• Proceedings of the Korea Water Resources Association Conference
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• 2010.05a
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• pp.754-758
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• 2010

케이블 교량에서 발생하는 사장케이블의 진동현상에 대한 현상학적 특성을 명확히 이해해야, 사장케이블의 적합한 제진설계가 가능하다. 본 연구에서는 유체의 흐름과 구조물의 진동을 동적으로 연계하여 해석하기 위하여, ADINA의 CFD 및 Structure 코드를 동적으로 연계하는 FSI(Fluid Flow with Structure Interaction) 기법을 이용하였다. 바람으로 인해 이중원형실린더의 풍상측과 풍하측 실린더에서는 와류가 방출되면서 외력이 작용하게 되며, 이러한 공기력은 풍하측 실린더의 고유진동 운동과 함께 와류진동현상을 유발한다. 본 연구에서는 풍하측 실린더의 와류진동 현상의 해석에 주안점을 두었다. 본 연구에서는 흐름의 레이놀즈수와 이중원형실린더에 대한 바람의 입사각을 변화시키며 풍하측 실린더에서 발생하는 와류진동의 크기를 분석하였다. 본 연구결과, 유입풍속 및 바람의 입사각에 따라 이중원형실린더에서 발생하는 일반적인 와류방출현상과 풍하측 실린더에 작용하는 공기력 및 변위양상을 예측할 수 있었다. 특히, 바람의 입사각이 $15^{\circ}$인 경우에는 풍하측 실린더에서 방출되는 와류로 인해 풍하측 실린더에는 비대칭의 공기력이 작용하며, 이는 풍하측 실린더가 2사분면에서 4사분면 방향으로 진동하는 원인이 되는 것으로 판단된다.

• Proceedings of the Korea Water Resources Association Conference
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• 2009.05a
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• pp.919-923
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• 2009

케이블 교량에서 발생하는 사장케이블의 진동현상에 대한 현상학적 특성을 명확히 이해해야, 사장케이블의 적합한 제진설계가 가능하다. 본 연구에서는 ADINA CFD 코드를 이용하여, 이중원형실린더에서 발생하는 와류방출현상과 실린더에 작용하는 외력을 해석함으로써, 사장케이블에서 발생하는 진동현상의 원인을 규명하고자 하였다. 이를 위하여 본 연구에서는 흐름의 레이놀즈수, 실린더간 간격과 이중원형실린더에 대한 바람의 입사각을 변화시키며 이중원형실린더에서 발생하는 와류방출현상과 이로 인해 실린더에 작용하는 항력, 양력과 같은 외력을 분석하였다. 분석 결과, 풍상측 케이블에는 일방향의 항력이 주로 작용하므로 케이블 진동이 제한적으로 발생하나, 풍하측 케이블에는 항력과 같은 규모의 진동하는 양력이 작용하는 것으로 나타났으며 이로 인해 풍하측 케이블에서 진동이 크게 발생하는 것으로 나타났다.

• Composites Research
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• v.26 no.1
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• pp.7-13
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• 2013

This paper describes the design of dual-structured and thick-walled cylinder made of composites and special steel. The structure of special steel and composites reduce the weight of a product maintaining its property which is proper to the characteristics. Hence they are used in the fields, such as various ground weapons, aerospace and sports industries, where high elasticity and low weight are required. Thus in this study, the analysis was conducted to find the most proper composite application method changing its types and angle of laminates for the design. Through the comparison of the results, we suggest the method for composite application which is the most appropriate to the designing purpose of this study.

• Composites Research
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• v.24 no.2
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• pp.22-29
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• 2011

To increase the performance of thick-walled cylinders recently their length is continually enlarged. For that reason it is important to reduce weight of the thick-walled cylinders. In this paper the FE models to predict and estimate effects on the composite tapes were created with MSC.Nastran/Patran v.2005. First of all a autofrettage method was applied to the 2D model of the AISI4340 cylinder reduced the thick. And then the comparison of the numerical results with analysis results showed and verified by using T300/5208, IM7/PETI5, IM7/8552 tapes. Those are predicted to the effects of the angle of the composite tapes and elastic modulus according to the composite properties.

• Proceedings of the KSME Conference
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• 2007.05a
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• pp.620-625
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• 2007

Autofrettage process is used for internal forming and sizing of cylinder designed to withstand high internal pressures. Once the tube is autofrettaged, it needs to be machined to its final dimensions both at the bore and its outer surface. This paper presents an analytical analysis and numerical analysis of machined compound cylinder using finite element code, ANSYS10.0. An analytical model for predicting the level of autofrettage following either inner, outer, or combined machining of the compound cylinder is developed for the autofrettage residual stress field is simulated by an autofrettaged pressure. The autofrettaged pressures are obtained by using trying-error method. As autofrettage percentage is 20 %, the numerical results are found to be in almost agreement with the analytical ones. However, as autofrettage percentage is 60 %, the numerical results have a little difference with the analytical ones.

• Proceedings of the Korea Information Processing Society Conference
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• 2010.11a
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• pp.691-692
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• 2010

본 논문에서는 입체영상 기법과 파노라마 영상 기술을 접목한 입체 파노라마 영상을 애너그리프 방식의 실린더 형태로 구현할 때, 애너그리프 합성 후 파노라마 스티칭 하는 방법과 파노라마 스티칭 후 애너그리프 합성하는 방식 두 가지로 각각 구현 해보고, 두 결과 영상의 Depth map 을 생성하여 입체감 형성 정도 및 왜곡 정도를 분석한다.

• Proceedings of the Optical Society of Korea Conference
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• 2002.11a
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• pp.80-81
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• 2002

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.32 no.6
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• pp.396-410
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• 2020

The design and the construction are carried out by installation of new caissons on the back or the front of existing caissons to increase the stability of existing caisson breakwater. In this study, we use the eigenfunction expansion method to analyze the effects of wave structure interaction when new porous dual circular caissons are installed on the back or the front of existing breakwater. The porous dual circular caisson which consisting of a porous outer cylinder circumscribing an impermeable inner cylinder is one type of seawater exchanging breakwater. The comparison of numerical results between present method and Sankarbabu et al. is made, and the wave force and the wave run-up acting on each porous dual circular caisson are calculated for various parameters by considering the wave structure interaction.

• Composites Research
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• v.25 no.4
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• pp.126-132
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• 2012

It is useful to have a quick analysis program in early design process for feasibility studies of composite cylinder because it takes long time and is not cost effective by commercial programs. In this paper, a GUI program is developed to calculate the stress distribution in a fast manner with the properties, the orientation angle and the stacking sequence of composite material using LabVIEW. The stress distributions of an autofrettaged cylinder and a composite cylinder with internal pressure are compared with the results by MSC Nastran/patran. The stress distribution of steel/composite cylinder is compared with the values of existing studies, and is proved. Furthermore, by calculating the stress distribution of an autofrettaged steel/composite cylinder, the stress distribution is estimated, and the program will be useful in an early design phase for feasibility studies.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.33 no.7
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• pp.1-8
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• 2005

For study on the unsteady wall interference effect, flows around a circular cylinder in closed test-section wind tunnels have been numerically investigated by solving compressible Navier-Stokes equations. The numerical scheme is based on a node-based finite-volume method with the Roe's flux-difference splitting and an implicit time-integration method coupled with dual time-step sub-iteration. The computed results showed that the unsteady pressure gradient over the cylinder is enhanced by the wall interference, and as a result the fluctuations of lift and drag are augmented. The drag is further increased because of the lower base pressure. The vortex shedding frequency is also increased by the wall interference. The pressure on the test section wall shows the harmonics having the shedding frequency contained in the wall effect.