• 대한수학회논문집
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• 제38권4호
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• pp.1281-1298
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• 2023

Let (M^2m, 𝜑, g) be a B-manifold. In this paper, we introduce a new class of metric on (M^2m, 𝜑, g), obtained by a non-conformal deformation of the metric g, called a generalized Berger-type deformed metric. First we investigate the Levi-Civita connection of this metric. Secondly we characterize the Riemannian curvature, the sectional curvature and the scalar curvature. Finally, we study the proper biharmonicity of the identity map and of a curve on M with respect to a generalized Berger-type deformed metric.

• Nuclear Engineering and Technology
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• 제56권3호
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• pp.772-784
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• 2024

The hexagonal nodal code RENUS has been enhanced to handle irregularly deformed hexagonal assemblies. The underlying RENUS methods involving triangle-based polynomial expansion nodal (T-PEN) and corner point balance (CPB) were extended in a way to use line and surface integrals of polynomials in a deformed hexagonal geometry. The nodal calculation is accelerated by the coarse mesh finite difference (CMFD) formulation extended to unstructured geometry. The accuracy of the unstructured nodal solution was evaluated for a group of 2D SFR core problems in which the assembly corner points are arbitrarily displaced. The RENUS results for the change in nuclear characteristics resulting from fuel deformation were compared with those of the reference McCARD Monte Carlo code. It turned out that the two solutions agree within 18 pcm in reactivity change and 0.46% in assembly power distribution change. These results demonstrate that the proposed unstructured nodal method can accurately model heterogeneous thermal expansion in hexagonal fueled cores.

• 대한수학회지
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• 제36권3호
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• pp.621-631
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• 1999

In this paper we briefly describe the geometry of the Cayley hyperbolic plane and we show that every uniform lattice in quaternionic space cannot be deformed in the Cayley hyperbolic 2-plane. We also describe the nongeometric bending deformation by developing the theory of the Cartan angular invariant for quaternionic hyperbolic space.

• 한국정밀공학회지
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• 제5권1호
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• pp.29-39
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• 1988

Plastically deformed layer beneath metal surface machined by orthogonal cutting was evaluated in terms of residual stress, microvickers hardness, side spread, and the side strain. An attempt was made to predict the depth of layer according to machining conditions particularly tool geometry and the shear plane angle. In this paper, we employed two models concerning the sliplines. The exact model was validated by comparision of computed and measured tool force and its angle, and the model offers an upper boundary of the deformed layer to be in good agreement with the experiment.

• 한국수소및신에너지학회논문집
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• 제32권4호
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• pp.228-235
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• 2021

Polymer electrolyte membrane fuel cells (PEMFC) are currently being used in various transport applications such as drones, unmanned aerial vehicles, and automobiles. The power required is different according to the type of use, purpose, and the conditions adjusted using a cell stack. The fuel cell stack is compressed to reduce the size and prevent fuel leakage. The unit cells that make up the cell stack are subjected to compression by clamping force, which makes geometrical changes in the porous media and it impacts on cell performance. In this study, finite elements method (FEM) and computational fluid dynamics (CFD) analysis for the deformed unit cell considering the effects of clamping force is performed. First, structural analysis using the FEM technique over the deformed gas diffusion layer (GDL) considering compression is carried out, and the resulting porosity changed in the GDL is calculated. The PEMFC model is then verified by a three-dimensional, two-phase fuel cell simulation applying the physical properties and geometry obtained before and after compression. The detailed simulation results showed different concentration distributions of fuel between the original and deformed geometry, resulting in the difference in the distribution of current density is represented at compressed GDL region with low oxygen concentration.

• 대한기계학회논문집
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• 제18권8호
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• pp.2005-2015
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• 1994

An analytical method based on the upper bound approach for the cup-bar axisymmetric combined extrusion is presented to determine the deformation zones as well as extrusion load and deformed geometry in the early stage. A new kiematically admissible velocity field is derived by the appropriate transformation of the original velocity field and applying the flow function approach. The derived velocity field is directly related to the boundary function for the plastically deforming zones and the parameter controlling the flow direction to the forward part or backward part. Experiments are carred out with the annealed aluminum 2024 at room temperature for the various area reductions. The workhardening effect is considered in the formulation as a function of the height ratio between the deformed billet and the orighinal billet to calculate the extrusion pressures. The theoretical predictions for the extrusion loads and deformed configuration are in good agreement with the experimental results.

• 콘크리트학회논문집
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• 제14권4호
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• pp.474-482
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• 2002

본 연구의 목적은 섬유의 부착시험을 통하여 섬유의 파괴없이 최대 인발저항을 가지고 시멘트 모체 내에서 완전한 정착작용을하는 구조용 합성섬유의 최적형상과 최적형상함수를 도출하는데 있다. 7가지 다른 형상의 구조용 합성섬유를 조사하였고 부착시험을 수행하였다. 부착시험의 변수는 7가지의 다른 형상이고, 2종류의 시멘트 모르타르의 배합이다. 부착시험 결과, 7가지 다른 형상중 crimped type이 계면인성(인발에너지)와 인발하중에서 가장 우수한 성능을 보였다. Crimped type을 기본으로 하여 섬유의 주기와 높이를 바꾸어 부착시험을 실시한 결과 최적형상함수, D= $b^{{\alpha}ο{\alpha}}$ $h^{λ{\beta}}$ 를 도출하였다.

• 한국자동차공학회논문집
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• 제9권5호
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• pp.165-172
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• 2001

Wheel bearing units were almost exclusively used for car front wheel, where the two ball rows are directly side by side with integrated rubber seal. The seal is of important for wheel bearing units due to the adverse environmental conditions with mud and splash water. The seal of wheel bearing units was designed to have geometry with multi lips, which elastic lip contacts and deforms with bearing. The equation of reaction force for deformed lip as cantilever beam was previously used for seal lip design. But it's result was not useful because deflection of the beam differs from lip's. In this study, deformed shape of the lip was assumed to and order function which is more similar to lip deformation and made the equation for reaction force prediction. The Reaction forces from each other equations were compared with results by FEA to prove usefulness of new equation.

• Journal of Information Display
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• 제1권1호
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• pp.20-24
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• 2000

We propose on a novel vertical configuration (VC) for a helix-deformed ferroelectric liquid crystal (HDFLC) display that has fast response, high contrast, analog gray scale capability, and wide-viewing characteristics. In contrast to a conventional HDFLC in a planar geometry, smectic layers arrange themselves parallel to the substrates, and thus, extremely uniform alignment of molecules in large area is naturally achieved in our new configuration without additional processes such as the rubbing and/or electric field treatment. Moreover, with a proper design of electrode patterns on the same substrate, multidomain switching is easily realized without employing any complex process of alignment. Our new VC-HDFLC is expected to provide a viable technology to produce a next-generation large area LCD suitable for processing the dynamic image at a video-rate.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 1999년도 춘계학술대회논문집
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• pp.84-87
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• 1999

This paper presents a preform design method that combines the analytic method and inference of known knowledge with neural network. The analytic method is a finite element method that is used to simulate backward extrusion with pre-defined process parameters. The multi-layer network and back-propagation algorithm are utilized to learn the training examples from the simulation results. The design procedures are utilized to learn the training examples from the simulation results. The design procedures are two methods the first the neural network infer the deformed shape from the pre-defined processes parameters. The other the network infer the processes parameters from deformed shape. Especially the latest method is very useful to design the preform From the desired feature it is possible to determine the processes parameters such as friction stroke and tooling geometry. The proposed method is useful for shop floor to decide the processes parameters and preform shapes for producing sound product.