• Journal of Korean Society of Steel Construction
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• v.15 no.3
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• pp.291-298
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• 2003

Recently, as the size of buildings structure becomes large increases, their mat area of building structure is supported or by an inhomogeneous foundation. This paper presents a vibration analysis on thick plates subjected to in-plane force is presented in this paper. The rectangular plate is isotropic, homogeneous, and composed of a linearly elastic material. A vibration analysis of the rectangular thick plate iwas done by useing ofarectangular finite element with 8 nodes and 9 nodes. In this study, the foundation was idealized as a Pasternak foundation model. A Pasternak foundation haves a shear layer on Winkler's model, which idealizes the foundation as a vertical spring. In order tTo analysze the vibration of a plate supported on by an inhomogeneous Pasternak foundation, the value of the Winkler foundation parameter of the central and border zones of the plate awere chosen as WFP1 and WFP2. (fFigure 4.). The Winkler foundation parameter of WFP1 and WFP2 is varied from 0 to 10, $10^2$, and $10^3$ and the shear foundation parameters is were 0, 5, and 10. The ratio of the in-plane force to the critical load iwas applied as 0.4 to 0.8

• Journal of the Society of Naval Architects of Korea
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• v.36 no.4
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• pp.95-104
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• 1999

Use of the ultra thick plate is being continuously increased in large off-shore structures, ships, bridges and skyscraper construction, due to increasingly large-sized steel structures and it seems that this trend will be maintained. But, occurrence of the lamella tearing has been reported in ultra thick plate used for construction. It is reportedly caused by impurities such S(sulfur), P(phosphorus) and others accumulated in the ultra thick plate's centerline in the thickness direction with strip shape or by restraint residual stress caused by the welding. In the ultra thick plate made by continuous casting method, occurrence of lamination is difficult to avoid because of the properties of production procedure. Therefore, with a view to reducing the lamella properties, this report tries tearing in the steel structure in the view of welding strength rather than metallic properties, this report tries to seek the optimum groove and welding procedure by using the computer simulation based on FEM(Finite Element Method).

• Journal of the Korea Academia-Industrial cooperation Society
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• v.4 no.2
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• pp.76-80
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• 2003

In this study, it is presented analysis results of bending problems in the orthotropic thick plates and the orthotropic thin plates. Finite element method in this analysis was used. Both Kirchoffs assumptions and Mindlin assumptions are used as the basic governing equations of bending problems in the orthotropic plates. The analysis results are compared between the orthotropic thick plates and the orthotropic thin plates for the variations of thickness-width ratios.

• Transactions of the Korean Society of Mechanical Engineers
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• v.16 no.7
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• pp.1278-1284
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• 1992

In plate rolling, it is desired to reduce the trimming loss by controlling the formation of defective end shapes. For this reason, edge rolling is frequently performed in the plate mill. In this paper, the effect of various process variables on the deformation of plate ends in edge rolling is examined by conducting experiments and finite element computer simulation. A focus is given to investigating the effect of edging on the width of the deformed plate trimming-free plate rolling.

• Journal of Welding and Joining
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• v.12 no.1
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• pp.7-15
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• 1994

알루미늄합금의 용도가 우주 항공기 부품에서 자동차, 선박, 건축 등 다양화되면서 이들 재료에 대한 용접기술 또한 산업현장의 주요한 과제로 등장하게 되었다. 알루미늄합금은 극히 활성이 높고, 열전도율이나 열팽창계수가 매우 큰 물리적 특성 및 액상과 고상간의 매우 큰 수소 용해도 차이 등의 특이한 성질을 가지고 있기 때문에 용접에 있어서는 기공이나 미세한 융합 불량이 발생하기 쉽고, 또 용접변형의 제어에도 세심한 배려를 요하는 등 우수한 용접부를 만들기 위해서 고려해야 할 문제를 가지고 있다. 특히 기공이 후판 알루미늄 합금 용접에 있어서 보수공사의 대부분을 차지하고 있으므로 기공 방지법을 확립하는 것은 매우 중요하다. 알루미늄 합금의 용접에 있어서 기공의 발생원인은 수소에 의한 것이라고 정립되어 있으나 그 방지법에 대해서는 많은 연구검토가 행해지고 있음에도 불구하고 수소의 공급경로가 매우 다양하고 복잡하기 때문에 아직 체계적으로 확립되어 있지 못한 실정이다. 본 해설에서는 후판 알루미늄 용접시 가장 큰 문제가 되는 기공의 발생 원인과 방지대책을 기 발표된 자료를 기초로 하여 요약 정리함으로써 앞으로 여러 생산현장에서의 알루미늄합금 용접 특히 MIG 용접 관련 문제점 해결에 도움이 되고자 한다.

• Journal of Welding and Joining
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• v.12 no.2
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• pp.1-10
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• 1994

노즐에서 분사되는 제트의 거동에 대해 전반적으로 고찰해보고, 실제 후판의 레이저 절단성 실험 을 통해 노즐의 영향 및 혼합가스의 절단면 질 향상효과 등을 살펴보았다. 간략히 요약하면 다음 과 같다. 아음속제트는 노즐압력을 증가함에 따라 절단압력도 증가하지만 노즐과 재료사이의 거 리를 가능한 작게 유지하여야 하는 제약이 있다. 따라서 사용중에 손상이 가기 쉽다. 이를 해결하 고자 초음속제트의 사용이 연구되고 있지만 shock의 형성으로 인해 노즐압과 절단압은 매우 비선 형적인 관계를 갖는다. 따라서 (i)고압에서도 MSD가 형성되지 않고 주기적인 압력 재상승이 나 타나도록 하거나, (ii)Laval노즐을 이용해 shock구조가 형성되지 않고 큰 절단거리를 얻도록 하는 방법이 제시되고 있다. 초음속노즐의 후판 절단 적용 가능성을 분석해 본 결과 유동 박리 현상으 로 인해 후판보다는 박판의 향상을 위해서는 적절한 조성의 혼합가스를 사용하는 것이 아주 효과 적이었으며, 보조 가수 제트를 채용해 slag제거를 효율적으로 수행 할 수 있음을 확인하였다.

• Journal of the Korean Society for Precision Engineering
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• v.12 no.3
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• pp.73-81
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• 1995

To find a way for establishing work roll initial crown according to roll conditions, computer simutation for predicting plate crown in plate mill is done and effects of roll conditions on plate crown is analyzed. Toll gap rorfile and plate crown are measured to be compared to the calculated values. As a result, regression equation to establish work roll initial crown according to roll conditions such as backup roll diameter, backup roll crown and work roll diameter is obtained.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1993.04b
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• pp.53-57
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• 1993

굽힘 가공(Bending Process)은 원통형의 다이(die)등을 이용하여 평판형 금속 판재에 프레스 하중을 가하여 임의의 굽 힘 형상을 영구적으로 만드는 가공법으로 소성가공을 하고 있는 대부분의 산업현장에서 널리 쓰이는 가공법 중의 하 나이다. 본 연구에서는 특수 목적이 대형구조물 혹은 대형차체에 주로 사용되어지는 고장력 후판을 대상으로 하여 여러종류의 굽힘각도에 따른 가공성 시험을 수행하고, 굽힘가공부위에서 채취한 시험편에 대한 기계적 물성시험을 통하 여 가공전의 모재와 비교, 분석하므로써 적절한 굽힘 가공조건 및 굽힘가공이 가능한 허용각도등을 결정할 수 있도록 하였다.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.27 no.2
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• pp.234-242
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• 2017

This study investigates vibro-acoustic characteristics of a short, thick cylinder containing a slot given a pined-free boundaries. Using the finite element analysis results, structural modes of the asymmetric cylinder (with a slot) are expressed as the linear combinations of modes of the symmetric cylinder made of same material with identical geometry except the slot. Based on synthesized modal vibrations, acoustic modes of the asymmetric cylinder are obtained with two approaches, i.e., Rayleigh integral calculation and modal expansion of the acoustic modes of the symmetric cylinder. Also, acoustic powers, max. sound pressure and directivity pattern are obtained from acoustic modes and verified with the boundary element analyses. Based on these results, the accuracy of proposed approaches in calculating the vibro-acoustic properties of a short, thick, asymmetric cylinder has been confirmed. The procedure can be applied to the similar cylinders with other boundaries or asymmetric properties. Also, attenuation of vibration and/or sound radiation of the cylinder type practical components can be studied using these approaches.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.21 no.8
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• pp.698-707
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• 2011

This paper is to analyze the stability of the thick plate on inhomogeneous Pasternak foundation, with linearly varying thickness and concentrated mass by finite element method. To verify this finite element method, the results of natural frequencies and buckling stresses by the proposed method are compared with the existing solutions. The dynamic instability regions are decided by the dynamic stability analysis of the thick plate on inhomogeneous Pasternak foundation, with linearly varying thickness and concentrated mass. The non-dimensional Winkler foundation parameter is applied as 100, 1000 and non-dimensional shear foundation parameter is applied as 5. The tapered ratios are applied as 0.25 and 1.0, the ratios of concentrated mass to plate mass as 0.25 and 1.0, and the ratio of in-plane force to critical load as 0.4. As the result of numerical analysis of the thick plate on inhomogeneous Pasternak foundation for $u{\times}v=300cm{\times}300cm$ and $a{\times}b=600cm{\times}600cm$, instability areas of the thick plate which has the larger rigidity of inner area are farther from ${\beta}$-axis and narrower than those which has the larger rigidity of outer area.