• Proceedings of the KSR Conference
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• 2011.10a
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• pp.1577-1582
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• 2011

Recently rapid construction of bridge is a main interest in construction. A research on rapid construction of pier coping is urgently needed because pier, which is a bridge understructure, directly affect lane reduction and increase of social cost. Precast assembly method and pre-assembly method are the main subjects of rapid construction. But these researches have focused not on reduction of reinforcement amount, but on modifying production method of coping. Reinforcement amount of design specification is as much as that of coping under constructing. So different approach is needed for reduction of reinforcement amount. In this paper, design of pier coping using strut-tie model was proposed for reduction of reinforcement amount and improvement of constructability. Railway bridge pier coping under constructing was analyzed using a finite element method and designed using strut-tie model.

• Journal of Korean Institute of Industrial Engineers
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• v.35 no.1
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• pp.15-39
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• 2009

Advanced planning and scheduling (APS) refers to a manufacturing management process by which raw materials and production capacity are optimally allocated to meet demand. APS is especially well-suited to environments where simpler planning methods cannot adequately address complex trade-offs between competing priorities. However, most scheduling problems of APS in the real world face both inevitable constraints such as due date, capability, transportation cost, set up cost and available resources. In this survey paper, we address three crucial issues in APS, including basic scheduling model, job-shop scheduling (JSP), assembly line balancing (ALB) model, and integrated scheduling models for manufacturing and logistics. Several evolutionary algorithms which adapt to the problems are surveyed and proposed; some test instances based on the practical problems demonstrate the effectiveness and efficiency of evolutionary approaches.

• Journal of Korean Institute of Industrial Engineers
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• v.20 no.3
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• pp.15-34
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• 1994

This paper considers the genetic algorithms(GAs) for the mixed model assembly line sequencing(MMALS) in which the objective is to minimize the overall line length. To apply the GAs to the MMALS, the representation, selection, genetic sequencing operators, and genetic parameters are studied. Especially, the existing sequencing binary operators such as partially map crossover(PMX), cycle crossover(CX), and order crossover (OX) are modified to be suitable for the MMALS, and a new sequencing binary operator called immediate successor relationship crossover (ISR) is introduced. These binary operators mentioned above and/or unary operators such as swap, insertion, inversion, displacement, and splice are compared to find operators which work well in the MMALS. Experimental results indicate that 1) among the binary operators ISR operator is the best, followed by the modified OX, and the modified PMX, with the modified CX being the worst, 2) among the unary operators inversion operator is the best, followed by displacement, swap, and insertion, with splice being the worst, and 3) in general, the unary operators perform better than the binary operators for the MMALS.

• Journal of the Korean Society for Precision Engineering
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• v.19 no.6
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• pp.35-42
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• 2002

Verification of tool collision Is an important issue in die and mold machining. In this paper three functions of verification for 3-axis milling machining are schematically explained. Operators of geometric models are explained at first, which will be used in the functions of verification. The first verification function is getting a collision-free region when a tool assembly and a part surface model are given. The second function estimates the shortest length of cutter shank with that the tool cuts all of a region without collision The last one is cutting simulation considering all parts of tool assembly as well as cutter blade. Proposed approaches can be easily implemented by using several basic operators of geometric model. An example to calculate collision-free region is presented also.

• Journal of the Korean Operations Research and Management Science Society
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• v.13 no.1
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• pp.13-13
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• 1988

This paper considers the sequencing problem in mixed model assembly lines with hybrid workstation types and sequence-dependent setup times. Computation time is often a critical factor in choosing a method of determining the sequence. We develop a mathematical formulation of the problem to minimize the overall length of a line, and present a tabu search technique which can provide a near optimal solution in real time. The proposed technique is compared with a genetic algorithm and a branch-and-bound method. Experimental results are reported to demonstrate the efficiency of the technique.

• Proceedings of the KSME Conference
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• 2007.05a
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• pp.602-607
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• 2007

The heavy duty diesel engine must have a large output for maintaining excellent mobility. The compacted graphite iron (CGI) is a material currently under study for the engine demanded for high torque, durability, stiffness and fatigue. In this study, three dimensional finite element model of a heavy-duty diesel engine was developed to conduct the stress analysis by using property of CGI. The FE model of the heavy duty diesel engine section consisting with four half cylinder was selected. The heavy duty diesel engine section include cylinder block, cylinder head, liner, bearing cap, bearing and bolt. The loading conditions of engine are pre-fit load, assembly force and gas force.

• Korean Journal of Computational Design and Engineering
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• v.17 no.1
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• pp.1-6
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• 2012

The End Coupling is main component of the aluminum hot roll process. The End Coupling is used for transmission of rotational power with heavy-duty load. Fracture of the End Coupling cause serious economic losses because an End Coupling is a very expensive component and it takes a long time to repair it. Therefore, preventing the destruction of the End Coupling is essential for ensuring a long mechanical life cycle. In this paper, the parametric study on the End Coupling was performed in order to minimize maximum stress under operation loads. To verify the interference of spindle assembly with modified End Coupling, kinematics simulation was performed by applying the various combination type and dynamic boundary condition of the spindle assembly. The interference of optimized model was not occurred during combination process and driving process. As a result of an optimum design for life extension on End Coupling, the maximum stress of modified End Coupling was lower than that of the initial model by 26%.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 1996.04a
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• pp.369-372
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• 1996

The factory under this study consists of mixed-model assembly lines and workcenters which provide parts to the main lines. Parts produced by the workcenter have different specifications for different product models. The workcenters fabricate parts in batches, and they are divided into two types. A type 1 center supplies parts only to the main line that is designated to the center while type 2 center provides parts to all the main lines. The purpose of this study is to develop a scheduling scheme for the workcenter, and the main objective of the schedules is to provide parts for the main lines without delay. The facts that make the scheduling challengeable are that 1) the different models existing together on a main line request different parts, 2) the spaces for part inventories are limited and 3) set up times are sequence dependent and long in some cases. This study presents developed scheduling schemes for the type 1 center and explains the scheduling and control structure used.

• Bulletin of the Korean Chemical Society
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• v.32 no.2
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• pp.620-624
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• 2011

In recent years, the study of self-assembly peptide used in drug delivery system has been attracted great interest from scientists. In the category are self-assembly peptides in the structure either with one hydrophobic surface and another hydrophilic or a hydrophobic head and a hydrophilic tail. Here, we focus on a novel designed peptide EYK with double amphiphilic surfaces, investigating on the capability of peptide as a carrier for hydrophobic compound model pyrene. The fluorescence data presented the dynamic process of the transfer, showing that the pyrene was in the crystalline form in peptide solution, and molecularly migrated from its peptide encapsulations into the membrane bilayers when the peptide-pyrene suspension was mixed with liposome vesicles. The results indicated that the peptide EYK could stabilize hydrophobic pyrene in aqueous solution and delivered it into EPC liposome as a potential carrier.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2000.06a
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• pp.627-632
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• 2000

A finite element model for the transient dynamic analysis of a PWR fuel assembly was developed and programmed as a name of DAMASS. The Newmark time integration method was used to solve the governing equation of motion. Results of the program was compared with those of ANSYS in terms of displacement and impact forces to show the validity of the model. Up to now it has capability of solving the linear impact of FA(s) and it will be extended to the non-linear analysis of a FA in the future.