• 대한토목학회논문집
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• 제26권6A호
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• pp.989-999
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• 2006

본 연구에서는 차량과 교량을 3차원으로 모델링하고, 교량의 노면조도 및 교량과 차량 사이의 상호작용을 고려하여 이동 차량이 교량을 통과할 때 교량의 선형동적해석을 수행할 수 있는 수치해석방법을 제시하였다. 3차원 차량모델에는 타이어의 접지폭을 고려하여 탠덤 다판스피링 차륜축의 피칭을 고려하여 단일차량인 2축과 3축 차량 및 5축 트랙터-트레일러를 각각 7-자유도, 8-자유도 미 14-자유도로 모델링하였다. 차량의 운동방정식은 Lagrange 방정식을 사용하여 유도하였고, 그 해는 Newmark-${\beta}$법을 사용하여 계산하였다. 교량의 노면조도는 평균값이 영인 정상확율분포롤 가정한 지수스팩트럴밀도를 사용하여 생성시켰다. 교량은 주형을 보요소로, 콘크리트 바닥판은 쉴요소를 이상화시켰으며 주형과 콘크리트 바닥판 사이는 Ragid Link를 사용하여 3차원으로 모델링하였다. 교량의 운동방정시은 모우드 중첩법을 사용하여 풀었다. 본 연구에서 제시한 수치해석방법으로 구한 결과와 Whittemoare 등과 Fenves 등이 실시한 실험값과 비교 검토하여 본 연구의 타당성을 입증하였다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2002년도 춘계학술대회 논문집
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• pp.536-539
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• 2002

The reverse engineering (RE) technology can quickly generate 3D point cloud data of an object by capturing the surface of a model using a 3D scanner. In the rapid prototyping (RP) technology, prototypes are rapidly produced from 3D CAD models in a layer-by-layer additive basis. In this paper, a physical human head shape is duplicated using a new RP process, the Transfer-type Variable Lamination Manufacturing process using expandable polystyrene foam sheet (VLM-ST), after the point cloud data of a human head shape measured from 3D SNX scanner are converted to STL file. From the duplicated human head shape, it has been shown that the VLM-ST process in connection with the 3D scanner is a fast and efficient process in that shapes with free surface, such as the human head shape, can be duplicated with ease. Considering the measurement time and the shape duplication time, the use of 3D SNX scanner and the VLM-ST process is expected to reduce the lead-time fur the development of new products in comparison with the other existing RE-RP connected manufacturing systems.

• 한국터널지하공간학회 논문집
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• 제20권3호
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• pp.609-623
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• 2018

건물하중의 영향을 받는 상태의 기존터널에 근접해서 터널보다 깊은 심도로 지반을 굴착하는 경우에 흙막이벽체의 거동이 기존터널의 존재로 인해 큰 영향을 받는 것으로 알려져 있다. 그런데 지상 구조물에 의해 받는 영향에 대한 연구 예가 많지 않다. 따라서 본 연구에서는 기존터널에 근접하여 지반을 굴착할 때 기존터널이 상부구조의 영향을 받는 상태에서 건물 위치에 따른 터널의 거동을 대형모형실험과 수치해석을 실시하여 측정하였다. 이를 위해 지표면에 건물하중이 없는 경우와 건물하중이 3가지 이격거리에 위치한 경우(0 m, 1D, 2D)에 대하여 각각 대형모형실험을 수행하였다. 본 논문에서는 흙막이벽체와 기존구조물의 영향을 받고 있는 터널의 거동에 대하여 연구하였다. 1 : 10의 축척으로 2.0 m (폭)${\times}$6 m (높이)${\times}$4.0 m (길이)의 크기를 가진 대형토조에서 실험을 수행하였다. 그 결과 흙막이벽체 배면에 있는 인접터널의 안정성은 근접굴착에 의해 뚜렷하게 영향을 받는 것으로 나타냈다.

• 한국멀티미디어학회논문지
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• 제24권11호
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• pp.1472-1480
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• 2021

Image stacking technique is one of the key techniques for complex surface reconstruction. The process includes sample collection, image processing, algorithm editing, surface reconstruction, and finally reaching reliable conclusions. Since this experiment is based on laser scanning confocal microscope to collect the original contour information of the sample, it is necessary to briefly introduce the relevant principle and operation method of laser scanning confocal microscope. After that, the original image is collected and processed, and the data is expanded by interpolation method. Meanwhile, several methods of surface reconstruction are listed. After comparing the advantages and disadvantages of each method, one-dimensional interpolation and volume rendering are finally used to reconstruct the 3D model. The experimental results show that the final 3d surface modeling is more consistent with the appearance information of the original samples. At the same time, the algorithm is simple and easy to understand, strong operability, and can meet the requirements of surface reconstruction of different types of samples.

• 전자공학회논문지D
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• 제35D권2호
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• pp.60-69
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• 1998

Polysilicon surface mdoification tecnique is developed to reduce the sticking of microstructures fabricated by micromachining. Modified anti-sticking grain holes are simply formed by two-step dry eth without additional photolithography nor deposition of thin films. Both process-induced sticking and in-use sticking are successfully reduced more than two times by adopting grain holed polysilicon substrate. A sticking model for cantilever beam is derived. This model includes bending moment stems from stress gradient along the thickness directionof structural polysilicon. Because the surface tension of rinse liquid and the surface energy of the solids to be stuk tend to decrease in recently developed anti-sticking techniques, the effect of stress gradient will play an important role to analyze the sticking phenomena. Effect of the temperature during post-release rinse and dry is modelled and verified experimentally. Based on developed anti-sticking polysilicon structure and the sticking model, sticking of microstructure, fabricated by simple wet process including sacrificial layer etch and rinse with deionized water without special equimpment for post-release rinse and dry was alleviated more than 3.5 times.

• 전자공학회논문지S
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• 제34S권6호
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• pp.21-29
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• 1997

In this paper, we propose a new approach for recovering 3-D shape and extracting the reflectance properties of surface from intensity images. Photometric stereo method(PSM) is genrally based on the direct illumination. In this paper, the reflectance function is derived by interoduceing the indirect diffuse illumination in PSM and then applied to hybrid reflectance model which consists of two components; the lambertian and the specular reflectance. Under the hybrid reflectance model and the indirect diffuse illumination circumstance, the reflectance properties of sample surface can be extracting by normal sampler and then 3-D shape of an object can be recovered based on extracting reflectance properties. This method is rapid because of using the reference table and simplifies the restriction condition about the reflectance function existing in prior studies. Th erecovery efficiency in our method is better than that in prior studies. Also, this method is applied to various types of surfaces by defining general reflectance function.

• 한국축산시설환경학회지
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• 제8권3호
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• pp.165-170
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• 2002

This study was carried out to measure the 3D-distance of a cow model teat for an application possibility on Robotic Milking System(RMS). A teat recognition algorithm was made to find 3D-distance of the model by using Gonzalrez's theory. Some of the results are as follows. 1 . In the distance measurement experiment on the test board, as the measured length, and the length between the center of image surface and the measured image point became longer, their error values increased. 2. The model teat was installed and measured the error value at the random position. The error value of X and Y coordinates was less than 5㎜, and that of Z coordinates was less than 20㎜. The error value increased as the distance of camera's increased. 3. The equation for distance information acquirement was satisfied with obtaining accurate distance that was necessary for a milking robot to trace teats, A teat recognition algorithm was recognized well four model cow teats. It's processing time was about 1 second. It appeared that a teat recognition algorithm could be used to determine the 3D-distance of the cow teat to develop a RMS.

• 국제학술발표논문집
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• The 7th International Conference on Construction Engineering and Project Management Summit Forum on Sustainable Construction and Management
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• pp.242-244
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• 2017

Excavation for construction is implemented in natural geographical terrain using a variety of construction equipment. Therefore, 3D excavation simulation requires integration of geographical and equipment modeling. This paper proposes a technique that integrates geographical and equipment modeling for 3D simulations of construction excavation. The geographical model uses a digital map to show ground surface changes during excavation and the equipment model shows equipment movement and placement. This combination produced a state of the art 3D simulation environment that can be used for machine guidance. An equipment operator can use the 3D excavation simulation to help construction equipment operators with decisions during excavation work and consequently improve productivity.

• Interaction and multiscale mechanics
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• 제1권2호
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• pp.279-301
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• 2008

This paper develops a 3D homogenization based continuum damage mechanics (HCDM) model for fiber reinforced composites undergoing micromechanical damage under monotonic and cyclic loading. Micromechanical damage in a representative volume element (RVE) of the material occurs by fiber-matrix interfacial debonding, which is incorporated in the model through a hysteretic bilinear cohesive zone model. The proposed model expresses a damage evolution surface in the strain space in the principal damage coordinate system or PDCS. PDCS enables the model to account for the effect of non-proportional load history. The loading/unloading criterion during cyclic loading is based on the scalar product of the strain increment and the normal to the damage surface in strain space. The material constitutive law involves a fourth order orthotropic tensor with stiffness characterized as a macroscopic internal variable. Three dimensional damage in composites is accounted for through functional forms of the fourth order damage tensor in terms of components of macroscopic strain and elastic stiffness tensors. The HCDM model parameters are calibrated from homogenization of micromechanical solutions of the RVE for a few representative strain histories. The proposed model is validated by comparing results of the HCDM model with pure micromechanical analysis results followed by homogenization. Finally, the potential of HCDM model as a design tool is demonstrated through macro-micro analysis of monotonic and cyclic damage progression in composite structures.

• International Journal of Aeronautical and Space Sciences
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• 제7권2호
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• pp.104-109
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• 2006

In this study, the equivalent plate model is developed using a finite element method(FEM) based on the first order shear deformation theory(FSDT). The substructure synthesis method is used to consider the control surface. For the verification of the equivalent model, the results of free vibration analysis are compared with the ones of 3D wing structure modeled by using the MSC/NASTRAN.