• Title/Summary/Keyword: Surface of revolution

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CONSTANT CURVATURES AND SURFACES OF REVOLUTION IN L3

  • Kang, Ju-Yeon;Kim, Seon-Bu
    • Honam Mathematical Journal
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    • v.38 no.1
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    • pp.151-167
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    • 2016
  • In Minkowskian 3-spacetime $L^3$ we find timelike or spacelike surface of revolution for the given Gauss curvature K = -1, 0, 1 and mean curvature H = 0. In fact, we set up the surface of revolution with the time axis for z-axis to be able to draw those surfaces on standard pictures in Minkowskian 3-spacetime $L^3$.

Efficient Computation for Connected Components of an Isophote in a Surface of Revolution (회전체의 Isophote 구성요소의 효율적인 계산)

  • Kim, Ku-Jin;Lee, In-Kwon
    • Journal of KIISE:Computer Systems and Theory
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    • v.29 no.8
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    • pp.440-444
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    • 2002
  • This paper presents an efficient and robust algorithm to compute the isophote of a surface of revolution. A surface of revolution can be decomposed to a set of cross-sectional circles. The surface normals along each cross-sectional circle form a cone. Using the characteristics of the normal vectors and the symmetric property of the surface of revolution, we propose a method to find the connected components of an isophote, which requires intersecting a planar curve(and its reflection) with two rays. Moreover, we propose a closed-form representation of an isophote as a parametric curve.

BOUR'S THEOREM IN 4-DIMENSIONAL EUCLIDEAN SPACE

  • Hieu, Doan The;Thang, Nguyen Ngoc
    • Bulletin of the Korean Mathematical Society
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    • v.54 no.6
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    • pp.2081-2089
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    • 2017
  • In this paper we generalize 3-dimensional Bour's Theorem to the case of 4-dimension. We proved that a helicoidal surface in $\mathbb{R}^4$ is isometric to a family of surfaces of revolution in $\mathbb{R}^4$ in such a way that helices on the helicoidal surface correspond to parallel circles on the surfaces of revolution. Moreover, if the surfaces are required further to have the same Gauss map, then they are hyperplanar and minimal. Parametrizations for such minimal surfaces are given explicitly.

SURFACES OF REVOLUTION WITH MORE THAN ONE AXIS

  • Kim, Dong-Soo;Kim, Young-Ho
    • The Pure and Applied Mathematics
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    • v.19 no.1
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    • pp.1-5
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    • 2012
  • We study surfaces of revolution in the three dimensional Euclidean space $\mathbb{R}^3$ with two distinct axes of revolution. As a result, we prove that if a connected surface in the three dimensional Euclidean space $\mathbb{R}^3$ admits two distinct axes of revolution, then it is either a sphere or a plane.

The Influence of the Fourth Industrial Revolution in Market Demands and the Directions for Developing Korean Surface Finishing Industries (4차 산업혁명에 따른 시장요구 변화와 한국 표면처리 산업의 발전방향에 대한 연구)

  • Lee, Seung-Jae;Hur, Jin-Young;Lee, Hong-Kee
    • Journal of the Korean institute of surface engineering
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    • v.51 no.1
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    • pp.71-78
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    • 2018
  • This paper examines various definitions of the fourth industrial revolution and its influence on typical market demands and manufacturing methods. And this study reviewed the policies of the major global competitors in preparedness for the fourth industrial revolution. In conclusion, this paper suggested various possible developing ways in which Korean companies, especially focused on surface treatment firms, could adapt and survive in such a revolutionary industrial circumstance change.

SURFACES OF REVOLUTION WITH POINTWISE 1-TYPE GAUSS MAP IN PSEUDO-GALILEAN SPACE

  • Choi, Miekyung;Yoon, Dae Won
    • Bulletin of the Korean Mathematical Society
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    • v.53 no.2
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    • pp.519-530
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    • 2016
  • In this paper, we study surfaces of revolution in the three dimensional pseudo-Galilean space. We classify surfaces of revolution generated by a non-isotropic curve in terms of the Gauss map and the Laplacian of the surface. Furthermore, we give the classification of surfaces of revolution generated by an isotropic curve satisfying pointwise 1-type Gauss map equation.

The Study on the Optimal Working Condition for Vibration, Surface Roughness and Cutting Temperature in End-milling (엔드밀 가공시 진동, 표면거칠기, 절삭온도에 미치는 최적가공조건에 관한 연구)

  • Hong, Do-Kwan;Kim, Dong-Young;Ahn, Chan-Woo
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.14 no.12
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    • pp.1322-1329
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    • 2004
  • End-milling has been used widely in industrial system because it is effective to a material manufacturing with various shapes. Recently the end-milling processing is needed the high-precise technique with good surface roughness and rapid time in precision machine part and electronic part. The optimum mechanical vibration of main spindle, surface roughness and cutting temperature have an effect on end-milling condition such as, cutting direction, revolution of spindle, feed rate and depth of cut, etc. Therefore, this study carried to decide the working condition for optimum mechanical vibration of main spindle, surface roughness and cutting temperature using design of experiments, ANOVA and characteristic function. From the results of experimentation, mechanical vibration has an effect on revolution of spindle, radial depth of cut, and axial depth of cut. The surface roughness has an effect on cutting direction, revolution of spindle and depth of cut. And then the optimum condition used design of experiments is upward cutting In cutting direction, 600 rpm in revolution of spindle, 240 mm/min in feed rate, 2 mm in axial depth of cut and 0.25 mm in radial depth of cut. By design of experiments and characteristic function, it is effectively represented shape characteristics of mechanical vibration, surface roughness and cutting temperature in end-milling.

Machining characteristics of micro end-mill using high revolution (고속회전을 이용한 마이크로 엔드밀의 가공특성)

  • Kim, Kisoo;Kim, Sangjin;Cho, Byoungmoo;Kim, Hyeungchul
    • 대한공업교육학회지
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    • v.31 no.2
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    • pp.350-363
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    • 2006
  • Recently, the micro end-milling processing is demanded the high-precise technique with good surface roughness and rapid time in milli-structure parts, micro machine parts and molding industry. The cutting conditions of micro end-milling has an effect on surface roughness of cutting surface. Therefore this study was carried out to cut stainless steel using high revolution air bearing spindle and micro end-mill and analyze the cutting condition to get the optimum surface roughness by design of experiment. From this study, surface roughness have an much effect according to priority on depth of cut, revolution of spindle and feed.

Analysis of Effect of Surface Temperature Rise Rate of 72.5 Ah NCM Pouch-type Lithium-ion Battery on Thermal Runaway Trigger Time (72.5 Ah NCM계 파우치형 리튬이온배터리의 표면온도 상승률이 열폭주 발생시간에 미치는 영향 분석)

  • Lee, Heung-Su;Hong, Sung-Ho;Lee, Joon-Hyuk;Park, Moon Woo
    • Journal of the Korean Society of Safety
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    • v.36 no.5
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    • pp.1-9
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    • 2021
  • With the convergence of the information and communication technologies, a new age of technological civilization has arrived. This is the age of intelligent revolution, known as the 4th industrial revolution. The 4th industrial revolution is based on technological innovations, such as robots, big data analysis, artificial intelligence, and unmanned transportation facilities. This revolution would interconnect all the people, things, and economy, and hence will lead to the expansion of the industry. A high-density, high-capacity energy technology is required to maintain this interconnection. As a next-generation energy source, lithium-ion batteries are in the spotlight today. However, lithium-ion batteries can cause thermal runaway and fire because of electrical, thermal, and mechanical abuse. In this study, thermal runaway was induced in 72.5 Ah NCM pouch-type lithium-ion batteries because of thermal abuse. The surface of the pouch-type lithium-ion batteries was heated by the hot plate heating method, and the effect of the rate of increase in the surface temperature on the thermal runaway trigger time was analyzed using Minitab 19, a statistical analysis program. The correlation analysis results confirmed that there existed a strong negative relationship between each variable, while the regression analysis demonstrated that the thermal runaway trigger time of lithium-ion batteries can be predicted from the rate of increase in their surface temperature.

Characteristics of Cutting Force and Surface Roughness in the High-Speed Machining of Die Material (금형강의 고속가공시 절삭력 및 표면조도의 특성)

  • 손창수;강명창;이용철;이득우;김정석
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 1996.11a
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    • pp.36-40
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    • 1996
  • The high-speed machining is one of the most effective technology to improve productivity. Because of the high speed and high feedrate, high-speed machining can give great advantages for the machining of dies and moulds. In this paper, high-speed milling for HP-4 die material was carried out with coated tungsten carbide ball endmill. In the high-speed machining, the cutting force and surface roughness of workpiece show very various characteristics at different cutting conditions. Especially surface roughness of workpiece depends largely on pick feed and feed per revolution of ball endmill. In the condition that pick feed and feed per revolution are equal, better surface roughness is measured. By obtaining good surface roughness at high speed, efficiency of machining can be increased.

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