• International Journal of Aeronautical and Space Sciences
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• v.18 no.3
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• pp.450-466
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• 2017

This paper defines the modified effective membrane stiffness, bending stiffness considering the directionally dependent mechanical properties and mode shape function of a composite lattice rectangular plate, which is assumed to be a Kirchhoff-Love plate. It subsequently presents an approximate method of conducting a buckling analysis of the composite lattice rectangular plate with various boundary conditions under uniform compression using the Ritz method. This method considers the coupled buckling mode as well as the global and local buckling modes. The validity of the present method is verified by comparing the results of the finite element analysis. In addition, this paper performs a parametric analysis to investigate the effects of the design parameters on the critical load and buckling mode shape of the composite lattice rectangular plate based on the present method. The results allow a database to be obtained on the buckling characteristics of composite lattice rectangular plates. Consequently, it is concluded that the present method which facilitates the calculation of the critical load and buckling mode shape according to the design parameters as well as the parametric analysis are very useful not only because of their structural design but also because of the buckling analysis of composite lattice structures.

• Transactions of the Korean Society of Mechanical Engineers
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• v.16 no.4
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• pp.630-648
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• 1992

The minimum weight design for simply-supported isotropic or symmetrically laminated stiffened cylindrical shells subjected to various loads (axial compression or combined loads) is studied by a nonlinear mathematical search algorithm. The minimum weight design in accomplished with the CONMIN optimizer by Vanderplaats. Several types of buckling modes with maximum allowable stresses and strains are included as constraints in the minimum weight design process, such as general buckling, panel buckling with either stingers or rings smeared out, local skin buckling, local crippling of stiffener segments, and general, panel and local skin buckling including stiffener rolling. The approach allows the consideration of various shapes of stiffening members. Rectangular, I, or T type stringers and rectangular rings are used for stiffened cylindrical shells. Several design examples are analyzed and compared with those in the previous literatures. The unstiffened glass/epoxy, graphite/epoxy(T300/5208), and graphite/epoxy aluminum honeycomb cylindrical shells and stiffened graphite/epoxy cyindrical shells under axial compression are analyzed through the present approach.

• Special Issue of the Society of Naval Architects of Korea
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• 2011.09a
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• pp.117-126
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• 2011

The buckling assessment of plate panels described in common structural rules (CSR) is to be determined according to the buckling utilization factor with hull girder stresses calculated on net hull girder sectional properties. As the thickness requirement for the buckling assessment of plate panels is not explicitly given in CSR, a lot of time is spent to find the proper thickness of plate panels until reaching to an allowable buckling utilization factor. In this study, in order to reduce time and cost, the thickness requirement of plate panels satisfying buckling assessment was derived. The structural design system included with the thickness requirement for buckling assessment was developed. The system is called as Oil-tanker Automated Structural Investigation System (OASIS). The design result of longitudinal strength members using OASIS was verified by Nauticus Hull which is the rule scantling software of DNV. Finally, optimum design of a double hull tanker for the minimum weight using OASIS was presented.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 1999.04a
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• pp.109-118
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• 1999

Lifeline system such as oil or gas pipelines and water supply facilities are vulneratble to seismic damages because they are widely exposed to ground failures. Most seismic design criteria of buried pipelines are based on the notion that the longitudinal compressive strain and therefore buckling controls the design. Buckling analysis of buried pipelines subjected to seismic loading is performed by considering the seismic load as the sinusoidally distributed compressive load on the beam on elastic foundation in contrast to existing studies where the buckling load is treated as an end load on the beam column, An approximated analytical solution is obtained by the energy method and its validity is confirmed by the linearized finite element buckling analysis. The results show the beam mode buckling because longitudinal strains at the buckling loads are substantially lower than the strain at the onset of local buckling.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 1997.10a
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• pp.254-261
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• 1997

In desingin plate bridges, the width-thickness ratio of flanges and webs are proportioned in such that the premature local buckling of flanges and webs prior to achievement of the full strength of plate-girders must be prevented. It is the common practive in most design codes that the flange local buckling strength and the web bend buckling strength are separately computed. In most practical plate girders, however, the flange buckles simultaneously when web bend-buckling occurs, vice versa. The primary purpose of the present study is to investigate the phenomenon, which may be called flange-web interactive buckling. Using the eight-node shell element available in the commercial multi-purpose program ABAQUS, the phenomenon was quantitatively investigated. Also presented are the effects of various factors such as the ratio of flange slenderness ratio to the web slenderness ratio, the ratio of flange width to the web depth, and the longitudinal stiffeners. A series of comparative studies with various design codes show that the present study provides more accurate and effective design basis in proportioning the flanges and webs.

• Journal of the Korean Society of Industry Convergence
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• v.15 no.1
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• pp.5-11
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• 2012

The Buckling of the member under compressive stress is likely to occur, which is an important factor determining the strength of structures. The objective of this study was to evaluate the member buckling strength of a circular hollow steel with ball joints and to compare with design specifications for load resistance factor of our country. Furthermore, we would like to suggest basic data for evaluation of buckling length of a circular hollow steel with ball joints according to comparative analysis. These results were summarized as follows: Buckling stress according to the test results on buckling was 1.21 times greater than LSD specifications of our country estimated the entire length of circular hollow steel with ball joints as buckling length. In addition, it was 1.16 times greater than when estimating the length except the ball as buckling length and 1.14 times grater than when excluding the ball and sleeve. Therefore, when estimating buckling stress of circular hollow steel with ball joints, their buckling length may be measured by the length except ball and sleeve.

• Journal of the Korean Society for Precision Engineering
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• v.23 no.9 s.186
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• pp.68-75
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• 2006

The lead frame manufactured by stamping process plays an important role in connecting semiconductor to PCB board. As a result of the miniaturization of semiconductor, its corresponding lead frame punch has been narrow. In case of the punch with high slenderness ratio such as lead frame punch, the punch can be broken suddenly due to buckling. To prevent the fracture of lead frame punch, some manufacturers have experientially attached stiffeners to weak parts of punch. The purpose of this study, therefore, is to suggest the guideline far design of stiffened punch. The optimal position and the number of stiffeners to be attached to punch are investigated by elastic buckling analysis. The elastic buckling analysis consists of the eigenvalue buckling analysis and nonlinear buckling analysis. The critical buckling load of elastic buckling analysis is compared with that of buckling test. Finally, the guideline far attaching stiffeners is suggested through analysis of cross section of lead frame punch such as moment of inertia and eccentricity.

• Journal of the Korean Society for Precision Engineering
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• v.16 no.3 s.96
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• pp.25-29
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• 1999

The lead frame manufactured by press stamping process, is an important part of semiconductor. The recent technical trend of semiconductor, chip sized and high performance package technology, requires the lead frame to be of more multi-leads and of fine ILP (Inner Lead Pitch). As the ILP is getting finer, its corresponding punch of the stamping die is getting narrower. The punch narrower than its stamping limit has been broken due to local buckling. This paper analyzed the phenomena of punch breakdown. Moreover, the punch design was modified to increase the critical limit of buckling force. This paper, also, suggested new design rules of the punch, which asks the modification of its lead frame design that has to be considered in the stage of semiconductor package design. The new design rules of lead frame design yields a good reliability of semiconductor package as well as a good quality of lead frame.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2006.04a
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• pp.993-1000
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• 2006

Practical stability design method of main members of cable-stayed bridges is proposed and discussed through a design example. For this purpose, initial tensions of stay cables and axial forces of main members are firstly determined using initial shaping analysis of bridges under dead loads. And then the effective buckling length using system elastic/inelastic buckling analysis and bending moments considering $P-{\delta}-{\Delta}$ effect by second-order elastic analysis are calculated for main girder and pylon members subjected to both axial forces and moments, respectively. Particularly, load combinations of dead and live loads, in which maximum load effects due to live loads are obtained, are taken into account and effects of live loads on effective buckling lengths are investigated.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.10a
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• pp.1008-1011
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• 2005

It is necessary for the design of lead frame punches in blanking to consider buckling because inner lead pitch of lead frame has been narrowed by miniaturization and high accumulation of semiconductor. In addition, if process variables change in press stamping process, the lift of punches is no longer influenced in wear and punches can be broken suddenly. To prevent the fracture of fine pitch lead frame punches, having considered applying reinforcement to it, this paper verified the design with buckling analysis. This study presents the optimal position and number of reinforcement to be attached to punches. Finally this study presents design rules of attaching reinforcement.