• Journal of KSNVE
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• 제7권4호
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• pp.689-700
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• 1997

There are many difficulties in designing the engine structure properly due to the strong conflicts between NVH characteristics and the high performance, light weight and low product cost. Many feasible noise reduction techniques should be carefully incorporated to meet such stringent noise requirements. It is also required that the engine development be carried out by introducing concurrent engineering, in which the analysis and test database are usefully applied to the detail designs from the 1st stage. This paper reviews the significance of the noise characteristics of the structure elements in relation to the combustion pressure. The mechanisms of the crank shaft rumbling, which is the main source having the bad influence on the sound quality, are also explained. The influences of dynamic behavior of engine structure on its noise are investigated, followed by discussions on experimental results of the features necessary for the design of low noise engine concepts.

• International Journal of Control, Automation, and Systems
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• 제5권3호
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• pp.234-242
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• 2007

A Concurrent Relay-PID controller (CRPID) for motor position servo systems is proposed in this paper. The proposed controller is composed of a deadband-relay subcontroller and a parallel PID subcontroller. The deadband-relay subcontroller is capable of improving the transient system performance while the PID subcontroller is responsible for near steady state system regulation. Systematic design methods for various controller components are developed. Design procedures are illustrated by an example. The proposed hybrid scheme is applied to a DC motor position servo system. Both numerical and experimental results demonstrate that the proposed controller performs satisfactorily and is superior to PID control alone.

• Journal of the Computational Structural Engineering Institute of Korea
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• 제21권1호
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• pp.113-124
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• 2008

Distributed operation of overall structural design process, by which product optimization and process parallelization are simultaneously implemented, is presented in this paper. The database-interacted hybrid method, which selectively takes the accustomed procedure of the conventional method in the framework of the optimal design, is utilized here. The staged application of design constraints reduces the computational burden for large complex optimization problems. Two kinds of numeric and graphic processes are simultaneously implemented by concurrent engineering approach in the distributed environment of PC networks. The former is based on finite element optimization method and the latter is represented by AutoCAD using AutoLISP programming language. Numerical computation and database interaction on servers and graphic works on independent clients are communicated through message passing. The numerical experiments for some steel truss models show the validity and usability of the method. This study has sufficient adaptability and expandability, in that it is based on general methodologies and industry standard platforms.

• Korean Journal of Computational Design and Engineering
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• 제12권1호
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• pp.50-57
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• 2007

In recent years, many robotics researches have been focused on developing human-friendly robots, that is, humanoid biped robots. The researches of humanoid robots include various areas such as hardware development, control of biped locomotion, artificial intelligence, human interaction, etc. The present work concerns the hardware development of a mid-size humanoid robot, BONOBO, focusing on rapid development of outer body parts with integrated application if CAD/CAM/CAE/RP. Most parts are three-dimensionally designed using 3D CAD, and effectively connected with CAE analyses using both kinematic simulation and structural analysis. In order to reduce lead time and investment cost for parts developments, Rapid Prototyping (RP) and CAM are selectively utilized for manufacturing body parts. These master parts are then replicated using the vacuum casting process, from which we can obtain plastic parts repeatedly. Through this integrated approach, the first prototype of BONOBO can be successfully developed with relatively low time and investment costs.

• Korean Journal of Computational Design and Engineering
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• 제9권4호
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• pp.406-415
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• 2004

The industrial environment for shipbuilding in 21st century requires increase in few type of ships and marine structures, international cooperation and globalization, while virtual enterprise environment is rapidly establishing. On the other hand, more and more efforts will be spent on internet based distributed and collaborative environment rather than being spent on unit level automations such as CAD, CAM and CAE, and the link between them. Recent internet technology and information technology in heterogeneous environment are being applied in shipbuilding industry as well as in other industries. While these technology are rapidly adopted in major shipyards, many small and medium-sized shipyards does not have enough resources to introduce system designed for large enterprise. In this paper, a prototype of Internet technology based basic planning system is implemented for the small and medium sized shipyards based on the internet technology and concurrent engineering concept. First, the system is designed from the user requirements. Then standardized development environment and tools are selected. These tools are used for defining and evaluating core application technologies for the system development. This can guarantee the survival of small and medium-sized shipyards in 21st century industrial environment.

• Computers and Concrete
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• 제6권2호
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• pp.133-153
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• 2009

Discrete element modeling (DEM) in concrete technology is concerned with design and use of models that constitute a schematization of reality with operational potentials. This paper discusses the material science principles governing the design of DEM systems and evaluates the consequences for their operational potentials. It surveys the two families in physical discrete element modeling in concrete technology, only touching upon probabilistic DEM concepts as alternatives. Many common DEM systems are based on random sequential addition (RSA) procedures; their operational potentials are limited to low configuration-sensitivity features of material structure, underlying material performance characteristics of low structure-sensitivity. The second family of DEM systems employs concurrent algorithms, involving particle interaction mechanisms. Static and dynamic solutions are realized to solve particle overlap. This second family offers a far more realistic schematization of reality as to particle configuration. The operational potentials of this family involve valid approaches to structure-sensitive mechanical or durability properties. Illustrative 2D examples of fresh cement particle packing and pore formation during maturation are elaborated to demonstrate this. Mainstream fields of present day and expected application of DEM are sketched. Violation of the scientific knowledge of to day underlying these operational potentials will give rise to unreliable solutions.

• Journal of the Korean Society for Precision Engineering
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• 제18권8호
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• pp.164-173
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• 2001

The configuration of injection molded part can be classified into primary feature and supplementary feature. Even though supplementary features such as ribs, snap fits and bosses make mold more complicated, which cause the increasement of the mold cost, supplementary features should be attached to primary features because of assembly, reinforcement, moldability and other functional purposes. But it is not easy for novice designers to design them appropriately because of the profound knowledge related to Injection molding. In this paper, the intelligent design tool called ISFD(Intelligent Supplementary Feature Designer) which supplies easy, simple, time and cost-effective design method has been studied and developed. A knowledge-based design system is a new tool which enables the concurrent design and CIM with integrated and balanced design decisions at the initial design stage of injection molding.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 한국정밀공학회 2005년도 춘계학술대회 논문집
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• pp.822-827
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• 2005

Recently engineering systems problems become quite large and complicated. For those problems, design requirements are fairly complex. It is not easy to design such systems by considering only one discipline. Therefore, we need a design methodology that can consider various disciplines. Multidisciplinary Design Optimization (MDO) is an emerging optimization method to include multiple disciplines. So far, about seven MDO methodologies have been proposed for MDO. They are Multidisciplinary Feasible (MDF), Individual Feasible (IDF), All-at-Once (AAO), Concurrent Subspace Optimization (CSSO), Collaborative Optimization (CO), Bi-Level Integrated System Synthesis (BLISS) and Multidisciplinary Optimization Based on Independent Subspaces (MDOIS). In this research, the performances of the methods are evaluated and compared. Practical engineering problems may not be appropriate for fairness. Therefore, mathematical problems are developed for the comparison. Conditions for fair comparison are defined and the mathematical problems are defined based on the conditions. All the methods are coded and the performances of the methods are compared qualitatively as well as quantitatively.

• Korean Journal of Computational Design and Engineering
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• 제1권3호
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• pp.177-188
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• 1996

An approach to providing computational support with an expert shell is discussed with the scope of an industrial wire harness design, especially at a manufacturing stage. Key issues include the development of an architecture that supports a frequent design change among engineers associated with different parts of the wiring design process and the development of hierarchical representations that capture the different characteristics (e.g., connectivity, configuration) of the harnesses. The abstraction of design information results in features, while the abstraction of drawing elements leads to the definition of objects. These abstractions are essential for efficient transactions among people and computer tools in a domain that involves numerous interacting constraints. In this paper the strategy for the problem decomposition, the definition of features, and the ways in which features are shared by various operations and design changes, are discussed. We conclude with a discussion of some of the issues raised by the project and the steps underway to address them.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 한국소음진동공학회 1997년도 춘계학술대회논문집; 경주코오롱호텔; 22-23 May 1997
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• pp.192-198
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• 1997

In the concurrent engineering, the CAD-based design model is necessary for multidisciplinary analysis and for computer-aided manufacturing (CAM). A shape and configuration design velocity field computation of structure has been developed using a computer-aided design (CAD) tool, Pro/ENGINEER. The design Parameterization with CAD tool is to characterize the change in dimensions and movements of geometric control points that govern the shape/orientation of the structural boundary. The boundary velocity is obtained by using a CAD-based finite difference method and the domain velocity field is obtained from finite element analysis (FEA) using the boundary displacement method. In this paper, the continuum configuration DSA for NVH problem, which requires the shape velocity field and the orientation velocity field at the same time, is developed using linear shape functions. For validation of continuum design sensitivity coefficients, design sensitivity coefficients are compared with the coefficients computed using by the finite difference method.