• Structural Engineering and Mechanics
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• 제5권1호
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• pp.69-83
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• 1997

A new efficient hybrid/mixed thin~moderately thick plate bending element with 6-node (HM6-14) is formulated based on the Reissner-Mindlin plate bending theory. The convergence of this element is proved by error estimate theories and verified by patch test respectively. Numerical studies on such an element as HM6-14 demonstrate that it has remarkable convergence, invariability to geometric distorted mesh situations, to axial rotations, and to node positions, and no "locking" phenomenon in thin plate limit. The present element is suitable to many kinds of shape and thin~moderately thick plate bending problems. Further, in comparison with original hybrid/mixed plate bending element HP4, the present element yields an improvement of solutions. Therefore, it is an efficient element and suitable for the development of adaptive multi-field finite element method (FEM).

• 대한기계학회논문집A
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• 제29권10호
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• pp.1336-1343
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• 2005

The detection mechanism of the flaw for the nondestructive testing using eddy current is related to the interaction of the induced eddy currents in the test specimen with flaws and the coupling of these interaction effects with the moving test probe. In this study, the two-dimensional electromagnetic finite element analysis(FEM) fur the eddy current signals of the aluminum plate with different depth of surface cracks is described and the comparison is also made between experimental and predicted signals analyzed by FEM. In addition, the characteristics of attenuation of the eddy current density due to the variation of the depth of a conductor are evaluated. The effective parameters for the application of eddy current technique to evaluate surface cracks are discussed by analyzing the characteristics of the eddy current signals due to the variation of crack depths.

• International Journal of Contents
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• 제11권2호
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• pp.1-8
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• 2015

In this paper, we describe a novel method for document layout analysis that is based on a Fuzzy Energy Matrix (FEM). A FEM is a two-dimensional matrix that contains the likelihood of text and non-text and is generated through the use of Fuzzy theory. The key idea is to define an Energy map for the document to categorize text and non-text. The proposed mechanism is designed for execution with a low-resolution document image, and hence our method has a fast processing speed. The proposed method has been tested on public ICDAR 2009 datasets to conduct a comparison against other state-of-the-art methods, and it was also tested with Korean documents. The results of the experiment indicate that this scheme achieves superior segmentation accuracy, in terms of both precision and recall, and also requires less time for computation than other state-of-the-art document image analysis methods.

• 한국기계가공학회지
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• 제5권3호
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• pp.51-57
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• 2006

Hydro-mechanical punching was developed for preventing burr formation. Circular hole punching and Finite element method(FEM) analysis were conducted to investigate shearing characteristics of this process in comparison with conventional and mechanical counter punching. In this process hydrostatic pressing with appropriate medium was utilized instead of counter punch, which resulted in the delay of the point that the fracture is initiated and clean shearing surface was obtained. FEM analysis was utilized to find out optimum processing parameters and shearing mechanism for burr-free hole punching.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 제36회 하계학술대회 논문집 B
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• pp.1183-1185
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• 2005

This paper describes the optimal design and performance characteristics of the BLDC Motor for Electrical Power Steering System. To develope the optimal dimension within a given volume, BLDC Motor with the low cogging torque is designed and analyzed by FEM analysis. The prototype BLDC Motor has 4 poles rotor and 24 slots stator. To estimate the prototype machine, this paper gives the comparison between the FEM results and the experiment ones.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2008년도 춘계학술대회 논문집
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• pp.333-336
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• 2008

There are many different kinds of forming processes to make a tubular product such as hydroforming and tube drawing. However, we should consider a better forming process in view point of energy consumption and $CO_2$ emission to save our earth. In this paper we have conducted FEM simulations to the various forming processes for sheet and tubular products to compare their energy consumptions. One example is tubular product and the other for drawn cup. From the comparisons of total energy for hydrofroming and tube sinking processes, hydroforming is consumed more energy than tube drawing. Also the cup drawing from sheet metal and tube sinking for the cup with flange indicate that the tube sinking is better than cup drawing of sheet metal in energy consumption.

• Steel and Composite Structures
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• 제21권6호
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• pp.1389-1410
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• 2016

This paper proposes a hybrid of topological derivative-based level set method (LSM) and isogeometric analysis (IGA) for structural topology optimization. In topology optimization a significant drawback of the conventional LSM is that it cannot create new holes in the design domain. In this study, the topological derivative approach is used to create new holes in appropriate places of the design domain, and alleviate the strong dependency of the optimal topology on the initial design. Furthermore, the values of the gradient vector in Hamilton-Jacobi equation in the conventional LSM are replaced with a Delta function. In the topology optimization procedure IGA based on Non-Uniform Rational B-Spline (NURBS) functions is utilized to overcome the drawbacks in the conventional finite element method (FEM) based topology optimization approaches. Several numerical examples are provided to confirm the computational efficiency and robustness of the proposed method in comparison with derivative-based LSM and FEM.

• Advances in Computational Design
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• 제9권2호
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• pp.81-96
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• 2024

Modeling and analyzing the dynamic behavior of fluid-soil-structure interaction problems are crucial in structural engineering. The solution to such coupled engineering systems is often not achievable through analytical modeling alone, and a numerical solution is necessary. Generally, the Finite Element Method (FEM) is commonly used to address such problems. However, when dealing with coupled problems with complex geometry, the finite element method may not precisely represent the geometry, leading to errors that impact solution quality. Recently, Isogeometric Analysis (IGA) has emerged as a preferred method for modeling and analyzing complex systems. In this study, IGA based on Non-Uniform Rational B-Splines (NURBS) is employed to analyze the seismic behavior of concrete gravity dams, considering fluid-structure-foundation interaction. The performance of IGA is then compared with the classical finite element solution. The computational efficiency of IGA is demonstrated through case studies involving simulations of the reservoir-foundation-dam system under seismic loading.

• 한국산학기술학회논문지
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• 제19권8호
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• pp.71-77
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• 2018

철근 콘크리트 암거 상부지반에 있어 아칭효과에 의한 지반의 상대적 변형 때문에 발생하는 침하거동을 평가하기 위해 Ritz 방법과 유한요소법을 적용하고 해석결과를 해석 해에 의한 결과와 상호 비교해 보았다. 유한요소법을 적용하여 절점외력을 구할 경우 요소별 국부좌표계에 관계없이 지표면으로부터의 깊이의 함수로 표현되는 전단응력이 반영되도록 주의할 필요가 있다. 암거 상부지반의 지표면에서의 변위는 해석방법에 상관없이 동일한 값을 보였다. Ritz 방법을 통해 구한 변위를 해석 해와 비교해 볼 때 가정한 변위의 차수를 증가시킬수록 해석 해에 근접한 결과를 보임을 알 수 있었다. 유한요소법에 의한 변위 또한 요소를 세분화 할수록 해석 해에 근접한 결과를 보임을 알 수 있었다. Ritz 방법에 의한 해석결과에 따르면 계산된 응력값이 해석 해에 근접한 결과를 보이지는 않았다. 유한요소법에 의한 응력의 경우 요소를 세분화 할수록 해석 해에 근접한 결과를 보였다. 본 연구에서 고려한 Ritz 방법과 유한요소법에 의한 해석결과를 해석 해와 비교한 결과 유한요소법에 의한 해석결과가 해석 해에 안정적으로 근접하는 결과를 보임을 알 수 있었다.

• 한국가스학회지
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• 제15권5호
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• pp.37-41
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• 2011

본 연구에서는 미국의 DOT-CFFC와 한국의 KS 기준에 근거하여 수소가스 복합소재 연료탱크에 대한 강도안전성을 FEM으로 해석하였다. 알루미늄 라이너 소재인 6061-T6와 탄소섬유 복합소재인 T800-24K로 적층이 형성되도록 감은 수소가스 복합소재 연료탱크는 130L의 저장용량을 갖으며, 70MPa의 충전압력으로 수소가스가 채워진다. FEM 해석결과에 의하면, 내부탱크를 형성하는 알루미늄 라이너에 작용하는 von Mises 응력 255.2MPa은 알루미늄 소재의 항복응력 대비 95%인 272MPa보다 낮기 때문에 안전하다. 또한, 복합소재 연료탱크에서 후프방향의 탄소섬유 응력비는 3.11이고, 헤리컬방향의 응력비는 3.04인 것으로 나타났다. 이들 응력비 데이터는 탄소섬유 복합소재 연료탱크에서 안전기준으로 권고한 2.4에 비해 높기 때문에 양방향 모두에서 안전하다. 따라서 70MPa의 충전압력을 갖는 130L 저장용량의 복합소재 연료탱크에 대한 강도안전성은 유용한 것으로 판단된다.