• KSCE Journal of Civil and Environmental Engineering Research
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• v.12 no.1
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• pp.197-205
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• 1992

For the optimal design of composite breakwaters, a computer program PROCOBRA is developed using the combined ALM-BFGS algorithm. A model formulation for the section design optimization problem of composite breakwaters is proposed where a concept of subsectional weighting factors is introduced in the objective function. Usability of the program is verified through a numerical example. From the study, it is found that the ALM-BFGS method is reliable and can be effectively applied for the design optimization of coastal structures. Compared with conventional design process, it is proved that the economical design of composite breakwaters is possible.

• Journal of the korean Society of Automotive Engineers
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• v.11 no.2
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• pp.24-33
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• 1989

본 고에서는 이러한 추세에 따라서, 보다 효율적인 optimization program에 대해서 소개하고자 한다. 사용한 최적화 알고리즘은 ALM(augmented lagrange multiplier) 방법을 적용해서 구속조건이 있는 문제를 구속조건이 없는 문제로 변환한 후, self-scaling BFGS(broydon-flecher-goldfarb-schanno)를 적용한다. BFGS의 각 descent 방향에서의 step 길이는, sequential search로 unimodal point를 구해서, golden section 방법으로 refine을 한후, cubic approximation을 적용해서 구한다.

• Journal of the Korean Society of Hazard Mitigation
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• v.10 no.3
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• pp.31-38
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• 2010

In this study, it is suggested that it has to reliability-based design methodology with respect to bridge structure-rail longitudinal interaction and bridge structure-vehicle interaction. For the structural analysis, commercial package, ABAQUS, are used for a three-dimensional finite element analysis. The optimization process utilizes a well-known optimizer, ADS(Automated Design Synthesis). Optimization technique is utilized the ALM-BFGS method for global area search and Golden Section Method for 1-D search. In general, ALM-BFGS method don't need the 1-D search, and that algorithm converge a 0.1~0.2 of Push-Off factor. But in this study, value of Push-Off factor is used 90, therefore 1-D search should be needed for effective convergency. That algorithm contains the "heuristic decision method". As a result of optimum design of 2-main steel girder birdge with 5${\times}$(1@50m), design methodology suggested in this study was demonstrated more economic and efficient than existing design and LCC optimization not considering bridge-rail longitudinal interaction and bridge-vehicle interaction.

• Transactions of the Korean Society of Mechanical Engineers
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• v.15 no.2
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• pp.544-556
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• 1991

The optimization of many engineering design problems requires a nonlinear programming algorithm that is robust and efficient. A general-purpose nonlinear optimization program IDOL (Interactive Design Optimization Library) is developed based on the Augmented Lagrange Mulitiplier (ALM) method. The ideas of selecting a good initial design point, using resonable initial values for Lagrange multipliers, constraints scaling, descent vector restarting, and dynamic stopping criterion are employed for computational enhancement to the ALM method. A descent vector is determined by using the Broydon-Fletcher-Goldfarb-Shanno (BFGS) method. For line search, the Incremental-Search method is first used to find bounds on the solution, then the bounds are reduced by the Golden Section method, and finally a cubic polynomial approximation technique is applied to locate the next design point. Seven typical test problems are solved to show IDOL efficient and robust.

• Proceedings of the Korea Concrete Institute Conference
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• 2000.10a
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• pp.253-258
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• 2000

Recently, the area of design optimization, especially structural optimization, has been and to be a continuous active area of research. And the design optimizations of port facilities have been achieved by many other civil engineers. But the design optimization of port facilities were limited to the design optimization of the breasting dolphin. This paper invested the design optimization of mooring pier and the foundations of mooring pier was suggested considering the convenience of repair and reinforcement work. The mooring pier devised with prestressed precast concrete panel and rigid frame welded wide flange beam to steel pipe pile. To accomplish the design optimization of mooring pier, the Augmented Lagrangian Multiplier Method(ALM) of ADS(Garret N. Vanderplaats) optimization routine, BFGS method as optimizer and Golden Section Method as one dimensional search were utilized. As a result, thirty percent of material cost for construction was reduced by design optimization. The tensile stress of concrete panel and bottom flage was critical constraints under service load. So, using high strength concrete and steel will be economical. And lots of initial values must be invested to accomplish the design optimization in design procedures.

• Transactions of the Korean Society of Mechanical Engineers
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• v.14 no.3
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• pp.594-602
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• 1990

A computer-aided design system of involute cylindrical gears(spur and helical gears) for power transmission is developed, in which the volume of a gear unit is minimized with satisfying various design constraints. As the design constraints, bending strength and pitting resistance of AGMA 218.01, scoring of Dudley's flash temperature, contact ratio, and involute interference of pinion are considered and effective factors for strength calculation(life, reliability, hardness ratio, load distribution, velocity, etc.) are also included. This complicated nonlinear optimization problem is solved by using ALM(Augmented-Lagrange-Multiplier) method with self scaling BFGS(Broydon-Fletcher-Goldfarb-Shanno) method employed for unconstrained optimization programming. This design method can be easily applied to designing power transmission gear unit in the machines of various kinds. It is expected for the proposed method to be a contribution for an automated design of gear unit towards weight minimization, miniaturization and high strength of gear unit.

• Journal of the Korean Society for Railway
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• v.12 no.6
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• pp.974-982
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• 2009

To improve the effectiveness and economics the bridge design methodology considering the bridge/rail longitudinal analysis and bridge/vehicle dynamic effect suggested in this study. The reliability-based Life-Cycle Costs(LCC) effective optimum design is applied to a 2-main steel girder bridge, 5$\times$(1@50m) for comparison with conventional design, initial cost optimization and equivalent LCC optimization. As a result of the optimum design based on reliability, it may be stated that the design of High-Speed railway bridges considering the bridge/rail longitudinal analysis and bridge/vehicle dynamic effect are more efficient than typical existing bridges and LCC optimization without respect to bridge/rail longitudinal analysis and bridge/vehicle dynamic effect. The result of optimization design considering the interaction, design methodology suggested in this study, is higher than result of initial cost optimization design in initial cost, but that has the advantage than result of initial cost optimization design in expected LCC.

• Journal of the Korean Society of Hazard Mitigation
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• v.10 no.6
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• pp.27-34
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• 2010

Recently, high-speed railway systems have gained increased interest as a means of environmental friendly transportation, and numerous bridges for high-speed railways have been constructed accordingly. However, bridge design for high-speed railways requires more consideration than conventional railway design because fast-moving trains will lead to significant impact on bridge structures. Thus, this research proposes a revised design considering both bridge-rail longitudinal interaction and dynamic effect of trains to ensure stability of fast travelling trains. To validate the proposed design algorithm, numerical analyses are performed and compared using a constructed 250 m long bridge with 5 spans for a high-speed railway. From the numerical results, the proposed optimum design of high-speed railway bridges exhibits the most economic life-cycle-cost (LCC) when compared with several existing design approaches.