• 한국정밀공학회지
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• 제25권7호
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• pp.116-123
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• 2008

In the fossil power plant, the reliability of the components which consist of the many welded parts depends on the quality of welding. The residual stress is occurred by the heat flux of high temperature during weld process. This decreases the mechanical properties as the strength of fatigue and fracture or causes the stress corrosion cracking and fatigue fracture. Especially, the accidents due to the residual stress occurred at the weld parts of high-temperature and high-pressure pipes and steam headers. Also, the residual stress of the welded part in the recently constructed power plants has been brought into relief as the cause of various accidents. The aim of this study is the measurement of the residual stress using the x-ray diffraction method. The merits of this are more accurate and applicable than other methods. The materials used for the study is P92 steel for the use of high temperature pipe on super critical condition. The variables of tests are the post-weld heat treatment, the surface roughness and the depth from the original surface. The test results were analyzed by the distributed characteristics of the full width at half maximum intensity (FWHM) in x-ray diffraction intensity curve and by the relation of hardness with FWHM.

• 척추신경추나의학회지
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• 제5권2호
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• pp.135-149
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• 2010

Objectives : This study was designed to observe the effect of Chuna manual therapy on the asymmetrical alignment. Methods : To analyze static structural alignment, posterior inferior ilium deviation(PI), inflare change of pelvis were checked from full spine AP X-ray. And Cobb's angle of spine and height of shoulder girdle were analyzed. To evaluate the pain visual analogue score(VAS) was scored. Chuna therapy treated 8-10 times for 1 month. Results and Conclusions : In 3 cases, VAS was improved significantly. Full spine AP X-ray shows improvement of structural imbalace. Shoulder height difference, cobb's angle, pelvic insufficiency improved considerably. These results suggest that Chuna therapy might be effective for malalignment patients.

• 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.

• Nuclear Engineering and Technology
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• 제54권9호
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• pp.3380-3389
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• 2022

We evaluated the performance of an improved hybrid median filter (IHMF) applied to X-ray computed tomography (CT) images obtained using a high-resolution photon-counting cadmium zinc telluride (CZT) detector. To study how the proposed approach improves the image quality, we measured the noise levels and the overall CT-image quality. We established a CZT imaging system with a detector length of 5.12 cm and thickness of 0.3 cm and acquired phantom images. To evaluate the efficacy of the proposed filter, we first modeled two conventional median filters. Subsequently, we were able to achieve a normalized noise power spectrum result of ~10^-8 mm², and furthermore, the proposed method improved the contrast-to-noise ratio by a factor of ~1.51 and the coefficient of variation by 1.55 relative to the counterpart values of the no-filter image. In addition, the IHMF exhibited the best performance among the three filters considered as regards the peak signal-to-noise ratio and no-reference-based image-quality evaluation parameters. Thus, our results demonstrate that the IHMF approach provides a superior image performance over conventional median filtering methods when applied to actual CZT X-ray CT images.

• Journal of Trauma and Injury
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• 제27권2호
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• pp.13-19
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• 2014

Purpose: In general, X-ray examinations are not recommended for radial head subluxation (pulled elbow) patients. The purpose of this study was to determine the frequency of X-ray examinations and to investigate the factors associated with the decision to perform an X-ray examination on a patient with a pulled elbow. Methods: Patients who visited the pediatric emergency department (ED) of one tertiary hospital from January 1, 2011, to December 31, 2012, with a diagnosis of radial head subluxation at discharge were enrolled in this study. Through retrospective chart reviews, factors that could have influenced the decision to perform an X-ray examination and their statistical relevance were analyzed. Results: A total 308 patients were enrolled, and 101 patients (32.8%) underwent X-ray examinations. Among the 252 patients with a typical pulled elbow, 65 underwent X-ray examination. This result showed statistical significance compared to atypical pull-elbow group (25.8% vs. 64.3%, p<0.001). Factors associated with the decision to perform an X-ray examination were analyzed using the Chi-square test and the Fisher's exact test. The mechanism of injury and consultation with an orthopedic surgeon (p=0.001) showed statistical significance. In the multivariable logistic regression, the odds ratio (OR) for the injury mechanism was 4.7 (95% CI: 1.8~8.8, p<0.001) and that for consultation with an orthopedic surgeon was 8.0 (95% CI: 1.6~40.7, p=0.004). Conclusion: One third of patients with a pulled elbow underwent X-ray examination, and patients with an atypical mechanism of injury underwent more frequent X-ray examinations than did patients with a typical mechanism of injury. The factors that could have influenced the decision to perform an X-ray examination were mechanism of injury and consultation with an orthopedic surgeon.

• 한국정보처리학회:학술대회논문집
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• 한국정보처리학회 2023년도 춘계학술발표대회
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• pp.687-688
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• 2023

Bone age assessment is a crucial task in pediatric radiology for assessing growth and development in children. In this paper, we explore the potential of Vision Transformer, a state-of-the-art deep learning model, for bone age assessment using X-ray images. We generate heatmap outputs using a pre-trained Vision Transformer model on a publicly available dataset of hand X-ray images and show that the model tends to focus on the overall hand and only the bone part of the image, indicating its potential for accurately identifying the regions of interest for bone age assessment without the need for pre-processing to remove background noise. We also suggest two methods for extracting the region of interest from the heatmap output. Our study suggests that Vision Transformer holds great potential for bone age assessment using X-ray images, as it can provide accurate and interpretable output that may assist radiologists in identifying potential abnormalities or areas of interest in the X-ray image.

• 한국안광학회지
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• 제13권2호
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• pp.17-22
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• 2008

목적: X선용 545 nm 형광판을 위한 결상광학계 개발. 방법: 캐논(Canon)사 CX2-70 모델을 참조하여 설계 기준을 정한 다음 Sigma 2000 광학 설계 프로그램으로 X선용 545 nm 형광판을 위한 결상광학계를 설계 제작하였다. 결과: 새로 설계 제작되어진 X선용 545 nm 형광판 결상광학계의 배율은 -0.225배이고, 이미지 크기는 90 mm${\times}$90 mm이며, 분해선폭은 30% MTF 값 기준으로 0.033 mm인 특성을 보여준다. 이는 캐논 CX2-70 모델보다 큰 화면으로 판독을 할 수 있고, 판독의 분해능도 우수함을 의미한다. 또한 이미지 측 NA값이 -0.196으로 캐논 CX2-70 모 델 -0.139보다 약$\sqrt{2}$배 크게 하였고, 물체 측 NA값도 0.044로 캐논 CX2-70 모델 0.022보다 약 2배 크게 하였다. 이는 필름의 감도를 4배 증가 시킬 수 있는 것을 의미하며 X선의 피폭시간을 1/4로 줄일 수 있음을 뜻한다. 결론: 이미지 크기가 90 mm${\times}$90 mm이고, 15 lines/mm에서 MTF 30% 이상인 특성을 가지며, 캐논 CX2-70 모델에 비해 X선 피폭시간을 1/4로 줄일 수 있는 새로운 X선용 545 nm 형광판 결상광학계를 설계 제작하였다.

• Current Optics and Photonics
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• 제4권1호
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• pp.9-15
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• 2020

Fresnel zone plates have been widely used in many applications, such as x-ray telescopes, microfluorescence, and microimaging. To obtain an x-ray Fresnel zone plate, many fabrication methods, such as electron-beam etching, ion-beam etching and chemical etching, have been developed. Fresnel zone plates fabricated by these methods will inevitably lead to some nonideal factors, which have an impact on the focusing characteristics of the zone plate. In this paper, the influences of these nonideal factors on the focusing characteristics of the zone plate are studied systematically, by numerical simulations based on scalar diffraction theory. The influence of the thickness of a Fresnel zone plate on the absolute focusing efficiency is calculated for a given incident x-ray's wavelength. The diffraction efficiency and size of the focal spot are calculated for different incline angles of the groove. The simulations of zone plates without struts, with regular struts, and with random struts are carried out, to study the effects of struts on the focusing characteristics of a zone plate. When a Fresnel zone plate is used to focus an ultrashort x-ray pulse, the effect of zone-plate structure on the final pulse duration is also discussed.

• 한국멀티미디어학회논문지
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• 제13권7호
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• pp.1062-1075
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• 2010

의료 영상 분야에서 영상의 분할 및 특성의 추출을 위하여 명암도 차이를 이용하는 방법이 널리 사용되고 있으며, 임계값을 결정한 뒤 이를 기준으로 영상을 이진화하는 임계값 방식이 잘 알려져 있다. 임계값 방식 중 자주 사용되는 방식이 임계값을 선택하는 데 효율적이면서, 효과적인 선정 기준을 제시하고 있는 Otsu 알고리즘이다. 하지만 흉부 X-ray 영상에 대해서는 Otsu 알고리즘의 적용으로 좋은 영상 분할 결과를 얻을 수 없다. 이는 폐 영역 주변에는 갈비뼈나 혈관과 같은 다양한 기관이 존재하여 따라서 명암도 레벨의 분포가 불명확하기 때문이다. 이러한 불명료성을 개선하기 위하여, 본 논문에서는 X-ray 영상의 배경을 배제한 후 Otsu 알고리즘을 적용하고, 명암 레벨 지도를 생성한 후, 이를 이용하여 X-ray 영상을 분할하는 효과적인 폐 영역 추출 알고리즘을 제시한다. 제안한 방법의 효과를 검증하기 위해 제안한 방법과 기존의 1차원 및 2차원 Otsu 알고리즘, 그리고 전문가의 육안 분할 결과와 비교하였다. 실험 결과, 제안한 방법이 기존 Otsu 방법에 비해 더 정확하게 폐 영역을 추출하였으며, 육안 분할 결과와 거의 비슷한 결과를 보여 주었다.

• 한방재활의학과학회지
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• 제30권2호
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• pp.125-137
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• 2020

Objectives The purpose of this study was to examine how changes in the cervical spine correlate with body posture changes in the whole body, and to find out the significance of complementary clinical application X-ray and Chuna posture analysis. Methods From January 1, 2019 to October 31, 2019, the results of 27 patients with pain in the vertebral region were analysed in accordance with the results of cervical X-ray and Chuna posture analysis. In order to confirm the significance of Chuna posture analysis results, the survey of 187 Chuna standard curriculum instruction qualification certifiers was conducted and the responses of 47 of them were analyzed. Results The occiput-atlas cline angle increases in both hypolordosis/hyperlordosis groups based on cervical lordosis angle, and increases further than in the hyperlordosis group. There were significant correlations between the changes in the cervical spine and the body posture changes in the whole body. There were no significant differences between cervical X-ray sagittal parameters and the body posture analysis parameters based on the patient's major disease codes. Conclusions As a result of conducting a survey on the clinical importance of the body posture analysis parameters, the importance of cervical parameters was verified. Changes in the cervical spine may not only cause other changes in the cervical region, but also affect the body posture changes in the whole body. The complementary application of X-ray and Chuna posture analysis results is helpful in clinical diagnosis and treatment of musculoskeletal disorders.