• Honam Mathematical Journal
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• v.38 no.2
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• pp.375-384
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• 2016

In this paper, we study the pseudo-symmetry of unit tangent sphere bundle. We prove that if the unit tangent sphere bundle $T_1M$ with standard contact metric structure over a locally symmetric $M^n$, $n{\geq}3$ is pseudo-symmetric, then M is of constant curvature.

• Journal of the Korean Mathematical Society
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• v.32 no.1
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• pp.151-160
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• 1995

The notion of finite type submanifold was introduced by B.-Y. Chen [1]. A lot of works were done in this field of study by many authors. B.-Y. Chen also extended this notion to pseudo-Riemannian submanifold of pseudo-Euclidean space ([2]).

• Communications of the Korean Mathematical Society
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• v.35 no.1
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• pp.251-260
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• 2020

In this paper, we show that it is Chen surfaces that non-minimal pseudo-Hermitian mass-symmetric 2-type Legendre surfaces in S⁵. Moreover, we show that pseudo-Hermitian mass-symmetric 2-type Legendre surfaces in S⁵ are the locally product of two pseudo-Hermitian circles.

• Bulletin of the Korean Mathematical Society
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• v.53 no.6
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• pp.1715-1723
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• 2016

We study the characteristic Jacobi operator ${\ell}={\bar{R}({\cdot},{\xi}){\xi}$ (along the Reeb flow ${\xi}$) on the unit tangent sphere bundle $T_1M$ over a Riemannian manifold ($M^n$, g). We prove that if ${\ell}$ is pseudo-parallel, i.e., ${\bar{R}{\cdot}{\ell}=L{\mathcal{Q}}({\bar{g}},{\ell})$, by a non-positive function L, then M is locally flat. Moreover, when L is a constant and $n{\neq}16$, M is of constant curvature 0 or 1.

• Communications of the Korean Mathematical Society
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• v.12 no.1
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• pp.109-112
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• 1997

In this paper, we study on a classification of hypersurfaces given by tansnormal functions on $R^{n+1}_1$. If M is a level set of a transnormal function on $R^{n+1}_1$, then it is one of a hyperplane, a cylinder around k-plane, a pseudo-sphere and a pseudo-hyperbolic space.

• Bulletin of the Korean Mathematical Society
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• v.56 no.4
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• pp.867-883
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• 2019

The canal surfaces foliated by pseudo spheres $\mathbb{S}_1^2$ along a space curve in Minkowski 3-space are studied. The geometric properties of such surfaces are shown by classifying the linear Weingarten canal surfaces, the developable, minimal and umbilical canal surfaces are discussed at the same time.

• Journal of Computational Design and Engineering
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• v.2 no.1
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• pp.55-66
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• 2015

To satisfy safety regulations of Economic Commission for Europe (ECE), the surface regions of automobile parts must have a sufficient degree of roundness if there is any chance that they could contact a sphere of 50.0 mm radius (exterior parts) or 82.5 mm radius (interior parts). In this paper, a new offset-based method is developed to automatically detect the possible sphere-contacting shape of such parts. A polyhedral model that precisely approximates the part shape is given as input, and the offset shape of the model is obtained as the Boolean union of the expanded shapes of all surface triangles. We adopt a triple-dexel representation of the 3D model to enable stable and precise Boolean union computations. To accelerate the dexel operations in these Boolean computations, a new parallel processing method with a pseudo-list structure and axis-aligned bounding box is developed. The possible sphere-contacting shape of the part surface is then extracted from the offset shape as a set of points or a set of polygons.

• Journal of The Korean Astronomical Society
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• v.28 no.2
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• pp.209-221
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• 1995

We have examined bulge morphology of 104 bright barred galaxies, using V-band surface photometry based on the Kiso Schmidt plates. By measuring the bulge ellipticity and bulge-disk misalignment, we have classified bulges into four morphological types: sphere, oblate spheroid, triaxial ellipsoid, and pseudo triaxial ellipsoid. About half of the observed galaxies are found to have triaxial bulges with mean ellipticity of 0.24. They are distributed uniformly along the Hubble sequence.

• Journal of Korean Medical classics
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• v.27 no.2
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• pp.97-107
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• 2014

Objectives : This study aims at exposing interaction between socio-cultural influence on medicine, and the strong quest for rational explanation concerning the evil-spirit(鬼邪) related disease, namely Sasu(邪祟), in medical history. Methods : In order to apprehend the change of perception, Chinese medical classics referring directly to Sasu(邪祟), as well as Korean medical classics from Joseon dynasty were reviewed. Results : In Chinese medical texts, discriminating pseudo-sasu(類似邪祟) from evil-spirit related sasu had been one of the main concerns. And Chinese were more inclined to specify treatment plan for pseudo-sasu than handling evil spirits. On the contrary, Korean medical texts show common interests in eliminating evil spirits throughout Joseon dynasty. Conclusions : Since medicine is under the influence of socio-cultural condition, it cannot escape from the epistemology of corresponding society. Evil-spirit related disease therefore could remain within the sphere of medical discussion until very recently. If we observe the disease under the frame of culture, we not only can obtain broader view on dynamic nature of medical conceptions, but also gain better insight to understand medical classics.

• The Journal of the Acoustical Society of Korea
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• v.38 no.5
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• pp.549-557
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• 2019

The acoustical scattering characteristics of a target are influenced by the material properties and structural characteristics of the target, which are critical information for acoustic detection and identification of underwater target. In particular, for thin elastic target, unique scattered signals are generated around the target by the Lamb wave. In this paper, the results of scattered signal measurement of aluminum spherical shell in the water tank using the stepped frequency sweep sine signal are presented. In particular, the scattering of the water-filled aluminum spherical shell is compared with that of the air-filled one both theoretically and experimentally. The difference of the scattered signals are analyzed using the pseudo Wigner-Ville distribution in terms of average frequency, frequency distribution, and energy of the scattered signal. The result shows that all observed parameters increased when the aluminum sphere was water-filled, and it is well matched to the theoretical expectation.