• Journal of the Korean Society for Nondestructive Testing
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• v.32 no.2
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• pp.149-154
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• 2012

The size and distribution of welding residual stress and welding deformation in welding structures have an effect on various sorts of damage like brittle failure, fatigue failure and stress corrosion cracking. So, research for this problem is necessary continuously. In this study, non-destructive technique using laser electronic speckle pattern interferometry, plate of welding specimen according to the external load on the entire behavior of residual stress are presented measurement techniques. Once, welding specimen force tensile loading, using electronic speckle pattern interferometry is measured. welding specimen of base metal and weld zone measure strain from measured result, this using measure elastic modulus. In this study, electronic speckle pattern interferometry use weld zone and base metal parts of the strain differences using were presented in residual stress calculated value, This residual stress value were calculated by numerical calculation. Consequently, weld zone of modulus high approximately 3.7 fold beside base metal and this measured approximately 8.46 MPa.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.4 no.1
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• pp.37-42
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• 2005

The localization of manufacturing technique development is actualizing for low cost with supplies of display devices. We need more high cutting technique because consumers want flat glasses of various sizes. Recently, most general two methods are normal wheel cutting and laser cutting, but both of them have some faults. First, the wheel cutting has cracks and sharp edges of sections. Second, it is easy for laser cutting to cut curved lines. however, it has thermal damage and low traverse speed. I suggest a new cutting method by high-wave frequency vibration wheel cutting(HFVC), which is good for quality improvement. Vertical cracks and crack depth is observed, after HFVC. When the average of the crack depth is $30{\mu}m$ and the average of the wallner liner depth is $200{\mu}m$, it has the most high quality of the sections in this experiment. As a result, when we consider between the normal wheel cutting method and the HFVC method, the latter has low cracks and good quality.

• Journal of Korean Society of Steel Construction
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• v.14 no.4
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• pp.529-538
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• 2002

Applications of corrugated plates (or folded plates) have been recently increasing due to certain economic and structural advantages. Likewise, applications of corrugated plates has been increasing because they are stronger compared to flat plates. Therefore, specifications of corrugated plates should be determined. There are many design details in almost every specification for flat plates. However, except the bending strength and the normal strength, there are no detailed design guides such as shear strength. Thus, it is difficult for engineers to design structures consisting of corrugated plates. As such, engineers need a guide in designing corrugated plates. Extensive numerical study was conducted in order to identify the relationship between the shear strength and geometric conditions for corrugated plates. An eight-node thin shell element (QSL8) of the commercial program LUSAS (version 13.2) was used. The study was able to come up with a formula that helps determine the shear strength of corrugated plates under various geometric conditions, the size of corrugation, the curvature of corrugation, and the thickness of the corrugated plate. Likewise, corrugated plates were found to have a higher shear buckling strength than flat plates.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.29 no.3
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• pp.285-292
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• 2016

In this study, FE-BE direct coupling methods of 1D and 2D problems are considered for the pontoon-type floating structure and the difference of the modeling dimensions is investigated for the hydroelastic response. The modeling dimensions are defined as the 1D problem consisting 1D beam-2D fluid coupling and the 2D problem consisting 2D plate-3D fluid coupling with zero-draft assumption. For case studies, hydroelastic responses of the 1D Problem are compared to those of the 2D Problem for a wide range of aspect ratio and regular waves. It is shown that the effects of the elastic behavior are increased by decreasing the incident wavelength, whereas the effects of the rigid behavior are increased by increasing the incident wavelength. In 2D problem, the incident wave angle can be considered, and slightly more accurate results can be obtained, but the computational efficiency is lower. On the other hand, in 1D problem with plate-strip condition, the incident wave angle cannot be considered, but when the aspect ratio is large, the overall responses can be analyzed through a simplified model, and the computational efficiency can be improved.

• Journal of the Society of Naval Architects of Korea
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• v.32 no.3
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• pp.116-125
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• 1995

In ship and of offshore structures, there exist many local panels of various shapes having many kinds of attachments reducible to damped spring-mass systems. For the vibration analysis of panels, analytical methods such as Rayleight-Ritz method or the assumed mode method can be efficiently applied. There have been many studies on the vibration analysis of rectangular panels using the analytical methods but relatively few for arbitrary shape panels. An efficient formulation based on the assumed mode method is presented for the vibration analysis of an arbitrary quadrangular plate having concentrated masses, supporting springs such as pillars and spring-mass systems. In the formulation, the natural coordinate system is used for the efficient treatment of an arbitrary quadrangular shape. Through some numerical calculations, accuracy and efficiency of the presented method are shown.

• Journal of the Korean Society of Propulsion Engineers
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• v.20 no.5
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• pp.60-69
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• 2016

This paper presents a numerical investigation on kerosene-air mixture detonation and behaviors of thermal elasto-plstic thin metal tube under detonation loading based on multi-material analysis. The detonation loading is modeled by the kerosene-air mixture detonation which is compared with Chapman-Jouguet (C-J) condition and experimental cell size. To conform the elasto-plastic model, plastic and elastic behaviors are verified by Taylor impact and plate bending motion, respectively. The numerical results are compared with the theory on burst pressure of tube. The critical deformable thickness with the thermal softening considered is good agreement with the theoretical value.

• Bulletin of the Society of Naval Architects of Korea
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• v.19 no.2
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• pp.1-11
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• 1982

Ship bottom structure is idealized by an equivalent orthotropic plate upon which uniform lateral, uni-axial and bi-axial loads act. Solutions in the form of series representing deflections and moments at the center are obtained in case of simply supported and fixed boundary conditions. Variables in the solutions are reduced and grouped in nondimensional parameters. Stresses in the members of actual plate-stiffener combination are calculated corresponding to moments obtained above. In this paper design curves of deflections and moments for two different sets of boundary conditions are given, and they are compared with Schade's design curves and Mansour's design curves. Some examples for application are given and compared with the results obtained by FEM(SAPIV) in appendix.

• Proceedings of the KSR Conference
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• 2005.05a
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• pp.344-349
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• 2005

The axially moving thin beam-plates exposed to sudden thermal loadings may experience severe vibrations through the thermal shock process. For accurate prediction of the thermal shock-induced vibrations, this paper develops a spectral element model for axially moving thermoelastic beam-plates. The spectral element model which is represented by spectral element matrix is formulated from the frequency-dependent dynamic shape functions which satisfy the governing equations in the frequency-domain. Thus, when compared with the classical finite element model in which simple polynomial functions are used as the shape functions, the spectral element model can provide exact solution by treating a whole uniform structure member as a single finite element, regardless of its length.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 1997.10a
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• pp.73-79
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• 1997

It is one of classical problems in the elastic theory to analyze contact stresses between elastic bodies. Concrete pavements under traffic wheel loads can be considered as one of these typical Problems. In the paper, Mindlin plate theory is used to consider the transverse shear effect, 8-node isoparametric plate bending element is adopted in this study, and an elastic plate resting on tensionless elastic half-space is analyzed by finite element method. The Boussineq's solution of elastic half-space is used to evaluate the flexibility of foundation. To obtain the boundary of contact area, the flexibility matrix of foundation is modified after each cycle of analysis iteratively. A Numerical example is presented by using these method.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.11a
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• pp.300-300
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• 2007

최근 전기전자기기 및 광학기기 등의 소형화 및 고기능에 맞추어 구동 장치의 소형화가 필수적으로 요구됨에 따라, 보다 간단한 구조의 다양한 소형 압전 선형 모터에 대한 개발이 활발히 진행되고 있다. 본 연구에서는 굴곡 진동 모드를 갖는 평판형의 압전체와 탄성체로 구성된 압전 트랜스듀서와 두 개의 압전 트랜스듀서를 연결하여 타원 운동을 구현하기 위해, 굴곡 변형이 발생하는 한 쌍의 압전 트랜스듀서에 $90^{\circ}$ 위상차를 갖는 정현파를 각각 인가하여, 한 쌍의 압전 트랜스듀서를 연결하는 돌출부에서 타원궤적을 형성하는 소형 압전 액츄에이터를 설계하였다. 유한요소해석 프로그램인 ATILA를 이용하여 결합부의 타원 궤적의 형성하기 위한 압전 트랜스듀서의 최적 동작 주파수로 운동 모드를 결정하고자 한다.