• Nuclear Engineering and Technology
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• 제53권5호
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• pp.1626-1633
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• 2021

In an industrial field, non-destructive testing (NDT) is commonly used to inspect industrial products. Among NDT methods using radiation sources, X-ray laminography has several advantages, such as high depth resolution and low computational costs. Moreover, an X-ray laminography system with stationary source array and compact detector is able to reduce mechanical motion artifacts and improve inspection efficiency. However, this system, called stationary inverse-geometry X-ray laminography (s-IGXL), causes truncation artifacts in reconstructed images due to limited fields-of-view (FOVs). In this study, we proposed a projection data correction (PDC) method to reduce the truncation artifacts arisen in s-IGXL images, and the performance of the proposed method was evaluated with the different number of focal spots in terms of quantitative accuracy. Comparing with conventional techniques, the PDC method showed superior performance in reducing truncation artifacts and improved the quantitative accuracy of s-IGXL images for all the number of focal spots. In conclusion, the PDC method can improve the accuracy of s-IGXL images and allow precise NDT measurements.

• Tribology and Lubricants
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• 제17권3호
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• pp.209-215
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• 2001

In view of the effects of the hardness of material on fatigue, rolling contact fatigue process in hard metals seems to differ from it in soft metals. This paper has been aimed to compare the rolling contact fatigue process according to the hardness of materials. Rolling contact fatigue tests using the ball bearings assembled with the inner race of four different hardness have been carried out. In addition, residual stress and half-value breadth on/below the inner raceway during individual rolling contact fatigue have been measured by X-ray diffraction. The results of this study showed that the change of residual stress and half-value breadth during the rolling contact fatigue on race way in hard metals is the same as in soft metals. However, plastic deformation by rolling contact in hard metals is in microscopic scale but only for soft metals in macroscopic scale.

• 한국방송∙미디어공학회:학술대회논문집
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• 한국방송공학회 2009년도 IWAIT
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• pp.732-736
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• 2009

In this paper we focus on EPI (Epipolar-Plane Image), the horizontal cross section of Ray-Space, and we propose a novel method that chooses objects we want and edits scenes by using multi-view images. On the EPI acquired by camera arrays uniformly distributed along a line, all the objects are represented as straight lines, and the slope of straight lines are decided by the distance between objects and camera plane. Detecting a straight line of a specific slope and removing it mean that an object in a specific depth has been detected and removed. So we propose a scheme to make a layer of a specific slope compete with other layers instead of extracting layers sequentially from front to back. This enables an effective removal of obstacles, object manipulation and a clearer 3D scene with what we want to see will be made.

• Nuclear Engineering and Technology
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• 제49권1호
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• pp.216-223
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• 2017

In this work, linear and mass attenuation coefficients, effective atomic number and electron density, mean free paths, and half value layer and $10^{th}$ value layer values of barium-bismuth-borosilicate glasses were obtained for 662 keV, 1,173 keV, and 1,332 keV gamma ray energies using MCNP-4C code and XCOM program. Then obtained data were compared with available experimental data. The MCNP-4C code and XCOM program results were in good agreement with the experimental data. Barium-bismuth-borosilicate glasses have good gamma ray shielding properties from the shielding point of view.

• 천문학회보
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• 제36권1호
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• pp.35.1-35.1
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• 2011

The solar X-ray telescopes, the Yohkoh SXT and the Hinode XRT, have observed for a couple of decades a variety of coronal structures in the range of wide field-of-view (FOV) covering the full solar disk. It has been emphasized that the optical structure of solar telescopes should be designed with care for improving the uniformity over the full FOV. The vignetting effect is one of the important optical characteristics for describing the performance of a telescope, which reflects the ability of collecting the incoming light at different locations and different photon energies. The correction of this vignetting effect would be an important calibration step that should be performed in advance, especially when the observed images are to be used for photometric purposes. Since the vignetting effect of solar X-ray telescopes shows wavelength dependence, a special care should be taken when, for example, performing the temperature analyses with thin and thick filters for flaring activities observed at the periphery of the full FOV. The results of analysis of pre-launch calibration data for the evaluation of vignetting effect will be introduced in detail.

• Journal of Plant Biology
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• 제36권1호
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• pp.29-34
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• 1993

Observation was made on early ontogeny of vascular cambium in the cotyledonary node of Pinus koraiensis seedling in order to clarify the cambial ontogeny of the node which was hardly elongated. In transverse view, the derivatives by the early periclinal divisions at the outer region of the procambial strands differentiated to protophloem with establishing a certain degree of radial seriations. Later, some cells in the central region of the procambial strands begin divide periclinally, eventually the cells, differentiate gradually to the vascular cambium. In tangential view, early procambium is consisted of homogeneous short cells with transverse end walls which are tansformed into the long cells and short cells gradually. The long cells continue intrusive growth and the short cells repeat transverse division. Finally, the long and short cells differentiated to cambial fusiform initials and ray initials respectively. In tangential section, the differentiation pattern of cambial initials resembles that of the stem of Ginkgo biloba. But in transverse view, the characteristics in the origin of vascular cambium of the cotyledonary node resembles that of root. The vascular cambium in cotyledonary node is completed after eleven prophylls were formed.

• 대한임상전기생리학회지
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• 제3권1호
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• pp.61-70
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• 2005

The purpose of study correlation between 3D-surface topography and Cobb angle in scoliotic patients. It would be recognizing possibility of clinical application with 3D-surface topography with scoliosis assessment and correlation analysis of obtained Cobb angle through measured results of surface topography and took X-ray of subjects with scoliosis, which used to 3D-surface topography of laser scan method. A scoliosis subjects 16(males 4, females 12) agreed for study's purport volunteer our study that diagnose the scoliosis through 3D-surface topography and X-ray. The results were as follow: It was shown that the relation of Cobb angle of scoliosis and itemized 3D-surface topography measurement in horizontal view(p<0.01). top difference of cervicothoracic and lumbar in anterior-posterior view(p<0.05), the top difference of thoracic, thoracolumbar(p<0.01). These results suggest that an itemized 3D-surface topography measurement was highly correlated with Cobb angle. It would be a useful diagnosis method and assessment of physical therapy plan.

• 천문학회보
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• 제38권1호
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• pp.64.1-64.1
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• 2013

The point spread function (PSF) of an optical system is in general defined as a two-dimensional intensity distribution which results from a single point source at infinity. It is an important key for the evaluation of the optical performance of an astronomical telescope. The PSFs of the soft X-ray telescope (SXT) aboard Yohkoh were measured in a wide range of the field-of-view under the in-flight configuration at White Sands Missile Range prior to launching the satellite. It has been known that the SXT PSF has a sharp peak at the core and the intensity drops very fast as it goes distant from the center. Due to the combination of this sharp peak at the PSF core and the effect of undersampling by a large pixel size, a carefully designed method is requested in the examination of the PSF data. The pattern of the SXT PSF is determined by the fitting of a mathematical functional form to the pre-launch experimental data. The elliptical Moffat function has been adopted for the evaluation of the SXT PSF. It is revealed from our study that the SXT PSF shows a peculiar characteristics, and thus a careful consideration on the undersampling effect and also a proper choice of statistics are necessary for the determination of the best fit function of the PSF. Details on the on- and off-axis SXT PSF in the field-of-view will be introduced and discussed in our presentation.

• 대한의용생체공학회:의공학회지
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• 제28권1호
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• pp.95-101
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• 2007

Recently, small-animal imaging technology has been rapidly developed for longitudinal screening of laboratory animals such as mice and rats. One of newly developed imaging modalities for small animals is an x-ray micro-CT (computed tomography). We have developed two types of x-ray micro-CT systems for small animal imaging. Both systems use flat-panel x-ray detectors and micro-focus x-ray sources to obtain high spatial resolution of $10{\mu}m$. In spite of the relatively large field-of-view (FOV) of flat-panel detectors, the spatial resolution in the whole-body imaging of rats should be sacrificed down to the order of $100{\mu}m$ due to the limited number of x-ray detector pixels. Though the spatial resolution of cone-beam CTs can be improved by moving an object toward an x-ray source, the FOV should be reduced and the object size is also limited. To overcome the limitation of the object size and resolution, we introduce zoom-in micro-tomography for high-resolution imaging of a local region-of-interest (ROI) inside a large object. For zoom-in imaging, we use two kinds of projection data in combination, one from a full FOV scan of the whole object and the other from a limited FOV scan of the ROI. Both of our micro-CT systems have zoom-in micro-tomography capability. One of both is a micro-CT system with a fixed gantry mounted with an x-ray source and a detector. An imaged object is laid on a rotating table between a source and a detector. The other micro-CT system has a rotating gantry with a fixed object table, which makes whole scans without rotating an object. In this paper, we report the results of in vivo small animal study using the developed micro-CTs.

• Journal of Trauma and Injury
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• 제25권4호
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• pp.241-246
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• 2012

Purpose: The objective of this study was to investigate the appropriateness of the cross table lateral cervical X-ray used in the emergency department for severely traumatized Korean patients. Methods: Patients visiting our institution from May 2011 to May 2012, who had injury severity score (ISS) > 15 and who received a cervical X-ray in the emergency department, were included in this study. Data including demographics, ISS score, GCS score, and place where the x-ray was taken were collected to evaluate their relationship with appropriate coverage of the cervical X-ray. The appropriateness of a cervical cross lateral view X-ray was evaluated using exposure of the basion, and the opisthion, as well as the distal level of exposure. Results: Fifty-two patients were included in this study. The identification rate of the basion was 79.2%, and the identification rate of the opisthion was 88.7%. Complete exposure of C7/T1 was accomplished in 3.8% of the patients. The ISS was higher for X-ray taken in the trauma bay, but the range of exposure showed no difference between the places where the X-rays taken. Patients who had exposure of C 5/6 or more had lower body weight and body mass index (BMI) compared with unexposed patients. Conclusion: In severely traumatized Korean patients, the adequacy of the cross table lateral cervical X-ray was inappropriate in most cases. No difference was observed in the exposure range between the places where the X-rays were taken, and patients with less exposure showed higher body weight and higher BMI.