• Journal of KIISE:Software and Applications
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• v.34 no.8
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• pp.689-696
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• 2007

It is important issue for software architects to estimate performance of software in the early phase of the development process due to the need to verify non-functional requirements and estimation of performance in various stages of architectural design. In order to analyze performance of software, there are many approaches to translate software architecture represented by Unified Modeling Language, into analytical models. However, in the development of agent-based systems, these approaches ignore or simplify the crucial details of the underlying performance of the agent platform. In this paper, we propose performance prediction methodology for agent based system using formal semantic descriptions, and then, we transform the descriptions into queuing network model which model reflects performance of hardware and software platform. We prove the accuracy of proposed methodology using prototype implementation. The accuracy is summarized at 80%.

• Journal of the Korea Society for Simulation
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• v.17 no.4
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• pp.133-142
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• 2008

AGV systems are widely used to increase the flexibility and the efficiency of the material handling systems. AGV systems are one of critical factors which determine the overall performance of the manufacturing systems. To this end, the optimal design for AGV systems is essential. Commercial simulation software is often used as an analysis tool during the design of AGV systems, however a series of procedures are desirable to simplify the analysis processes. In this paper, we present and develop the architecture for unidirectional AGV systems simulator which is able to consider approximate optimal unidirectional flow path and various operational parameters. The designed AGV systems simulator is based on JAVA, and it is developed to support designing approximate optimal unidirectional network by using Tabu search method. In addition, it enables users to design and evaluate AGV systems and to analyze alternative solutions easily. Simulation engine is consists of layout designer, AGV operation plan designer, and integrated AGVS layout designer. Users enter their system design/operation information into input window, then the entered information is automatically utilized for modeling and simulating AGV systems in simulation engine. By this series of procedures, users can get the feed back quickly.

• Korean Journal of Computational Design and Engineering
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• v.13 no.2
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• pp.139-152
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• 2008

In order to survive worldwide competition, today's industries are experiencing strong pressure to introduce higher quality products with lower cost and shorter lead-time. Therefore, the role of design in the process of product development is increasing in significance. In this research, two methods for improving the design capability are proposed: construction of design environment and design automation using 3D CAD system. The designers and design process are the core of product design using 3D CAD system. In order to maximize the design performance, construction of the design environment including selection of a suitable system, designer training for best use of the system, establishment of an efficient design process, and stabilization of the environment are required. A method is suggested to construct design environment by systematizing the contents of the projects and consulting experiences carried out for various categories of business such as electronic devices, motorcycles, electricity parts, sanitary wares, injection molds, and die casing molds. Design automation helps reduce tedious and time-consuming jobs, simplify complicated and error-prone modeling and drawing works to shorten the lead time and improve the product quality. To develop a design automation system, understanding the process and the related knowledge on design are very important before implementing the system using API provided by 3D CAD system. In this research, an eight-step procedure is proposed for the development of a design automation system. These eight steps are analysis of needs, determination of specification, verification of specification using 3D CAD system, inspection of related API functions, programming, field test, application in practice, and maintenance. A case study in which five design automation systems in the design of turbine generators using the proposed method is introduced in detail. These systems play important roles in the generation of various output items including 3D models, drafts, material information, and NC data. The case study shows how effectively the design time is reduced and the quality improved using those systems.

• Korean Journal of Computational Design and Engineering
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• v.11 no.4
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• pp.289-302
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• 2006

It is becoming a common trend that many designers work on a very complex assembly together in a collaborative environment. In this environment, every designer should be able to see the whole assembly in a full detail or in a rough shape at least. Even though the hardware technology is being improved very rapidly, it is very difficult to display a very complex assembly at a speed to allow smooth interactions for designers. This problem could be solved if a designer could manipulate his portion of the assembly in a full resolution while the remaining portion of the assembly is displayed in a rough resolution. It is also desired that the remaining portion is converted to the full resolution when needed. To realize this environment, the capabilities to simplify the portions of an assembly and to reset to the original resolution should be added to the current CAD systems. Thus operators realizing multi-resolution on B-rep are proposed in this paper. They are: wrap-around, smooth-out, and thinning operator. Through appropriately applying these operators sequentially, an assembly model of any desired resolution can be easily generated. Of course, the assembly can go back to the finer resolution. In this paper, the data structures and the processes to realize these operators are described and a prototype modeling system with these operators is also demonstrated.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.42 no.6
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• pp.861-868
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• 2022

A key use of applying building information modeling (BIM) to the construction stage of a project is to help identify construction obstacles and to visualize construction status according to the progress of the construction schedule. When employing 4D simulation for this purpose, start and finish dates for each activity and a 3D model of the activity must be prepared. In this work, in order to simplify the configuration of a 4D model, minimum attribute information of the BIM model produced in the design stage was used to construct a system that generated activity information in the construction stage using a clustering algorithm. Its usefulness as actual schedule management information was then analyzed.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.3
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• pp.2272-2278
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• 2015

Recently the importance of renewable energy is stood out regarding to the international concern about global environmental issues. Wind power is beginning to receive attention as one of renewable energy, and world-wide researches about wind power are being carried out. In the wind power system, tower structure plays an important roles for continuous and stable generation of electricity. Researchers use various analytical models to research and develop about tower structures. In this study, the effects of natural frequencies of various wind turbine tower models have been analyzed. It is possible to simplify the detailed parts of models by using modified tower unit weight since the results of 1st natural frequency show that the difference is only 0.14%. Since the difference in natural frequency is greater than 10%, according to the boundary condition, the simple fix end support is not appropriate to represent the real structure of the tower. It is expected that the result of this study may be utilized to establish the criterion about appropriate modelling method.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.30 no.4
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• pp.329-334
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• 2017

The structures, which are made up with the huge number of degrees-of-freedom and the assembly of substructures, have a great complexity. In order to increase the computational efficiency, the analysis models have to be simplified. Many substructuring techniques have been developed to simplify large-scale engineering problems. The techniques are very powerful for solving nonlinear problems which require many iterative calculations. In this paper, a modal derivatives-based model order reduction method, which is able to capture the stretching-bending coupling behavior in geometrically nonlinear systems, is adopted and investigated for its performance evaluation. The quadratic terms in nonlinear beam theory, such as Green-Lagrange strains, can be explained by the modal derivatives. They can be obtained by taking the modal directional derivatives of eigenmodes and form the second order terms of modal reduction basis. The method proposed is then applied to a co-rotational finite element formulation that is well-suited for geometrically nonlinear problems. Numerical results reveal that the end-shortening effect is very important, in which a conventional modal reduction method does not work unless the full model is used. It is demonstrated that the modal derivative approach yields the best compromised result and is very promising for substructuring large-scale geometrically nonlinear problems.

• Journal of Soil and Groundwater Environment
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• v.14 no.5
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• pp.18-28
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• 2009

Both feasibility and accuracy of lumped approach to group 12 organic compounds in mixtures into a fewer number of pseudocompounds in sorption processes were evaluated using mixtures containing organic compounds with various physicochemical properties and low-surface-area mineral sorbents. The lumped approach for sorption to simulated mineral sorbents was developed by cluster analysis from statistics. Using the lumped approach, the sorption estimated from both reduced number of pseudocompounds and their sorption parameters (i.e., $K_f$, n) can approximate sorption behavior of complex organic mixtures. Additionally, the pseudocompounds for various mixtures to different types of low-surface-area mineral sorbents can be estimated a priori from the physicochemical properties of organic compound (i.e., ${\gamma_w}^{sat}$). Therefore, the lumped approach may help to simplify the complex fate and transport model of organic contaminant mixtures, reduce experimental efforts, and yet provide results that are statistically identical for practical purposes. Further research is warranted to enhance the accuracy of lumped approach using the multiple regression analysis considering the H-bonding capacity, site concentrations, functional groups for mineral sorbents.