• Bulletin of the Society of Naval Architects of Korea
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• v.24 no.4
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• pp.45-52
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• 1987

In this paper, merits and demerits of Nelder and Mead Penalty Function Method(SUMTNM) and Flexible Tolerance Method(FTM) are investigated from the standpoint of generality, accuracy and efficiency. SUMTNM is combined with Nelder and Method and SUMT, but FTM improves the values of the objective function by using information provided by feasible points as well as certain nonfeasible points termed near-feasible points. Therefore, FTM uses more information than SUMTNM for minimizing object function. The structural analysis of a vertically corrugated bulkhead is performed by collapse mechanism and plate buckling analysis. Based on the results of this analysis, minimum structural weight design of a corrugated bulkhead by use of above two optimization techniques is carried out by investigating the effects of sizes of bulkhead on the structural weight.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 1996.04a
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• pp.182-189
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• 1996

The focus of this study is on the problem of the design of structure of undetermined topology. This problem has been regarded as being the most challenging of structural optimization problems, because of the difficulty of allowing topology to change. Conventional approaches break down when element sizes approach to zero, due to stiffness matrix singularity. In this study, a novel nonlinear Programming formulation of the topology Problem is developed and examined. Its main feature is the ability to account for topology variation through zero element sizes. Stiffness matrix singularity is avoided by embedding the equilibrium equations as equality constraints in the optimization problem. Although the formulation is general, two dimensional plane elasticity examples are presented. The design problem is to find minimum weight of a plane structure of fixed geometry but variable topology, subject to constraints on stress and displacement. Variables are thicknesses of finite elements, and are permitted to assume zero sizes. The examples demonstrate that the formulation is effective for finding at least a locally minimal weight.

• Coupled systems mechanics
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• v.11 no.3
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• pp.259-266
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• 2022

Non-Traditional Optimization methods are successfully used in solving many engineering problems. Shaft is one of important element of machines and it is used to transmit power from a machine which produces power to a machine which absorbs power. In this paper, ten non-traditional optimization methods that are ALO, GWO, DA, FPA, FA, WOA, CSO, PSO, BA and GSA are used to find minimum weight of hollow shaft to get global optimal solution. The problem has two design variables and two inequality constraints. The comparative results show that the Particle Swarm Optimization outperforms other methods and the results are validated using ANSYS.

• Journal of The Korean Society of Agricultural Engineers
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• v.57 no.4
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• pp.11-19
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• 2015

The important properties of EVA (ethylene vinyl acetate) redispersible polymer was waterproof, densification of internal pore space of concrete and ball bearing and micro filler. Also, the significant role of polypropylene(PP) fiber was crack control and blockade of movement for deterioration factors. The most studies for EVA were limited in the field of mortar and PP fiber reinforced concrete had been studied in the state of being restricted unit water content, rich mix and mixing much of the fiber without considering construction site. Therefore, the control mix design were applied in ready mixed concrete using 10 % fly ash of total cement weight used in batch plant. On the basis of control mix design, EVA contents ranging from 0 % to 10 % of total cement weight and PP fiber contents ranging from 0 % to 0.5 % of EVA concrete volume were used in the mix designs. The results showed the maximum compressive strength value was measured at EVA 5.0 % and PP fiber 0.1 %, the minimum water absorption ratio was at EVA 10 % and PP fiber 0 %, the durability factor for freezing and thawing resistance was at EVA 5.0 % and PP fiber 0.3 % and the minimum weight reduction ratio of resistance to sulfuric acid attack was at EVA 10 % and PP fiber 0.5 % after curing age 42days. Meanwhile, From these results, PP fiber reinforced EVA concrete would be very benefit, if each optimal mix types were used in hydraulic structures, underground utilities and agricultural structures.

• Structural Engineering and Mechanics
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• v.70 no.2
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• pp.169-178
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• 2019

The replacement of damaged components is an important task for long-span bridges. Conventional strategy for component replacement is to close the bridge to traffic, so that the influence of the surrounding environment is reduced to a minimum extent. However, complete traffic interruption would bring substantial economic losses and negative social influence nowadays. This paper investigates traffic control technologies without interruption for component replacement of long-span bridges. A numerical procedure of traffic control technologies is proposed incorporating traffic microsimulation and site-specific data, which is then implemented through a case study of cable replacement of a long-span cable-stayed bridge. Results indicate traffic load effects on the bridge are lower than the design values under current low daily traffic volume, and therefore cable replacement could be conducted without traffic control. However, considering a possible medium or high level of daily traffic volume, traffic load effects of girder bending moment and cable force nearest to the replaced cable become larger than the design level. This indicates a potential risk of failure, and traffic control should be implemented. Parametric studies show that speed control does not decrease but increase the load effects, and flow control using lane closure is not effectual. However, weight control and gap control are very effective to mitigate traffic load effects, and it is recommended to employ a weight control with gross vehicle weight no more than 65 t or/and a gap control with minimum vehicle gap no less than 40 m for the cable replacement of the case bridge.

• International Journal of Precision Engineering and Manufacturing
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• v.3 no.2
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• pp.15-21
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• 2002

A control-structure combined optimal design problem is discussed taking a 3-D truss structure as a design object. We use descriptor forms for a controlled object and a generalized plant because the structural parameters appear naturally in these farms. We consider not only minimum weight design problem for structure system, but also suppression problem of the effect of disturbances for control system as the purpose of the design. A numerical example shows the validity of combined optimal design of structure and control systems. We also consider the validity of sensor-actuator collocation for control system design in this paper.

• Journal of Power System Engineering
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• v.8 no.1
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• pp.69-74
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• 2004

A structure-control combined optimal design problem is discussed taking a 3-D truss structure as a design object. We use descriptor forms for a controlled object and a generalized plant because the structural parameters appear naturally in these forms. We consider not only minimum weight design problem for structure system, but also suppression problem of the effect of disturbances for control system as the purpose of the design. A numerical example shows the validity of combined optimal design of structure and control systems. We also consider the validity of sensor-actuator collocation for control system design in this paper.

• Journal of Ocean Engineering and Technology
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• v.20 no.3 s.70
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• pp.7-14
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• 2006

This paper discusses the structural design and analysis of a 6,000 meters depth-rated capable deep-sea unmanned underwater vehicle (UUV) system. The UUV system is currently under development by Maritime and Ocean Engineering Research Institute(MOERI), Korea Ocean Research and Development Institute (KORDI). The UUV system is composed of three vehicles - a Remotely Operated Vehicle (ROV), an Autonomous Underwater Vehicle (AUV) and a Launcher - which include underwater equipment. The dry weight of the system exceeds 3 tons hence it is necessary to carry out the optimal design of structural system to ensure the minimum weight and sufficient space within the frame for the convenient use of the embedded equipments. In this paper, therefore, the structural design and analysis of the ROV and launcher frame system were carried out, using the optimizing process. The cylindrical pressure vessels for the ROV were designed to resist the extreme pressure of 600 bars, based on the finite element analysis. The collapse pressure for the cylindrical pressure vessels was also checked through a theoretical analysis.

• Structural Engineering and Mechanics
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• v.27 no.5
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• pp.575-588
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• 2007

In this paper, two algorithms are presented for the optimum design of geometrically nonlinear steel space frames using tabu search. The first algorithm utilizes the features of short-term memory (tabu list) facility and aspiration criteria and the other has long-term memory (back-tracking) facility in addition to the aforementioned features. The design algorithms obtain minimum weight frames by selecting suitable sections from a standard set of steel sections such as American Institute of Steel Construction (AISC) wide-flange (W) shapes. Stress constraints of AISC Allowable stress design (ASD) specification, maximum drift (lateral displacement) and interstorey drift constraints were imposed on the frames. The algorithms were applied to the optimum design of three space frame structures. The designs obtained using the two algorithms were compared to each other. The comparisons showed that the second algorithm resulted in lighter frames.

• Proceedings of the KSR Conference
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• 2004.06a
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• pp.1197-1204
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• 2004

The metropolitan cities and operation companies of urban transit railway are driving to construct the LRT(light rail transit) system because of the advantage of construction cost and environmental serviceability. This study suggests the optimal design method of steel box girder considering dynamic characteristics of LRT with rubber wheel. The behavior and design constraints are formulated based on the structural design criteria for LRT. Genetic algorithm is applied to the minimum weight design of structural system. A typical example is solved to illustrate the applicability of the proposed minimization algorithm. From the results of application example, the optimum design of steel box girder is successfully accomplished. Therefore, this system can act as a consultant to assist novice designers in the design of steel box girder for LRT with rubber wheel.