• Nuclear Engineering and Technology
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• 제49권1호
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• pp.234-244
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• 2017

Natural frequencies of immersed square sections decrease due to a contribution of added mass to the movement of square sections. In this study, natural frequencies of square sections are obtained as a function of gap size between the square section and a rigid square wall using the finite element method. Additionally, they are used to extract the added mass effect on translational and rotation motions. Published information and studies on the translational and torsional vibration of square beams are also examined for practical use. D coupling of a square section is also investigated for multiple square sections. The suggested added mass estimation can be applicable to the spent fuel storage design of a pressurized light water modulated nuclear power plant.

• Structural Engineering and Mechanics
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• 제23권5호
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• pp.563-577
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• 2006

This study involves a series of experiments on the buckling strength of eccentrically compressed cold-formed stainless steel square hollow-section columns. The principal parameters in this study are slenderness ratios ($L_k/r$ = 30, 50, 70) and magnitude of eccentricity e (0, 25, 50, 75, 100 mm) on the symmetrical end-moment. The objectives of this paper are to obtain the buckling loads by conducting a series of experiments and to compare the behavior of the eccentrically compressed cold-formed stainless steel square hollow-section columns with the results of the analysis. The ultimate buckling strength of the square-section members were determined with the use of a numerical method in accordance with the bending moment-axial force (M-P) interaction curves. The behavior of each specimen was displayed in the form of a moment-radian (M-${\theta}$) relationship. The numerically obtained ultimate-buckling interaction curves of the beam columns coincided with the results of the experiments.

• 한국강구조학회 논문집
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• 제18권5호
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• pp.525-534
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• 2006

기둥과 보를 핀접합부로 연결하는 경우 볼트열과 기둥플랜지면 사이의 편심거리에 의해 강관면에 국부적인 모멘트가 유발 되어 기둥의 내력을 저하시킬 수 있다. 본 논문에서는 각형강관 기둥-보 핀접합부를 대상으로 유한요소해석 프로그램을 이용하여 기둥의 폭과 두께 변화, 내부보강 유무, 축력의 유무에 의한 변수로 모멘트에 의한 각형강관 기둥의 내력저하를 규명하기위해 해석을 수행 하였다. 유한요소해석결과에 대한 신뢰성을 확보하기 위해 일부 실험체를 제작하여 실험을 수행하였다. 각형강관 기둥-보 핀접합부의 내력식을 제안하기 위해 항복선 이론을 적용하였다. 그 결과 각형강관 기둥-보 편접합부의 모멘트에 의한 기둥의 내력은 폭과 두께의 증가에 따라 향상되었으며 기둥의 폭두께비가 동일하여도 기둥의 크기 증가로 내력이 향상되었다. 각형강관 기둥의 무보강형태에 대한 내력의 한계치를 제시 하였으며 한계치를 만족하지 못하는 경우 기둥 내부의 보강이 필수적이다. 따라서 각형강관 기둥의 내력 향상과 제작성을 고려하여 수평보강재 의 형태를 제안하였다. 최종적으로 모멘트에 의한 내력저하를 고려한 각형강관 기둥-보 핀접합부의 내력식을 무보강형태와 수평보강형태로 각각 제안하였다.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2001년도 추계학술대회 논문집
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• pp.208-211
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• 2001

In the drawing from round billet to non-circular section there are two different processes through solid hole die(HD) and the other cassette roller dies(CRD). The CRD process has several cassette type rollers and a billet is able to move through the given gaps between two profiled rollers. The objective of this study is based on the analysis and evaluation of two aforementioned processes using experiments and finite element simulation. In order to simulate the multi-stage drawing process from circular sectioned billet to rounded square section, the finite element analysis is applied to the process using a commercially available DEFORM-3D code. Two types of experimental drawing tests through designed and manufactured dies for pure copper and aluminum alloy are carried out at room temperature. The analysis included comparison of material properties before and after drawing of each process and also provide some useful information by a FEM simulation.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1990년도 봄 학술발표회 논문집
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• pp.116-121
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• 1990

Baxed on the results tested by various researchers, a complete stress-strain relation of plain and confined concrete is proposed. The peak strength and the corresponding strain are calculated by using the Mohr-Coulomb theory and elastic tri-axial constitutive relation. A parametric study was conducted to assess the influence of the plain concrete strength, the degree of confinement, the shape of the section, and the tie configuration for the square section. According to this model, the behavior of concrete section is predicted, and compared with experimental data and other proposed models on circular and square sections. A good agreement between theoretical and experimental results is observed.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1995년도 춘계학술대회 논문집
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• pp.187-191
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• 1995

An experimental study to analyze thd hot extrusion processes of regular square section through square dies is carried out by using plasticine as a model material at room temperature. The experimental setup for the extrusion of squared section from round billets through square dies is designed and manufactured. In order to visullize the plastic flow in the extrusion process the technique of gridding on the planes of the sysmmetries and a stacking the desks with different colors are employed. Velocity fields on the symmetry planes are obtained by using grid distortion.

• 소성∙가공
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• 제5권1호
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• pp.55-60
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• 1996

In the finite element analysis of metal forming processes the updated Lagrangian approach has been widely and effectively used to simulate the non-steady state problems. however some difficulties have arisen from abrupt flow change as in extrusion through square dies. In the present work an ALE(arbitrary Lagrangian-Euleria) finite element formulation for deforma-tion analysis are presented fro rigid-viscoplastic materials. The developed finite element program is applied to the isothermal analysis of square die extrusion of a square section. The computational results are compared with those by the updated Lagrangian finite element analysis.

• 한국자동차공학회논문집
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• 제2권1호
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• pp.65-72
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• 1994

Collapse characteristics of thin-walled hatted section tubes are investigated. The square section members with flanges are substituted by the equivalent rectangular tube. The stiffening effects of flanges are transformed to the restraining plate with the equivalency of buckling strength. The square tubes of single-hatted and double-hatted sections are investigated. The double-hatted section members show symmetric and antisymmetric crushing modes depending on the stiffness of flanges. The single-hatted section members show only symmetric modes. The bifurcation point of the compact crushing modes are investigated by experiments and shown almost same thickness-width ratio of the rectangular tubes. A large maximum crippling strength can be obtained by double-hatted section members with proper flange dimensions.

• 대한기계학회논문집B
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• 제26권7호
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• pp.927-936
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• 2002

An experimental study has been conducted to investigate the heat/mass transfer characteristics within a film cooling hole of square cross-section for various blowing ratios and Reynolds numbers. The experiments have been performed using a naphthalene sublimation method and the flow field has been analyzed by numerical calculation using a commercial code. A duct flow enters into a film cooling hole in a cross-direction. For the film cooling hole with square cross-section, it is observed that the reattachment of separated flow and the vortices within the hole enhance considerably the heat/mass transfer around the hole entrance region. The heat/mass transfer on the leading edge side of hole exit region increases as the blowing ratios decrease because the main flow induces a secondary vortex. Heat/mass transfer patterns within the square film cooling hole are changed little with the various Reynolds numbers.

• International Journal of Naval Architecture and Ocean Engineering
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• 제7권5호
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• pp.906-919
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• 2015

The Deep Draft Semi-Submersible (DDS) concepts are known for their favourable vertical motion performance. However, the DDS may experience critical Vortex-Induced Motion (VIM) stemming from the fluctuating forces on the columns. In order to investigate the current-induced excitation forces of VIM, an experimental study of flow characteristics around four square-section cylinders in a square configuration is presented. A number of column spacing ratios and array attack angles were considered to investigate the parametric influences. The results comprise flow patterns, drag and lift forces, as well as Strouhal numbers. It is shown that both the drag and lift forces acting on the cylinders are slightly different between the various L/D values, and the fluctuating forces peak at L/D = 4.14. The lift force of downstream cylinders reaches its maximum at around ${\alpha}=15^{\circ}$. Furthermore, the flow around circular-section-cylinder arrays is also discussed in comparison with that of square cylinders.