• Journal of the Society of Naval Architects of Korea
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• v.41 no.6
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• pp.91-101
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• 2004

For the grillage which is common types of structures in marine and land-based structural system, the elastic response and design methods are usually applied. However, plastic analysis and design methods are considered Tn those structures to maintain the structural stability at the limit states. In grillage design, the central intersection point load may be used as a worst loading condition. However, a point load may often move around on the grid system. in such case, the worst load point would not necessarily be at the central point. To investigate the variation of plastic collapse load according to the location of moving load between intersections, the plastic collapse loads are obtained for the three types of grillages with simply-supported ends. From the result of each case, it is confirmed that the worst load point is located between intersections. General formulae related with plastic collapse loads for the three groups of grillages with simply-supported boundaries are derived. Those plastic collapse formulae for the grillages are applied to the design of pontoon deck, and optimum design procedure is illustrated. Consequently, general formulae for the plastic collapse of grillages derived from this study can be easily applied to the plastic analysis and optimum design of similar grillages.

• Advances in Computational Design
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• v.1 no.1
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• pp.1-25
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• 2016

Domes are architectural and elegant structures which cover a vast area with no interrupting columns in the middle, and with suitable shapes can be also economical. Domes are built in a wide variety of forms and specialized terms are available to describe them. According to their form, domes are given special names such as network, lamella, Schwedler, ribbed, and geodesic domes. In this paper, an optimum topology design algorithm is performed using the enhanced colliding bodies optimization (ECBO) method. The network, lamella, ribbed and Schwedler domes are studied to determine the optimum number of rings, the optimum height of crown and tubular sections of these domes. The minimum volume of each dome is taken as the objective function. A simple procedure is defined to determine the dome structures configurations. This procedure includes calculating the joint coordinates and element constructions. The design constraints are implemented according to the provision of LRFD-AISC (Load and Resistance Factor Design-American Institute of Steel Constitution). The wind loading act on domes according to ASCE 7-05 (American Society of Civil Engineers). This paper will explore the efficiency of various type of domes and compare them at the first stage to investigate the performance of these domes under different kind of loading. At the second stage the wind load on optimum design of domes are investigated for Schwedler dome. Optimization process is performed via ECBO algorithm to demonstrate the effectiveness and robustness of the ECBO in creating optimal design for domes.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.103-104
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• 2008

This paper proposes an alternative methodology for deciding an optimum deterministic reliability level (IRR; Installed Reserve Rate) by using probabilistic reliability criterion (LOLE; Loss of Load Expectation). Additionally, case studies using the proposed method induce the characteristics of relationship between the probabilistic reliability index (LOLE) and deterministic reliability index (IRR) for 2008 year in Korea power system. The case study presents a possibility that an optimum IRR level in Korea can be assessed using the proposed method. Korea power system has been using the LOLE criterion to determine the adequacy of installed capacity (ICAP) requirement. The criterion in Korea is that the loss of load expectation shall not exceed the available capacity more than five day in ten years (=0.5[days/year]). The probabilistic reliability evaluation and production cost simulation program which is called PRASim is used in order to evaluate the relationship and optimum IRR in this paper.

• Journal of the Korean Society for Precision Engineering
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• v.28 no.2
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• pp.226-232
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• 2011

In this study, an optimized design of a triaxial load cell has been developed by the use of finite element analysis, design of experiment and response surface method. The developed optimal design was further validated by both stress-strain analysis and natural vibration analysis under an applied load of 30 kgf. When vertical, horizontal, and axial loads of 30 kgf were applied to the load cell with the optimal design, the calculated strains were satisfied with the required strain range of $500{\times}10^{-6}{\pm}10%$. The natural vibration analysis exhibited that the fundamental natural frequency of the optimally designed load cell was 5.56 kHz and higher enough than a maximum frequency of 0.17 kHz which can be applied to the load cell for wind-tunnel tests. The satisfactory sensitivity in all triaxial directions also suggests that the currently proposed design of the triaxial load cell enables accurate measurements of the multi-axial forces in wind-tunnel tests.

• Proceedings of the Korean Geotechical Society Conference
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• 2001.03a
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• pp.379-386
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• 2001

Piled raft foundations are usually used to reduce total and differential settlements of superstructures. In the piled raft foundations, the raft is often on its own able to provide adequate bearing capacity and only few widely spaced piles are added to the foundation to keep settlements be1ow a certain limit. In this paper, experimental studies on the load sharing ratio between piles and raft are carried out. Also, for evaluating the application of optimum design technique using a genetic algorithm, optimal locations of files are compared with the results of laboratory model tests. from tile results of laboratory model tests, there are found that the load sharing ratio between files and raft is depended on the number of piles and stiffness of raft, and the optimal locations of piles became concentrated on the middle of rafts. From these results of laboratory model tests, the optimum technique using a genetic algorithm is acknowledged to the application in the piled raft.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 1992.10a
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• pp.79-89
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• 1992

This study is directed to propose a stability analysis and Design Criteria for Bridge Caisson foundations, with Could possibly replace the traditionals W.S.D. provisions of the Current Code, based on the FBOR(Load Factors based on optimum Reliability). The optimum reliability indices(Vertical bearing Capacity : $\beta$opt : 3.19, Lateral bearing Capacity : $\beta$opt= 3.15(ordinary), $\beta$opt : 2.93 (earthquake), Shearing resistance Capacity ; $\beta$opt : 2.87) are Selected as optimal Values Considering our practice base on the Calibration with the current Bridge Caisson foundation design Safety provisions, Load and resistance factors are measure by Using the proposed uncertainties and the Selected optimum reliability indices. furthermore, a set of nominal safety factors are proposed for the U.S.D. design provisions.

• Transactions of the Korean Society of Mechanical Engineers
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• v.18 no.5
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• pp.1117-1125
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• 1994

A UBET program is developed for determining the optimum sizes of preform of a rib-web part in axisymmetric closed-die forging. The program consists of forward and backward tracing processes. In forward process, material flow, degree of die filling, and forging load are predicted. In backward tracing process, the optimum dimensions of initial billet and preform are determined from the final-shape data without flash. The above program is easy to handle input data with and is convenient to visualize the whole process of closed-die forging with. Experiments are carried out with pure plasticine billets at room temperature. The theoretical predictions of the forging load and the flow pattern are in good agreement with the experimental results.

• 연구논문집
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• s.22
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• pp.65-74
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• 1992

This paper aims at calculating optimum design dimensions to minimize the weight satisfied strain and stress intensity of the frame while loading maximum weight into a mechanical press in the static condition. Analysis of the frame was carried out by using the FEM, then the optimum condition was obtained by using these data. As modeling in the finite element analysis has great impact on the reliablity of analysis results, the analyzed object was selected a 150-ton mechanical press of J Company, the part little affected to structural rigidity was simplified, the load condition was considered in the only maximum load, the boundary condition was used by giving symmetric displacement due to symmetric boundary condition, the finite element was applied a linear membrane element. An intermediate processor program applied the normal ANSYS to analyze finite elements was developed, and the design sensitivity was calculated. This program was applied to the optimum design.

• ETRI Journal
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• v.38 no.3
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• pp.568-578
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• 2016

A wireless power transfer (WPT) system is usually classified as being of either a two-coil or four-coil type. It is known that two-coil WPT systems are suitable for short-range transmissions, whereas four-coil WPT systems are suitable for mid-range transmissions. However, this paper reveals that the two aforementioned types of WPT system are alike in terms of their performance and characteristics, differing only when it comes to their matching-network configurations. In this paper, we first find the optimum load and source conditions using Z-parameters. Then, we estimate the maximum power transfer efficiency under the optimum load and source conditions, and we describe how to configure the matching networks pertaining to both types of WPT system for the given optimum load and source conditions. The two types of WPT system show the same performance with respect to the coupling coefficient and load impedance. Further, they also demonstrate an identical performance in the two cases considered in this paper, that is, a strong-coupled case and a weak-coupled case.

• Earthquakes and Structures
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• v.18 no.2
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• pp.185-199
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• 2020

A computationally-efficient method for multi-criteria optimisation is developed for performance-based seismic design of friction energy dissipation dampers in RC structures. The proposed method is based on the concept of Uniform Distribution of Deformation (UDD), where the slip-load distribution along the height of the structure is gradually modified to satisfy multiple performance targets while minimising the additional loads imposed on existing structural elements and foundation. The efficiency of the method is demonstrated through optimisation of 3, 5, 10, 15 and 20-storey RC frames with friction wall dampers subjected to design representative earthquakes using single and multi-criteria optimisation scenarios. The optimum design solutions are obtained in only a few steps, while they are shown to be independent of the selected initial slip loads and convergence factor. Optimum frames satisfy all predefined design targets and exhibit up to 48% lower imposed loads compared to designs using a previously proposed slip-load distribution. It is also shown that dampers designed with optimum slip load patterns based on a set of spectrum-compatible synthetic earthquakes, on average, provide acceptable design solutions under multiple natural seismic excitations representing the design spectrum.