• Korean Journal of Construction Engineering and Management
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• v.22 no.1
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• pp.36-46
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• 2021

With an increasing trend toward high-rise modular construction, the simultaneous use of tower cranes at a modular construction site has recently been observed. Tower crane layout planning (TCLP) has a significant effect on cost, duration, safety and productivity of a project. In a modular construction project, particularly, poor decision about the layout of tower cranes is likely to have negative effects like additional employment of cranes and redesign, which will lead to additional costs and possible delays. It is, therefore, crucial to conduct thorough inspection of field conditions, lifting materials, tower crane capacity to make decisions on the layout of tower cranes. However, several challenges exist in planning for a multi-crane construction site in terms of safety and collaboration, which makes planning with experience and intuition complicated. This paper suggests a multi-objective optimization model for selection of the number of tower cranes, their models and locations, which minimizes cost and conflict. The proposed model contributes to the body of knowledge by showing the feasibility of using multi-objective optimization for TCLP decision-making process with consideration of trade-offs between cost and conflict.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2018.05a
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• pp.39-40
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• 2018

The goal of site layout planning(SLP) is to maximize the productivity and efficiency of the construction by reducing travel distance and material handling cost and manpower. However, SLPs are static layout schemes, which cannot be reorganized during the construction process to correspond with errors, phase transition, changing working environments on the site. To solve this problem, researches on dynamic site layout planning(DSLP) are emerging. This preliminary study clarifies characteristics of temporary facility's variables to develop the vertical DSLP algorithm of high-rise building construction.

• Journal of Korean Institute of Industrial Engineers
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• v.29 no.3
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• pp.222-229
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• 2003

In this paper, we address a layout design problem, PTN[2], for determining an appropriate 2-class-based dedicated storage layout in a class of unit load storage systems. Our strong conjecture is that PTNI2] is NP-hard. Restricting PTN[2], we provide three solvable cases of PTN[2] in which an optimal solution to the solvable cases is one of the partitions based on the PAI(product activity index)-nonincreasing ordering. However, we show with a counterexample that a solution based on the PAI-non increasing ordering does not always give an optimal solution to PTN[2]. Utilizing the derived properties, we construct an effective heuristic algorithm for solving PTN[2] based on a PAI-non increasing ordering with performance ratio bound. Our algorithm with O($n^2$) is effective in the sense that it guarantees a better class-based storage layout than a randomized storage layout in terms of the expected single command travel time.

• Ocean Systems Engineering
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• v.2 no.4
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• pp.271-287
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• 2012

Due to its large size, a ship is first divided into scores of blocks and then each block is constructed through various shops, such as the assembly shop, the painting shop, and the outfitting shop. However, each block may not be directly moved to the next shop and may be temporarily laid at a block stockyard because the working time in each shop is different from each other. If blocks are laid at the block stockyard without any planning, the rearrangement of the blocks by a transporter is required because the blocks have the different in and out time. In this study, a block layout method based on the genetic algorithm was proposed in order to minimize the rearrangement of the blocks in the block stockyard. To evaluate the applicability of the proposed method, it was applied to simple layout problems of the block stockyard. The result shows that the proposed method can yield a block layout that minimizes the total relocation cost of moving obstacle blocks in the block stockyard.

• Proceedings of the KSME Conference
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• 2008.11a
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• pp.410-411
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• 2008

A topology optimization technique to develop extremely light trailer frame structure is performed due to the strong needs of the customers and makers owing to high level of oil price. First, the overall layout of the frame is derived using topology optimization and then, final specification is also derived utilizing DOE optimization technique for mass product.

• International Journal of Aeronautical and Space Sciences
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• v.9 no.2
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• pp.18-33
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• 2008

This paper presents design optimization of a new Active Twist Rotor (ATR) blade and conducts its aeroelastic analysis in forward flight condition. In order to improve a twist actuation performance, the present ATR blade utilizes a single crystal piezoelectric fiber composite actuator and the blade cross-sectional layout is designed through an optimization procedure. The single crystal piezoelectric fiber composite actuator has excellent piezoelectric strain performance when compared with the previous piezoelectric fiber composites such as Active Fiber Composites (AFC) and Macro Fiber Composites (MFC). Further design optimization gives a cross-sectional layout that maximizes the static twist actuation while satisfying various blade design requirements. After the design optimization is completed successfully, an aeroelastic analysis of the present ATR blade in forward flight is conducted to confirm the efficiency in reducing the vibratory loads at both fixed- and rotating-systems. Numerical simulation shows that the present ATR blade utilizing single crystal piezoelectric fiber composites may reduce the vibratory loads significantly even with much lower input-voltage when compared with that used in the previous ATR blade. However, for an application of the present single crystal piezoelectric actuator to a full scaled rotor blade, several issues exist. Difficulty of manufacturing in a large size and severe brittleness in its material characteristics will need to be examined.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.11a
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• pp.355.1-355
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• 2002

Topology optimization is widely accepted as a conceptual design tool for the product design. Since the resulted layout of the topology optimization is a kind of digital images represented by the density distribution, the seamless process is required to transform digital images to the CAD model for the practical use. In this paper, the general process to construct a CAD model is developed to apply for topology images based on elements. (omitted)

• Journal of the Korean Institute of Telematics and Electronics
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• v.24 no.6
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• pp.1056-1067
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• 1987

This paper presents a design procedure for building block integrated circuits that is based on the digraph relaxation model. A set of optimization procedure is prosented for a minimum area and routing-fecsible placement of IC building blocks. Chip area optimization is subject to perimeter and area constraints on the component rectangles in the dissection.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2006.11a
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• pp.934-937
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• 2006

This investigation presents a topology formulation to design optimal poroelastic acoustic foams to maximize absorbing ability. For successful formulation, a single set of equations based on Biot's theory is adopted and an appropriate material interpolation strategy is newly developed. Because there was no earlier attempt to solve poroelastic acoustic foam design problems in topology optimization setting, many challenging issues including modeling and interpolation must be addressed. First, the simulation accuracy by a proposed unified model encompassing acoustic air and poroelastic material was checked against analytical and numerical results. Then a material interpolation scheme yielding a distinct acoustic air-poroelastic material distribution was developed. Using the proposed model and interpolation scheme, the topology optimization of a two-dimensional poroelastic acoustic foam for maximizing its absorption coefficient was carried out. Numerical results show that the absorption capacity of an optimized foam layout considerably increases in comparison with a nominal foam layout.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2012.04a
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• pp.361-366
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• 2012

In this paper, we propose the efficient technique that reduces the number of spot-welds and increases the structural rigidity by using the topology optimization technique. Eigen value analysis is used to evaluate the rigidity of the optimized model. As a first step, the topology optimization is performed to find optimal spot-weld distributions. In this study, the design objective is to maximize the weighted frequencies. The volume fractions of the weld components are used as design constraints, and also the densities of each element in the individual design space are used as design variables. And then, to consider the possibility of spot-weld failure, the contribution rate analysis was performed by using the orthogonal array method of DOE. The spot-welds in the rear panel part are reinforced according to estimation results of the contribution rate analysis. Finally, we obtained optimized spot-weld layout model which has the reduced number of spot-welds and the improved dynamic stiffness.