• Journal of Ocean Engineering and Technology
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• v.24 no.1
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• pp.20-33
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• 2010

The paper deals with strength design of a riser support installed on floating production storage and offloading (FPSO) vessel under various loading conditions - operation, extreme, damaged, one line failure case (OLFC) and installation. The design problem is formulated such that thickness sizing variables are determined by minimizing the weight of a riser support structure subject to stresses constraints. The initial design model is generated based on an actual FPSO riser support specification. The finite element analysis (FEA) is conducted using MSC/NASTRAN, and optimal solutions are obtained via moving least squares method (MLSM) in the context of response surface based approximate optimization. For the meta-modeling of inequality constraint functions of stresses, a constraint-feasible moving least squares method (CF-MLSM) is used in the present study. The method of CF-MLSM, compared to a conventional MLSM, has been shown to ensure the constraint feasibility in a case where the approximate optimization process is employed. The optimization results present improved design performances under various riser operating conditions.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.27 no.6
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• pp.864-870
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• 2003

In recent engineering, the designer has become more and more dependent on the computer simulations such as FEM(Finite Element Method) and BEM(Boundary Element Method). In order to optimize such implicit models more efficiently and reliably, the meta -modeling technique has been developed for solving such a complex problems combined with the DACE(Design and Analysis of Computer Experiments). It is widely used for exploring the engineer's design space and for building approximation models in order to facilitate an effective solution of multi-objective and multi-disciplinary optimization problems. Optimization of a train suspension is performed according to the minimization of forty -six responses that represent ten ride comforts, twelve derailment quotients, twelve unloading ratios, and twelve stabilities by using the Kriging model of a train suspension. After each Kriging model is constructed, multi -objective optimal solutions are achieved by using a nonlinear programming method called SQP(Sequential Quadratic Programming).

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2004.05a
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• pp.404-409
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• 2004

A compressor loop pipe is the most important part in a refrigerator from the view of structural vibration and noise. Vibration energy generated from a compressor's inner body is transmitted to the shell and outside through the loop pipe. For this reason it is very important to design a compressor loop pipe. But, for geometrical complexity and dynamic nonlinearity of the loop pipe, analysis and design of the loop pipe is very difficult. So the statistical and experimental methods have to be used for design of this system. The response surface method (RSM) becomes a popular meta-modeling technique f3r the complex system as this loop pipe. As starting point of loop pile's optimization, FEA model and simple experimental model are used instead of the real loop pipe model. After RS model was constructed, using sensitivity-based optimizer performed optimization for the loop pipe. And the moving least square method (MLSM) was applied to reduce the approximation error.

• Computers and Concrete
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• v.21 no.4
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• pp.441-449
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• 2018

FE models for complex or large-scaled structures that need detailed modeling of structural components are usually constructed using commercial analysis softwares. Updating of such FE model by conventional sensitivity-based methods is difficult since repeated computation for perturbed parameters and manual calculations are needed to obtain sensitivity matrix in each iteration. In this study, an FE model updating procedure avoiding such difficulties by using response surface (RS) method and a Pareto-based multiobjective optimization (MOO) was formulated and applied to FE models constructed with a commercial analysis package. The test building is a low-rise reinforced concrete building that has been seismically retrofitted. Dynamic properties of the building were extracted from vibration tests performed before and after the seismic retrofits, respectively. The elastic modulus of concrete and masonry, and spring constants for the expansion joint were updated. Two RS functions representing the errors in the natural frequencies and mode shape, respectively, were obtained and used as the objective functions for MOO. Among the Pareto solutions, the best compromise solution was determined using the TOPSIS (Technique for Order of Preference by Similarity to Ideal Solution) procedure. A similar task was performed for retrofitted building by taking the updating parameters as the stiffness of modified or added members. Obtained parameters of the existing building were reasonably comparable with the current code provisions. However, the stiffness of added concrete shear walls and steel section jacketed members were considerably lower than expectation. Such low values are seemingly because the bond between new and existing concrete was not as good as the monolithically casted members, even though they were connected by the anchoring bars.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.17 no.4
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• pp.847-856
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• 2013

This paper presents an AP placement technique considering indoor location-awareness and examines its performance. The proposed AP placement technique is addressed from three performance metrics: location-awareness and AP-based wireless network performance as well as its cost. The proposed AP placement technique consists of meta-heuristic algorithms that yield a near optimal AP configuration for given performance metrics, and deterministic algorithms that improve the fast convergence of the near optimal AP configuration. The performance of the AP placement technique presented in this paper is measured under the environments simulating indoor space, and numerical results obtained by experimental evaluation yield the fast convergence of a near-optimal solution to a given performance metric.

• Journal of Korean Association for Spatial Structures
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• v.15 no.2
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• pp.87-94
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• 2015

This paper aimed at modeling a fine triangular grid for network dome by using Harmony Search (HS) algorithm. For this purpose, an optimization process to find a fine regular triangular mesh on the curved surface was proposed and the analysis program was developed. An objective function was consist of areas and edge's length of each triangular and its standard deviations, and design variables were subject to the upper and lower boundary which was calculated on the nodal connectivity. Triangular network dome model, which was initially consist of randomly irregular triangular mesh, was selected for the target example and the numerical result was analyzed in accordance with the HS parameters. From the analysis results of adopted model, the fitness function has been converged and the optimized triangular grid could be obtained from the initially distorted network dome example.

• Transactions of the Korean Society of Automotive Engineers
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• v.22 no.2
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• pp.115-122
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• 2014

Injection pressure is one of factors that influence part quality. In this paper, injection pressure was minimized by optimizing valve gate locations. In order to perform design optimization, MAPS-3DTM (Mold Analysis and Plastic Solution-3D) was used for injection mold analysis and PIAnOTM (Process Integration, Automation and Optimization) was used as process integration and design optimization. Also we adapted meta models based on design of experiments for efficiency. By using introduced methodology, we were able to obtain a result so that maximum injection pressure reduced by 28% compared to the initial design. And the validity of the proposed method could also be demonstrated.

• The Journal of Society for e-Business Studies
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• v.10 no.4
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• pp.19-33
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• 2005

In this study, we propose a methodology of mating it easy to integrate the heterogeneous and distributed information of e-Business environments with the semantic web components , knowledge representation, ontology and agents. It is based on a collaborative interoperable environment, which should be constructed by meta-modeling and employing agents , and the syntactic/semantic integration. We adopt OWL(Web Ontology Language) to specify ontology in a layered architecture for each agent to use, which is based on the IRDS (Information Resource Dictionary Standard) framework. And we give an illustrative example using the terms from PSL(Process Specification Language)-ontology. By defining, managing and sharing resources and business-processes on the proposed framework, it could be possible to get rid of the cause of redundancy and inconsistency.

• Journal of the Korean Society for Precision Engineering
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• v.16 no.9
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• pp.25-34
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• 1999

In spite of the advance of 3D solid modeling technology, there are some distinct areas where 2D CAD S/W are still dominant, and more competent comparing with 3D CAD S/W. For example, in the manufacturing of 2D-shaped electrical parts, most related manufacturing tools have 2D geometric features by nature, and 3D solid models applied to these parts have substantial overheads. Nevertheless, most 2D CAD S/W have no topological inquiry services because they have no such information on their geometrical database inherently. Thus, it is needed to extract such information from 2D CAD database for developing more advanced application such as automated drafting/design S/W. In this paper, the extraction of topological information from 2D CAD has been performed in general way using concept of B-rep. A general extraction algorithm, data structure and meta file format for 2D topological object have been developed and successfully applied to the development of the automated lead frame die design system in Samsung Aerospace. it is also possible to provide a flexible, powerful topology-oriented functionality on any common 2D CAD S/W.

• Journal of Internet Computing and Services
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• v.20 no.2
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• pp.69-76
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• 2019

Recent Enterprise System has component driven real-time distributed architecture (RDA) and this kind of architecture should performed with satisfying strict constraints on life cycle of object and response time such as synchronization, transaction and so on. Microsoft's .NET platform supports RDA and is able to implement services including before mentioned time restriction and security service by only specifying attribute code and maximizing advantages of OMG's Model Driven Architecture (MDA). In this study, a method to automatically generate an extended model of essential elements in an enterprise-system-based RDA as well as the platform specific model (PSM) for Microsoft's .NET platform are proposed. To realize these ideas, the functionalities that should be considered in enterprise system development are specified and defined in a meta-model and an extended UML profile. In addition, after defining the UML profile for .NET specification, these are developed and applied as plug-ins of the open source MDA tool, and extended models are automatically generated using this tool. Accordingly, by using the proposed specification technology, the profile and tools can easily and quickly generate a reusable extended model even without detailed coding-level information about the functionalities considered in the .NET platform and RDA.