• 호남수학학술지
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• 제38권2호
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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.

• 대한수학회지
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• 제32권1호
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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]).

• 대한수학회논문집
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• 제35권1호
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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.

• 대한수학회보
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• 제53권6호
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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.

• 대한수학회논문집
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• 제12권1호
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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.

• 대한수학회보
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• 제56권4호
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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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• 제2권1호
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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.

• 천문학회지
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• 제28권2호
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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.

• 대한한의학원전학회지
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• 제27권2호
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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.

• 한국음향학회지
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• 제38권5호
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• pp.549-557
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• 2019

표적의 음향 산란 특성은 표적의 재료 특성과 구조적 특성에 영향을 받으며, 이는 음향을 이용하여 수중에서 표적을 탐지, 식별하고자 할 때 매우 중요한 정보가 된다. 특히, 얇은 탄성체의 경우 램파(Lamb wave)에 의해 표적 주변 유체에 산란파가 생성된다. 본 논문에서는 계단 주파수 스윕 사인 파형을 이용하여 수조에서 알루미늄 구의 산란 신호를 측정한 결과를 제시한다. 특히 알루미늄 구의 내부에 물이 채워져 있는 경우와 공기가 채워져 있는 경우에 대하여 산란 신호의 차이를 측정하고 이론 모델과 비교하였다. 또, 내부 물질에 따른 표적 산란 신호 차이를 유사 위그널-빌 분포를 이용하여 분석하고, 유도파의 평균 주파수, 주파수 분포, 에너지의 차이를 비교하였다. 분석 결과, 구의 내부에 물이 채워진 경우가 공기가 채워진 경우에 비해 유도파의 평균 주파수, 주파수 분포, 에너지가 증가하는 것을 확인하였으며 이는 이론적인 예상과 부합한다.