• Journal of the Society of Naval Architects of Korea
• /
• v.46 no.1
• /
• pp.87-95
• /
• 2009

The applicability of optimization techniques for hull surface fitting has been important in the ship design process. In this research, the Genetic Algorithm has been used as a searching technique for solving surface fitting problem and minimizing errors between B-spline surface and the ship's offset data. The encoded design variables are the location of the vertex points and parametric values. The sufficient accuracy in surface fitting implies not only various techniques for computer-aided design, but also the future production design.

• International Journal of Aerospace System Engineering
• /
• v.2 no.2
• /
• pp.10-14
• /
• 2015

To design airfoils for novel airplanes, new knowledge of aerodynamics is required. In this study, modified Parametric SECtion (PARSEC) which is a airfoil representation is applied to airfoil design using a multi-objective genetic algorithm to obtain an optimal airfoil for consideration in the development of a Martian airplane. In this study, an airfoil that can obtain a sufficient lift and glide ratio under lower thrust is considered. The objective functions are to maximize maximum lift-to-drag ratio and to maximize the trailing edge thickness. In this way, information on the low Reynolds number airfoil could be extracted efficiently. The optimization results suggest that the airfoil with a sharper thickness at the leading edge and higher camber at the trailing edge is more suitable for a Martian airplane. In addition, several solutions which has thicker trailing edge thickness were found.

• International Journal of Naval Architecture and Ocean Engineering
• /
• v.7 no.4
• /
• pp.655-669
• /
• 2015

The Overall Motion Sickness Incidence is applied to the hull form optimization of a wave piercing high-speed catamaran vessel. Parametric hull modelling is applied to generate two families of derived hull forms, the former varying the prismatic coefficient and the position of longitudinal centre of buoyancy, the latter instead the demi-hull separation. Several heading angles are analysed in a seaway, considering all combinations of significant wave height and zero-crossing period under two operating scenarios. The optimum hull is generated and vertical accelerations at some critical points on main deck are compared with the parent ones. Finally a comparative analysis with the results obtained for a similarly sized monohull passenger ship is carried out, in order to quantify, by the OMSI, the relative goodness in terms of wellness onboard of monohulls and catamarans, as a function of sea states and operating scenarios.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
• /
• 2002.10a
• /
• pp.40-44
• /
• 2002

선박 설계시 최적화에 있어 종래에는 Random search Parametric study, Hook&Jeeves Method등이 사용되어져 왔으나 1960년대 Genetic algorithm이 소개되고 꾸준히 발전함과 함께 선박 설계에서도 Genetic algorithm이 사용되기 시작하였다. 본 논문에서는 이러한 Genetic algorithm 중 Simple Genetic algorithm(SGA), Micro Genetic algorithm(MGA), Threshold Genetic algorithm(TGA), Hybrid Genetic algorithm(HGA)을 선박 설계에 적용하여 그 성능을 비교 검토해 보았다. MGA는 계산 부담을 줄이기 위해 작은 개체로 효율적인 탐색을 하며, TGA는 local optimum에서 쉽게 벗어나게 할 수 있는 특징이 있다. HGA는 Hook&Jeeves Method를 Genetic algorithm과 병합되어 있다. 이를 바탕으로 본 논문에서 망간단괴 수송선의 경제성을 평가한다. 평가 방법은 연간 300만톤을 생산한다고 가정하여 연간 운송 용적을 동호제약으로 해서 최적화를 한 뒤, 이를 이용하여 몇가지 Case로 나누어서 초기 자본, 연간 비용, 20년간 총 비용을 계산하여 가장 경제적인 선박을 선택한다.

• Proceedings of the Korean Geotechical Society Conference
• /
• 2006.03a
• /
• pp.530-535
• /
• 2006

The Pusan clays are soft and thick deposits and in some places, they reach even up to 50-70m. So, the pile foundations are inevitable in almost all cases. But they are significantly expansive when the length of the pile reaches about 70m. In this study, a comprehensive parametric study has been carried out in order to reduce the pile length and number of piles required in turn the cost of the foundation for particular building. A belled shaft pile has been optimized for a typical soil profile using the PLAXIS (FEM code). These results have shown a new direction of the pile foundation in Pusan, Korea. The results including the variation of contact pressures at the bottom of the bell, optimization of the angle of the bell and height of the bell in terms of the diameter of the shaft. And also, the design curves have been generated so that they can be directly used for design of belled shaft foundations. However, the structural strength criterion is being checked in the concerned laboratory.

• Journal of the Korean Society of Industry Convergence
• /
• v.25 no.1
• /
• pp.121-129
• /
• 2022

With the recent increase in international trade volume the trade volume through ships is also continuously increasing. The treatment of ballast water goes through the following five steps, samples are taken and analyzed at each step, and samples are obtained using a suction pump. These suction pumps have low efficiency and thus need to be improved. In this study, it is to optimize the form of the impeller which affects directly improvements of performance to determine the capacity of suction pump and to fulfill the purpose of this research. To do it, we have carried out parametric design as an input variable, geometric form for the impeller. By conducting the flow analysis for the optimum form, it has confirmed the value of improved results and achieved the purpose to study in this paper. It has selected the necessary parameter for optimizing the form of the pump impeller and analyzed the property using experiment design. And it can reduce the factor of parameter for local optimization from findings to analyze the property of form parameter. To perform MOGA(Multi-Objective Genetic Algorithm) it has generated response surface using parameters for local optimization and conducts the optimization using multi-objective genetic algorithm. with created experiment cases, it has performed the computational fluid dynamics with model applying the optimized impeller form and checked that the capacity of the pump was improved. It could verify the validity concerning the improvement of pump efficiency, via optimization of pump impeller form which is suggested in this study.

• International Journal of Aeronautical and Space Sciences
• /
• v.15 no.4
• /
• pp.383-395
• /
• 2014

According to the requirement of wing weight estimation and frequent adjustments during aircraft conceptual design, a wing weight estimation method considering the constraints of structural strength and stiffness is proposed to help designers make wing weight estimations rapidly and accurately. This method implements weight predictions on the basis of structure weight optimization with stiffness constraints and strength constraints, which include achievement of wing shape parametric modeling, rapid structure layout, finite element (FE) model automated generation, load calculation, structure analysis, weight optimization, and weight computed based on modeling. A software tool is developed with this wing weight estimation method. This software can realize the whole process of wing weight estimation with the method and the workload of wing weight estimation is reduced because much of the work can be completed by the software. Finally, an example is given to illustrate that this weight estimation method is effective.

• Wind and Structures
• /
• v.18 no.2
• /
• pp.195-213
• /
• 2014

Recently, the horizontal axis rotor performance optimizer (HARP_Opt) tool was developed in the National Renewable Energy Laboratory, USA. This innovative tool is becoming more popular in the wind turbine industry and in the field of academic research. HARP_Optwas developed on the basis of two fundamental modules, namely, WT_Perf, a performance evaluator computer code using the blade element momentum theory; and a genetic algorithm module, which is used as an optimizer. A pattern search algorithm was more recently incorporated to enhance the optimization capability, especially the calculation time and consistency of the solutions. The blade optimization is an aspect that is highly dependent on experience and requires significant consideration on rotor control strategies, wind data, and generator type. In this study, the effects of rotor control strategies including fixed speed and fixed pitch, variable speed and fixed pitch, fixed speed and variable pitch, and variable speed and variable pitch algorithms on optimal blade shapes and rotor performance are investigated using optimized blade designs. The effects of environmental wind data and the objective functions used for optimization are also quantitatively evaluated using the HARP_Opt tool. Performance indices such as annual energy production, thrust, torque, and roof-flap moment forces are compared.

• International Journal of CAD/CAM
• /
• v.5 no.1
• /
• pp.1-10
• /
• 2005

A new approach based on vector field clustering for tool path optimization of 5-axis CNC machining is presented in this paper. The strategy of the approach is to produce an efficient tool path with respect to the optimal cutting direction vector field. The optimal cutting direction maximizes the machining strip width. We use the normalized cut clustering technique to partition the vector field into clusters. The spiral and the zigzag patterns are then applied to generate tool path on the clusters. The iso-scallop method is used for calculating the tool path. Finally, our numerical examples and real cutting experiment show that the tool path generated by the proposed method is more efficient than the tool path generated by the traditional iso-parametric method.

• International Journal of Fluid Machinery and Systems
• /
• v.9 no.2
• /
• pp.150-158
• /
• 2016

In this paper, a new framework that works the automatic execution with less design cycle time and human intervention bottlenecks is introduced to optimize the vortex shedder design by numerical integration method. This framework is based on iSIGHT combined with the pre-processor GAMBIT, and flow analysis software FLUENT. Two vortex shedders, circular with slit and triangular- semi circular cylinder, are employed as the designed models to be optimized, and DOE driver is used for optimization. According to the essential properties of a vortex shedder, it has found that the best diameters are 30mm for circular cylinder with slit and 30 to 35 mm for tri-semi cylinder. For slit ratio, 0.1 and 0.15 are the optimized values for circular with slit and tri-semi cylinder respectively. And it is found that these optimal results generated by DOE automated design cycle are in well agreement with the experiment.