• 대한수학회논문집
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• 제34권3호
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• pp.863-879
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• 2019

In this paper we study the Myers' theorem for orientable Riemannian hypersurfaces under some restrictions on the mean curvature, the second-order mean curvature, or the divergence of the shape operator and give some estimates for the diameter of such hypersurfaces.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 1999년도 제29회 춘계학술대회
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• pp.317-324
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• 1999

The present work is an attempt to calculate the steady state pressure and perturbed pressure of herringbone grooved journal bearings. A generalized coordinate system is introduced to handle the complex bearing geometry. The coordinates are fitted to the groove boundary and the Reynold's equation is transformed to be fitted to this coordinates system using the Gauss divergence theorem. This method makes it possible to deal with an arbitrary configuration of a lubricated surface. The characteristics of finite herringbone grooved journal are well calculated using this method.

• Tribology and Lubricants
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• 제16권6호
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• pp.432-439
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• 2000

The present work is an attempt to calculate the steady state pressure and perturbed pressure of herringbone grooved journal bearings. A generalized coordinate system is introduced to handle the complex bearing geometry. The coordinates are fitted to the groove boundary and the Reynold's equation is transformed to be fitted to this coordinate system using the Gauss divergence theorem. This method makes it possible to deal with an arbitrary configuration of a lubricated surface. The caharacteristics of finite herringbone groove journal bearing are well calculated using this method.

• 대한수학회보
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• 제52권3호
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• pp.699-705
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• 2015

Two well known facts from elementary number theory are proven by using Bergman spaces.

• Korean Journal of Mathematics
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• 제18권4호
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• pp.425-440
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• 2010

Using Green's theorem, elliptic boundary value problems can be converted to boundary integral equations. A numerical methods for boundary integral equations are boundary elementary method(BEM). BEM has advantages over finite element method(FEM) whenever the fundamental solutions are known. Helmholtz type equations arise naturally in many physical applications. In a boundary integral formulation for the exterior Neumann there occurs a hypersingular operator which exhibits a strong singularity like $\frac{1}{|x-y|^3}$ and hence is not an integrable function. In this paper we are going to remove this hypersingularity by reducing the regularity of test functions.

• 한국광학회:학술대회논문집
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• 한국광학회 1989년도 제4회 파동 및 레이저 학술발표회 4th Conference on Waves and lasers 논문집 - 한국광학회
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• pp.165-168
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• 1989

A finite-element method is developed to calculate the impedance of arbitrarily shaped electrodes on traveling-wave modulators. This method employs the divergence theorem to obtain the total charge on an electrode from the node potential values. By using this method, the impedance of multi strip-line electrodes on anisotropic inhomogeneous dielectric media was analysed and the effect of non-zero electrode thickness was calculated.

• Tribology and Lubricants
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• 제26권5호
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• pp.283-290
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• 2010

In this study, the stiffness and damping coefficients of herringbone grooved air journal bearings are studied. A generalized coordinate transformation method to handle the complex geometry of incompressible fluid bearing is modified for compressible fluid. The modified equations are discretized by the base of finite difference method. A new computer program using Visual C++ language is developed. The load carrying capacity and stiffness and damping coefficients are calculated according to the design parameters like groove depth or the number of grooves and compared to that of plain air journal bearings.

• 한국지능시스템학회논문지
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• 제15권2호
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• pp.127-134
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• 2005

본 논문은 고정 파라미터를 갖는 퍼지 PID 제어기의 퍼지화 과정에서 입력공간의 제한으로 제어입력이 제한되어 발생하는 제어시스템의 상승시간 지연과 불안정성을 개선하기 위해 가변 파라미터를 갖는 퍼지 PID 제어기를 제안하고 설계방법과 추종성능을 기술한다. 제어기의 파라미터는 소이득정리로부터 제어시스템의 BIBO 안정도 조건을 만족하도록 가변되어 전체 제어시스템에 대한 BIBO 안정도를 만족시킨다.

• 대한기계학회논문집
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• 제17권2호
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• pp.445-451
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• 1993

For the calculation of transonic laminar flow fields in cascades of turbomachinery, a finite volume method employing Jameson's Runge-Kutta integration scheme as a basic algorithm is presented. The cell-vertex scheme introducing half-spacing mesh cells is developed. For the velocity gradients in the stress terms the integration with divergence theorem is used for the average concept. Some numerical results show good agreement with experimental data.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 하계학술대회 논문집 E
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• pp.2287-2289
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• 1999

In this paper, a new method for calculating capacitance in multi-electrode system with arbitrarily shape is presented. This new approach based on divergence theorem and Gauss's law is achieved by Surface-Contacted Element(SCE) for Gaussian surface. To evaluate capacitance in multi-electrode system, two dimensional finite element method using only the elements which is contacted one nod (PE: Point-Element) or two nod (FE: Face-Element) with surface is employed. The proposed SCE method has short computing time to calculate capacitance which is because it uses only SCE elements and needs one calculation loop while exiting FEM method in servral loops. This method is verified by application in calculating capacitance using potential detection device model which is composed with anode, cathode, and floating electrode.