• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2001년도 ICCAS
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• pp.63.3-63
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• 2001

Inspection and shape measurement of three-dimensional objects are widely needed in industries for quality monitoring and control. In this paper, we propose a three dimensional volume reconstruction method, which is an iterative method and as uniform and simulated algebraic reconstruction technique (USART). In this method, two or more x-ray images projected from different views are needed, and also the geometry of the imaging system need to be a priori identified well. That is to say, the relative locations between the x-ray source, imaging plane and the object should be determined exactly by calibration. To achieve this, we propose a series of coordinate calibration methods of the x-ray imaging system using grid pattern images. Some experimental results of these calibrations is presented and discussed in detail ...

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2001년도 ICCAS
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• pp.28.2-28
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• 2001

Three dimensional shape measurement techniques are widely needed in industries for product quality monitoring and control. X-ray imaging method is a promising technology to achieve three-dimensional Information, both the surface and inner structure of an object, since it can overcome the limitations of conventional visual or optical methods such as an occlusion problem or surface reflection properties. In this paper, we propose three dimensional volume reconstruction method based on x-ray stereo imaging technology. Here, the stereo images of an object from two different views are taken by changing the object pose rather than moving imaging plane as in conventional stereo vision method. We propose a series of image processing techniques to extract the features efficiently from x-ray images, where the occluded features in case of normal camera vision could be found ...

• Journal of the Korean Wood Science and Technology
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• 제20권1호
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• pp.38-45
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• 1992

Fine and alkali-swollen structures of native cellulose fibers were investigated by x-ray diffraction methods. The results of fine structures are shown in Table 1. In meridional x-ray diffractograms, the relative intensity ratio R of (002) to (004) for cellulose I was ca. 0.05 and for regenerated cellulose it was ca. 0.45. It was considered that the transformation from cellulose I to cellulose II resulted from the packing or conformational change of cellulose chain. Finally. although cellulose I was not detected in the alkali-swollen celluloses treated for 1 hr to 24 hrs, washing and drying them resulted in the generation of considerable amounts of cellulose I and the amount decreased with increasing alkali duration.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2007년도 하계종합학술대회 논문집
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• pp.293-294
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• 2007

The purpose of this study is prove the effectiveness of an energy subtraction image for the detection of pulmonary nodules and the effectiveness of multi-resolutional filter on an energy subtraction image to detect pulmonary nodules. Also we study influential factors to the accuracy of detection of pulmonary nodules from viewpoints of types of images, types of digital filters and types of evaluation methods. As one type of images, we select an energy subtraction image, which removes bones such as ribs from the conventional X-ray image by utilizing the difference of X-ray absorption ratios at different energy between bones and soft tissue. Here we select two evaluation methods and make clear the effectiveness of multi-resolutional filter on an energy subtraction image.

• 한국결정학회지
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• 제8권1호
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• pp.20-25
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• 1997

고분해도의 X-선 산란을 위해 두 실험 방법이 개발됐다. 그 방법들은 (1) 2-결정 회절 스펙트로메터 (DCD)설치와 (2) 3-결정 회절 스펙트로메터 (TCD) 설치였다. Si(511)-시료(hkl)의 DCD배열로 Si(333), Si(004), GaAs(004)의 rocking curve를 그렸다. 또한 단일체 단색 평행기와 $K_{\alpha1}$ 선택기를 포함하는 Si(111)-Si(111)-Si(511)-sample(hkl)의 TCD배열로 Si(333), Si(004) 그리고 GaAs(004)의 rocking curve를 그렸다. DCD와 TCD에 의한 rocking curve의 FWHM의 차이가 논의됐다. DCD에 의한 $In_{0.037}Ga_{0.0963}As/GaAs$의 (004) 및 (115) 반사 토포그라프가 행해졌다.

• 한국결정성장학회지
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• 제8권4호
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• pp.581-586
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• 1998

초크랄스키 실리콘 기판의 뒷면에 형성된 기계적 손상이 미치는 효과에 대하여 고찰하였다. 기계적 손상의 정도는 레이저 여기/극초단파 반사 광전도 감쇠법에 의한 소수반송자 재결합 수명, X-선 단면 측정 및 습식 산화/선택적 식긱 방법으로 평가하였다. 그 결과, 웨이퍼 뒷면에 가해지는 기계적 손상의 세기가 강할수록 소수반송자 재결합 수명은 짧아지고, 산만 산란 정도와 X-선 과잉 강도의 적분값은 비례적으로 증가하였으며, 그 값을 Grade 1의 손상된 웨이퍼에서의 과잉 강도로 정규화하면 과잉 강도의 상대 정량비는 Geade 1:Grade 2:Grade 3 = 1:7:18.4이다.

• 제어로봇시스템학회논문지
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• 제5권3호
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• pp.353-362
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• 1999

This paper presents a shape reconstruction method for automatic inspection of the solder joints on PCBs using X-ray. Shape reconstruction from X-ray radiographic image has been very important since X-ray equipment was used for improving the reliability of inspection result. For this purpose there have been lots of previous works using tomography, which reconstructs the correct shape, laminography or tomosynthesis, which are very fast algorithm. Latter two methods show outstanding performance in cross-sectional image reconstruction of lead type component, but they are also known to show some fatal limitations to some kinds of components such as BGA, because of shadow effect. Although conventional tomography does not have any shadow effect, the shape of PCB prohibits it from being applied to shape reconstruction of solder joints on PCB. This paper shows that tomography using Iterative Reconstruction Technique(IRT) can be applied to this difficult problem without any limitations. This makes conventional radiographic instrument used for shape reconstruction without shadow effect. This means that the new method makes cost down and shadow-free shape reconstruction. To verify the effectiveness of IRT, we develop three dimensional model of BGA solder ball, make projection model to obtain X-ray projection data. and perform a simulation study of shape reconstruction. To compare the performance of IRT with that of conventional laminography or tomosynthesis, reconstruction data are reorganized and error analysis between the original model are also performed.

• Journal of Radiation Protection and Research
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• 제41권2호
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• pp.111-115
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• 2016

Background: The scattered photons cause reduction of the contrast of radiographic image and it results in the degradation of the quality of the image. In order to acquire better quality image, an anti-scattering x-ray gird should be equipped in radiography system. Materials and Methods: The X-ray anti-scattering grid of the inclined type based on the hybrid concept for that of parallel and focused type was tested by MCNP code. The MCNPX 2.7.0 was used for the simulation based test. The geometry for the test was based on the IEC 60627 which was an international standard for diagnostic X-ray imaging equipment-Characteristics of general purpose and mammographic anti-scatter grids. Results and Discussion: The performance of grids with four inclined shielding material types was compared with that of the parallel type. The grid with completely tapered type the best performance where there were little performance difference according to the degree of inclination. Conclusion: It was shown that the grid of inclined type had better performance than that of parallel one.

• 척추신경추나의학회지
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• 제6권1호
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• pp.53-61
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• 2011

Objective: The purpose of this study is to evaluate the disc block subluxation for lumbar scoliosis and herniation of nucleus pulpous (HNP). Methods: We used AP & Lateral view X-ray for patients. And we measured of disc wedge angle, vertebral body rotation to evaluate the typical and atypical disc block subluxation. Results: On the analysis of the lateral view X-ray, 4th lumbar intervertebral disc angle (I.V.D angle) showed $4^{\circ}$, $5^{\circ}$, $3^{\circ}$, $0^{\circ}$ in the cases. On the 4th lumbar analysis of the AP view X-ray, lumbar scoliosis showed right disc wedge angle was $11^{\circ}$ (case 1), $17^{\circ}$ (case 2) and left vertebral body rotation was 13mm, 6mm. Lumbar HNP showed left disc wedge angle was $5^{\circ}$ (case 3), $4^{\circ}$ (case 4) and left vertebral body rotation was 2mm, 4mm. Conclusions: Disc block subluxation has been in lumbar scoliosis, but not been in lumbar HNP.

• 천문학회지
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• 제48권2호
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• pp.139-154
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• 2015

We carry out three-dimensional hydrodynamic simulations of the supernova remnants (SNRs) produced inside molecular clouds (MCs) near their surface using the HLL code (Harten et al. 1983). We explore the dynamical evolution and the X-ray morphology of SNRs after breaking through the MC surface for ranges of the explosion depths below the surface and the density ratios of the clouds to the intercloud media (ICM). We find that if an SNR breaks out through an MC surface in its Sedov stage, the outermost dense shell of the remnant is divided into several layers. The divided layers are subject to the Rayleigh-Taylor instability and fragmented. On the other hand, if an SNR breaks through an MC after the remnant enters the snowplow phase, the radiative shell is not divided to layers. We also compare the predictions of previous analytic solutions for the expansion of SNRs in stratified media with our onedimensional simulations. Moreover, we produce synthetic X-ray surface brightness in order to research the center-bright X-ray morphology shown in thermal composite SNRs. In the late stages, a breakout SNR shows the center-bright X-ray morphology inside an MC in our results. We apply our model to the observational results of the X-ray morphology of the thermal composite SNR 3C 391.