• Journal of Korean Society of Industrial and Systems Engineering
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• v.34 no.2
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• pp.112-120
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• 2011

The early phase of design intrinsically contains multiple sources of uncertainty in describing design, and nevertheless the decision-making process at this phase exerts a critical effect upon drawing a successful design. This paper proposes a set-based design approach for multi-objective design problem under uncertainty. The proposed design approach consists of four design processes including set representation, set propagation, set modification, and set narrowing. This approach enables the flexible and robust design while incorporating designer's preference structure. In contrast to existing optimization techniques, this approach generates a ranged set of design solutions that satisfy changing sets of performance requirements.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.10
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• pp.486-492
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• 2019

The system-based approach is needed to select an optimal mix of weapon systems and ship platform among a variety of design alternatives with the uncertainties of the initial required operational capability. In the early-phase design, which included a feasibility study and concept design, it is possible to cause problems when a review of the operational concept, database development, and systematic design are not done, thereby producing uncertain and unstable requirements. To select the best solution without trial-and-error, the U.S. navy has applied the set-based method for the early-phase design of a new ship-to-shore connector. The ship synthesis model plays an important role in applying the set-based method, but only a few countries possess this model and have prohibited this model from being transferred to other countries. This paper suggests a set-based method using a genetic algorithm and decision-making theory through benchmarking existing ship data. The algorithm was verified using the DDG-51 class ship synthesis model to optimize the weapon system design, which has been released for research purposes.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.61 no.12
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• pp.1903-1910
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• 2012

This paper presents a data based low-order controller design algorithm for a linear time-invariant process with a time delay. The algorithm is composed by combining an identification step based on open loop pulse test with a low-order controller design step to obtain the entire set of controllers achieving multiple performance specifications. The initial information necessary for this algorithm are merely the width and amplitude of a rectangular pulse, a controller of four types (PI, PD, PID, first-order), and design objectives. Various parametric approaches that have been developed are merged in the controller design algorithm. The resulting controller set satisfying the design objectives are displayed on the 2D and 3D graphics and thus it is very easy for us to pick a controller inside the admissible set because we can check the corresponding closed-loop performances visually.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.38 no.3
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• pp.127-135
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• 2015

Universal design is defined as the design process of products and environments usable by all people to the greatest extent possible, without the need for adaptation or specialized design. The benefits of universal design have been promoted primarily through illustrative 'success stories' of public, residential and occupational environments and products. While case examples may be informative, they may unfortunately be limited in terms of generality to other designs or tasks. Therefore, design methods and criteria that can be applied systematically in a range of situations to encourage universal design are needed. In addition, the seven principles of universal design are intended to guide the design process. The principles provide a framework that allows a systematic evaluation of new or existing designs and assists in educating both designers and consumers about the characteristics of more usable products and environments. However, exactly how these principles are incorporated into the design process has beenleft up to the designer. Since the introduction of universal design, designers have become familiar with the principles of universal design, and they have developed many products based on universal design. However, the principles of universal design are qualitative, which means designers cannot quantitatively evaluate their designs. Some have worked to develop more systematic ways to evaluate products and environments by providing design guidelines for each of the principles. However, recommendations have not yet been made regarding how to integrate performance measures of universal design into the product design process before the product is mass produced. Furthermore, there are sets of requirements regarding each user group that has different age and ability. Consequently, there is an urgent need for design methods, based on a better understanding of age and ability related factors, which will lead to a universally designed product or environment. The authors have proposed the PSD (Preference Set-Based Design) method that can generate a ranged set of feasible solutions (i.e., robust and flexible solution set) instead of single point solution that satisfies changing sets of design targets. The objective of this paper is to develop a general method for systematically supporting the universal design process. This paper proposes the applicability of PSD method to universal design. Here, the proposed method is successfully illustrated with a universal design problem.

• Korean Journal of Computational Design and Engineering
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• v.1 no.3
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• pp.242-256
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• 1996

Although feature-based design is a promising approach to fully integrating CAD/CAM, current feature-based design approaches seldom provide methodologies to easily define and design features. This paper proposes a new approach to integrating parametric design with feature-based design to overcome those limitations by globally decomposing a design into a set of features and locally defining and positioning each feature by geometric constraints. Each feature is defined as a parametric shape which consists of a feature section, attributes, and a set of constraints. The generalized sketching and sweeping techniques are used to simplify the process of designing features. The proposed approach is knowledge-based and its computational efficiency in geometric reasoning is improved greatly. Parametrically designed features not only have the advantage of allowing users to efficiently perform design changes, but also provide designers with a natural design environment in which they can do their work more naturally and creatively.

• Korean Journal of Construction Engineering and Management
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• v.12 no.4
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• pp.50-58
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• 2011

Lean concept is management philosophy that defines a customer's value and eliminates wasteful and impeditive factors. Management philosophy of Lean in the construction industry is referred to as "Lean Construction". Now this concept has expanded to achieve effective productivity during the design phase. Currently the norm of the domestic design process has been Point-based Design(PBD). It involves selecting a single structurally-feasible design option early and then refining that single design as more information becomes available throughout the design process. This single design is then re-worked until a solution is found that is feasible for all parties. On the contrary, Set-based Design(SBD) is based on lean processes to eliminate waste and improve project productivity. It focuses on keeping the design space as open as long as possible, to allow "subdesign" to advance and not labeling them as secondary in importance. Preserving the maximum number of feasible designs as long as possible reduces the likelihood that rework will be necessary and allows all project participants to utilize their unique expertise to make the project successful. This study proposes that the design methodology of minimizing waste and increasing productivity through SBD of AHP, one of the decision making process so as to compare PBD with SBD and tries to find decision making process and then suggest that application methodology through performs case study of SBD process.

• Steel and Composite Structures
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• v.21 no.6
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• pp.1389-1410
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• 2016

This paper proposes a hybrid of topological derivative-based level set method (LSM) and isogeometric analysis (IGA) for structural topology optimization. In topology optimization a significant drawback of the conventional LSM is that it cannot create new holes in the design domain. In this study, the topological derivative approach is used to create new holes in appropriate places of the design domain, and alleviate the strong dependency of the optimal topology on the initial design. Furthermore, the values of the gradient vector in Hamilton-Jacobi equation in the conventional LSM are replaced with a Delta function. In the topology optimization procedure IGA based on Non-Uniform Rational B-Spline (NURBS) functions is utilized to overcome the drawbacks in the conventional finite element method (FEM) based topology optimization approaches. Several numerical examples are provided to confirm the computational efficiency and robustness of the proposed method in comparison with derivative-based LSM and FEM.

• Korean Journal of Computational Design and Engineering
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• v.4 no.2
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• pp.139-152
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• 1999

This paper presents a feature-based approach to extracting machining features fro a feature-based design model. In the approach, a design feature to machining feature conversion process incrementally converts each added design feature into a machining feature or a set of machining features. The proposed approach an efficiently handle protrusion features and interacting features since it takes advantage of design feature information, design intent, and functional requirements during feature extraction. Protrusion features cannot be directly mapped into machining features so that the removal volumes surrounding protrusion features are extracted and converted it no machining features. By utilizing feature information as well as geometry information during feature extraction, the proposed approach can easily overcome inherent problems relating to feature recognition such as feature interactions and loss of design intent. In addition, a feature extraction process can be simplified, and a large set of complex part can be handled with ease.

• Nuclear Engineering and Technology
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• v.54 no.6
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• pp.2221-2229
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• 2022

In this research, for improving the measurement performance of Prompt Gamma-ray Neutron Activation Analysis (PGNAA) set-up, a new optimization method for set-up design was proposed and investigated. At first, the calculation method for Signal-to-Noise Ratio (SNR) was proposed. Since the SNR could be calculated and quantified accurately, the SNR was chosen as the evaluation parameter in the new optimization method. For discussing the feasibility of the SNR optimization method, two kinds of PGNAA set-ups were designed in the MCNP code, based on the SNR optimization method and the previous signal optimization method, respectively. Meanwhile, the single element spectra analysis method was proposed, and the analysis effect of single element spectra as well as element sensitivity were used for comparing the measurement performance. Since the simulation results showed the better measurement performance of set-up designed by SNR optimization method, the experimental set-ups were built for the further testing, finally demonstrating the feasibility of the SNR optimization method for PGNAA setup design.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2007.04a
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• pp.157-162
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• 2007

A new level set based topology optimization employing inner-front creation algorithm is presented. In the conventional level set based topology optimization, the optimum topology strongly depends on the initial level set distribution due to the incapability of inner-front creation during optimization process. In the present work, in this regard, an inner-front creation algorithm is proposed. in which the sizes. shapes. positions, and number of new inner-fronts during the optimization process can be globally and consistently identified by considering both the value of a given criterion for inner-front creation and the occupied volume (area) of material domain. To facilitate the inner-front creation process, the inner-front creation map which corresponds to the discrete valued criterion of inner-front creation is applied to the level set function. In order to regularize the design domain during the optimization process, the edge smoothing is carried out by solving the edge smoothing partial differential equation (PDE). Updating the level set function during the optimization process, in the present work, the least-squares finite element method (LSFEM) is employed. As demonstrative examples for the flexibility and usefulness of the proposed method. the level set based topology optimization considering lightweight design of 3D shell structure is carried out.