• 한국정밀공학회지
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• 제17권11호
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• pp.69-74
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• 2000

Roughness of curved surfaces finished with flexible tools depends on the tool/work contact pressure and area. In this study, non-Hertzian closely conforming elastic contact theory is employed to analyze the tool/work contact and to generate a tool path producing a constant pressure at initial contact points. Finishing experiments on curved surfaced are conducted using the tool path. For comparison, curved surface finishing is also performed along the tool path producing a constant tool/work interference depth. It is demonstrated that the tool path of constant contact pressure improves the finished surface roughness.

• Steel and Composite Structures
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• 제39권1호
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• pp.1-20
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• 2021

An exact solution based on refined third-order theory (TOT) has been presented for functionally graded porous curved beams having deep curvature. The displacement field of the refined TOT is derived by imposing the shear free conditions at the outer and inner surfaces of curved beams. The properties of the two phase composite are tailored according the power law rule and the effective properties are computed using Mori-Tanaka homogenization scheme. The equations of motion as well as consistent boundary conditions are derived using the Hamilton's principle. The curved beam stiffness coefficients (A, B, D) are obtained numerically using six-point Gauss integration scheme without compromising the accuracy due to deepness (1 + z/R) terms. The porosity has been modeled assuming symmetric (even) as well as asymmetric (uneven) distributions across the cross section of curved beam. The programming has been performed in MATLAB and is validated with the results available in the literature as well as 2D finite element model developed in ABAQUS. The effect of inclusion of 1 + z/R terms is studied for deflection, stresses and natural frequencies for FG curved beams of different radii of curvature. Results presented in this work will be useful for comparison of future studies.

• 대한조선학회논문집
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• 제36권3호
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• pp.134-143
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• 1999

선박의 선미부와 선수부는 복잡한 곡을 가진 블록들의 조립으로 만들어진다. 이러한 복잡한 곡률 분포를 가진 이중 곡면을 성형하기 위해서 조선소에서는 롤러 굽힘 가공과 선상 가열을 이용하고 있다. 일차적으로는 롤러 굽힘에 의한 가공으로 실린더 형상이나 원추 형상의 곡면을 만들고 난 후, 선상 가열을 수행하여 목적 형상으로 이차 가공을 한다. 본 논문은 곡면 가공에서 선행되는 일차 가공의 정보로서 가공 방향과 가공 후 형상을 결정하는데 목적이 있다. 목적 형상의 가우스 변환(Gauss mapping)으로부터 가공 방향에 관한 정보를 결정하고 목적 형상과 롤러 굽힘 가공에 의해 변형된 판 사이의 기하학적 관계를 이용하여 롤러 굽힘 가공의 모양을 결정하는 알고리즘을 제시하였다.

• 한국공간구조학회논문집
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• 제16권1호
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• pp.53-64
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• 2016

Solar power is being spotlighted recently as a new energy source due to environmental problems and applications of solar power to curved structures are increasing. Solar panels installed on curved surfaces have different efficiencies depending on its position and the efficient positioning of solar panels plays a critical role in the design of solar power generation systems. In this study, the changing characteristics of solar irradiance were analyzed for hemispherical dome with a large curvature and the positioning of solar panels that can efficiently utilize solar energy was investigated. With an icosahedron-based hemispherical dome consisting of triangular elements as target model, a program for calculating solar irradiance using a normal vector of the solar module on each face was developed. Furthermore, the change of solar irradiance according to the sun's path was analyzed by time and season, and its effects on shades were also examined. From the analysis results, the effective positioning could be determined on the basis of the efficiency of the solar panels installed on the dome surfaces on solar irradiance.

• 대한조선학회논문집
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• 제52권1호
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• pp.70-76
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• 2015

The ship hull is accomplished by assembling various curved surfaces. There are numerous existing methods for ship hull processing, which need certain appropriate processing methods to enable it to be more efficient. The curved hull plates can be divided into convex region and saddle region. It is common to use line heating method to form a saddle region, when it comes to a convex region, it will be triangle heating method to be utilized. A precise analysis for curvature domain is required for the application of proper processing method. There exist various problems on existing calculation methods of curvature domain. Therefore, a more powerful method is demanded to it more accurately. In this study, a method called Dual Contouring is applied to extract curved surfaces, which is able to improve accuracy of extracted area. Based on all above, a best-suited heat processing method should be selected.

• 한국전자파학회:학술대회논문집
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• 한국전자파학회 2005년도 종합학술발표회 논문집 Vol.15 No.1
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• pp.217-220
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• 2005

In this paper describes novel m antenna using aperture matched type slot structure. It substitutes edge diffractions by curved-surface diffractions which have a tendency to provide an undisturbed energy flow across the junction, around the curved surface, and into free-space. The proposed antenna is composed of a CPW feed structure, exponential tapered slot and the curved sectional at the edge. experimental resulte show that aperture matched type slot improve the performance of the UWB antenna.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2017년도 춘계 학술논문 발표대회
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• pp.62-63
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• 2017

According to the rapid development of digital technology, the free formed buildings with complex and various curved surfaces are being constructed. Most of the external cladding of free formed buildings have been applied materials such as metal, glass, FRP, GFRC, etc. However, these materials have many disadvantages such as a complicated manufacturing process for realizing 3D irregular shape and an increase in production period and cost. Therefore, the studies for UHPC which is an optimized material for overcoming this problem for a long time in overseas. This study reviewed the remodeling construction of Samsung-dong KEB Hana Bank appling the exterior curved UHPC panel for the first time in Korea. As a result, we confirmed the possibility of UHPC panels with various free formed shapes.

• Korean Journal of Geomatics
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• 제3권1호
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• pp.43-51
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• 2003

This paper presents the benefits of using close-range digital photogrammetric techniques for measuring the roughness of rock surfaces, using digital stereo images obtained from a Rolleiflex 6006 metric camera. To precisely measure surface roughness, we researched on how to use the flat and curved reference surface obtained from geometrically corrected digital images of the rock surface by using the least squares method. To test the precision of the proposed technique, the surface roughness has been measured between the reference surface and sample areas of very smooth-surfaced rock. Then the results were compared with the measurements obtained from a laser sensor profilometer.

• 한국정보통신학회논문지
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• 제4권5호
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• pp.931-936
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• 2000

이 논문에서는 완만한 곡면을 모델링하기 위한 새로운 CPFDTD 앨거리즘을 제안한다. 이 구조에서는 기존의 근접 전계 대여 근사법을 피하기 위하여, 변형된 궤적상의 전계 성분을 확장 궤적 전계, 무변형 궤적 전계, 그리고 준-사용 전계로 세분한다. 기존의 몇몇 방법들과 개선된 방법을 I-면 흔 안테나의 해석에 적용하여 각각의 방법으로 계산된 원거리 필드 패턴을 측정치와 비교함으로써, 개선된 CPFDTD법의 정확도를 검증한다.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2004년도 추계학술대회 논문집
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• pp.439-444
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• 2004

A new efficient intelligent machining strategy named the Steepest Directed Tree method is presented in this study, which makes surface model discrete with triangulation meshes and the cutter paths track along the tree directions. In order to formulate these algorithms practically, it is deduced the multi-stage machining approach of uncut volume caused by cutter gouging in the course of milling using flat end mill. It is systematized the checking process the cutter interference by grouping the 6 kinds of gouging types, which yields the environment of connectivity data lists including CL-data, and then the multi-stage machining strategy, that minimizes uncut area by continuously sequencing the generative subsequent CL-paths, is shamed to determine the second tool path for the next uncut area and to compose the operating multi-stage cutting processes. The completed machining system of curved surfaces is evaluated by testing the practical machining experiments which have various kinds of shape conditions.