• 소성∙가공
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• 제8권3호
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• pp.294-305
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• 1999

A vision-based surface-strain measurement system has been still improved since the authors devel-oped the first version of it. New algorithms for the subpixel measurement and surface smoothing are introduced to improve the accuracy and precision in the present study. The effects of these algorithms are investigated by error analysis. And the equations required to calculate 3D surface-strain of a shell element are derived from the shape function of a linear solid finite-element. The influences of external factors on the measurement error are also examined, and several trials are made to obtain possible optimal condition which may minimize the error.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 1997년도 춘계학술대회논문집
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• pp.213-216
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• 1997

The measurement of 3D surface strain using the image processing method is another approach for strain measurement. The advantage of this method is that strains at several points included in a captured image can be obtained automatically from only one process. In this study, the whole process of automated surface strain measurement is presented. The strain distribution on a LDH specimen is illustrated as a result of the trial to develope an automated strain measurement system.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 1997년도 추계학술대회논문집
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• pp.142-146
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• 1997

An automated surface-strain measuring system is developed in the present study, which consists of the hardware to capture and to display digital images and the software to calculate the 3-D informations of grid points. The software is implemented using the image processing technique, and includes a program for the camera calibration and the post-processor to display the strain distribution. An LDH(limitting dome height) test specimen is measured its surface-strain as an application of the present system.

• 한국균학회지
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• 제11권4호
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• pp.169-175
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• 1983

벼키다리병(病)에 이병(罹病)된 벼에서 531균주를 분리(分離)하여 5가지 기준(基準)을 두고 분류(分類)한 결과(結果) Strain I, II, III과 IV로 분류(分類)한 수 있었다. 그중에서 Strain IV가 가장 많이 우리나라 분포(分布)되었으며 병원성도 강(强)한 것으로 나타났다. 5가지기준(基準)은 기주(寄主)의 병징(病徵), 포자형성(胞子形成), 대형분생포자격막수(大型分生胞子隔膜數), 균총의 색깔과 약제(藥劑)의 반응(反應)이었다. Strain I은 병원성(病原性)이 약하게 나타났으며 pionnotes안에 $6{\sim}7$개(個)의 격막(隔膜)을 가진 대형분생포자(大型分生胞子)를 형성(形成)하며 균총의 색깔은 표면(表面)과 이면(裏面)에 전부(全部) reddish purple을 보인다. Strain II는 병원성(病原性)은 약(弱)하나 pionnotes안에 소형분생포자를 형성(形成)하며 균총의 색깔은 표면(表面)과 이면(裏面)에 전부(全部) reddish purple을 보인다. Strain III는 병원성(病原性)이 강(强)하여 심하게 도장(徒長) 시키며 sporodochia안에 4개의 격막(隔膜)을 가진 대형분생포자(大型分生胞子)를 형성(形成)하며 균총의 색깔은 표면(表面)에는 yellowish red 이면(裏面)에는 reddish purple를 보인다. Strain IV은 병원성(病原性)이 강(强)하여 심하게 도장(徒長)시키기도 하고 고사(枯死)시킨다. sporodochia안에 주로 3개(個)의 격막(隔膜)을 가진 대형분생포자(大型分生胞子)를 형성(形成)하며 균총의 색깔은 표면(表面)과 이면(裏面) 전부(全部) yellowish red를 보이는 것이 특징이다.

• 소성∙가공
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• 제7권6호
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• pp.575-585
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• 1998

An automated surface-strain measuring system using the image processing technique is developed in the present study which consists of the hardware to capture and to display digital images. and the software to calculate the 3-D informations of grid points from two views. New or improved algorithms for the mapping and establishing correspondence of grid points and elements the camera calibration and the subpixel measurement of grid points are implemented. As an application of the present system the surface-strains of deformed blanks in the limitting dome height test the square cup deep-drawing and punch stretching to obtain the forming limit diagram are measured. The results are com-pared with those obtained by conventional manual methods.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 1999년도 춘계학술대회논문집
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• pp.269-272
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• 1999

It is still hard to measure the strain distribution over entire surface of a medium or large-size stamped part even by using an automated strain measurement system. Several methods which enable to enlarge the measurement range without losing accuracy and precision are suggested in this study, The superposition of images having different high-lightened or damaged part each other results in an enhanced image. A new method for constructing the element connectivity from a line-thinned image makes it possible to identify up to 1,000 elements. And the geometry assembling algorithm is proved very efficient in which the whole area to be measured is divided into several parts ; the coordinate transformation between every two adjacent parts is obtained from the concept of the least square error ; and the 3-D shape or strain distribution over the whole surface is assembled,

• 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.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2000년도 춘계학술대회논문집
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• pp.129-133
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• 2000

It is reasonable to use the stereo vision and image processing technique to digitize 3D coordinates of grid points and to evaluate surface strains on a sheet metal parts. However this method has its intrinsic problems such as the difficulty in enhancement of bad images inevitable error due to digital image resolution of camera and frame grabber unreliability of strains and thickness evaluated from coarse grid on the corner area with large curvature and the limitation of the area that can be measured at a time. Therefore it is still hard to measure strain distribution over the entire surface of a medium,- or large-sized stamped part at a time even by using an automated strain measurement system. In this study the curvature correction algorithm based on the grid refinement and the geometry assembling algorithm based on the global error minimization (GEM) scheme are suggested. Several applications are presented to show the reliability and efficiency of these algorithms.

• 한국축산식품학회지
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• 제26권4호
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• pp.497-502
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• 2006

한국인 유아의 분변에서 분리한 10종의 분리균주를 포함하여 총 16종의 bifidobacteria에 대한 Caco-2 세포에 대한 부착성과 세포 표면 소수성을 측정하였다. 부착성과 세포 표면소수성 모두 균주에 따라 상이한 결과를 나타내었으며 균종에 따른 경향은 관찰되지 않았다. 실험 균주 중에서 B. longum D6, B. longum H4, B. breve Ml, B. thermophilum ATCC 25525, B. suis ATCC 27533, B. animalis subsp. lactis BB12 균주가 세포 표면 소수성이 높게 나타났으며, Caco-2 세포에 대한 부착성은 B. bifidum B3, B. longum D6, B. longum H4, B. thermophilum ATCC 25525, B. suis ATCC 27533, B. animalis subsp. lactis BB12, B. longum 2 등이 우수하였다. 또한 Caco-2세포에 200개 이상이 부착되는 실험 균주는 모두 60% 이상의 세포 표면 소수성을 나타내고 있으므로, 부착성이 우수한 균주 선발 시 분리 균주의 세포 표면 소수성을 측정하여 선발하는 것이 가능하다고 판단되었다.

• 산업기술연구
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• 제17권
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• pp.21-29
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• 1997

In this paper, an adaptive image binarization scheme is proposed for automated surface strain measurement. At first, we reviewed an image based 3D deformation factor measurement briefly. Then, a new adaptive thresholding method is proposed for the extraction of lattice pattern from a deformed plate image using its local mean and variance. Some experimental results are presented to verify the effectiveness of our approaches.