• Journal of the Korean Mathematical Society
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• v.32 no.4
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• pp.803-814
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• 1995

Let $\Sigma$ be the class of all complex-valued, harmonic, orientation-preserving, univalent mappings defined on $\Delta = {z : $\mid$z$\mid$ > 1}$ that map $\infty$ to $\infty$.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1997.04a
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• pp.1003-1008
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• 1997

In this paper, the prediction of cutting force and tool deflection in the ball-end milling process are studied. Identifying various cutting region using Z-map, cutting force in the ball-end milling process can be predicted. Cutting force deflects the tool and the tool deflection changes the cutting force. Tool deflection is included in the cutting force prediction. Tool deflecition also causes machining error of the machined surface. A series of experiments were performed to verify the simulated cutting force and machining error.

• Journal of the Korean Mathematical Society
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• v.45 no.6
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• pp.1705-1723
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• 2008

Let n be a 2-step nilpotent Lie algebra which has an inner product <, > and has an orthogonal decomposition $n\;=z\;{\oplus}v$ for its center z and the orthogonal complement v of z. Then Each element z of z defines a skew symmetric linear map $J_z\;:\;v\;{\longrightarrow}\;v$ given by <$J_zx$, y> = for all x, $y\;{\in}\;v$. In this paper we characterize Jacobi fields and calculate all conjugate points of a simply connected 2-step nilpotent Lie group N with its Lie algebra n satisfying $J^2_z$ = A for all $z\;{\in}\;z$, where S is a positive definite symmetric operator on z and A is a negative definite symmetric operator on v.

• Journal of the Korean Society for Precision Engineering
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• v.15 no.12
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• pp.212-219
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• 1998

During machining of dies and molds with sculptured surfaces. the cutter contact area changes continuously and results in cutting force variation. In order to implement cutting force prediction model into a CAM system, an effective and fast method is necessary. In this paper. a new method is proposed to predict mean cutting force. The cutter contact area in the spherical part of the cutter is obtained using Z-map, and expressed by the grids on the cutter plane orthogonal to the cutter axis. New empirical cutting parameters were defined to describe the cutting force in the spherical part of cutter. Before the mean cutting force calculation, the cutting force density in each grid is calculated and saved to force map on the cutter plane. The mean cutting force in an arbitrary cutter contact area can be easily calculated by summing up the cutting force density of the engaged grid of the force map. The proposed method was verifed through the slotting and slanted surface machining with various inclination angles. It was shown that the mean force can be calculated fast and effectively through the proposed method for any geometry including sculptured surfaces with cusp marks and holes.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2004.04a
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• pp.289-292
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• 2004

In order to identify the origin and nature of the spilled oil in the potential source, we analyzed the pattern of alkyi PAM(Polynuclear Aromatic Hydrocarbons) in fuel standard and environmental samples. Alkyl PAM patterns are used for fuel-type identification in weathered environmental samples. Detection of alkyl PAH was achieved by operation CC/MS in the SIM mode. We chose ions of naphthalene(m/z 128), C1-naphthalene(m/z 142), C2-naphthalene(m/z 156), C3-naphthalene(m/z 170), C4-naphthalene(m/z 184) for the comparison of this pattern according to the type of fuel. We analyzed tile pattern of alkyl PAH in neat gasoline, kerosene, diesel, and JP-8, and in groundwater samples which were collected in monitoring wells. The distribution map of alkyl-naphthalene shows different patterns among four different fuel types (gasoline, kerosene, diesel, and JP-8). Particularly, tile distribution map of kerosene and JP-8 is found to be of value in identifying fuel type in that the difference is clear. Therefore distribution patterns of alkyl-PAH compounds provide another useful tool for fuel-type identification of petroleum fuels.

• Journal of the Chungcheong Mathematical Society
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• v.4 no.1
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• pp.11-38
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• 1991

Let $E_n$ be the real ordered space of all $n{\times}n$ Hermitian Matrices and let T be a positive linear operator from $E_2$ to $E_3$. We prove in this paper that T is extreme if and only if T is unitarily equivalent to a map of the form $S_z$ for some $z{\in}C^2$ where $S_z$ is defined by $S_z(xx^*)=ww^*$, $w_i=x_iz_i$ for i = 1, 2 and $w_3=0$.

• Communications of the Korean Mathematical Society
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• v.38 no.4
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• pp.1019-1028
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• 2023

Let 𝔄 and 𝔅 be unital prime *-algebras such that 𝔄 contains a nontrivial projection. In the present paper, we show that if a bijective map Θ : 𝔄 → 𝔅 satisfies Θ(_*[X ⋄ Y, Z]) = _*[Θ(X) ⋄ Θ(Y), Θ(Z)] for all X, Y, Z ∈ 𝔄, then Θ or -Θ is a *-ring isomorphism. As an application, we shall characterize such maps in factor von Neumann algebras.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2000.04a
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• pp.391-396
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• 2000

Today most companies are designing their automobile shapes by using 3 dimensional CAD software, CATIA. And they used to design 2 dimensional press dies to do some elastic work on their products, but they are currently trying to make use of dimensional software, Pro-Engineer. In this case, they have to change the 3 dimensional product design data to the proper format data for the following process. This paper will show the data loss and the deformation during data transfer between CATIA and Pro-Engineer, and then suggest a solution for these problems. Product's surface will be automatically placed by automatic press tipping angle setting in CATIA to prevent the product from being stuck in the press die. The 2 dimensional section view which is based on the tipping angle setting is created by Z-map. And, to remove the data loss and the data deformation in pro-Engineer, the product surface are delivered to the next process after it is changed to the 2 dimensional Z-map curves in CATIA. finally, this paper suggests an algorithm to develop the automatic design program for the press layout which regenerates product shape surface from the previous process.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.11 no.6
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• pp.38-44
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• 2002

Today most companies are designing their automobile shapes by using 3 dimensional CAD software, CATIA. And they used to design 2 dimensional press dies to do some elastic work on their products, but they are currently trying to make use of 3 dimensional software, Pro-Engineer. In this case, they have to change the 3 dimensional product design data to the proper format data for the following process. This paper will show the data loss and the deformation during data transfer between CATIA and Pro-Engineer, and then suggest a solution for these problems. Product's surface will be automatically placed by automatic press tipping angle setting in CATIA to prevent the product from being stuck m the press die. The 2 dimensional section view which is based on the tipping angle setting is created by Z-map. And, to remove the data loss and the data deformation in Pro-Engineer, the product surface are delivered to the next process after it is changed to the 2 dimensional Z-map curves in CATIA. Finally, this paper suggests an algorithm to develop the automatic design program for the press layout which regenerates product shape surface from the previous process.

• The Pure and Applied Mathematics
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• v.9 no.1
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• pp.1-7
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• 2002

For A bounded subset G of a metric Space (X,d) and $\chi \in X$, let $f_{G}$ be the real-valued function on X defined by $f_{G}$($\chi$)=sup{$d (\chi, g)\in:G$}, and $F(G,\chi)$={$z \in X:sup_{g \in G}d(g,z)=sup_{g \in G}d(g,\chi)+d(\chi,z)$}. In this paper we discuss some properties of the map $f_G$ and of the set $ F(G, \chi)$ in convex metric spaces. A sufficient condition for an element of a convex metric space X to lie in $ F(G, \chi)$ is also given in this pope.