• 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.

• 한국정밀공학회지
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• 제16권7호
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• pp.119-124
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• 1999

A method to find the line of sight ray in space which corresponds to a point in an image plane is presented. The line of sight ray is defined by two points which are the intersections between the two calibration planes and the sight ray. The intersection point is found by the oblique coordinate mapping between the image plane and the calibration plane in the space. The proposed oblique coordinate mapping method has advantages over the transformation matrix method in the required memory space and computation time.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1987년도 한국자동제어학술회의논문집(한일합동학술편); 한국과학기술대학, 충남; 16-17 Oct. 1987
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• pp.786-790
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• 1987

This paper describes a systein which enables a fast 3 -dimensional profile measurement using a slit-ray projection method. One distinctive feature of this system is that a real-time video is processor is employed in order to reduce the amount of image data to be processed without eliminating essential information. Experimental results show that a calibrating method presented for the TV camera and the slit-ray projector is convenient and enables sufficient accurate measurements.

• International Journal of Contents
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• 제4권1호
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• pp.12-15
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• 2008

In this paper, we propose a new method of background removing for digital self-adaptive acquisition in medical X-ray imaging. We analysis the construction of video digital acquisition system and main factors of acquired image quality, propose a more efficiency method to against background non-uniformly. With proposed method, non-uniform illumination back ground was well removed without image quality degradation.

• 제어로봇시스템학회논문지
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• 제8권1호
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• pp.21-27
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• 2002

Inspection and shape measurement of three-dimensional objects are widely needed in industries for quality monitoring and control. A number of visual or optical technologies have been successfully applied to measure three-dimensional surfaces. However, those conventional visual or optical methods have inherent shortcomings such as occlusion and variant surface reflection. X-ray vision system can be a good solution to these conventional problems, since we can extract the volume information including both the surface geometry and the inner structure of any objects. In the x-ray system, the surface condition of an object, whether it is lambertian or specular, does not affect the inherent characteristics of its x-ray images. In this paper, we propose a three-dimensional x-ray imaging method to reconstruct a three dimensional structure of an object out of two dimensional x-ray image sets. To achieve this by the proposed method, two or more x-ray images projected from different views are needed. Once these images are acquired, the simultaneous algebraic reconstruction technique(SART) is usually utilized. Since the existing SART algorithms have several shortcomings such as low performance in convergence and different convergence within the reconstruction volume of interest, an advanced SART algorithm named as USART(uniform SART) is proposed to avoid such shortcomings and improve the reconstruction performance. Because, each voxel within the volume is equally weighted to update instantaneous value of its internal density, it can achieve uniform convergence property of the reconstructed volume. The algorithm is simulated on various shapes of objects such as a pyramid, a hemisphere and a BGA model. Based on simulation results the performance of the proposed method is compared with that of the conventional SART method.

• 대한방사선기술학회지:방사선기술과학
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• 제7권1호
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• pp.67-70
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• 1984

Radiographic units have changeable factors in x-ray outputs, Therefore, an exposure factor by basic experimental study must be made out about each x-ray installation, but this is very intricate methods and not a practical business. Authors tried out a new method to make simple exposure factors. The first, we had a experimental object radiograph taken to find the output of each radiographic unit. The second, by obtained x-ray density we found the difference in x-ray output. and lastly, we made a new and simple correction method to use the obtained output and x-ray density.

• 한국정보통신학회논문지
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• 제14권7호
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• pp.1687-1692
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• 2010

본 논문에서는 Blu-ray 디스크의 기록을 위한 Laser Diode의 온도특성을 고려한 기록품질의 개선방법에 대해 연구했다. 주변 온도변화에 따라 Blu-ray Laser Diode는 전류-전압 관계로부터 미분저항이 변화하게 되는데 이러한 미분저항이 저온에서 기록품질에 미치는 영향에 대해 분석하고 개선하는 방법을 제안한다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2002년도 하계학술대회 논문집 Vol.3 No.2
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• pp.853-856
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• 2002

Present. direct method x-ray conversion detector is studied by abroad medical instrument and country with amorphous Selenium. And we search the method for large area x-ray detector. Amorphous-Selenium based photoreceptor is widely used on the X-ray conversion materials. But amorphous-selenium based x-ray conversion detector is broken by high voltage and leakage defect point. In this paper, We investigated top-electrode distance rate to improve defect point and high voltage broken. The result to appoint to made large area x-ray conversion detector with base data.

• 한국항공우주학회지
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• 제42권6호
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• pp.515-521
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• 2014

본 논문에서는 Ray-tracing 기법을 이용하여 그레고리안 안테나의 부반사판을 축변환 후 회전하여 급전혼으로 회귀되는 전파를 없애 이득 및 정재파비를 개선 시키고 부반사판의 크기와 전체적인 부피를 줄여 효율적인 구조를 갖는 축변위그레고리안 안테나를 설계하였다. 설계된 급전혼의 방사패턴을 이용하여 급전혼-부반사판-주반사판으로 전달되는 전파의 경로를 추적하여 주반사판 개구면에서의 전계분포를 구하고 이로부터 원거리 복사패턴을 계산하는 프로그램을 작성하여 안테나 성능을 최적화 하였다. 설계된 안테나는 CST와 제작 측정을 통해 계산결과와 비교하여 이득, 빔폭, 방사패턴, 부엽준위, 반사손실이 계산 결과와 매우 유사함을 확인함으로써 Ray-tracing기법에 대한 타당성을 검증하였다.

• 분석과학
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• 제35권2호
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• pp.69-81
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• 2022

The method of measuring and classifying the energy category of neutrons directly using raw data acquired through a CZT detector is not satisfactory, in terms of accuracy and efficiency, because of its poor energy resolution and low measurement efficiency. Moreover, this method of measuring and analyzing the characteristics of low-energy or low-activity gamma-ray sources might be not accurate and efficient in the case of neutrons because of various factors, such as the noise of the CZT detector itself and the influence of environmental radiation. We have therefore developed an efficient method of analyzing radiation characteristics using a neutron and gamma-ray analysis algorithm for the rapid and clear identification of the type, energy, and radioactivity of gamma-ray sources as well as the detection and classification of the energy category (fast or thermal neutrons) of neutron sources, employing raw data acquired through a CZT detector. The neutron analysis algorithm is based on the fact that in the energy-spectrum channel of 558.6 keV emitted in the nuclear reaction ¹¹³Cd + ¹n → ¹¹⁴Cd + in the CZT detector, there is a notable difference in detection information between a CZT detector without a PE modulator and a CZT detector with a PE modulator, but there is no significant difference between the two detectors in other energy-spectrum channels. In addition, the gamma-ray analysis algorithm uses the difference in the detection information of the CZT detector between the unique characteristic energy-spectrum channel of a gamma-ray source and other channels. This efficient method of analyzing radiation characteristics is expected to be useful for the rapid radiation detection and accurate information collection on radiation sources, which are required to minimize radiation damage and manage accidents in national disaster situations, such as large-scale radioactivity leak accidents at nuclear power plants or nuclear material handling facilities.