• 한국정보통신설비학회:학술대회논문집
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• 한국정보통신설비학회 2008년도 정보통신설비 학술대회
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• pp.531-534
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• 2008

Image Hash specifies as a descriptor that can be used to measure similarity in images. Among all image Hash methods, histogram based image Hash has robustness to common noise-like operation and various geometric except histogram _equalization. In this_paper an improved histogram based Image Hash that is using "Imadjust" filter I together is proposed. This paper has achieved a satisfactory performance level on histogram equalization as well as geometric deformation.

• Journal of Computing Science and Engineering
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• 제11권3호
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• pp.79-91
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• 2017

In this paper, the abdominal-deformation measurement scheme is conducted on a shape-flexible mannequin using the DIC technique in a stereo-vision system. Firstly, during the integer-pixel displacement search, a novel fractal dimension based on an adaptive-ellipse subset area is developed to track an integer pixel between the reference and deformed images. Secondly, at the subpixel registration, a new mutual-learning adaptive particle swarm optimization (MLADPSO) algorithm is employed to locate the subpixel precisely. Dynamic adjustments of the particle flight velocities that are according to the deformation extent of each interest point are utilized for enhancing the accuracy of the subpixel registration. A test is performed on the abdominal-deformation measurement of the shape-flexible mannequin. The experiment results indicate that under the guarantee of its measurement accuracy without the cause of any loss, the time-consumption of the proposed scheme is significantly more efficient than that of the conventional method, particularly in the case of a large number of interest points.

• 동력기계공학회지
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• 제18권4호
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• pp.78-84
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• 2014

The estimation of deformation and strain for the twill-weave carbon fiber reinforced plastic composite(CFRP) during the test with a digital image correlation system were implemented experimentally. The carbon fiber reinforced plastic composites have been developed as the edge technology materials. The plain, twill and satin weave types are commonly used for the CFRP composites. Thus, it is essential to find the deformation characteristics for those types of CFRP more easily. Especially the DIC method can express the visual strain distributions at the full range of the interested areas in the structures. In this study, the mechanical properties of twill-weave CFRP composite and the variation of strains in a full field of the specimen were estimated. The experiments were performed under a tensile loading and 3-point bending test with strain gages. Futhermore the DIC deformation results were estimated for the comparison. The results showed the deformation and strain contours visually well in all region of the interested areas and so usefulness for the safety control of the structures.

• 반도체디스플레이기술학회지
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• 제18권1호
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• pp.102-104
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• 2019

Registering different kinds of clinical images widely used in diagnostic and surgery planning. However, cause of tumor growth or effected by gravity, human tissue has plenty of non-rigid deformation with clinically. Non-rigid registration allows the mapping of straight lines to curves. Therefore, such local deformation makes registration more complicated. In this work, we mainly introduce intra-subject, inter-modality registration. This paper mainly studies the nonlinear registration method of 2D medical image registration. The general medical image registration algorithm requires manual intervention, and cost long registration time. In our work to reduce the registration time in rough registration step, the barycenter and the direction of main axis of the image is calculated, which reduces the calculation amount compared with the method of using mutual information.

• 한국안전학회지
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• 제26권5호
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• pp.27-32
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• 2011

Recently new technological development needs the advances in the fields of new materials. The most advanced design is not useful if new material's performance is not realized adequately for bearing the service loads and conditions. FGMs suggests the reasonable solution for the those requirements because of its wide range microstructure and the continuous constitutions. It's especially good for the heat-resisting components, piezoelectricity and aerocraft fields. However the fabrication and its experimental estimation methods have not been established because of its various freedom of material's properties. Therefore it is necessary to develope the fabrication method and estimation of strength and deformation. The experiments are conducted under a four point flexural test. According to results, this study shows that FGMs is well fabricated and the deformation and strain fields are expressed very well by digital image correlation method.

• 한국통신학회논문지
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• 제35권4C호
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• pp.408-414
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• 2010

CCTV이미지에서 교통정보를 수집하려고 할 때 관측자가 카메라를 움직이면 설치된 검지영역이 손실되고 복원하려고 해도 기계적 오차로인해 어려움을 겪게 된다. 그래서 어안이나 거울을 이용하면 카메라를 움직이지 않아도 된다. 하지만 이러한 상황하에서 가장 큰 문제점은 영상의 왜곡이다. 본 논문에서는 이러한 왜곡을 극복하기 위해 비선형 확산 방정식을 이용한 분할과 이 영역에디포메이션을 적용하여 디블러링 한 후 차량정보 수집을 시도한 결과 이전 결과보다 5% 향상된 결과를 얻었다.

• 한국항공우주학회지
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• 제49권8호
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• pp.617-626
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• 2021

비행체의 초음속 비행 중 고온 환경에서의 열 거동은 비행체의 열 구조 설계에 중요하다. 본 연구에서는 전역-국부 다중 디지털 이미지 상관기법을 사용하여 노치 구조물의 전 영역의 열변형 및 응력집중 현상에 대해 관찰/분석하였다. 다중 DIC 시스템은 2D DIC 시스템과 3D DIC 시스템으로 구성되었다. 가열 챔버를 이용하여 노치 시편을 가열하였으며 여러 온도에서 다중 DIC 시스템을 사용하여 구조물의 변형 이미지를 촬영하고 분석하였다. 다중 DIC 기법을 사용하여 노치 시편의 전 영역 변형률과 노치 부위의 응력집중 현상을 계측/분석하였으며 ABAQUS^TM 프로그램을 이용하여 노치 시편에 대해 유한요소해석을 진행하고 실험결과와 비교 분석하였다. 본 연구를 통해 다중 DIC 시스템의 열변형 계측과 응력 집중 현상의 연구 분석에서의 활용 가능성을 보여주었다.

• 대한기계학회논문집
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• 제16권9호
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• pp.1728-1735
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• 1992

본 연구에서는 실시간 홀로그래피 간섭계(real time holographic interfero- metry ststem)를 구성하고 위상변이법과 디지탈 영상처리를 이용하여 물체 변형을 실 시간으로 자동 측정이 가능하도록 하였다. 한편 광학계 구성과 대상물체의 상태에 따른 오차 요인을 해석하기 위해서 외팔보를 대상물체로 하여 측정된 변형값과 이론값 을 비교하였다. 응용예로써는 터빈 블레이드(turbine blade)에 굽힘력이 가해질때 나타나는 미소변형을 측정하였다.

• Nuclear Engineering and Technology
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• 제53권7호
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• pp.2312-2322
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• 2021

In recent studies, the creep rate of Zircaloy-4, one of the basic property parameters of the nuclear fuel code, has been commonly used with the axial creep model proposed by Rosinger et al. However, in order to calculate the circumferential deformation of the fuel cladding, there is a limitation that a difference occurs depending on the anisotropic coefficients used in deriving the circumferential creep equation by using the axial creep equation. Therefore, in this study, the existing axial creep law and the derived circumferential creep results were analyzed through a circumferential creep test by the internal pressurization method in the isothermal conditions. The circumferential creep deformation was measured through the optical image analysis method, and the results of the experiment were investigated through constructed IDECA (In-situ DEformation Calculation Algorithm based on creep) code. First, preliminary tests were performed in the isotropic β-phase. Subsequently in the anisotropic α-phase, the correlations obtained from a series of circumferential creep tests were compared with the axial creep equation, and optimized anisotropic coefficients were proposed based on the performed circumferential creep results. Finally, the IDECA prediction results using optimized anisotropic coefficients based on creep tests were validated through tube burst tests in transient conditions.

• 소성∙가공
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• 제32권1호
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• pp.20-27
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• 2023

In this study, the deformation of materials was measured using the video and tracking API of OpenCV. Circular markers attached to the material were selected the region of interests (ROIs). The position of the marker was measured from the area center of the circular marker. The position and displacement of the center point was measured along the image frames. For the verification, tensile tests were conducted. In the tensile test, four circular markers were attached along the longitudinal and transverse directions. The strain was calculated using the distance between markers both in the longitudinal and transverse direction. As a result, the stress-strain curve obtained using machine vision is compared to the stress-strain curve obtained from the DIC results. RMSE values of the strain from the machine vision and DIC were less than 0.005. In addition, as a measurement example, a bending angle and springback measurement according to bending deformation, and a moving position measurement of a punch, a blank holder, and a die by time change were performed. Using the proposed method, the deformation and displacement of the materials were measured precisely and easily.