• Journal of KSNVE
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• v.8 no.1
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• pp.57-74
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• 1998

This paper is concerned with a combination of experimental and analytical investigation aimed at identifying modeling errors, accounted for the lack of correlation between experimental measurements and analytical predictions of the modal parameters for lap joint panels. A nonlinearity vibration test methodology, initiated from the theoretical analysis, is suggested for measurements of dynamic stiffnesses in a lap joint using the rivet fastener. Based on the experimental evidence on discrepancies between measured and predicted frequencies, improved finite element models of the joint are developed using PATRAN and ABAQUS, in which the beam element size is evaluated from the joint stiffnesses readily determined in the test. The beam element diameter as a principal design parameter is tuned to match experimental results within the evaluated bound value. Frequencies predicted by the proposed numerical model are compared with frequencies measured by the test. Improved predictions based on this new model are observed when compared with those based on conventional modeling practices.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.20 no.4
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• pp.463-468
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• 2007

Some network equipments made in Korea were exposed to severe earthquake in Japan several years ago. More than a hundred slim base transfer network stations had been seized with the severe earthquake at Nigata and it was reported that less than fifteen sets showed blackout by interruption of electricity, not by the structural failure. The purpose of this paper is to check the structural safety of the network equipments by performing table test, and the static and dynamic finite element analysis. For the dynamic test, the station weighing 200 kg was subjected to the Zone 3 earthquake loading of GR-63-CORE on the shaking table to obtain the dynamic responses to compare with the analysis results. It is shown that the FE analysis results are a little bit larger than that of the experimental values. And the sensitivity analysis and optimization for the natural frequency is performed and it is found that the first natural frequency is sensitive to small design change as shown in the results. And the dynamic response of optimized design is less than the original design.

• Composites Research
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• v.20 no.4
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• pp.25-30
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• 2007

The advanced fiber-reinforced laminated composites are widely used in a variety of engineering applications such as aerospace, marine, mechanical and civil engineering for weight savings because of their high specific strength and stiffness. The material properties of ply is known to have larger variations than that of conventional materials and very sensitive to the loading direction. Therefore, it is important to consider the variations on designing the laminated composite. This paper demonstrates the importance of considering uncertainties through examining the effect of material properties variations on various design requirements such as tip deflection, natural frequency and buckling stress using COMSOL-MATLAB interface.

• Korean Journal of Optics and Photonics
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• v.14 no.4
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• pp.443-448
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• 2003

A study on optimum design of the lightweight mirror of a satellite camera is presented. An optical surface deformation of the lightweight mirror, which is a principal component of the camera system, is an important factor affecting the optical performance of the whole camera system. In this study, optimum design of the lightweight mirror is presented. Total weight of the mirror to reduce the optical surface deformation and the launching cost is used as an objective function. Peak-to-valley value and natural frequency of the mirror are given as constraints to the optimization problem. The sensitivities of the objective function and constraint are calculated by a finite difference method. The optimization procedure is carried out by the commercial optimizer, DOT. As a verification of the optimum design of the mirror, two design examples are treated. In the real application example, the lightweight mirror with 600mm effective diameter is treated. The optimized results with various design variables, which are obtained by considering thickness limitations, are analyzed.

• The Journal of Engineering Geology
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• v.17 no.1 s.50
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• pp.15-25
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• 2007

In general, the life and asset casualties that occur due to landslide or slope failure in urban areas are larger than that in rural areas. In order to reduce the casualties, a slope management program is necessary to categorize slopes based on properties and to manage them systematically. The slope management system is the establishment of the data base for the geological and geotechnical factor according to slope stability, and the utilization of the data base to manage slopes. The suitable system must develop to slopes in urban area through the survey, analysis and evaluation process. Based on the above necessity, the slope management program which is applicable to slope management in an urban area has been developed at Hwangryung Mt. in Busan as a target area. The developed slope management program has various functions such as slope ID number of each slope or sub-region of a mountain, making a slope data sheet, analysis and grouping of slope stability, and establishment of a data base. The slope management program is constructed by use of GIS, and the survey, test and analysis data according to all slopes can be input and edited into the program. The program can also be utilized practically by end users due to the convenient input, edition printing, management and operation of slope data. Therefore, the slope management system has been established on the application of the developed program in Busan which is located in slope area. As the system is widely applied to other cities, the slope in urban area can be managed systematically and the slope hazards can be minimized.