• Journal of the Korean Society of Radiology
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• v.14 no.5
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• pp.635-642
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• 2020

The purpose of this study was to analysis the effects of shielding area of field configuration with changing of sensitivity and density on tube current (milliampere-seconds, mAs) and image quality in automatic exposure control (AEC) system. The equipment used a digital radiography device (Digital Diagnost, Philips, Netherlands), which has a integral type with an X-ray tube and an indirect digital detector. The AEC system conditions were consisted of 9 setting environments, that mode changing of the sensitivity (S200, S400, S800) and the density (+2.5, 0, -2.5). The tube current evaluated automatically exposed mAs under 81 combination conditions crossed by AEC conditions in fixed at 40 kVp. The image quality evaluated the radiographic images that selected valid images by visual assessment the radiographic images of the self-produced conical pyramid phantom and then measured their signal to noise ratio (SNR). As a result, the maximum tube current was 60.0 mAs that automatically exposed conditions were the 100% of shielding area and the sensitivity of S200 and the density of +2.5. The minimum tube current was 0.9 mAs with non-shielding area and the sensitivity of S800 and the density of -2.5. When the shielded area 0% with the sensitivity of S200 and the density of +2.5, the maximum SNR was the highest as 25.2. But when the shielded area 25% with the sensitivity of S800 and the density of -2.5, the minimum SNR was the lowest as 4.7.

• The Journal of the Korea Contents Association
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• v.18 no.1
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• pp.232-240
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• 2018

This study is to suggest a method to evaluate the detector performance using change of absorbed dose and histogram according to sensitivity change of Auto Exposure Control(AEC). The experiment site is skull, abdomen pelvis and the accuracy of the detector was evaluated by measuring the absorbed dose of the detector sensitivity S200, S400, S800, S1000. Also the dynamic range of the detector was evaluated through the histogram analysis. As a result, the absorbed dose decreased gradually as the sensitivity was set higher from S200 to S1000. And through the sensitivity histogram analysis, as the sensitivity of the skull is set higher, the amount of information at both ends of the histogram is lost. Abdomen and pelvis areas showed underflow phenomena in which the amount of information in the first part of the histogram was lost as the sensitivity was set higher. In conclusion, the detector accurately implemented the sensitivity change, but the dynamic range of the image due to the sensitivity change of the AEC due to the deterioration of the detector performance can not be realized properly and it was found that the evaluation through the absorbed dose and the histogram is useful when evaluating the performance of the detector.

• Journal of radiological science and technology
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• v.36 no.2
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• pp.111-122
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• 2013

This study was carried out to reduce patient dose through focus-detector distance, kilovoltage, and a combination of copper filters. In the C, L-spine lateral, Skull AP views were obtained by making changes of 60-100 kV in tube voltage and of 100-200 cm in focus-detector distance and by adding a copper filter when using an auto exposure control device in the digital radiography equipment. The incident dose showed 90 kV, 0.3 mmCu in C-spine lateral with 0.06 mGy under the condition of 200 cm; 100 kV, 0.3 mmCu with 0.40 mGy under the condition of 200 cm and 90 kV 0.3 mmCu in Skull AP with the lowest value of 0.24 mGy under the condition of 140 cm. It was observed that entrance surface dose decreased the most when was increased by 150 cm, 70 kV (C-spine lateral), 81 kV (L-spine lateral). It was also found out that as the between the focus-detector increased in the expansion of the video decreased but the difference was not significant when the distance was 180 cm or more. Skull AP showed the most reduction in the entrance surface dose when the tube voltage was changed by 80 kV, 0.1 mmCu, and 120 cm. Therefore, when using the automatic exposure control device, it is recommended to use the highest tube voltage if possible and to increase focus-detector distance at least by 150~200 cm in wall and 120~140 cm in table in consideration of the radiotechnologist's physical conditions, and to combine 0.1~0.3 mmCu and higher filters. It is thus expected to reduce patient dose by avoiding distortion of images and reducing the entrance surface dose.

• The Journal of the Korea Contents Association
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• v.19 no.4
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• pp.368-380
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• 2019

This study proposes a method to evaluate the performance of a detector by analyzing the dynamic step wedge and histogram according to the change of the tube voltage and sensitivity when using the Automatic Exposure Control (AEC). The performance of a detector was evaluated by measuring X-ray quality, Entrance Surface Dose (ESD), tube current, dynamic range corresponding to detector sensitivities of S200, S400, S800, S1000 per tube voltage of 60, 70, 81, 90 kVp. As a results, all of the qualities satisfied the acceptance criteria, and the Entrance Surface Dose and tube current were decreased stage by stage as sensitivity was set higher. In the dynamic step wedge, the observable dynamic range has also increased as tube voltage became higher. The histogram showed the quantization separation phenomena as the tube voltage was set higher. The higher the sensitivity, the more the underflow and overflow occurred in which the amount of information on both ends of the histogram was lost. In conclusion, the deterioration in the performance of the detector was found to be insufficient to realize the change of the tube voltage and sensitivity when using the Automatic Exposure Control, and it is useful to use dynamic step wedge and histogram in evaluating detector performance evaluation.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.42 no.1
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• pp.181-192
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• 2017

Recently, many researches are carried out for Advanced Driver Assistant Systems(ADAS). Especially, many studies are carried out to analyze the road situation using road images. In order to improve the performance of the road situation analysis, it is necessary to acquire images with appropriate exposure time. In this paper, we design and implement multi exposure smart vehicular camera which provides road traffic information to driver. Proposed device can acquire road traffic information by on-board camera and various sensors. And we propose an auto exposure control algorithm for the road environment to increase accuracy of image recognition. In addition, we also propose the switching ROI method that apply existing ROI techniques to overcome a limited computation power of embedded devices. We developed prototype of multi exposure smart vehicular camera and performed experiments to evaluate proposed auto exposure control algorithm and switching ROI method. The results show that the average accuracy of image recognition increased by 13.45%.

• Journal of radiological science and technology
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• v.39 no.4
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• pp.483-491
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• 2016

The conditions after exposure to digital mammography and digital breast tomosynthesis were analyzed. The examinations for the ACR phantom were done using manual exposure, not auto exposure, to examine image discrimination and patient dose. As a result, the following results were derived: In the CC exposure, the kVp was 2kVp higher while mAs decreased to 58.6% for the 3D tomography. Such result showed an approximate decrease of 60mAs. At that time, the patients' Average Glandular Dose (AGD) was 1.65mGy in 2D and 1.87mGy in 3D; thus, AGD of 3D was shown to have about 1.13times higher. The result of the manual exposure revealed a reduced mAs of up to 80%; there was no effect in the assessment standard in terms of image discrimination, resulting in more than 10 points. When mAs was reduced to 80% in the manual exposure for ACR phantom, AGD was decreased to 0.66mGy. The diagnostic values of images were maintained and patients dose was reduced in the manual exposure in the AEC condition for 3D. Since the use of 3D has recently increased, using the manual exposure has been recommended in this study to improve the diagnostic value, while, simultaneously reducing patients dose.

• Journal of radiological science and technology
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• v.41 no.2
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• pp.115-122
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• 2018

We aims to perform comparative analysis on the dose area and image qualities varying on the slice thickness when using Automatic Exposure Controller (AEC) and manual exposure; thus, it wants to suggest a measure to reduce exposure dose by setting the optimal examination condition for each slice thickness. The method was to set the thickness as Thin, Normal, and Heavy adult and evaluate the dose area, spatial resolution, low contrast resolution, Signal to Noise Ratio (SNR) and Contrast to Noise Ratio (CNR) according to each slice thickness by using the AEC and the manual exposure controller. The dose area according to each slice thickness all increased both when using the AEC and the manual exposure. However, the manual exposure showed lower dose area product than the AEC. Spatial resolutions and low contrast resolutions were all observed to be higher than the evaluation standard. Also, the SNR and CNR of each thickness all increased when using the AEC. When using the manual exposure, SNR and CNR increased in all cases other than the Heavy Adult. Consequently, the Thin and Normal Adult showed dose reduction about 2 times when using the manual exposure controller, while ensuring the image quality. Heavy adult was able to maintain good image quality by using AEC.

• KOREAN POULTRY JOURNAL
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• v.23 no.4 s.258
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• pp.95-103
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• 1991

계사시설, 환경관리, 시설자동화, 자동통제 및 전산화, 계분의 처리와 이용에 관해 검토해 보았다. 노후시설의 개선 또는 계사를 신축할 때는 다음과 같은 사항을 고려하여 계획을 세워야 한다. $\bullet$계사내부의 적정온도 유지를 위한 단열 $\bullet$자동급이 시설, 즉 사료탱크에서 체인 또는 링급이기로 사료의 자동이동 $\bullet$현재의 케이지에 가능한 자동집란 장치 $\bullet$여건이 적합하다면 자동화 케이지로 교체 $\bullet$노출된 급수통을 니플로 교체 $\bullet$계란 유통시 냉장이 완벽히 이루어지지 않는다면 계란 품질 보전을 위한 미네랄 코팅 $\bullet$계분처리방식중 노동력절감 및 공해방지 측면에서 가장 바람직한 형태를 선택 $\bullet$계사를 신축하는 경우 자동화 케이지 시스템과 계류장방식의 계분처리 체계의 선택을 신중히 검토 위와 같은 사항들은 산란계사 시설개선을 위한 의사결정에 도움을 줄 것으로 확신된다. 의사결정의 최종선택기준은 수익성에 있다!

• Review of KIISC
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• v.24 no.2
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• pp.35-41
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• 2014

자동차 산업 인프라의 발달로 자동차 사용 인구는 지속적으로 증가하고 있으며, 이에 따른 자동차 사고도 매년 증가하고 있다. 자동차 사고는 개인 및 사회의 비용손실과 즉결되므로 많은 운전자들이 자동차용 블랙박스(사고영상기록장치)를 구입하여 장착하고 있다. 이런 자동차용 블랙박스는 교통사고 시점의 영상을 저장 재생 하므로 정확한 사고원인을 규명하는데 활용되고 교통사고를 예방하는 효과가 있다. 그러나 그 이면에 자동차용 블랙박스는 자동차가 운행될 때 마다 영상을 촬영하고 저장되기 때문에 의도되지 않은 개인의 사생활이 노출 될 수 있으며 또한 저장된 사고영상 데이터를 의도적으로 조작하여 교통사고의 원인규명을 방해하는 문제가 발생 하기도 한다. 본 연구에서는 이러한 문제를 해결하기 위한 국내 관련 동향을 알아보고 보안기술을 적용 할 수 있는 방안을 제시하고자 한다.

• Proceedings of the Korean Society of Disaster Information Conference
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• 2022.10a
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• pp.347-348
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• 2022

본 연구에서는 무인이동체를 활용한 철도교량의 외관조사 점검을 보다 효율적이고 객관성 있게 수행하기 위하여 무인이동체를 통해 촬영된 이미지를 딥러닝 기반 분석기술을 활용하여 손상 자동으로 분석 하기위한 기술을 연구하였다. 철도교량의 외관 손상 중 균열, 콘크리트 박리·박락, 누수, 철근노출에 대한 손상 이미지를 추출하여 딥러닝 분석 모델을 생성하고 학습한 분석 모델을 적용한 시스템을 실제 현장에 적용 테스트를 수행하였으며 학습 구현된 분석모델의 검측 재현율을 검토한 결과 평균 95%이상의 감지성능을 검토할 수 있었다. 개발 제안된 자동손상분석 기술은 기존 육안점검 결과 대비 보다 객관적이고 정밀한 손상 검측이 가능하며 철도 유지관리 분야에서 무인이동체를 활용한 외관조사 업무를 수행함에 있어 기존 대비 객관적인 결과도출과 소요시간, 비용저감이 가능할 것으로 기대된다.