• 대한수학회보
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• 제61권1호
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• pp.281-290
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• 2024

We consider the total scalar curvature functional, and show that if the second variation in the transverse traceless tensor direction is negative, then the metric is Einstein. We also find the relation between the second variation and the Lichnerowicz Laplacian.

• International Journal of CAD/CAM
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• 제6권1호
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• pp.65-71
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• 2006

Based on the smoothness criterion of minimum curvature variation of the curve, tangent angle constraints guaranteeing an optimized geometric Hermite (OGH) curve both mathematically and geometrically smooth is given, and new methods for constructing composite optimized geometric Hermite (COH) curves are presented in this paper. The comparison of the new methods with Yong and Cheng's methods based on strain energy minimization is included.

• 소성∙가공
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• 제22권6호
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• pp.310-316
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• 2013

Recently, numerical predictions of surface deflection based on curvature analysis have been developed. In the current study, a measure of surface deflection is proposed as the maximum variation of curvature difference between the panel and the tool in order to account for surfaces that have high curvature. The current study focused on the assessment of accuracy for the surface deflection prediction with the consideration of planar anisotropy. As an example, a shallow rectangular drawn part with rectangular embossing was considered. In terms of the proposed surface deflection measure, the maximum variation of curvature difference, the prediction with a planar anisotropic model shows better correspondence with experiment than the one using a normal anisotropic model.

• 한국공간구조학회논문집
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• 제8권4호
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• pp.57-64
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• 2008

본 연구는 설치와 해체가 용이하여 간이식 구조에서 활용되는 시저스 전개형 구조에 관한 것으로, 입면상의 곡률변화 방법을 고찰하고 그에 따른 구조특성을 파악하고자 한 것이다. 먼저 시저스 구조의 입면상 곡률과 시저스부재의 내부절점 편심거리와의 관계를 식과 그래프를 이용하여 나타내었다. 이에 따라, 동일한 시저스부재에서 내부절점 편심거리를 조절하여 곡률을 변화시킬 수 있는 해석모델을 고찰함으로써, 곡률변화에 따른 시저스 구조부재들의 구조적 특성을 고찰하였다. 또한 고찰된 구성방식에 근거하여 실 모델을 제작하고 전개과정을 살펴봄으로써 실제 전개가능성을 검토하였다.

• 산업기술연구
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• 제19권
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• pp.261-268
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• 1999

It is a main object to find out the effect of curvature of pipe on the thermal flow field in copper pipe. the toroidal coordinate system is chosen for this project. 3-D numerical works are done by a commercial code, PHOENICS. The flow and temperature field are simulated and analysed on the view point of variation of pressure and temperature with Dean number. The results show that the strong recirculation phenomena and secondary flow are established and then a lot of pressure drop along main flow direction occurs at the curved portion of pipe and the temperature variation has a reversed trend of pressure variation along the axis of pipe.

• 로봇학회논문지
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• 제18권1호
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• pp.18-28
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• 2023

This study introduces a smart wrist band system with pressure measurements using wrist skin curvature variation due to finger motion. It is easy to wear and take off without pre-adaptation or surgery to use. By analyzing the depth variation of wrist skin curvature during each finger motion, we elaborated the most suitable location of each Force Sensitive Resistor (FSR) to be attached in the wristband with anatomical consideration. A 3D depth camera was used to investigate distinctive wrist locations, responsible for the anatomically de-coupled thumb, index, and middle finger, where the variations of wrist skin curvature appear independently. Then sensors within the wristband were attached correspondingly to measure the pressure change of those points and eventually the finger motion. The smart wrist band was validated for its practicality through two demonstrative applications, i.e., one for a real-time control of prosthetic robot hands and the other for natural human-computer interfacing. And hopefully other futuristic human-related applications would be benefited from the proposed smart wrist band system.

• Korean Journal of Mathematics
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• 제19권1호
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• pp.25-32
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• 2011

This paper is a direct continuation of [1]. In this paper we investigate some properties of ES-curvature tensor of g - $ESX_n$, with main emphasis on the derivation of several useful generalized identities involving it. In this subsequent paper, we are concerned with contracted curvature tensors of g - $ESX_n$ and several generalized identities involving them. In particular, we prove the first variation of the generalized Bianchi's identity in g - $ESX_n$, which has a great deal of useful physical applications.

• Korean Journal of Mathematics
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• 제19권4호
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• pp.381-390
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• 2011

This paper is a direct continuation of [1]. In this paper we derive tensorial representations of contracted ES curvature tensors of $g-ESX_n$ and prove several generalized identities involving them. In particular, a variation of the generalized Bianchi's identity in $g-ESX_n$, which has a great deal of useful physical applications, is proved in Theorem (2.9).

• 한국산학기술학회논문지
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• 제9권4호
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• pp.1081-1085
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• 2008

본 논문에서는 곡률을 측정하기 위해 파이버 브래그 격자를 이용한 곡률 센서에 대해 연구하고자 한다. 곡률의 변화를 측정하기 위해 브래그 공진파장의 이동 변화를 측정하였다. 실험견과로부터 곡률이 $0\;m^{-1}$에서 $10\;m^{-1}$까지 증가함에 따라 반사 스펙트럼은 감소하나. 브래그 공진 파장의 변화량은 선형적으로 증가함을 알 수 있었으며, 기울기는 대략 $8.8\;pm/m^{-1}$ 이었다. 한편, 반사 스펙트럼은 곡률이 증가함에 따라 감소하였다.

• Computers and Concrete
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• 제11권6호
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• pp.515-529
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• 2013

The moment-curvature relation for simple bending is a well-studied subject and the classical moment-curvature diagram is commonly found in literature. The influence of axial forces has generally been considered as compression onto symmetrically reinforced cross-sections, thus strain at the reference fiber never has been an issue. However, when dealing with integral structures, which are usually statically indeterminate in different degrees, these concepts are not sufficient. Their horizontal elements are often completely restrained, which, under imposed deformations, leads to moderate compressive or tensile axial forces. The authors propose to analyze conventional beam cross-sections with moment-curvature diagrams considering asymmetrically reinforced cross-sections under combined influence of bending and moderate axial force. In addition a new diagram is introduced that expands the common moment-curvature relation onto the strain variation at the reference fiber. A parametric study presented in this article reveals the significant influence of selected cross-section parameters.