• 한국군사과학기술학회지
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• 제23권6호
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• pp.609-617
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• 2020

Non-destructive inspection using X-rays is used as a method to check the inside of products. In order to accurately inspect, a X-ray image requires a higher spatial resolution. However, the reduction in pixel size of the X-ray detector, which determines the spatial resolution, is time-consuming and expensive. In this regard, a DMM has been proposed to obtain an improved spatial resolution using the same X-ray detector. However, this has a limitation that the motion blur phenomenon, which is a decrease in spatial resolution. In this paper, motion blur was removed by applying Non-Blind Deconvolution to the DMM image, and the increase in spatial resolution was confirmed. DMM and Non-Blind Deconvolution were sequentially applied to X-ray images, confirming 62 % MTF value by an additional 29 % over 33 % of DMM only. In addition, SSIM and PSNR were compared to confirm the similarity to the 1/2 pixel detector image through 0.68 and 33.21 dB, respectively.

• 대한전기학회논문지:시스템및제어부문D
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• 제55권4호
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• pp.165-172
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• 2006

In this paper we present a technique for detecting cross-reference points that allows improving watermark detect-ability. In general, Harris detector is commonly used for finding salient points. Harris detector is a kind of combined corner and edge detector which is based on neighboring image data distribution, therefore it has some limitation to find accurate salient points after watermark embedding or any kinds of digital attacks. The new method proposed in this paper used not data distribution but geometrical structure of a normalized image in order to avoid pointing error caused by the distortion of image data. After normalization, we constructed pre-specified number of virtual lines from top to bottom and left to right, and several of cross points were selected by a random key. These selected points specify almost same positions with the accuracy more than that of Harris detector after digital attacks. These points were arranged by a random key, and blocks centered in these points were formed. A reference watermark is formed by a block and embedded in the next block. Because same alteration is applied to the watermark generated and embedded blocks. the detect-ability of watermark is improved even after digital attacks.

• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2012년도 추계학술대회
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• pp.997-999
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• 2012

방사선 진단 목적으로 디지털 X-ray 영상 디텍터는 널리 사용 되고 있다. 비정질 셀레늄(amorphous selenium, a-Se)은 직접 방식 디텍터의 광전도체(photoconductor)를 구성하는 주요 재질 중 하나로 많은 관심을 받고 있다. 본 연구는 2차원 디바이스 시뮬레이터를 사용하여 파란색 빛을(파장=486 nm) 조사한 상태에서 고전압(High voltage, HV)을 인가하여 비정질 셀레늄 광전류 크기를 분석 하였다. 또한 비정질 셀레늄 내부의 전자-정공 생성 율, 전자-정공 재결합 율, 전자/정공의 농도 분포도에 추가로 분석한 연구 결과이다. 본 시뮬레이션 방법은 직접방식 디지털 X-ray 영상 디텍터 분석에 있어서 유용한 방법으로 향후 디지털 방사선 영상 디텍터 개발에 많이 응용될 것으로 예상된다.

• 대한디지털의료영상학회논문지
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• 제8권1호
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• pp.27-32
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• 2006

The rapid development in digital acquisition technology in radiography has not been accompanied by information regarding optimum radiolographic technique for use with an amorphus silicon flat panel detector. The purpose of our study was to compared imaging characteristics and image quality of an amorphus silicon flat panel detectors for digital chest radiography. All examinations were performed by using an amorphus silicon flat panel detector. Chest radiographs of an chest phantom were obtained with peak kilovoltage values of 60$\sim$150 kVp. Published data ell the effect of x-ray beam energy on imaging characteristics and image qualify when using an amorphus silicon flat panel detector. It is important that radiographers are aware of optimum kVp selection for an amorphus silicon flat panel detector system, particularly for the commonly performed chest examination.

• 한국컴퓨터정보학회논문지
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• 제23권1호
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• pp.67-74
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• 2018

In this paper, we propose an efficient scene based non-uniformity correction algorithm which performs the offset correction using the uniform obtained from input scenes for Infrared camera. In general, pixel outputs of a infrared detector can not be uniform. Therefore, the non-uniformity correction procedure need to be performed to make the image outputs uniform. A typical non-uniformity correction method uses a black body at the laboratory to obtain the output of the infrared detector's pixels for two temperatures, HOT and COLD, and calculates the non-uniformity correction parameters. However, output characteristics of the Infrared detector changes while the Infrared camera is operated, the fixed pattern noise of the Infrared detector and dead pixels are generated. To remove the noise, the offset correction is generally performed. The offset correction procedure usually need the additional device such as a thermo-electric cooler, shutter, or non-uniformity correction lens. Therefore, we introduce a general scene based non-uniformity correction technique without additional equipment, and then we propose an improved non-uniformity correction algorithm based on image to solve the problem of the existing technique.

• 한국방송∙미디어공학회:학술대회논문집
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• 한국방송∙미디어공학회 2019년도 추계학술대회
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• pp.58-60
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• 2019

Double JPEG compression detection is one of the most important ways of exposing the integrity of the JPEG image in image forensics. Several methods have been proposed for discriminating against the double JPEG image. In this paper, we propose a new method for restoring the JPEG compressed image and making the detector confused by introducing a Generative Adversarial Network (GAN). First, a generator network is designed for restoring the JPEG compressed image and analyzed the quality. Then, the restored image is tested with the double compression detector for evaluating the robustness of the proposed GAN model. The detection accuracy reduces from 98% to 58%.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2005년도 춘계학술대회 논문집
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• pp.9-14
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• 2005

The nature of the signals collected by an SEM(Scanning Electron Microscope) in order to form images are all dependent on the detector used to collect them, and the quality of an acquired image is strongly influenced by detector performance. Therefore, the development of detector with high performance is very important in pulling up the resolution of SEM This study presents the secondary electron detector for use in scanning electron microscope, electric circuit and I/V conversion circuit for driving that detector.

• 대한방사선기술학회지:방사선기술과학
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• 제43권4호
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• pp.235-242
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• 2020

Scanogram is that combine several practical images into one image to observation. So it is an important consideration in many clinical situation such as iliac measurement, leg alignment measurement and Scoliosis. Currently, scanogram examinations are mainly conducted for children and elderly patients. In this study, in order to apply the longbone detector to children or elderly patients who are difficult to cooperate with, we compared the longbone detector from D equipment with the G equipment discovery 656 Puls equipment in reproducibility of images, distribution of irradiation dose, scattering dose, irradiation time and image acquisition time. D equipment took more than twice as much time as G equipment. The scattered dose generated about 50% more G equipment than D equipment. In the whole spine scanogram and the measurement length of the lower leg, D equipment was also measured longer than G equipment. However, both methods did not show much difference from the CT scanogram, so there was no problem in measurement. The height of the thyroid radiation dose of G equipment was produced more radiation than D equipment. However, the longbone detector deviated from the x-ray center line relative to the tube rotation method, and was measured lower by the directionality of the measuring instrument, so that the error could not be corrected. In the conclusion of study, using the longbone detector is excellent for applying to children or elderly patients to reduce scattering dose. However, using CR may be useful to normal patients. Because, the image quality may deteriorate due to an imbalance of dose difference in thickness depending on the body part. So, it is useful to using a compensation filter or tube rotation method when we take a whole spine scanogram.

• 대한방사선기술학회지:방사선기술과학
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• 제45권4호
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• pp.305-312
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• 2022

The proportion and testing of portable radiation tests, which are limited at the request of the doctor, are gradually increasing only for patients in emergency situations and difficulties in moving. However, as there are many limiting factors compared to fixed devices, this study intends to measure and analyze the distortion of images according to the angle of the detector and the change in dose according to the position of the subject. For distortion experiments using a mobile radiation generator used in Hospital A, the SID was tilted by 110 cm, 14"×17" wireless FPD detector to 0°, -5°, -10°, -15°, -20°, and -35° to measure the change in area. The dose according to the location of the detector was analyzed on average by measuring the central dose at 110 cm of the SID and measuring the dose of 9 locations three times each. The analysis result of distortion by location according to the angle of the detector showed a statistically significant difference (f=58.74, p<0.000). Therefore, it can be seen that the angle of the detector and the tube is closely related to the distortion of the image. The difference in dose by location of the detector increased with respect to the center - pole, and decreased with the + pole. Tests using mobile radiation generators will require careful efforts by clinicians to position patients in the center of the detector for accurate diagnosis, and efforts will be made to level the angle between the mobile radiation generators and the detector.

• 대한디지털의료영상학회논문지
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• 제9권2호
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• pp.17-21
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• 2007

The purpose to recognize change of average pixel value of acquisition image by control panel's density and right set up method of speed (sensitivity) and exposure dose(mAs) change that dose in purpose digital flatpanel-detector. X -ray generator DHF-158H2(Hitachi, Japan). Detector CXDI 4OG(Canon, Japan), 12 : 1 grid and exposure ray 135 kVp, 250 mA, 10 ms. focus-detector distance 180 cm and used AEC mode. DICOM reflex analysis program used image J that is digital reflex analysis program that offer in United States America National Health Center(National Institutes of Health : NlH) phantom used chest phantom(Anthromorphic : Flukebrome.medicaI USA). An experiment chest phantom that consist by formation equivalence material use because density value( -3${\sim}$+3) in X-ray control panel and seep that is speed step(slow, medium, fast) each control experimentalize. image analysis reflex neted through an experiment using image j each image compare. These was change in dose according to slow, medium, fast and density's change in an experiment result. According to detector sensitivity and density condition set, dose was relationship dissimilarity 500% from 200%. The dose came highest when is density +3 to slow. and dose more increases gray scale's extent could know that rise. Could know whether how equipment set is important through this experiment. cause of disease which change by digital radiography system forward is thought to increase more, it is considered that suitable education by this and continuous interest about equipment need absolutely.