• Kyungpook Mathematical Journal
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• 제58권3호
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• pp.547-557
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• 2018

We establish some characterizations of isoparametric surfaces in the three-dimensional Euclidean space, which are associated with the Laplacian operator defined by the so-called II-metric on surfaces with non-degenerate second fundamental form and the elliptic linear Weingarten metric on surfaces in the three-dimensional Euclidean space. We also study a Ricci soliton associated with the elliptic linear Weingarten metric.

• 한국수학교육학회지시리즈B:순수및응용수학
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• 제20권3호
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• pp.149-158
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• 2013

In this article, we study the Gauss map of generalized slant cylindrical surfaces (GSCS's) in the 3-dimensional Euclidean space $\mathbb{E}^3$. Surfaces of revolution, cylindrical surfaces and tubes along a plane curve are special cases of GSCS's. Our main results state that the only GSCS's with Gauss map G satisfying ${\Delta}G=AG$ for some $3{\times}3$ matrix A are the planes, the spheres and the circular cylinders.

• Kyungpook Mathematical Journal
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• 제60권3호
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• pp.585-597
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• 2020

In this study, we classify surfaces of revolution of Type 1 in the three dimensional Galilean space 𝔾₃ in terms of the position vector field, Gauss map, and Laplacian operator of the first and the second fundamental forms on the surface. Furthermore, we give a classification of surfaces of revolution of Type 1 generated by a non-isotropic curve satisfying the pointwise 1-type Gauss map equation.

• Macromolecular Research
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• 제12권4호
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• pp.342-351
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• 2004

Poly(ethylene glycol) (PEG1K) and sulfonated PEG (PEG1K-SO$_3$) methacrylate (MA) copolymers have been prepared and characterized. The structures of the synthesized copolymers were confirmed by $^1$H and $^{13}$ C NMR spectroscopy and elemental analysis. The bulk characteristics of the copolymers were evaluated by viscosity and thermal analysis. The surface properties of the copolymers were investigated using dynamic contact angle measurements and electron spectroscopy for chemical analysis. The hydrophilicity of the surfaces modified with PEG1KMA or PEG1K-SO$_3$MA increased, possibly as a result of the orientation of the hydrophilic PEG1KMA/PEG1K-SO$_3$MA chains into the water phase. Platelets adhered less to the surfaces of the copolymers than they did to a polyurethane control. In addition, adhesion of platelets to the copolymer surfaces decreased upon increasing the chain density of PEG1KMA and sulfonated PEG1KMA in the copolymers. Both bacterial adhesion and protein adsorption were significantly reduced on the copolymer surfaces and their levels differ depending on the kind of surface or media.

• Tribology and Lubricants
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• 제24권3호
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• pp.122-128
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• 2008

To reduce the friction losses and the wear amounts in the piston assembly two methods were proposed. One is the modification of surface profile of the skirt part. The surface coating is another method to protect the sliding surfaces. To modify the profile of the skirt surfaces the surfaces were ground to have three different shapes of profiles. Also, several coatings, such as graphite, TiN, and $MoS_2$, and DLC, were used to protect the surfaces of the piston skirts. The specimens of the skirt and the cylinder bores were tested with the reciprocating wear tester. SAE 5W40 engine oil was used in boundary lubrication regime. Among several coatings the graphite and DLC coatings were very effective to reduce the friction forces. Especially, DLC film represented much better tribological performances than the others. The friction coefficient of the graphite coating was the lowest, but the graphite coating was not effective to protect the surfaces.

• 호남수학학술지
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• 제32권4호
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• pp.777-790
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• 2010

We study surfaces in the 3-dimensional Euclidean space with two family of planar lines of curvature. As a result, we establish some characterization theorems for such surfaces.

• Kyungpook Mathematical Journal
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• 제50권2호
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• pp.337-343
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• 2010

We study affine translation surfaces in $\mathbb{R}^3$ and get a complete classification of such surfaces with constant Gauss-Kronecker curvature.

• 대한수학회보
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• 제35권1호
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• pp.119-125
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• 1998

We determine the possible types of Chern classes of rank 2 stable bundles (mod Picard groups) on the Enriques surfaces and their covering K3 surfaces.

• 대한소아치과학회지
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• 제37권2호
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• pp.159-167
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• 2010

유치열에 존재하는 우식패턴을 연구하기 위하여 유치열을 가진 유아들을 대상으로 치면별 우식경험도 조사를 실시하고 군 집분석과 다차원척도분석을 실시하였다. 연구대상은 36개월 이상 71개월 이하의 어린이 815명이었다. 군집분석에서 먼저 분리된 네 개의 군집은, 유치는 (1) 유구치, (2) 상악 유절치, (3) 하악 제1유구치, (4) 상악 제1유구치, 유치면은 (1) 하악 유구치 교합면과 상악 제2유구치 교합면, (2) 상악 유중절치 근심면, (3) 하악 제1유구치 교합면, (4) 상하악 제2유구치 교 합면의 분리, 유치면군은 (1) 상악 유전치 인접면, (2) 하악 유구치 교합면, (3) 상악 유전치 협설면, (4) 상악 유구치 협설 면, 인접면, 교합면 및 하악 유구치 협설면과 인접면이었다. 다차원척도분석에서 상호간에 가장 멀리 떨어진 순서로 보았을 때, 유치는 하악 제1유구치, 상악 제1유구치, 상악 유중절치, 상악 유측절치, 하악 제2유구치, 상악 제2유구치, 기타 유치(유견치, 하악 유절치)로 나눌 수 있었고, 유치면은 하악 유구치 교합면, 상악 유중절치 근심면, 상악 유구치 교합면, 기타 유치 면으로 나눌 수 있었으며, 유치면군은 상악 유전치 인접면, 상악 유전치 협설면, 하악 유구치 교합면, 기타 유치면군으로 나눌 수 있었다.

• 대한수학회보
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• 제53권1호
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• pp.227-245
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• 2016

A generalized constant ratio surface (GCR surface) is defined by the property that the tangential component of the position vector is a principal direction at each point on the surface, see [8] for details. In this paper, by solving some differential equations, a complete classification of Lorentz GCR surfaces in the three-dimensional Minkowski space is presented. Moreover, it turns out that a flat Lorentz GCR surface is an open part of a cylinder, apart from a plane and a CMC Lorentz GCR surface is a surface of revolution.