• 제어로봇시스템학회:학술대회논문집
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• 1989.10a
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• pp.848-855
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• 1989

By structural comparison of process optimization strategies based on Simultaneous Modular Approach, they can be classified into two groups : the Sequential Module Based Approach and the Two-Tier Approach. The Sequential Module Based Approach needs rigorous models and a set of accurate solutions are guranteed. However, it requires large amount of computation time. In the Two-Tier Approach composed of rigorous and simplified models, optimization calculation uses simplified models, therefore comparatively smaller amount of computation time is required but the obtained solutions may not be accurate. These optimization problems were somewhat improved by the alternate application of the two strategies. In this study, improved optimization strategy is suggested, in which Jacobian Matrix is modified to accomodate the strong points of above mentioned strategies. The results of case study show that this approach is superior to the other strategies.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2001.04a
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• pp.895-898
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• 2001

This paper presents an optimization cutting speed(OCS) program developed to improve the machining precision and tool life in high speed machining using ball end milling. This program optimized the cutting speed that is changing at any time in free surface machining of an automobile part like a connecting load die. The technique of optimization cutting speed makes the CAD/CAM-generated NC code go through a reverse post process, conducts cutting simulation, and obtain the effective tool diameter of the ball end milling. Then it changes the spindle revolution to within the range of critical cutting speed fit for the material of the workpieces depending upon the effective tool diameter. In this study, the machining precision and tool life were compared for the two connecting load dies processed using the general cutting method and the proposed optimization cutting speed technique, respectively.

• Journal of the Korean Society for Precision Engineering
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• v.22 no.8 s.173
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• pp.108-117
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• 2005

In modern industrial society, many kinds of valves have been used to control fluid flow. For the optimization of a ball valve, a quarter of spherical ball was modeled and evaluated. However, there is a difficulty in the application of the optimization technique because of the complexity of the fluid and the restriction of analysis. Therefore, in this study, it is performed to evaluate the stability of an initial model using FEM(Finite Element Method) and CFD. In addition, a shape optimization design of the valve is accomplished using an orthogonal arrangement and characteristic functions. From the result, a new design method is represented that could overcome the time and space restriction in structural design, such as the divided ball valve with less experiment.

• Journal of Advanced Marine Engineering and Technology
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• v.24 no.3
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• pp.99-105
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• 2000

For multi-body dynamic problems. especially coalescent eigenvalue problems with multiobjective optimization, the design sensitivity analysis is too much complicated mathematically and numerically. Therefore, this article proposes a new technique for structural dynamic modification using a mode modification and homologous structures design method with Genetic Algorithm(GA). In this work, the homologous structure of the resiliently mounted multi-body for marine diesel generator systems is studied and the problem is treated as a combinational optimization problem using the GA. In GA formulation, fitness is defined based on penalty function approach. That include homology, allowable stress and minimum weight of common plate.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1997.10a
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• pp.37-42
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• 1997

Off-line feed rate scheduling is an advanced methodology to automatically determine optimum feed rates for the optimization of NC code. However, the present feed rate scheduling systems have lim~tations to generate the optimized NC codes because they use the material removal rate or non-generalized cutting force model. In this paper, a feed rate scheduling system based on an improved cutting force model that can predrct cutting forces exactly in general machining was presented. Original blocks of NC code were divided to small ones with the modified feed rates to adjust the peak value of cutting forces to a constant vale. The characteristic of acceleration and deceleration for a given machrne tool was considered when off-line feed rate scheduhng was performed. Software for the NC code optimization was developed and applied to pocket machining simulation.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.1701-1704
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• 2003

This paper presents a new optimization technique of acceleration curve for a wafer transfer crane movement in which high speed and low vibration are desirable. This technique is based on a genetic algorithm with a penalty function for acceleration optimization under the assumption that an initial profile of acceleration curves constitutes the first generation of the genetic algorithm. Especially the penalty function consists of the violation of constraints and the number of violated constraints. The proposed penalty function makes the convergence rate of optimization process using the genetic algorithm more faster than the case of genetic algorithm without a penalty function. The optimized acceleration of the crane through the genetic algorithm and commercial dynamic analysis software has shown to have accurate movement and low vibration.

• Journal of the Korean Society for Precision Engineering
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• v.21 no.10
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• pp.137-146
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• 2004

This is the second of two companion papers concerned with the analysis and design of a pneumatic vibration isolation system. The properties of the system are clarified by observation of the transmissibility surface calculated by the models and algorithm developed in the first paper of this research. It Is shown that the nonlinear model proposed in this research is more closer to experimental results than the linear model that have been used in previous studies. The design optimization of the major design variables that affect the performance of the system is achieved by using the condition for attenuation, disturbance rejection and maximum damping in resonance peak. The design space search method is adopted for the optimization of the orifice area. The models, transmissibility calculation algorithms and design optimization techniques developed in this research are shown to be greatly helpful to the optimal design of the pneumatic vibration isolation system by experiment.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2003.04a
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• pp.15-20
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• 2003

Most engineering products contain more than one component. Failure occurs either at the connection itself or in the component at the point of attachment of the connection in many engineering structures. The allocation and design of connections such as bolts, spot-welds, adhesive etc. usually play an important role in the structure of multi-components. Topology optimization of connection component provides more practical solution in design of multi-component connection system. In this study, a topology optimization based on density distribution approach has been applied to optimal location of fasteners such as T-shape, L-shape and multi-component connection system. From the results, it was verified that the number of iteration was reduced, and the optimal topology was obtained very similarly comparing with ESO method. Therefore, it can be concluded that the density distribution method is very suitable for topology optimization of multi-component structures.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2001.05a
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• pp.1168-1173
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• 2001

Compressors are the main source of noise of refrigerators and air-conditioning unit. Recent studies on the sound propagation of rotary compressors showed that the accumulator is a significant source of noise generation. This paper describes a design change of a rotary compressor for noise reduction using topology optimization. Topology optimization has been developed and used to find the most effective structural configuration in the early stage of design procedures. FE model of the rotary compressor composed of all the components is built for the topology optimization. Topology optimization results show that the empirical design for the present structure fail to constrain some resonance modes and a new component is required.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2004.05a
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• pp.410-415
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• 2004

The oscillation of the fluid caused by external forces is call ed sloshing, which occurs in moving vehicles with contained liquid masses, such as trucks, railroad cars, aircraft, and liquid rocket. This sloshing effect could be a severe problem in vehicle stability and control. In this study, the optimization design technique for reduction of the sloshing using evolutionary method is suggested. Two evolutionary methods are employed, respectively the artificial neural network(ANN) and genetic algorithm. An artificial neural network is used for the analysis of sloshing and genetic algorithm is adopted as optimization algorithm. As a result of optimization design, the optimized size and location of the baffle is presented