• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.23 no.2
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• pp.62-69
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• 2009

For the fault diagnosis of power transformer, we develop a diagnosis algorithm based on support vector machine. The proposed fault diagnosis system consists of data acquisition, fault/normal diagnosis, and identification of fault. In data acquisition part, concentrated gases are extracted from transformer for data gas analysis. In fault/normal diagnosis part, KEPCO based decision rule is performed to separate normal state from fault types. The determination of fault type is executed by multi-class SVM in identification part. As the simulation results to verify the effectiveness, the proposed method showed more improved classification results than conventional methods.

• East Asian mathematical journal
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• v.40 no.1
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• pp.1-23
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• 2024

Let M be a semi-invariant submanifold of codimension 3 with almost contact metric structure (𝜙, 𝜉, 𝜂, g) in a complex space form M_n+1(c). We denote by A, K and L the second fundamental forms with respect to the unit normal vector C, D and E respectively, where C is the distinguished normal vector, and by R_𝜉 = R(𝜉, ·)𝜉 the structure Jacobi operator. Suppose that the third fundamental form t satisfies dt(X, Y) = 2𝜃g(𝜙X, Y) for a scalar 𝜃(≠ 2c) and any vector fields X and Y , and at the same time R_𝜉K = KR_𝜉 and ∇_{𝜙∇𝜉𝜉}R_𝜉 = 0. In this paper, we prove that if it satisfies ∇_𝜉R_𝜉 = 0 on M, then M is a real hypersurface of type (A) in M_n(c) provided that the scalar curvature $\bar{r}$ of M holds $\bar{r}-2(n-1)c{\leq}0$.

• Bulletin of the Korean Mathematical Society
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• v.55 no.6
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• pp.1791-1809
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• 2018

Let T be the singular integral operator with nonsmooth kernel which was introduced by Duong and McIntosh, and $T_q(q{\in}(1,{\infty}))$ be the vector-valued operator defined by $T_qf(x)=({\sum}_{k=1}^{\infty}{\mid}T\;f_k(x){\mid}^q)^{1/q}$. In this paper, by proving certain weak type endpoint estimate of L log L type for the grand maximal operator of T, the author establishes some quantitative weighted bounds for $T_q$ and the corresponding vector-valued maximal singular integral operator.

• Journal of the Korean Mathematical Society
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• v.58 no.4
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• pp.1035-1058
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• 2021

Under certain rather weak size conditions assumed on the kernels, some weighted norm inequalities for singular integral operators, related maximal operators, maximal truncated singular integral operators and Marcinkiewicz integral operators in nonisotropic setting will be shown. These weighted norm inequalities will enable us to obtain some vector valued inequalities for the above operators.

• Bulletin of the Korean Mathematical Society
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• v.58 no.2
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• pp.507-514
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• 2021

Vector-valued Eisenstein series of weight 3/2 are often not holomorphic. In this paper we prove that, for an even lattice Ḻ, if there exists an odd prime p such that Ḻ is local p-maximal and the determinant of Ḻ is divisible by p2, then the Eisenstein series of weight 3/2 attached to the discriminant form of Ḻ is holomorphic.

• Journal of applied mathematics & informatics
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• v.40 no.3_4
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• pp.587-601
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• 2022

We find the characterizations of the curvatures of Legendre curves and magnetic curves in Kenmotsu manifolds with C-parallel and C-proper mean curvature vector fields in the tangent and normal bundles. Finally, an illustrative example is presented.

• Journal of the Korean Society for Precision Engineering
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• v.13 no.10
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• pp.46-55
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• 1996

As industrial standard data, the STL format which approximates three dimensional CAD model to triangular facets, is used for RP(Rapid Prototyping) system in recent days. Because most RP system take the only form of two dimensional line segments as an input stream inspite of its imperfectness while converting into STL format, a CAD model is converted into a standard industrial format which is composed of many triangular facets. The error verifying process is composed of four main steps, and these are 1) Remove facets with two or more vertices equal to each other. 2) Fix overlapping error such as more than three facets adjacent to anedge. 3) Fill holes in the mesh by using Delaunay triangulation method. 4) Correct the wrong direction and normal vectors. This paper is concerned with serching the mentioned errors in advance and modifying them.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 1998.06b
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• pp.41-44
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• 1998

In this paper, a new method of obtaining specular surface shape by using five degrees of freedom camera system is described. The normal vectors of the surface are extracted by achieving the coincident between the camera axis and the surface normal vector. This method uses a five degrees of freedom (5DOF) camera to fulfill this task. From the normal vector data, the shape of the surface is reconstructed. The result shows that the methodology improves the 3-D shape of object measurement with good accuracy.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.53 no.4
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• pp.227-233
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• 2004

In stressed power system due to the presence of increased nonlinearity and the existence of nonlinear modal interactions. there exist some limitations to the use of conventional linear system theory to identify the optimum sites for a controller. This paper suggests an approach based on the method of normal forms to identify the optimum sites for controllers with incorporating the nonlinear interaction . In this paper, nonlinear participation factors and coupling factors are proposed as measures of the nonlinear interactions, and identification procedure of optimum sites for a controller is also proposed. The proposed procedure is applied to the 10-generator New England System and the KEPCO System in the year of 2010, and the results illustrate its capabilities.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.53 no.4
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• pp.227-227
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• 2004

In stressed power system due to the presence of increased nonlinearity and the existence of nonlinear modal interactions. there exist some limitations to the use of conventional linear system theory to identify the optimum sites for a controller. This paper suggests an approach based on the method of normal forms to identify the optimum sites for controllers with incorporating the nonlinear interaction . In this paper, nonlinear participation factors and coupling factors are proposed as measures of the nonlinear interactions, and identification procedure of optimum sites for a controller is also proposed. The proposed procedure is applied to the 10-generator New England System and the KEPCO System in the year of 2010, and the results illustrate its capabilities.