• Journal of the Society of Naval Architects of Korea
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• v.40 no.6
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• pp.12-19
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• 2003

Corrugated bulkheads for a bulk carrier are divided into watertight bulkheads and deep tank bulkheads. Design of the watertight bulkheads is principally determined by the permissible limit of Classification and IACS requirements. But, the verification of strength through finite element analysis is indispensable for design of the deep tank bulkheads. A stage for stress evaluation of corrugated part is required for optimum structural design of the deep tank bulkheads. Since the finite element analysis for real model requires excessive amount of calculation time, in this study one corrugated structure is replaced with beam element and is idealized as 2 dimensional frame structure connected to upper and lower stool Minimum weight design of the deep tank bulkheads is performed through generalized sloped deflection method(GSDM) as direct calculation method. The purpose of this study is the development of design system for the minimization of steel weight of deep tank bulkheads as well as watertight bulkheads. Discrete variables are used as design variables for the practical design. Evolution strategies(ES) is used as an optimization technique.

• International Journal of High-Rise Buildings
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• v.6 no.1
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• pp.49-72
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• 2017

The Guangzhou International Finance Centre (IFC) is a landmark building that symbolizes the emerging international strength of Guangzhou, China's third largest city. It is also one of the dual iconic towers along the main axis of Guangzhou Zhujiang New Town. Arup adopted a total engineering approach in embracing sustainability and aiming at high efficiency solutions based on performance-based design principles covering structures, building services, fire engineering, vertical transportation, and façade performance to constitute an efficient and cost-effective overall building design. Through dynamic integration of architectural and engineering principles, Guangzhou IFC represents a pioneering supertall building in China. It adopts a diagrid exoskeleton structural form that is clearly expressed through the building's façade and gives the building its distinctive character. The aerodynamic shape of the building not only presents the aesthetic quality of elegant simplicity, but also reduces the effects of wind, thereby reducing the size and weight of the structure. State-of-the-art advanced engineering methods, such as optimization techniques and nonlinear finite element modelling, were applied in parallel with large-scale experimental programs to achieve an efficient and high-performance design taking into account the constructability and cost-effectiveness for a project of this scale.

• Polymer(Korea)
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• v.32 no.1
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• pp.19-25
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• 2008

The purpose of this study was improving the rheology properties of dentifrice by finding optimum binders polymer system which consists of carboxymethylcellulose (CMC), carbomer, and Mg/Al silicate. Response surface methodology (RSM) was employed to investigate the correlation between polymers and rheological properties of dentifrice and to optimize responses. Rheological properties were measured with oscillatory rheometer. As a result, it was identified that gel strength and yield stress were dependent on contents of CMC and carbomer and CMC caused long stringiness of dentifrice. And springness of dentifrice was dependent on contents of CMC and Mg/Al silicate. Optimum components proportion of polymers and silicate were obtained by responses optimization process. According to determined optimum components proportion, it was possible to observe a dentifrice with improved rheological properties.

• Journal of Welding and Joining
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• v.23 no.4
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• pp.41-47
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• 2005

Generally, the use of robots in manufacturing industry has been increased during the past decade. GMA(Gas Metal Arc) welding process is an actively Vowing area, and many new procedures have been developed for use with high strength alloys. One of the basic requirement for the automatic welding applications is to investigate relationships between process parameters and bead geometry. The objective of this paper is to develop a new approach involving the use of neural network and multiple regression methods in the prediction of bead geometry for GMA welding process and to develop an intelligent system that visualize bead geometry in order to employ the robotic GMA welding processes. Examples of the simulation for GMA welding process are supplied to demonstrate and verify the proposed system developed using MATLAB. The developed system could be effectively implemented not oかy for estimating bead geometry, but also employed to monitor and control the bead geometry in real time.

• International Journal of Concrete Structures and Materials
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• v.11 no.2
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• pp.301-313
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• 2017

This paper presents the fibre-matrix interfacial properties of hooked end steel fibres embedded in ultra-high performance mortars with various water/binder (W/B) ratios. The principle objective was to improve bond behaviour in terms of bond strength by reducing the (W/B) ratio to a minimum. Results show that a decrease in W/B ratio has a significant effect on the bond-slip behaviour of both types of 3D fibres, especially when the W/B ratio was reduced from 0.25 to 0.15. Furthermore, the optimization in maximizing pullout load and total pullout work is found to be more prominent for the 3D fibres with a larger diameter than for fibres with a smaller diameter. On the contrary, increasing the embedded length of the 3D fibres did not result in an improvement on the maximum pullout load, but increase in the total pullout work.

• Journal of Ocean Engineering and Technology
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• v.27 no.2
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• pp.27-32
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• 2013

A valve is a marine structure that is subjected to multiple seawater loads. Therefore, it is necessary to define the kind of loads applied to it to confirm whether the structure has sufficient strength. In this research, we aimed to find the optimal solution for the stress and deformation of valves under various loads. We first selected design variables and implement a finite element analysis according to changes in the thickness of each component of a valve based on a central composite design. Next we developed a regression model of the response surface. Using this model, we calculated the optimal objective value based on NSGA-II. Finally, to confirm the correspondence between the optimal objective value and the real FEM value, we compared the optimal result and structural analysis result to verify the performance of NSGA-II.

• Proceedings of the KSME Conference
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• 2001.06b
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• pp.216-221
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• 2001

The equivalent source method(ESM) is used for the calculation of the internal pressure field for an enclosure which can have arbitrary boundary conditions and may include internal objects which scatter the sound field. The advantage of using ESM is that it requires relatively low computing cost and is easy to model the internal diffracting objects. In the ESM modelling, some of the equivalent positions are chosen to be the same as the first order images of the source inside the enclosure, some are positioned on a spherical surface some distance outside the enclosure. The normal velocity on the surfaces of the enclosure walls is evaluated at a larger number of positions than there are equivalent sources. The sum of the squared difference between this velocity and the expected is minimized by adjusting the strength of the equivalent sources. This study is on the optimal equivalent source positions, the far field sources. Typically, the far field sources are evenly distributed on a surface of a virtual sphere which is centered at the enclosure with a sufficiently large radius. In this study, optimal far field source locations are searched using simulated annealing method and simulation results showed that optimally located sources gave better accuracy even with a smaller number of far field sources.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.17 no.5
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• pp.10-22
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• 2008

In an automotive body structure, a design configuration that fulfills structural requirements such as deflection, stiffness and strength is necessary for structural design and is composed of various components. The integrated design is used to obtain a minimum weight structure with optimal or feasible performance based on conflicting constraints and boundaries. The mechanical design must begin with the definition of one or more concepts for structure and specification requirements in a given application environment. Structural optimization is then introduced as an integral part of the product design and used to yield a superior design to the conventional linear one. Although finite element analysis has been firmly established and extensively used in the past, geometric and material nonlinear analyses have also received considerable attention over the past decades. Also, nonlinear analysis may be useful in the area of structural designs where instability phenomena can include critical design criteria such as plastic strain and residual deformation. This proposed approach can be used for complicated structural analysis for an integrated design process with the nonlinear feasible local flexibilities between system and subsystems.

• Steel and Composite Structures
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• v.20 no.3
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• pp.545-569
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• 2016

Stiffeners have widely been used in lateral load resisting systems to improve the buckling stability of shear panels in steel frames. However, due to major differences between plate girders and steel plate shear walls (SPSWs), use of plate girder equations often leads to uneconomical and, in some cases, incorrect design of stiffeners. Hence, this paper uses finite element analysis (FEA) to describe the effect of the rigidity and arrangement of stiffeners on the buckling behavior of plates. The procedures consider transverse and/or longitudinal stiffeners in various practical configurations. Subsequently, curves and formulas for the design of stiffeners are presented. In addition, the influence of stiffeners on the inward forces subjected to the boundary elements and the tension field angle is investigated as well. The results indicate that the effective application of stiffeners in SPSW systems not only improves the structural behavior, such as stiffness, overall strength and energy absorption, but also leads to a reduction of the forces that are exerted on the boundary elements.

• Nuclear Engineering and Technology
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• v.40 no.2
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• pp.127-132
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• 2008

An experimental loop operating with water at supercritical conditions(25MPa, $600^{\circ}C$ in the test section) is designed for operation in the research reactor LVR-15 in UJV Rez, Czech Republic. The loop should serve as an experimental facility for corrosion tests of materials for in-core as well as out-of-core structures, for testing and optimization of suitable water chemistry for a future HPLWR and for studies of radiolysis of water at supercritical conditions, which remains the domain where very few experimental data are available. At present, final necessary calculations(thermalhydraulic, neutronic, strength) are being performed on the irradiation channel, which is the most challenging part of the loop. The concept of the primary and auxiliary circuits has been completed. The design of the loop shall be finished in the course of the year 2007 to start the construction, out-of-pile testing to verify proper functioning of all systems and as such to be ready for in-pile tests by the end of the HPLWR Phase 2 European project by the end of 2009.