• Proceedings of the Korea Contents Association Conference
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• 2006.05a
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• pp.541-544
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• 2006

Currently the bolt joint defect occurs from the steel bridge which is in the process of using but that investigation about each kind defect is lacking state. Research to see consequently the high strength bolt joint sliding conduct bring the model it used a structural analysis program LUSAS numerical analysis execution and a plan for Steel Box Girder Bridge copying full-size H-Beam and plan pretensioned bolt force 100%. 75%, 50% and 25% pretensioned force it acted in standard. And a hold an examination, against the sliding loads which it follows in the pretensioned force it will analysis.

• Journal of the Korean Geotechnical Society
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• v.16 no.4
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• pp.63-70
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• 2000

The quantitative analyses and the mechanical interpretation of discontinuity planes are the most important factor for the study of strength and deformation properties of rock masses containing discontinuity planes. However, the relationship between the factors investigated in the field and the actual mechanical properties of discontinuity planes is not fully understood. The main purpose of this study is to investigate the effects of density, length, and spacing of joints on elastic modulus of rock masses as these values vary. A new parameter which has a direct relation with the elastic modulus of discontinuity planes is also preposed in this study. The combination of finite element methods and homogenization methods has been used for the numerical analyses of a uintcell with discontinuity planes, which is generated using random-number generation methods. The elastic modulus of the discontinuity plane is found from the numerical analyses. The final results propose not only the relation between the investigation parameters of discontinuity planes and the elastic modulus of rock masses but also a new parameter, an effect area ratio having a linear relation with the elastic modulus of rock masses.

• Composites Research
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• v.14 no.3
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• pp.42-50
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• 2001

Modeling of damage initiation in singly oriented ply (SOP) Fiber Metal Laminate (FML) under concentrated loading conditions was studied. The finite element method (FEM) base on the first order shear deformation theory is used for th\ulcorner modeling of damage initiation in SOP FML. The failure indices (FI) of the fiber prepreg and the metal laminate were calculated by using the Tasi-Hill failure criterion and the Miser yield criterion, respectively. To verify the present method, the failure analysis was conducted under uniaxial loading and cylindrical bending, then the analysis under concentrated load was conducted. The results show that the analysis is reasonable. An indentation test was conducted to compare a damage initiation load with a calculated FI. The test was conducted under two side clamped conditions to study the fiber orientation effect. Indentation curve was fitted using the Hertz equation and a damage initiation load is defined that the point which deviate the fitted curve from the real indentation curve. The damage initiation loads were obtained under various fiber orientations and compared with calculated FIs. The experiment was well matched with calculated FI. This results shows that the present method is suitable for the damage initiation modeling of SOP FML.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.34 no.7
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• pp.837-842
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• 2010

The wiper system of a vehicle is important because it wipes the windshield, thereby enabling drivers to see through the windshield even under conditions of rain and snow. The blade is the key component of the wiper system because it wipes the windshield. When wiper-arm spring causes the blade to be pressed on the windshield optimum performance of wiping can be achieved when appropriate contact pressure is maintained. In this study, a dynamic analysis of the wiper system is carried out. A three-dimensional finite-element model of the wiper system is generated using SAMCEF, a commercial structural dynamic analysis program. The distribution of the contact pressure of the blade in its dynamic state is calculated. The simulation result is compared to the experiment result. Using the results of this study, the contact pressure of the blade can be estimated.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.35 no.10
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• pp.1243-1248
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• 2011

Internal defects are a major concern in the casting process because they have a significant influence on the strength and fatigue life of casting products. In general, they cause stress concentration and can be a starting point of cracks. Therefore, it is important to understand the effects of internal defects on mechanical properties such as fatigue life. In this study, fatigue experiments on tensile specimens with internal defects were performed. The internal defects in the casting product were scanned by an industrial CT scanner, and its shape was simplified by ellipsoidal primitives for the structural and fatigue analysis. The analysis results were compared with experimental results for casting products with internal defects. It was demonstrated that it is possible to consider internal defects of casting products in stress and fatigue analysis. The proposed method provides a tool for the prediction of the fatigue life of casting products and the investigation of the effects of internal defects on mechanical performance.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.37 no.10
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• pp.984-991
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• 2009

In this study, transonic aeroelastic response analyses have been conducted for the DLR-F4(wing-body) aircraft configuration considering shockwave and flow separation effects. The developed fluid-structure coupled analysis system is applied for aeroelastic computations combining computational structural dynamics(CSD), finite element method(FEM) and computational fluid dynamics(CFD) in the time domain. It can give very accurate and useful engineering data on the structural dynamic design of advanced flight vehicles. For the nonlinear unsteady aerodynamics in high transonic flow region, Navier-Stokes equations using the structured grid system have been applied to wing-body configurations. In transonic flight region, the characteristics of static and dynamic aeroelastic responses have been investigated for a typical wing-body configuration model. Also, it is typically shown that the current computation approach can yield realistic and practical results for aircraft design and test engineers.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.40 no.6
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• pp.499-505
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• 2012

Vibratory loads imposed by the rotating blade upon the fuselage has been one of major obstacles in rotorcrafts. A new concept of rotor blade is currently developed to adopt an Active Trailing-edge Flap (ATF) to alleviate such obstacles. The flap is mounted at 65~85% spanwise location from the rotor hub. The nominal rotational speed of the blade is as high as 1,528 RPM, to match the required tip Mach number. Structural integrity is one of the important design aspects to be maintained and monitored in this special type of rotor. This is due to that many detailed components, which drive the flap, are inserted inside the rotating blade. To conduct its structural design and analysis, CAMRAD-II and the one-dimensional beam analysis are used. At the same time, three-dimensional finite element analysis are also used, such as MSC. PATRAN/NASTRAN, in order to analyze the details of the present active blade. As a result, comparable characteristics for the present rotor are predicted by both approaches.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.7
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• pp.2341-2348
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• 2010

In this paper, strain and stress on space frame are analyzed at racing car under crash loads. As the deformation is reduced to a minimum during crash and the vulnerable parts are grasped, the safety of driver is ensured. The vehicle frame is modelled with truss structure by inputting the material property of carbon steel on finite element analysis. The increase of impulse momentum is due to speed change at frontal collision. This influence effected on vehicle frame is also analyzed by ANSYS program. The deformation of the frame is studied by applying the crash loads at front, side and rear directions. Though the influence on the seat of driver is small at frontal and rear crash, the deformation due to impact is progressed into this seat. The safety of frame is enhanced by making up for these weak deformations and these results of simulation analysis can be applied to the production of the actual vehicle frame.

• Journal of IKEEE
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• v.23 no.2
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• pp.517-523
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• 2019

Recently, researches about automobile seat having function to support the comfort to driver and passenger during the driving are conducted in various fields including automobile seat having massage function. The effect of massage depends on the pattern of massage such as time, magnitude, and shape. In this paper, linear motor actuator, which is used as driving method in the automobile massage seat, and electromagnetic analysis method, which is used to improve the magnetic efficiency in the design of autuator, is proposed. Electromagnetic analysis using finite element method is conducted in the design of linear motor actuator. Input voltage shape for massage pattern is calculated by simulation using mathematical model of actuator. Performance test for massage pattern generation is conducted with automobile massage seat having developed actuator and controller. It is verified that developed actuator system is applicable in the automobile massage seat.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.50 no.9
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• pp.609-616
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• 2022

The performance of antenna reflectors crucially depends on the faceting error of the surface. The force density method (FDM) has been widely used for the form-finding analysis of the cable nets of reflectors. However, after performing form-finding of some cable nets, the effective reflective area will decrease. In addition, nonlinear deformations of the cable can not be achieved by using the FDM. Thus, an effective form-find methodology is proposed in this research. The whole parts of the cable networks are described by the absolute nodal coordinate formulation. The form-finding analysis of the reflector with standard configuration is performed to validate the proposed methodology. The influence of boundary condition changes on the configuration accuracy of the cable net is investigated.