• 한국해안·해양공학회논문집
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• 제21권3호
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• pp.209-215
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• 2009

케이슨식 방파제의 신뢰성해석 시 파고와 조위의 확률변동성을 고려하기 위한 하중면 이용방법을 제안하였다. 케이슨식 방파제 전면에 전달되는 수평파력과 양력을 전면조위와 파고의 일차함수로 추정하였으며 추정한 하중면을 일계신뢰도법을 이용한 신뢰성 해석에 적용하였다. 수치해석에서 하중면을 이용한 케이슨식 방파제의 활동 및 전도 파괴확률을 산정하였으며 몬테카를로 모사법의 결과와 비교하였다.

• 대한조선학회논문집
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• 제29권3호
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• pp.15-20
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• 1992

이 논문에서는 화가의(Painter's) 알고리듬을 사용하여 3차원 자유형상곡면(Three dimensional free form surface)을 가시화하는 방법을 개발하였고, 특히 선체형상은 Open 균일 B-Spline 곡면으로 정의하였다. 컴퓨터그래픽스를 응용하여 와이어프레임, 숨은면제거, 묘영등의 가시화를 위한 프로그램을 완성하였다. 또한 선체곡면의 순정을 검토하기 위해 Gaussian 곡률값을 15등급으로 구분하여 등급별 색(color)처리 하였다.

• 한국결정성장학회:학술대회논문집
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• 한국결정성장학회 2000년도 Proceedings of 2000 International Nano Crystals/Ceramics Forum and International Symposium on Intermaterials
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• pp.127-142
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• 2000

The charged cluster model states that chemical vapor deposition (CVD) begins with gas phase nucleation of charged clusters followed by cluster deposition on a substrate surface to form a thin film. A two-chambered CVD system, separated by a 1-mm orifice, was used to study gold deposition by thermal evaporation in order to determine if the CCM applies in this case. At a filament temperature of 1523 and 1773 K, the presence of nano-meter sized gold clusters was found to be positive and the cluster size and size distribution increased with increasing temperature. Small clusters were found to be amorphous and they combined with clusters already deposited on a substrate surface to form larger amorphous clusters on the surface. This work revealed that gold thin films deposited on a mica surface are the result of the sticking of 4-10 nm clusters. The topography of these films was similar to those reported previously under similar conditions.

• 대한조선학회지
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• 제17권4호
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• pp.13-20
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• 1980

The integral equation method to solve the boundary-value problem of a 2-dimensional body oscillating in the presence of a free surface generally breaks down at and near irregular frequencies due to the hypothetical flow inside the body. In this paper singularity distributions were extended to an inner free surface to remove the irregular frequency as Ohmatsu's work in 1978, and the solution for the above problem was found by using stream function. For various bodies including Lewis form cylinders, the hydrodynamic forces were calculated numerically at various wave numbers. From the results we concluded that the irregular frequencies can be removed even for the Lewis form cylinder as Ohmatsu done for circular cylinders, and calculated hydrodynamic forces by the present method are little higher than those of Ohmatsu's when the singularities are put on the inner free surface of the body. We specially point out that the solution for heaving motion converges in an oscillatory manner but not for swaying and rolling motions.

• 한국정밀공학회지
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• 제18권4호
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• pp.97-103
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• 2001

Accuracy of a machined part is determined by the relative motion between the cutting tool and the workpiece. One of the important factors which affects the relative motion is the geometric errors of a machine tool. In this study, firstly, geometric errors are measured by laser interferometer, and the positioning error of each control point selected uniformly on the control surface CAD model can be estimated from th oirm shaping model and geometric error data base. Where a form shaping function is derived from the link of homogeneous transformation matrix. Secondly, control points are shifted to the estimated amount of positioning errors. A new control surface is modeled with NURBS(Non Uniform Rational B-Spline) surface approximation to the shifted control points. By generating tool paths to the redesigned control surface, we reduce the machining error quite.

• 한국건축시공학회지
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• 제10권5호
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• pp.137-143
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• 2010

본 연구는 거푸집에 부착하는 코팅재료에 따른 콘크리트 표면광택도 비교 분석으로서 시멘트모르터로 제작한 시험체의 광택도를 분석하고 유동화제를 혼합한 콘크리트와 혼합하지 않은 콘크리트의 노출콘크리트 표면 광택의 특성을 분석한 것이다. 시멘트모르터를 이용한 코팅재료별 광택도 분석에서 광택도가 가장 높게 나타난 코팅재료는 7번 재료로 액체포장재의 일부이며 2번째는 3번 재료로 투명필름을 이용한 재료이다. 코팅필름의 소재에 따라 광택도가 다르게 나타난 것으로 미루어 소재의 표면입자 상태와 화학적 구성요소의 따라 다른 것으로 판단된다. 콘크리트의 표면상태를 매끄럽게 하기 위해서는 불투수성이며 매우 밀실한 표면을 가진 코팅재료를 사용하는 것이 효과적이다.

• Steel and Composite Structures
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• 제38권5호
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• pp.583-597
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• 2021

This article develops a nonclassical model to analyze bending response of squared perforated microbeams considering the coupled effect of microstructure and surface stress under different loading and boundary conditions, those are not be studied before. The corresponding material and geometrical characteristics of regularly squared perforated beams relative to fully filled beam are obtained analytically. The modified couple stress and the modified Gurtin-Murdoch surface elasticity models are adopted to incorporate the microstructure as well as the surface energy effects. The differential equations of equilibrium including the Poisson's effect are derived based on minimum potential energy. Exact closed form solution is obtained for bending behavior of the proposed model considering the classical and nonclassical boundary conditions for both uniformly distributed and concentrated loads. The proposed model is verified with results available in the literature. Influences of the microstructure length scale parameter, surface energy, beam thickness, boundary and loading conditions on the bending behavior of perforated microbeams are investigated. It is observed that microstructure and surface parameters are vital in investigation of the bending behavior of perforated microbeams. The obtained results are supportive for the design, analysis and manufacturing of perforated nanobeams that commonly used in nanoactuators, nanoswitches, MEMS and NEMS systems.

• 대한수학회보
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• 제52권5호
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• pp.1569-1578
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• 2015

We study helicoidal surfaces with the non-degenerate third fundamental form in Minkowski 3-space. In particular, we mainly focus on the study of helicoidal surfaces with light-like axis in Minkowski 3-space. As a result, we classify helicoidal surfaces satisfying an equation in terms of the position vector field and the Laplace operator with respect to the third fundamental form on the surface.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2015년도 춘계 학술논문 발표대회
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• pp.126-127
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• 2015

New technologies using a CNC machine to reduce the production cost of free-form buildings are being developed. To produce free-form members with such technologies, a vast free form building should be first divided into multiple panels that can be produced. Considering the curved surface of free-form buildings, the shape and size of divided freeform panels vary, which will lead to a great deal of errors. Currently, the engineers and designers complete the panelizing work through trials and errors even in large-scale projects, which results in increased construction duration and cost. Thus, it is necessary to develop a freeform panelizing technology to maximize the economic effects of free-form concrete member production technology. The purpose of the study is to analyze influence factors on panelizing of free-form buildings, which is a preceding research for development of a panelizing technology. The influence factors drawn will provide a core basis for development of panelizing technologies for free-form buildings.

• 한국건설관리학회논문집
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• 제4권4호
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• pp.88-95
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• 2003

탈수거푸집공법은 거푸집 표면에 잉여수를 배출시킬 수 있는 구멍을 뚫고 내측에 섬유포를 부착하여 콘크리트 타설시 잉여수 및 혼입공기를 배출시키는 공법으로 시공상의 워커빌리티를 확보하면서 콘크리트 표층부 품질을 강화시킬 수 있다. 따라서 제치장 콘크리트 표면의 강도를 극대화할 뿐만 아니라, 수밀한 콘크리트 표층부를 생성하기 때문에 물이나 공기, 염분 등이 침투하기 어려워 콘크리트의 내구성을 크게 향상시킬 수 있다. 그러나 현재 국내에서는 이론적으로는 제기되고 있으나, 관련규준 및 시공방법에 대한 연구가 부재해 공사현장에서 적용할 기회가 없는 실정이다. 이에 본 연구에서는 물성실험을 통해 탈수거푸집 설계를 위한 기초자료를 제공하고, 이를 바탕으로 한 현장적용실험을 통해 탈수거푸집공법의 실용화 방안을 제안하고자 한다.