• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 1992년도 춘계학술대회 논문집 92
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• pp.115-130
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• 1992

The analysis of thermoplastic automotive bumpers needs not only characterizations of the thermomechanical properties of thermoplastic materials but also the finite element method which can solve the problems with a large deflection, an elastic-inelastic deformation, and a change of a contact state. This paper describes the modeling techniques in the finite element analysis in order to get a good prediction of thermoplastic bumper behaviors. Simplification effects of a complex geometry of thermoplastic bumpers are studied by comparing the results from static loading tests and the finite element analysis.

• 한국CDE학회논문집
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• 제1권2호
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• pp.122-132
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• 1996

Features are generic shapes with which engineers associate certain attributes and knowledge useful in reasoning about the product. Feature-based modeling systems support additional levels of information beyond those available in geometric modelers. The objective of this study is to develop a PC level feature-based modeling system which explicitly represents dimensions of the part. The feature-based modeler retains all the benefits of traditional B-rep. solid models, and represents the dimensions at a high level of a abstraction so that dimension driven geometry can be achieved.

• 한국기계연구소 소보
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• 통권19호
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• pp.163-169
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• 1989

Many computer programs are being developed to aid the design of physical models. These efforts highlight the importance of computer model of three dimensional object. In this paper a CAD application program is introduced which can be implemented to modeling some part that composed with 3 types of surface form ; free form surface, fillt surface, surface of revolution, and a geometry description language which can represent a shape efficiently is preseneted.

• Nuclear Engineering and Technology
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• 제54권11호
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• pp.4220-4225
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• 2022

Monte Carlo (MC) simulations are increasingly being used as an alternative or supplement to the gamma spectrometric method in determining the full energy peak efficiency (FEPE) necessary for radionuclide identification and quantification. The MC method is more advantageous than the experimental method in terms of both cost and time. Experimental calibration with standard sources is difficult, especially for specimens with unusually shaped geometries. However, with MC, efficiency values can be obtained by modeling the geometry as desired without using any calibration source. Modeling the detector with the correct parameters is critical in the MC method. These parameters given to the user by the manufacturer are especially the dimensions of the crystal and its front edge, the thickness of the dead layer, dimensions, and materials of the detector components. This study aimed to investigate the effect of the front edge geometry of the detector crystal on efficiency, so the effect of rounded and sharp modeled front edges on the FEPE was investigated for <300 keV with three different HPGe detectors in point and volume source geometries using PHITS MC code. All results showed that the crystal should be modeled as a rounded edge, especially for gamma-ray energies below 100 keV.

• International Journal of Naval Architecture and Ocean Engineering
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• 제6권4호
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• pp.935-946
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• 2014

This paper investigates the noise transmission performance of industrial mufflers widely used in ships based on the CAE modeling and simulation. Since the industrial mufflers have very complicated internal structures, the conventional Transfer Matrix Method (TMM) is of limited use. The CAE modeling and simulation is therefore required to incorporate commercial softwares: CATIA for geometry modeling, MSC/PATRAN for FE meshing and LMS/SYSNOISE for analysis. Main sources of difficulties in this study are led by complicated arrangement of reactive elements, perforated walls and absorption materials. The reactive elements and absorbent materials are modeled by applying boundary conditions given by impedance. The perforated walls are modeled by applying the transfer impedance on the duplicated node mesh. The CAE approach presented in this paper is verified by comparing with the theoretical solution of a concentric-tube resonator and is applied for industrial mufflers.

• 한국수학교육학회지시리즈A:수학교육
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• 제49권3호
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• pp.313-328
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• 2010

Mathematical modeling has been observed in the way of a possibility to contribute in improving students' problem solving abilities. One of the important views of real life problem context could be described such as a useful ways to interpret the real life leading to children's abstraction process. The problem contexts for the grade 6 with mathematical modeling perspectives were developed by reviewing the current 7th National Mathematics Curriculum of Korea. Those include the 5 content areas such as number & operation, geometry, measurement, probability & statistics, and pattern & problem solving. One of problem contexts, "Space", specially designed for pattern & problem solving area, was applied to the grade 6 students and analyzed in detail to understand student's mathematical modeling progress.

• 한국정밀공학회지
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• 제14권2호
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• pp.136-144
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• 1997

Usually triangular patches are used to transfer geometric shape in Rapid Prototyping CAM system. STL, a list of triangles, is de facto standard in RP industry. Because STL does not have topological infoma- tion, it can cause errornous results. So STL should be verified before using. After adding support structures to anchor the part to the platform and to prevent sagging or distortion, slicing and layer by layer manufactur- ing process are done. But triangular patch is surface model and cannot provide sufficient information on geometry in the above processes. So, geometric modeling is necessary in verifying STL, adding support structures and slicing. It is natural that triangle based modeling is the best when tringular patches are used as input. Considering support structures, solid and faces coexist in RP process. Therefore non-manifold modeler is required. In this study, triangle based non-manifold geometric modeling is proposed for RP sys- tem consistent with STL input.

• 한국가시화정보학회지
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• 제5권2호
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• pp.20-25
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• 2007

The geometry of a commercial passenger airplane is realized based on a Boeing 747-400 model through the photographic scanning and reverse engineering. The each element consisting of the plane such as fuselage, wing, vertical fin, stabilizer and engines, is individually generated and then the whole body is assembled by the photomodeler. The maximum error in the realized airplane is about 1.4% comparing with the real one. The three-dimensional inviscid steady compressible governing equations are solved in the unstructured tetrahedron grid system, and in a finite volume method using STAR-CD when the airplane flies at the cruise condition. The pressure distribution on the surface and the wing-tip vortices are visualized, and in addition to the aerodynamics coefficients, lift and drag are estimated.

• 조명전기설비학회논문지
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• 제18권5호
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• pp.35-41
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• 2004

본 연구에서 사용된 방전 기체는 오염물의 제거 및 박막 표면 정제 등의 연구 분야에 응용되고 있는 질소 가스를 사용하였으며, 1차원 동심구 모델의 개발로 인하여, 접지 면적을 넓게 함에 따라 경방향으로의 플라즈마 분포가 중심축의 분포와 동일하다는 1차원적 가정이 적절하지 못하다는 Barnes 모델을 보완할 수 있었다. 일정한 인가 전압하에서는 입체각($\omega$)의 증가에 따라 질소 플라즈마를 구성하는 각 입자의 수밀도 분포, 전계 및 포텐셜이 감소함을 볼 수 있었다. 그러나 면적비가 증가하면서 구동 전극에서의 각 입자들의 움직임은 상대적으로 높은 전계로부터 더욱 활발하게 형성됨에 따라 직렬 연결된 블로킹 콘덴서에서 발생하는 자기 바이어스 전압은 증가하는 것을 알 수 있었다.

• 한국전산구조공학회논문집
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• 제30권4호
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• pp.283-288
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• 2017

스폿 용접 접합의 삼차원 모델링을 위하여 강한 불연속이 내장된 유한요소를 사용하였다. 스폿 용접의 기하학적 형상을 유한요소망 대신 요소에 내장된 불연속 면에서의 특수한 응집 법칙을 이용하여 표현하였다. 이를 통하여 기존의 적응적 유한요소망을 이용하는 접근법과 달리 스폿 용접의 국부적인 형상에 독립적인 유한요소망을 구성할 수 있다. 또한, 스폿 용접의 형상을 명시적으로 고려하여 모델링함으로써 기존의 점 구속조건을 이용하는 접근법과 달리 망 독립적인 해를 얻을 수 있다.