• Journal of the Korean Society of Hazard Mitigation
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• v.9 no.1
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• pp.9-13
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• 2009

A simple outline for teaching adaptive scheme based finite element method for planar problems as a part of computer aided teaching of structural engineering curriculum is presented. Displacement based finite element formulation for planar problems and representative strain value based adaptive scheme for mesh generation are considered. As examples, a cantilever beam with a concentrated load treated as a planar problem and stretching of a plate with a circular hole are analyzed with displacement based finite element method with adaptive meshes. The examples and outlines show how adaptive based finite element method may become an essential part of computer aided teaching of structural engineering.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.26 no.5
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• pp.385-392
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• 2013

The finite element method has become the most widely used method of structural analysis and recently, the method has often been applied to complex dynamic and nonlinear structural analyses problems. Even for these complex problems, where the responses are hard to predict, finite element analyses yield reliable results if appropriate element types and meshes are used. However, the dynamic and nonlinear behaviors of a structure often include large deformations in various portions of the structure and if the same mesh is used throughout the analysis, some elements may deform to shapes beyond the reliable limits; thus dynamically adapting finite element meshes are needed in order for the finite element analyses to be accurate. In addition, to satisfy the users requirement of quick real run time of finite element programs, the algorithms must be computationally efficient. This paper presents an adaptive finite element mesh generation scheme for dynamic analyses of structures that may adapt at each time step. Representative strain values are used for error estimates and combinations of the h-method(node movement) and the r-method(element division) are used for mesh refinements. A coefficient that depends on the shape of an element is used to limit overly distorted elements. A simple frame example shows the accuracy and computational efficiency of the scheme. The aim of the study is to outline the adaptive scheme and to demonstrate the potential use in general finite element analyses of dynamic and nonlinear structural problems commonly encountered.

• Journal of the Korean Society of Hazard Mitigation
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• v.10 no.1
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• pp.23-28
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• 2010

Reliable dynamic analysis is essential in order to properly maintain structures so that structural hazards may be minimized. The finite element method (FEM) is proven to be an affective approximate method of structural analysis if proper element types and meshes are chosen. When the method is applied to dynamics analyzed in time domain, the meshes may need to be modified at each time step. As many meshes need to be generated, adaptive mesh generation schemes have become an important part in complex time domain dynamic finite element analyses of structures. In this paper, an adaptive mesh generation scheme for dynamic finite element analyses of structures is described. The concept of representative strain value is used for error estimates and the refinements of meshes use combinations of the h-method (node movement) and the r-method (element division). The validity of the scheme is shown through a cantilever beam example under a concentrated load with varying values. The example shows reasonable accuracy and efficient computing time. Furthermore, the study shows the potential for the scheme's effective use in complex structural dynamic problems such as those under seismic or erratic wind loads.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.37 no.1
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• pp.49-56
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• 2024

An automated dynamic structural analysis module stands as a crucial element within a structural integrated mitigation system. This module must deliver prompt real-time responses to enable timely actions, such as evacuation or warnings, in response to the severity posed by the structural system. The finite element method, a widely adopted approximate structural analysis approach globally, owes its popularity in part to its user-friendly nature. However, the computational efficiency and accuracy of results depend on the user-provided finite element mesh, with the number of elements and their quality playing pivotal roles. This paper introduces a computationally efficient adaptive mesh generation scheme that optimally combines the h-method of node movement and the r-method of element division for mesh refinement. Adaptive mesh generation schemes automatically create finite element meshes, and in this case, representative strain values for a given mesh are employed for error estimates. When applied to dynamic problems analyzed in the time domain, meshes need to be modified at each time step, considering a few hundred or thousand steps. The algorithm's specifics are demonstrated through a standard cantilever beam example subjected to a concentrated load at the free end. Additionally, a portal frame example showcases the generation of various robust meshes. These examples illustrate the adaptive algorithm's capability to produce robust meshes, ensuring reasonable accuracy and efficient computing time. Moreover, the study highlights the potential for the scheme's effective application in complex structural dynamic problems, such as those subjected to seismic or erratic wind loads. It also emphasizes its suitability for general nonlinear analysis problems, establishing the versatility and reliability of the proposed adaptive mesh generation scheme.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 1995.04a
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• pp.958-961
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• 1995

MODROC 기법이 대표적인 일반화된 기계-셀 형성 기법은 부품 생산비용, 부품가공시간, 공정순서, 로트 크기 등을 고려하여, 기계-셀을 형성함에 있어, 보다 현실적인 접근을 추구한 것이다. 그러나, 수리적 문제 해결의 한계로 인해 현실 접근성이 제한되며, 신경망을 이용한 기존의 기법들 역시 수리적 제한환경을 설정한 것이어서 현실적인 응용가능성이 떨어지고 있다. 본 논문에서는 공정순서와 공장배치를 고려하여 기계-셀의 효율적인 형성을 꾀하였다. 신경망 모델인 자기조직화 형성기법을 응용하였으며, 공장 작업영역과 기계-셀의 위치가 주어짐에 따라 공정순서를 고려하여 물류의 이동을 최소화하는 기계-셀의 형성 방법을 꾀하였다. 본 기계-셀 형성 방법은 기존의 방식에 비해 짧은 시간에 기계-셀을 형성할 수 있으며, 그에 따른 부품군의 형성은 공정을 고려하여 총 물류량을 감소시키는 방향으로 결정되는 장점을 갖고 있다. 또한, 다변화되는 환경에 대한 적응성과 예외적 요소(exceptional element)에 대한 셀 형성 및 처리가 매우 유연하게 나타내어 진다. 본 연구에서는 공정 간에 기계의 중복이 있는 경우의 기계-셀 형성 문제에 대해 제한된 기법을 적용하였다.

• Computational Structural Engineering
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• v.6 no.3
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• pp.99-112
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• 1993

One of the characteristics of Delaunay-Voronoii methods of mesh generation is local remeshing ability in comparison with other methods, which is very useful in adaptive finite element applications. Main part of the process is to construct remeshing element group out of the whole elements and to remesh it. Adjacent element array, accompanied with an additional algorithm of several lines, is introduced to make the process simple so that implementation of the concept is possible at the level of general PC users.

• Proceedings of the Korean Society of Computer Information Conference
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• 2013.07a
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• pp.15-18
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• 2013

본 논문에서는 교통상황을 실시간으로 반영하여 최적의 이동경로를 제공하는 적응형 내비게이션 시스템을 제안한다. 본 시스템은 세 가지 요소로 구성되어있다. 첫 번째로 도로교통망 중 한 구획의 도로상황정보를 수집하고 공유하는 Traffic Control Center (TCC). 두 번째로 개별적인 도로나 교차로에 설치되어 차량으로부터 도로상황정보를 수집하는 Road Side Unit(RSU). 마지막으로 차량들 간의 망 형성을 위해서 사용되는 Dedicated Short Range Communications(DSRC)를 기반으로 차량에 설치된 단말기가 있다. DSRC를 기반으로 RSU와의 통신하는 단말기는 실시간 도로교통정보를 기반으로 운전자에게 최적의 경로를 제공한다. 이동속도와 같은 교통정보는 단말기에서 측정되고, RSU로 전송된다. RSU는 이 정보를 처리하여 해당 도로의 도로상황지수를 생성하고, 주기적으로 TCC에 전송한다. TCC는 RSU로부터 도로상황지수를 통합하여 TCC의 관할 구획의 모든 차량에 대해 도로교통정보를 만든다. 마지막으로 단말기는 효율적인 경로안내를 위해 최적의 경로를 도출하여 운전자에게 제공한다. 따라서 단말기, RSU, TCC간의 상호작용을 통해 AINS는 동적인 교통상황(정체, 교통사고 등)을 기반으로 새로운 형태의 적응형 지능 내비게이션을 제공할 수 있다.

• Korean Journal of Agricultural and Forest Meteorology
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• v.16 no.3
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• pp.157-168
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• 2014

From a complex systems perspective, ecohydrological systems in forests may be characterized with (1) large networks of components which give rise to complex collective behaviors, (2) sophisticated information processing, and (3) adaptation through self-organization and learning processes. In order to demonstrate such characteristics, we applied the recently proposed 'process networks' approach to a temperate deciduous forest in Gwangneung National Arboretum in Korea. The process network analysis clearly delineated the forest ecohydrological systems as the hierarchical networks of information flows and feedback loops with various time scales among different variables. Several subsystems were identified such as synoptic subsystem (SS), atmospheric boundary layer subsystem (ABLS), biophysical subsystem (BPS), and biophysicochemical subsystem (BPCS). These subsystems were assembled/disassembled through the couplings/decouplings of feedback loops to form/deform newly aggregated subsystems (e.g., regional subsystem) - an evidence for self-organizing processes of a complex system. Our results imply that, despite natural and human disturbances, ecosystems grow and develop through self-organization while maintaining dynamic equilibrium, thereby continuously adapting to environmental changes. Ecosystem integrity is preserved when the system's self-organizing processes are preserved, something that happens naturally if we maintain the context for self-organization. From this perspective, the process networks approach makes sense.

• KIPS Transactions on Computer and Communication Systems
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• v.5 no.1
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• pp.17-26
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• 2016

IoT means things space networks that form the intelligent relationship such as sensing, networking, information processing about human being, things and service without explicit mutual cooperation of human being. Lately many IoT groups such as AllSeen Alliance, OIC launched a platform for IoT. Self-adaptive is aimed at implementation without the need for decisions of human being during the operation, so that the machine can respond to changes in its own determination. There is a need to apply the concept of self-adaptive to existing IoT and IoT platform. So In this paper, We look for trends of existing IoT, IoT platform and comparisons by applying a self-adaptive concept to IoT, IoT platform. In addition as an example of this paper, we suggest lacking self-adaptive elements to OIC.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2003.10a
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• pp.403-409
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• 2003

The finite element method is one of the most widely used method of structural analysis that has wide applications in diverse fields of engineering and science. The method has been proven effective and reliable in many practical problems. One of the reasons for the methods' popularity is its ease of use, but still the user has to input the finite element mesh which affects the accuracy of the results. The knowledge required to form an effective mesh for a given problem is somewhat complex and for sometime there has been research effort to automate the generation of the mesh and this is called the adaptive mesh generation scheme. A good adaptive mesh scheme seemed to require an accurate assessment of error and generally this requires some additional computation. This paper looks into the possibility of generating adaptive meshes based on representative strain values in each finite element method. The proposed adaptive scheme does not require additional computations other that looking up the data values already computed as finite element analysis results and simple manipulations of these data. Two plane stress problems, a plate with a hole and a deep beam with a concentrated load at the end are considered to show the progress of the improved generation of adaptive meshes using the scheme.