• Proceedings of the Computational Structural Engineering Institute Conference
• /
• 2011.04a
• /
• pp.224-227
• /
• 2011

케이블구조의 기하학적 비선형해석을 위한 탄성포물선 케이블요소를 제시한다. 탄성현수선 케이블요소에 대한 적합조건과 접선강도행렬을 토대로 장력이 충분히 도입되어 자중에 의한 처짐 형상이 포물선에 가깝다는 가정 하에서 무응력길이를 포함하는 탄성포물선 케이블요소의 비선형 힘-변형관계식과 접선강도 행렬을 구한다. 또한 현(chord)방향으로 두 케이블요소의 등가 공칭장력식을 정의한다. 탄성포물선 케이블 요소의 수치적인 정확성을 확인하기 위하여, 경사진 케이블을 탄성현수선과 탄성포물선 케이블요소로 각각 모델링하여 매개변수 해석을 수행하고 비교, 분석한 결과를 제시한다.

• Journal of the Computational Structural Engineering Institute of Korea
• /
• v.20 no.1
• /
• pp.1-7
• /
• 2007

This study introduces an elastic parabolic cable element for initial shaping analysis of cable-stayed bridges. First, an elastic catenary cable theory is shortly summarized by deriving the compatibility condition and the tangent stiffness matrices of the elastic catenary cable element. Next, the force-deformation relations and the tangent stiffness matrices of the elastic parabolic cable elements are derived from the assumption that sag configuration under self-weights is small. In addition the equivalent cable tension is defined in the chord-wise direction. Finally, to confirm the accuracy of this element, initial shaping analysis of cable-stayed bridges under dead loads is executed using TCUD in which stay cables are modeled by an elastic parabolic cable and an elastic catenary cable element, respectively. Resultantly it turns that unstrained lengths of stay cables, the equivalent cable tensions, and maximum tensions by the parabolic cable element are nearly the same as those by the catenary cable elements.

• Journal of the Korean Society of Manufacturing Technology Engineers
• /
• v.21 no.4
• /
• pp.677-682
• /
• 2012

For the product with small diameter, long column, and parabolic shape, the forging formability of the high-carbon steel wire rod was investigated in this study. By using the three-dimensional finite element method, the formability of wire was reviewed by forming analysis for the desired parabolic shape of local part. Analysis results due to forging direction, forging velocity, friction coefficient and constraint location were also investigated. On the basis of these results, it is noted that the forging direction has the big influence when the product with long column is forged. As the forging velocity increases, buckling tends to be limited and formability of parabolic shape is improved. By constraining the lower parabolic shape part to suppress plastic strain, the effect depending on friction coefficient is not almost appeared. And good parabolic shape is obtained at the region of the forging velocity of more than 0.5 m/s.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.31 no.5A
• /
• pp.361-367
• /
• 2011

This study introduces an elastic parabolic cable element for initial shaping analysis of cable-supported structures. First, an elastic catenary cable theory is shortly summarized by deriving the compatibility condition and the tangent stiffness matrices of the elastic catenary cable element. Next, the force-deformation relations and the tangent stiffness matrices of the elastic parabolic cable elements are derived and discussed under the assumption that sag configuration under self-weights is small. In addition the equivalent cable tension is defined in the chord-wise direction. Finally, to demonstrate the accuracy of the elastic parabolic cable element, nonlinear relationships of nominal cable tension-chord length and nominal cable tension-tangential stiffness for a single element are presented and compared with results using an elastic catenary cable theory as the slope is varied.

• The Journal of the Acoustical Society of Korea
• /
• v.33 no.6
• /
• pp.383-391
• /
• 2014

In order to detect underwater acoustic signals, various SONAR array types have been developed, including towed line array SONAR system (TASS). However, the TASS suffers from performance degradation which is caused by aperture deformation during a turn, because the TASS have a long-aperture array. A parabolic array model for turning TASS have been developed to solve the degradation problem occurred during a turn. In this paper, adaptive beamforming system is developed using the parabolic TASS model to cancel interference signals. The developed beamforming system is based on generalized sidelobe canceller (GSC) structure and self-tuning adaptive algorithm.

• Journal of the Korean Society of Hazard Mitigation
• /
• v.5 no.1 s.16
• /
• pp.55-62
• /
• 2005

Parabolic arch ribs are widely used in practical. In case of circular arch ribs. Inelastic in-plane buckling behaviors were investigated by Trahair(1996). Recently Yong-lin Pi & Bradford(2004) investigated about in-plane design equation for circular arch ribs. In $1970{\sim}1980$. In-plane buckling strength about parabolic arch ribs were studied by some japan researchers (Sinke, Kuranishi). Study results of Sinke & kuranishi are only valid for rise-span ratio $0.1{\sim}0.2$. In this paper. The researchers investigated about in-plane inelastic buckling behaviors of parabolic arch ribs having rise-span ratio from 0.1 to 0.4. From the results. When the rise-span ratio increase, flexural moments increase and influence of axial force to in-plane buckling strength decrease. Finally, buckling curves for parabolic arch ribs subjected distributed loading along the axis were suggested.

• Journal of the Korean Society for Marine Environment & Energy
• /
• v.12 no.4
• /
• pp.273-278
• /
• 2009

Overtopping Wave Energy Convertor (OWEC) is an offshore wave energy convertor for collecting the overtopping waves and converting the water pressure head into electric power through the hydro turbines installed in the vertical duct which is fixed in the sea bed. The numerical wave tank based on the commercial computational fluid dynamics code Fluent is established for the corresponding analysis. Several incident wave conditions and shape parameters of the overtopping device are calculated. The straight line type and parabolic type of the sloping arm are compared in the optimal designing investigation of the overtopping characteristics and discharge for OWEC device. The numerical results demonstrate that the parabolic sloping arm is available for wave running up and the overtopping discharge increasing.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.28 no.1A
• /
• pp.79-87
• /
• 2008

This paper investigates the in-plane stability of fixed shallow arches. The shape of the arches is parabolic and the uniformly distributed load is used in the study. The nonlinear governing equilibrium equation of the general arch is adopted to derive the incremental form of the load-displacement relationship and the buckling load of the fixed shallow arches. From the results, it is found that buckling modes (symmetric or asymmetric) of the arches are closely related to the dimensionless rise H, which is the function of slenderness ratio and the rise to span ratio of such arches. Moreover, the threshold of different buckling modes and buckling load for fixed shallow arches are proposed. A series of finite element analysis are conducted and then compared with proposed ones. From the comparative study, the proposed formula provides the good prediction of the buckling load of fixed shallow arches.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.6 no.3
• /
• pp.1-9
• /
• 1986

Dynamic stability of parabolic shallow arches, which are supported by hinges at both ends, is investigated. The Runge-Kutta method is used to perform time integrations of the differential equations of motion with proper boundary conditions. Based on Budiansky-Roth criterion, dynamic critical load combinations are evaluated numerically for cases of step loads of infinite duration and impulse loads, individually. The results are plotted to get interaction curves. The loci of the dynamic critical loads, which are obtained in this study, are proposed as boundaries between the dynamic stability and instability regions for the parabolic shallow arches. The results for the parabolic shallow arches are also compared with those for sinusoidal arches of the same arch rises. According to the investigation, the dynamic stability regions for the parabolic arches are larger than those for the sinusoidal arches. However, it is shown that the arch rise is the more governing factor than the shape.

• Journal of the Korean Crystal Growth and Crystal Technology
• /
• v.13 no.5
• /
• pp.247-253
• /
• 2003

In this study, a numerical analysis of the deposition of gallium arsenide from TMGa and arsine in a horizontal MOCVD reactor is performed to investigate the effect of inlet diffuser shape of reactor on the flow and deposition characteristics. The effects of two geometric parameters (diffuser angle, diffuser shape) on the growth rate, growth rate uniformity, flow uniformity and pressure loss are presented. As a results, it is found that the optimum linear diffuser angle is in the range of $50^{\circ}$∼$55^{\circ}$ and parabolic diffuser in the range of $40^{\circ}$∼$45^{\circ}$ from the viewpoint of growth rate uniformity, flow uniformity and average growth rate. It is also found that variation of diffuser angle has greater impact on growth rate uniformity than average growth rate particularly in parabolic diffuser.