• Proceedings of the Computational Structural Engineering Institute Conference
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• 2001.04a
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• pp.128-136
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• 2001

This paper presents an optimum deck and girder system design for minimizing the life-cycle cost (LU) of steel box girder bridges. The problem of optimum LCC design of steel box girder bridges is formulated as that of minimization of the expected total LCC that consists of initial cost, maintenance cost, expected retrofit costs for strength, deflection, and crack. To demonstrate the effect of LCC optimum design of steel box girder bridges, the LCC optimum design is compared with conventional design method for steel box girder bridges design. From the numerical investigations, it may be positively stated that the optimum design of steel box girder bridges based on LCC will lead to more rational, economical and safer design.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 1998.04a
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• pp.210-215
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• 1998

To design a space frame structure by the conventional method is not easy in practical sense since it is generally a three-dimensional complicated form, and stability and nonlinear problems are not easily checked in the design process. This paper describes two modules, the Model Generator which is based on PATRAN user interface that enables users to generate a complicated finite element model; the Optimum Design Module which analyzes output results of analysis program, and designs members of a space frame. The Model Generator is based on PCL while C++ language is used in the Optimum Design Module. Structural analysis is performed by using ABAQUS. All of these modules constitute Space Frame Integrated Design System. The Core of the system is PATRAN database, in which the Model Generator creates information of a finite element model. Then, PATRAN creates input files needed for the analysis program from the information of the finite element model in the database, and in turn, imports output results of analysis program to the database. Finally, the Optimum Design Module processes member grouping of a space frame based on the output results, and performs optimal member selection of a space frame. This process is repeated until the desired optimum structural members are obtained.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.24 no.2 s.173
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• pp.319-328
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• 2000

This paper presents a new design method of the 1 generation wheel bearing unit using a numerical optimization technique in order to increase bearing fatigue life. For calculating the fatigue life, a method of load analysis is studied on the automotive wheel bearing system. The design variables selected are ball size, initial contact angle, number of balls, pitch diameter, pre-load, and distance between ball centers. The method of feasible directions in ADS (Automated Design Synthesis) is utilized to automatically find the optimum design variables. To validate the design method, a computer program is developed and applied to a practical passenger car model. The optimum design results demonstrated the effectiveness of the proposed design method showing that the system life of the optimally designed wheel bearing unit is enhanced in comparison with that of the initial ones within the given available design space.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.33A no.12
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• pp.72-76
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• 1996

A CMP system is newly proposed and analyzed by a home-made computer progarm. The proposed system is possibly to lower bull's eye effects such that the planarity of a wafer surface using a CMP system can be drasitcally improved. The optimum conditions for a design of the proposed system are verified using the home-made simulation program. For the proposed CMP system with a 12" diameter of platen, the optimum design conditons are the 0.09", 0.10", 0.12", and 0.14", clearance from the platern edge for wafer diameters of 5", 6", 8", and 12", respectively. These clear distance such as 0.09", 0.10", 0.12", and 0.14" are optimum lengths of the sample wafers extended ffrom the platen edge. In other words, shorter orbital lengths result in lowering of Bull's eye effects.

• Journal of Korean Society of Steel Construction
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• v.13 no.4
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• pp.337-349
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• 2001

This study present an optimum deck and girder system design for minimizing the life-cycle cost (LCC) of orthotropic steel deck bridges. The problem of optimum LCC design of orthotropic steel deck bridges is formulated as that of minimization of the expected total LCC that consists of initial cost, maintenance cost, expected retrofit costs for strength, deflection, and fatigue. To demonstrate the effect of LCC optimum design of orthotropic steel deck bridges, the proposed optimum LCC design is compared with the conventional method for orthotropic steel deck bridges design. From the numerical investigations, it may be positively stated that the proposed optimum design procedure for orthotropic steel deck bridges based on the LCC will lead to more rational, economical and safer design.

• Proceedings of the KSME Conference
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• 2001.06c
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• pp.158-163
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• 2001

This study is the selection of optimum forming condition for RP system using ADS. Program using ADS reduces the required time for feedback between design and manufacturing of workpiece. When we produce rapid prototype using RP system, we investigate the relationship between Facetres in system variable number of AutoCAD and roundness of rapid prototype, and we will find optimum forming condition in RP system.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1997.10a
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• pp.689-693
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• 1997

This paper deals wth the impact and the transient analysis of the impact absorbing system consist of double damping. piston and sprlng system in spreader to increaas efficlcncy of it. It shows the optimum damping coefficient and spring constant under the limited stroku of Impact absorbing system using for crane spreader and the optimum condition of impact absorbing system causing certain reaction force as time. which is characteristic of dashpot and rubber. This system absorbed 11.5 and 88.5 % impact energq at the spring and the damper respectively.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1994.03a
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• pp.7-34
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• 1994

;Recently the sheet forming simulation technology revealed great progress in the sense of practical application in the automotive, electric/electronics and aviation/space industries. The goal of sheet forming simulation is to embedded in the design engineering system which is consisted by the analysis and synthesis modules. This design simulation system predicts the slackness of sheet and estimate the formability, and search the optimum material/forming/structure conditions. This OVER-ALL OPTIMUM DESIGN can be classified as follow; 1. ANALYZING PROCEDURE: Numerical simulation based on nonlinear theories -geometry, material and friction nonlinearities- 2. OPTIMIZATION PROCEDURE: Optimum design based on mathematical programing and AI technologies, those are implemented in CAD/CAM/CAE System - Concurrent Engineering System-. In this paper, four subjects will be discussed; (1) State of arts of computer simulation technologies in Japan. (2)History of sheet forming simulation. (3) Benchmark problems. (4) Future technology in the sheet forming simulation.ation.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.14 no.6
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• pp.52-60
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• 2005

Ultra-precision positioning systems basically require high natural frequency and sufficient workspace. To cope with this requirement, flexure hinge mechanisms have been developed. However, previous designs are difficult to satisfy the functional requirements of the system due to difficulty in modeling and optimization process applying fur the independent axiomatic design. Therefore, this paper suggests a new design and design procedure based on semi-coupled, axiomatic design. A spatial 3-DOF parallel type micro mechanism is chosen aa an exemplary device. Based on preliminary kinematic analysis and dynamic modeling of the system, an optimum design is conducted. To check the effectiveness of the optimal parameters obtained by theoretical approach, simulation has been performed by FEM.

• 한국신재생에너지학회:학술대회논문집
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• 2006.06a
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• pp.249-252
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• 2006

Wind turbine gearbox is a complex mechanical system that includes gear trains, shafts, bearings, and gearbox housings. All these component are interacting with each other therefore changing certain design parameter will affect other components. RomaxDesigner enables a reduction in development period by simulating the full gearbox system. The gear pairs, bearings and shafts are represented as analysis objects and the complex components are modelled by means of reduced stiffness matrices. The software allows durability analysis and advanced contact analysis including the effects of system misalignments in gear and bearing. In this paper the 2MW wind turbine gearbox was model led and a study on optimum design was conducted