with the solutions obtained by the ANSYS code. Numerical studies show that the proposed approach is capable of investigating large deflection of inelastic planar structures and providing an excellent numerical performance.

• 한국실내디자인학회논문집
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• 제21권4호
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• pp.68-76
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• 2012

Contemporary architecture has a tendency to concretely approach based on the concept of Deuleuze's 'fold' diversity problems creating continuously potential diversities within Post-structural paradigm. Contemporary architecture relates to human life through its relation with human being. The research investigates through case study the possible relation of the concept of Deulezue's 'fold', one of his concepts of 'unfolding' based on Monadology, with logic of creation that constructs a space in contemporary architectural space. Eight contemporary architectural spaces since 1990 with architectural embodiment of Deulezue's 'fold' concept have been selected as cases. Based on the fact that the potential possibility of a space can be embodied by the thinking of 'fold', the research draws four physical activities such as 'properties connection', 'beyond border', 'diversity of circulation' and 'potential opportunity', through which it studies on the principle of actualization of space creation. Consideration of metaphysical theory as a pre-modern and outdated one may lose a huge potentiality. Leibniz's metaphysics can be rediscovered as a model that provides diverse potentiality. The concept of 'fold' in Monadology needs be reconsidered because it possibly suggests a methodology that embodies through the actualization of space the meanings underlain in contemporary architectural space.

• Steel and Composite Structures
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• 제38권3호
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• pp.257-270
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• 2021

This paper presents a displacement-based numerical methodology following the Euler-Bernoulli theory to simulate the 2 nonlinear behavior of steel structures. It is worth emphasizing the adoption of co-rotational finite element formulations considering large displacements and rotations and an inelastic material behavior. The numerical procedures proposed considers plasticity concentrated at the finite elements nodes, and the simulation of the steel nonlinear behavior is approached via the Strain Compatibility Method (SCM), where the material constitutive relation is used explicitly. The SCM is also applied in determining the sections bearing capacity. Moreover, the present numerical approach is not limited to a specific structural member cross-sectional typology, with the residual stress models introduced explicitly in subareas of steel cross-sections generated by a 2D discretization. Finally, results consistent with the literature and with low processing time are presented.