• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2001년도 추계학술대회(한국공작기계학회)
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• pp.292-297
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• 2001

Twin screw extruders are the heart of the polymer processing industry. They are used at some stage in nearly all polymer processing operations. This paper is concerned with the basic elements of the extruder design. The proper design of the geometry of the extruder screw is of crucial importance to the proper functioning of the extruder. If the material transport instabilities occur as a result of improper screw geometry, even the most sophisticated computerized control system cannot solve the problem. For this purpose, a characteristic design on flights shape of the extruder screw. This paper presents cross section designs of a closely intermeshing twin screw extruder with double-flighted screw elements, and channel depth characteristics for a double flighted corotating self-wiping twin screw extruder.

• 한국지능시스템학회논문지
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• 제12권3호
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• pp.255-260
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• 2002

This paper describes a fuzzy-based system for analyzing the stress intensity factors (SIFs) of three-dimensional (3D) cracks. A geometry model, i.e. a solid containing one or several 3D cracks is defined. Several distributions of local node density are chosen, and then automatically superposed on one another over the geometry model by using the fuzzy knowledge processing. Nodes are generated by the bucketing method, and ten-coded quadratic tetrahedral solid elements are generated by the Delaunay triangulation techniques. The singular elements such that the mid-point nodes near crack front are shifted at the quarter-points, and these are automatically placed along the 3D crack front. The complete finite element(FE) model is generated, and a stress analysis is performed. The SIFs are calculated using the displacement extrapolation method. To demonstrate practical performances of the present system, semi-elliptical surface cracks in a inhomogeneous plate subjected to uniform tension are solved.

• 한국정보통신학회논문지
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• 제9권2호
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• pp.415-421
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• 2005

어레이 소자의 방사 또는 수신 특성은 소자 상호결합 효과 때문에 고립된 소자의 특성과 달라지게 되며, 따라서 어레이 성능은 고립된 소자를 가정하여 설계할 경우의 성능과 다르게 된다. 접지판 위에 위치한 삼각형 격자 구조를 가진 직사각형 다이폴 어레이에 미치는 상호 결합의 영향을 소자패턴을 고려하여 논의하였다. 소자 이득 함수를 이용하여 소자가 균일하게 분포되거나 소자간격이 체감된 어레이에서 부엽(sidelobe)에 미치는 소자 상호결합 효과의 영향을 점검하였다. 상호결합 효과가 존재할 때, 소자간격이 체감된 어레이에서의 부엽의 성능이 소자간격이 균일하게 분포된 어레이와 비교하여 향상되는 것을 보여주었다. 컴퓨터 시뮬레이션을 제시하였다.

• 한국학교수학회논문집
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• 제25권1호
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• pp.61-77
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• 2022

본 연구는 고등학교 기하 교과서에 수록된 이차곡선 성질 관련 세부 학습 내용을 중심으로 교과서별 편차에 대하여 살펴보았다. 고등학교 기하 교과서에서 다루어지고 있는 내용 요소의 다양성에 대하여 비판하고 이에 대한 대안을 제시하고자 하는 것보다 내용 요소의 다양성의 실태분석에 초점을 두었다. 교육과정에서는 이차곡선의 실생활 활용적 측면을 강조하여 그 유용성과 가치를 인식하게 하도록 할 것을 명시하고 있다. 그러나 분석 결과 교육과정의 취지와 교과서의 구성이 다소 부합하지 못하고 있었으며, 교과서별 내용 요소의 편차가 상당히 큼을 확인할 수 있었다. 교수·학습의 다양성을 인정하는 측면에서 이차곡선의 도입 방식과 성질의 교과서별 다양성은 충분히 인정될 수 있는 부분이다. 그러나 대학수학능력시험과 같은 전국단위 평가를 통한 대학입시 체제를 지향하고 있는 우리의 교육 현실에서 그 결과는 사회 전반적으로 매우 민감하기 때문에 수학 교과서의 내용적 다양성은 평가적 측면에서 유불리로 해석되기도 한다. 교과서 교수 학습·내용 요소의 다양성을 인정하는 동시에 평가의 평등성 측면을 반영할 수 있는 교과서 구성에 대하여 재고가 필요한 시점이다.

• 한국의상디자인학회지
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• 제18권4호
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• pp.63-75
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• 2016

This study examines the organic geometry in Isabel Toledo's collections in terms of the practicality of American sportswear tradition. This study conducts literary survey combined with case analysis of Toledo's works from her debut collection in 1985 to the recent ones. The organic geometry in Toledo's designs refers to the conversion of two-dimensional garment patterns into three-dimensional garment forms with the body as a medium, which is classified into the following categories in this study. First, 'fluidity' describes Toledo's highly fluid jersey dresses which maintain consistent structures by patchwork draping and suspension technique. Second, 'reductionist structure' illustrates that simple geometric shapes such as circles and squares disappear as soon as worn on the body. Third, 'origami construction' explains folding two-dimensional fabrics into three-dimensional forms, which causes the outlines of the body to appear abstract. Toledo's designs deliver the tradition of American sportswear through the organic geometry of garment construction. Toledo's works are authentic American in the aspects that they are functional and modern; they satisfy the practical needs, prioritize the movements of wearers, pursue multi-functions, and their ornamental elements are accompanied by the construction of garments. Isabel Toledo presents designs drawing on her unwavering aesthetics while continuously developing and experimenting creative ways of garment construction.

• 대한수학교육학회지:학교수학
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• 제10권1호
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• pp.123-138
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• 2008

이 연구의 목적은 새수학의 전형이라 할 수 있는 SMSG의 넓이 교수-학습 방식에 대한 비판적 고찰을 통해 새수학 실패의 원인을 교수학적 측면에서 밝히는 것이다. SMSG의 계량도식에 따른 넓이 도입 방식의 독특성에 대해 파악하기 위해 Euclid의 $\ll$원론$\gg$, De Morgan의 $\ll$Elements of arithmetic$\gg$, 그리고 Legendre의 (Elements of geometry and trigonometry) 를 살펴보았다. 또, SMSG의 넓이 교수-학습 방식에 대한 Wittenberg(1963)과 Moise(1963)의 논쟁에 대해 고찰함으로써 초등성과 넓이개념에 대한 심상 형성이 SMSG의 넓이 교수-학습 방식의 성패의 중요한 관건이었다는 점을 확인하였다. 더 나아가 SMSG 넓이 교수-학습 방식이 닮음, 같은 넓이, 통약불가능성등과 같은 수학 내용과의 단절을 초래한다는 점에서 초등성과 기하적 심상의 부재를 낳을 수밖에 없었고, 그것이 SMSG 교수-학습 실패의 원인이라는 것을 보였다.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 1997년도 추계학술대회 논문집
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• pp.304-309
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• 1997

Elastic elements, at first, were extensively used in suspensions as vibration isolators at joints. Nowadays they are used to improve stability and handling. The design of these elements has become a very important matter since the loading condition of the mechanism gives a mew suspension geometry without any modification. This paper presents an analysis of forces and moments of joints with elastic elements in the McPherson suspension mechanism to evaluate accurately the elastic deformation using the displacement matrix method in conjunction with the equilibrium equations. First the suspension is modeled as a multi-loop spatial rigid-body guidance mechanism which has elastic elements at the hardpoints of the suspension. Then a method and design euqations are developed to analyze the suspension characteristics by the various tire load. Also the displacement matrices and constraint equations for links are appllied to determine the sensitivity of the suspension mechanism. Finally this approach may conduct a realistic design of suspension mechanisms with elastic elements to improve the performance of the automobile under various driving conditions.

• 한국수학사학회지
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• 제33권2호
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• pp.103-114
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• 2020

In 1607, Matteo Ricci and Xu Guangqi translated Euclid's 《Elements》 and published 《Jihe yuanben, 幾何原本》. Though 《Elements》 consists of 13 volumes (or 15 volumes according to its editions), they translated only the first 6 volumes on the plane geometry. Why did they do so? This paper discusses about the three questions which naturally arise: What might be the motive of the translation of the 《Elements》? What method did they adopt for the translation? And why did they translate the 6 volumes, especially, the first 6 volumes, not completing the whole?

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 2002년도 Proceedings of the International Welding/Joining Conference-Korea
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• pp.752-756
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• 2002

Variable weld bead penetrations related to the base metal chemistry of stainless steels in GTA welding have been under constant investigations due to their industrial implications. It has been proposed that among other elements, the sulfur content of steels determines the weld pool geometry, particularly its penetration. It is suggested that the surface tension temperature gradient of steels becomes positive with appropriate dosing in sulfur and results in inward melt flow, propitious for deeper welds. However, the chemistry of industrial steels is complex due to the presence of multiple minor elements either deliberately added or remnant impurity traces. With this in view, investigations on 41 austenitic and nine martensitic stainless steels were carried to see if there existed any possible relation between the weld profile and some of the designated elements. The results suggest no direct correlation between sulfur or any other major or trace element and weld penetration. At first glance the results are contradictory to what is often asserted.

• 소성∙가공
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• 제5권2호
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• pp.165-175
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• 1996

the process of strip twisting is practiced for the manufacture of some commercial parts such as elements for tube type line mixers. A thin metal strip with rectangular cross section is twisted thru an angle greater than 180。. Initial geometry is altered in to a complex one with dimen-sional changes. In practice several tryouts are necessary to obtain required dimensional accu-racies. A simple analysis model is proposed to predict the dimensional changes forming torque and axial force.