• Transactions of the Korean Society of Mechanical Engineers A
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• v.30 no.6 s.249
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• pp.698-704
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• 2006

This paper presents an electrode shape design method for the multi-mode sensors that could deteict the selected structural multiple modes. The structure used for this study is an isotropic cantilever beam type with a PVDF (polyvinylidene fluoride) which is bonded onto the structure as a sensor. The shape optimization problem is solved by using Genetic Algorithm (GA) with an appropriate objective function. The performance of analytical optimal shape sensor is compared with that of experimental work. The results show that the, obtained electrode shape sensors have good performance to detect the multiple vibration modes simultaneously.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2009.05a
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• pp.215-219
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• 2009

For the effective manufacture of doubly curved metal plates, a line array roll set (LARS) process is proposed. The suggested process utilizes a pair of upper and lower symmetric roll assemblies. In the process, the initial plate is progressed into the final shape in a stepwise or pathwise manner according to the basic principle of the incremental forming process. In this work, the intermediate shape which is closest to a final shape is proposed to fabricate the desired shape effectively in design of forming schedule. The intermediate shape has homogeneous curvature in a longitudinal and transverse direction so that it can be fabricated easily without complicated controls of rolls in the roll set. The method of approximation using genetic algorithm is proposed and applied to some actual ship hulls to evaluate the efficiency of the algorithm.

• Smart Structures and Systems
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• v.3 no.1
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• pp.89-114
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• 2007

Two aspects of the design of a small-scale smart wing are addressed in this work, related to the ability of the wing to modify its cross section assuming the shape of two different airfoils and to the possibility of deflecting the profiles near the trailing edge in order to obtain hingeless control surfaces. The actuation is provided by one-way shape memory alloy wires eventually coupled to springs, Shape Memory Alloys (SMAs) being among the most promising materials for this kind of applications. The points to be actuated along the profiles and the displacements to be imposed are selecetd so that they satisfactorily approximate the change from an airfoil to the other and to result in an adequate deflection of the control surface; the actuators and their performances are designed so that an adequate wing stiffness is guaranteed, in order to prevent excessive deformations and undesired airfoil shape variations due to aerodynamic loads. The effect of the pressure distributions, calculated by way of the XFOIL software, and of the actuators loads, is estimated by FE analyses of the loaded wing. Two prototypes are then realised incorporating the variable airfoil and the hingeless aileron features respectively, and the verification of their shapes in both the actuated and non-actuated states, supported by image analysis techniques, confirms that interesting results are achievable with the proposed lay out and design considerations.

• Journal of Drive and Control
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• v.14 no.2
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• pp.37-44
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• 2017

In this study, in order to prevent cavitation in a variable swash-plate type hydraulic pump, a basic model impeller has been applied to a new pump, and the impeller shape has been optimized through flow analysis. Based on the analysis results, we could propose an impeller shape with high efficiency and low possibility of cavitation in comparison with the basic model. The simplification of the basic shape of the impeller of the hydraulic pump was performed in three parts in the order of hub shape, wing, and curvature, and eight design parameters were defined to satisfy the design requirement. Compared with the initial model of the impeller, when the differential pressure of the optimum model increased, the efficiency was improved. It achieved the goal of design improvement because cavitation did not occur under the rated operating conditions.

• Proceedings of the Korean Geotechical Society Conference
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• 2002.10a
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• pp.659-664
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• 2002

New design method about the spread footing was developed using only soil and geosynthetics. This footing will be able to replace the concrete footing at constructing the foundation of small structures. As shown in Fig-3(b), after excavating the ground in semicircular shape, geosynthetics is layed on the semicircular shape of ground and let the soil filled. Geosynthetics of upper side are fixed tightly each other It can be thought to be a kind of great bag with semicircular shape. We performed two kinds of experiments to investigate the deformation and the failure shape of spread footing reinforced by geosynthetics. First, after making model ground with aluminium rods, the lattice point of 1cm ${\times}$ 1cm size of the side of aluminium rods have been painted with various kinds of colors. We have observed the movement of painted rods during loading. Second, we have taken pictures about failure process using B-shutter method. Analysing the behavior of model ground reinforced in a semicircular shape, we could know the reinforced one has much greater and wider plastic area than unreinforced one at failure. Based on the experimental results, new design method was proposed, which has a possibility to apply at the field works.

• International Journal of Ocean System Engineering
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• v.3 no.3
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• pp.152-157
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• 2013

This study, a new concept design of the stem and aims to determine the suitability of various carbon/PEEK composite designs for artificial hip joints. Shear stress tested with alternative materials of the Ti-based stem for artificial hip joints. In addition, FEA is conducted according to the fiber ply orientation and the load condition for carbon/PEEK composites. The stem shape of two types was designed through the shape normal of the femur. Multidirectional load cases were used for each FEA model. In the case of general shape, the results show that the stress of ply orientation case II was lower than for cases I and III. On the other hand, in the case of the curved shape, ply orientation case I was lowest. In the case of the Ti stem, the stress of the curved shape was 18% lower than the general shape.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.21 no.9
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• pp.28-34
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• 2022

The flow at the top surface of the hopper is of particular industrial interest. Previously, the velocity distribution inside the hopper was predicted using the simple, void and spot models, which are equations for the particle flow field. However, because these equations cannot predict the velocity distribution at the top surface, a new equation has been recently proposed. This study employed the discrete element method with the changed shape of the particles. Based on the results, the shape of the particle had no effect on the discharge angle and shape of the velocity distribution; however, it greatly affected the size of the velocity distribution and bed thickness of the flowing particles. Therefore, in the future, it is necessary to modify the theoretical equation by considering the shape of the particles.

• Journal of the Korean housing association
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• v.21 no.5
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• pp.23-33
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• 2010

In the late twentieth century, the multistory housing has become the most preferred housing type. Moreover, in multistory housing design, not only interior design but also exterior design, uniqueness and characteristic have been added as significant factors in design to break simplicity and uniformity. The purpose of this study is to understand the tendency of the elevation design in Europe and to suggest the idea for elevation design for domestic. Also, each elements of elevation were analyzed through classification and schematization which categorized by its own characteristic. Design elements can be classified into three categories. They are corresponding with inner spaces, emphasizing visual expression of exterior material and texture, and presenting aesthetic factors of building shape. Those are named as the Spatial Externalization, the Visual Expression, and the Expression of Building Shape. In this frame nineteen elevations of sixteen different cases were analysed. As a result of case studies, it is clear that elevation designs were not standardized and each cases has its own characteristics. Also it showed how the each design elements can be coordinated as a total design and how they expressed identities of each housing. This study could contribute to motivate diversifying the design of multistory housing.

• International Journal of Fluid Machinery and Systems
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• v.4 no.1
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• pp.14-24
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• 2011

In this paper, design optimization for mixed-flow pump impellers and diffusers has been studied using a commercial computational fluid dynamics (CFD) code and DOE (design of experiments). We also discussed how to improve the performance of the mixed-flow pump by designing the impeller and diffuser. Geometric design variables were defined by the vane plane development, which indicates the blade-angle distributions and length of the impeller and diffusers. The vane plane development was controlled using the blade-angle in a fixed meridional shape. First, the design optimization of the defined impeller geometric variables was achieved, and then the flow characteristics were analyzed in the point of incidence angle at the diffuser leading edge for the optimized impeller. Next, design optimizations of the defined diffuser shape variables were performed. The importance of the geometric design variables was analyzed using $2^k$ factorial designs, and the design optimization of the geometric variables was determined using the response surface method (RSM). The objective functions were defined as the total head and the total efficiency at the design flow rate. Based on the comparison of CFD results between the optimized pump and base design models, the reason for the performance improvement was discussed.

• Proceedings of the Korean Geotechical Society Conference
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• 1993.03a
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• pp.1-8
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• 1993

This paper concerns the analytical concept of tunnel design for the case where the groundwater level remains almost to a standstill even though the steady state groundwater flow occurs through tunnel drainage systems. The effect of the seepage force is considered in analysis. Two case strudies are made : the one the round shape tunnel ; the other the horse shape. The design moments, shear forces and axial forces are calculated and these results are compared to the case of water proof tunnel design as well as the case of the tunnel design without groundwater consideration.