• Title/Summary/Keyword: Geometrical Shape

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A study on the spatial relations and shape rules in architecture shown the Froebel's categories of building gifts (프뢰벨 은물의 형식범주에 나타난 건축공간관계 및 형태구축에 관한 연구)

  • 황태주
    • Korean Institute of Interior Design Journal
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    • no.31
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    • pp.12-18
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    • 2002
  • This study was performed to construct the spatial systems and shape grammars in architecture based on Froebel's educational idea and building gifts. Especially, it studies on the geometrical principles of Froebel's building gifts and it's types, and then illustrates applied examples about design vocabularies, spatial relations and shape rules of the spatial systems and shape grammars in architecture. The conclusions of this study that starts these purpose are as follows. First, Froebel's educational theory is based on principles and rules which are perceived through the observation of nature, and Froebel's kindergarten method consists of geometrical building gifts and categories of geometrical forms. Second, the characteristics of Froebel's building gifts are mathematical size, proportion, symmetry and the rules of spatial relation. Third, the development to the construction of spatial systems and shape grammars in architecture focus on the vocabularies of architectural elements, and Froebel's building gifts are used for illustration of examples in these formula.

Mo-tip Field Emitter Array having Modified Gate Insulator Geometry (변형된 게이트 절연막 구조를 갖는 몰리브덴 팁 전계 방출 소자)

  • Ju, Byeong-Kwon;Kim, Hoon;Lee, Nam-Yang
    • The Transactions of the Korean Institute of Electrical Engineers C
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    • v.49 no.1
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    • pp.59-63
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    • 2000
  • For the Mo-tip field emitter array, the method by which the geometrical structure of the gate insulator wall could be modified in order to improve field emission properties(turn-on voltage and gate leakage current). The device having a gate insulator of complex shape, which means the combined geometrical structure with round shape made by wet etching and vertical shape made by dry etching processes, was fabricated and the field emission properties of the three kinds of devices were compared. As a result, the electric field applied to tip apex could be increased and gate leakage current could be decreased by employing the gate insulator having geometrical wall structure of mixed shape. Finally, the obtained empirical results were analyzed by simulation of electric field distribution at/near the tip apex and gate insulator using SNU-FEAT simulator.

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Effect of Geometrical Similarity between Twist Drill on the Shape of Chip Produced (드릴의 기하학적 상사성이 칩형상에 미치는 영향)

  • 최만성
    • Proceedings of the Korean Society of Machine Tool Engineers Conference
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    • 1999.10a
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    • pp.513-518
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    • 1999
  • In this study, geometrical similarity conditions for drills of various diameters are discussed. The effect of geometrical similarity on the chip shape and forces of different sized conventional drills has been experimentally confirmed. Drilling tests are carried out for SM45C by using the conventional HSS drills. The torque and thrust forces are measured and compared with those chip forms. Chip shape in drilling are affected by three factors being flow angle, side and up curl of the chip. It is found that the feedrate and drill diameter are more affected than cutting speed on the chip form and cutting forces. The similarity conditions gives easily to estimate the chip shape, the thrust and the torque for drills of different diameters.

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Effect of Geometrical Similarity between Twist Drill on the Shape of Chip Produced. (드릴구멍 상사성이 칩형상에 미치는 영향)

  • 최만성
    • Journal of the Korean Society of Manufacturing Technology Engineers
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    • v.9 no.6
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    • pp.118-126
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    • 2000
  • In this study, geometrical similarity conditions for drills of various diameters are discussed. The effect of geometrical similarity on the chip shape and forces of different sized conventional drills has been experimentally confirmed. Drilling tests are carried out for SM45C by using the conventional HSS drills. The torque and thrust forces are measured and compared with those chip forms. Chip shape in drilling are affected by three factors being flow angle, side and up curl of the chip. It is found that the feedrate and drill diameter are more affected than cutting speed on the chip form and cutting forces. The similarity conditions gives easily to estimate the chip shape, the thrust and the torque for drills of different diameters.

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Cutting Condition Selection for Geometrical Accuracy Improvement in End Milling (엔드밀 가공에서 형상 정밀도 향상을 위한 절삭 조건 선정)

  • 류시형;최덕기;주종남
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2003.06a
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    • pp.1784-1788
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    • 2003
  • For the improvement of geometrical accuracy in end milling, cutting method and cutting condition selection are investigated in this paper. As machining processes are composed of several steps such as roughing, semi-finishing. and finishing, cutting forces and tool deflection are calculated considering surface shape generated by the previous cutting. The effects of tool teeth numbers, tool geometry, and cutting conditions on the form error are analyzed. Using the from error prediction method from tool deflection, cutting condition for geometrical accuracy improvement is discussed. The characteristics and the difference of generated surface shape in up and down milling are dealt with and over-cut free condition in up milling is presented. The form error reduction method by alternating up and down milling is also suggested. The effectiveness of the presented method is examined from a set of cutting tests under various cutting conditions. This research contributes to cutting process optimization for the geometrical accuracy improvement in die and mold manufacture.

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Relationship Between Flat End-mill Shape and Geometrical Characteristics in Side Walls Generated by End-milling Process (엔드밀링 공정에 의하여 생성된 측벽의 기하학적 특성과 평엔드밀 형상 사이의 관계)

  • Kim, Kang
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.39 no.1
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    • pp.95-103
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    • 2015
  • This paper presents the effects of the tool shape on the geometrical characteristics of flat end-milled side walls. A tool shape is characterized by such parameters as helix angle, number of cutting edges, and diameter. The geometrical characteristics of the side walls are represented by the surface profiles in the feed and axial directions, which are orthogonal to each other. The geometrical defects in each direction are estimated based on the instantaneous apparent cutting areas, which are represented by the interference area between the tool and workpiece and that between the cutting edge and workpiece. It is confirmed that a geometrical defect in the feed direction is formed when the tool leaves the workpiece and the curvature of the tool path changes. Defects in the axial direction are also found in the side walls, except for the defect zone in the feed direction. An up-cut using an end-mill with a steeper helix angle, a greater number of cutting edges, and a smaller diameter are thus found to improve the geometrical accuracy of end-milled side walls.

3D Vision Inspection Algorithm using Geometrical Pattern Matching Method (기하학적 패턴 매칭을 이용한 3차원 비전 검사 알고리즘)

  • 정철진;허경무;김장기
    • Journal of Institute of Control, Robotics and Systems
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    • v.10 no.1
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    • pp.54-59
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    • 2004
  • We suggest a 3D vision inspection algorithm which is based on the external shape feature. Because many electronic parts have the regular shape, if we have the database of pattern and can recognize the object using the database of the object s pattern, we can inspect many types of electronic parts. Our proposed algorithm uses the geometrical pattern matching method and 3D database on the electronic parts. We applied our suggested algorithm fer inspecting several objects including typical IC and capacitor. Through the experiments, we could find that our suggested algorithm is more effective and more robust to the inspection environment(rotation angle, light source, etc.) than conventional 2D inspection methods. We also compared our suggested algorithm with the feature space trajectory method.

Grouping Parts Based on Group Technology Using a Neural Network (신경망을 이용한 GT 부품군 형성의 자동화)

  • Lee, Sung-Youl
    • IE interfaces
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    • v.11 no.2
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    • pp.119-124
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    • 1998
  • This paper proposes a new part family classification system (IPFACS: Image Processing and Fuzzy ART based Clustering System), which incorporates image processing techniques and a modified fuzzy ART neural network algorithm. IPFACS can classify parts based on geometrical shape and manufacturing attributes, simultaneously. With a proper reduction and normalization of an image data through the image processing methods and adding method in the modified Fuzzy ART, different types of geometrical shape data and manufacturing attribute data can be simultaneously classified in the same system. IPFACS has been tested for an example set of hypothetical parts. The results show that IPFACS provides a good feasible approach to form families based on both geometrical shape and manufacturing attributes.

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Tool Deflection and Geometrical Accuracy in Side Wall Milling (측벽 밀링에서 공구 변형 및 형상 정밀도)

  • 류시형;주종남
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2003.06a
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    • pp.1811-1815
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    • 2003
  • Investigated is the relationship between tool deflection and geometrical accuracy in side wall machining. Form error is predicted directly from the tool deflection without surface generation. Developed model can predict the surface form error about three hundred times faster than the previous method. Cutting forces and tool deflection are calculated considering tool geometry, tool setting error, and machine tool stiffness. The characteristics and the difference of generated surface shape in up milling and down milling are discussed. The usefulness of the presented method is verified from a set of experiments under various cutting conditions generally used in die and mold manufacture. This study contributes to real time surface shape estimation and cutting process planning for the improvement of geometrical accuracy.

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Robust Watermarking Scheme Against Geometrical Attacks Using Alignment of Image Features (영상특징 정렬을 이용한 기하학적 공격에 강인한 워터마킹 기법)

  • Ko Yun-Ho
    • Journal of Korea Multimedia Society
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    • v.9 no.5
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    • pp.624-634
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    • 2006
  • This paper presents a new watermarking scheme that is robust against geometrical attacks such as translation and rotation. The proposed method is based on the conventional PSADT(Polar Coordinates Shape Adaptive Discrete Transform) method which is an robust watermarking scheme for an arbitrarily-shaped image such as character images. The PSADT method shows perfect robustness against geometrical attack if there is no change in the shape of the image object. However, it cannot be utilized to watermark general rectangular images because of the missing alignment between the watermarked signals in the embedding and extracting side. To overcome this problem we propose a new watermarking scheme that aligns the watermark signal using the image inherent feature, especially corner. Namely the proposed method decides a consistent target region whose shape and position isn't changed by any malicious attack and then embeds the watermark in it using the PSADT method. Experimental results show the robustness of the proposed method against geometrical attacks as well as image compression.

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