인공적 인접면 치아우식증의 구내방사선사진과 디지털 영상의 진단능 평가

허민석,유동수,Heo Min-Suk,You Dong-Soo 대한영상치의학회 1994 Imaging Science in Dentistry Vol.24 No.2

Recently, the digital image was introduced into radiological image. The digital image has the power of contrast enhancement, histogram control, and other digitally enhancement. At the point of the resolution, periapical radiograph is superior to the digital image, but enhanced digital procedure improves the diagnostic ability of the digital image. The purpose of this study was to evaluate the diagnostic ability of artificial proximal caries in conventional radiographs, digital radiographs and enhanced digital radiographs (histogram specification). ROC (Receiver Operating Characteristic) analysis and paired t-test were used for the evaluation of detectability, and following results were acquired: 1. The mean ROC area of conventional radiographs was 0.9274. 2. The mean ROC area of unenhanced digital image was 0.9168. 3. The mean ROC area of enhanced digital image was 0.9339. 4. The diagnostic ability of three imaging methods was not significant difference(p>0.05). So, the digital images had similar diagnostic ability of artificial proximal caries to conventional radiographs. If properly enhanced digital image, it may be superior to conventional radiographs.

항공촬영(UAV) 기법을 이용한 발파암 파쇄도 이미지 분석

강대우 ( Dae-woo Kang ),허원호 ( Wonho Hur ),이하영 ( Ha-young Lee ) 대한화약발파공학회 2017 화약발파 Vol.35 No.1

발파암의 파쇄도 분석에는 이미지 엣지 검출기법을 응용한 사진분석 방법이 주로 사용되어 왔으며, 이들 이미지 획득은 주로 파쇄암의 정면에서 디지털 이미지로 획득하였다. 그러나 기본적으로 이미지 분석은 정면촬영이 아닌 평면 촬영 이미지를 이용하게 되어 있으나, 거대한 암반 사면을 평면 촬영할 수 있는 수단이 없었다. 따라서 부득이하게 정면 촬영된 이미지를 임의 왜곡 또는 확대하여 평면 촬영 각도와 유사하게 조절함으로서 해결하였다. 근래에 이르러 무인항공기(UAV)가 발전하면서 이를 통해 발파암의 파쇄 상황을 간단히 고화질디지털 이미지화 할 수 있게 되었고, 이를 통해 파쇄암이 쌓여있는 각도에 최대한 평면인 이미지를 획득하고 이미지 분석을 할 수 있게 되었다. 본 연구는 무인항공기와 무인항공기용 카메라를 이용해 발파 파쇄암의 정면 및 평면 디지털 이미지를 동시에 획득하고 각각을 비교 분석하였다. 그 결과 평면 촬영된 이미지의 분석 결과가 기존 정면 촬영된 이미지의 분석결과에 비해 정확도가 크게 향상되었음을 확인하였다. In Analysis of Fragmentation of rock blasted, The photo analysis method has been mainly used and these image acquisitions are mainly obtained by digital image from the front of the crushed rock. However, Image analysis is basically advantage of the image of planar shooting not front shooting but There is no way to take a photograph of huge plane rock slope. Thus, Unavoidably It is resolved by distorting or extending the image filmed at the front as well as adjusting it similar to its angle of plane shooting. Lately, With advancing unmanned aerial vehicle, It can simply image the fragment conditions of blasted rock of a high-definition digital image and Through it, It can acquire the most planar image to angle which accumulate cataclastic rock and also can make image analysis. In this study, It has been confirmed that tolerance value of analysis result of image filmed flatly is markedly lower than the existing front filmed image.

고속 푸리에 변환을 기반으로 디지털 이미지 상관법의 분석 속도 향상 알고리즘에 관한 연구

홍경민,박락규,최인영 국제차세대융합기술학회 2020 차세대융합기술학회논문지 Vol.4 No.2

디지털 이미지 상관법(DIC)은 reference image와 reference image가 변화된 후의 이미지에 대한 상관관 계를 분석하는 영상 분석 기반의 계측 방법이다. 그러나 변화된 후의 지점을 추적하기 위해 관심 영역에서 변형된 시편의 모든 지점을 추적하려면 광범위한 반복 계산 프로세스가 필요하다. 계산 시간을 줄이기 위해 고속 푸리에 변환(FFT)을 적용했지만 큰 변형에 대한 추적은 쉽지 않다. DIC의 계산 속도를 향상시키고 상관 계수가 감소하 는 것을 방지하기 위해 변위 피드백을 갖춘 새로운 FFT 기반의 상관 분석 알고리즘을 제안하고자 한다. 새로운 FFT 기반의 방법을 기존 DIC를 이용한 계산 속도와 비교하였다. 본 논문에서 제안된 방법의 계산 속도가 기존의 방법보다 약 3배 빠르다는 것을 입증하였다. 또한, 피드백 업데이트 없이 FFT-DIC에서는 10% 이상의 변형율을 추적을 못하지만, 새로운 알고리즘은 추적하는데 실패하지 않는다. Digital Image Correlation (DIC) is a measurement method based on image analysis that calculates the correlation between the original reference image and the deformed one. However, an extensive iterated calculation process is required to trace every point on the deformed specimen in the area of interest. The Fast Fourier Transform (FFT) has been adopted to reduce the calculation time, but the FFT method easily loses tracking for large deformation. A new FFT-based correlation analysis algorithm with displacement feedback is proposed to improve the calculation speed of the DIC system and to prevent the correlation coefficient from declining. The calculation rate using the conventional DIC method was compared with that using our new feedback FFT-based approach. This paper demonstrates that the calculation speed of the proposed method was about three times faster than that of the conventional technique. In addition, no tracking failure comes out by our new algorithm even though only FFT-DIC without feedback updating lost tracking over 10% strain.

대표 이미지 생성을 통한 레이아웃 기반 유사 문서 검색: MS 파워포인트 사례를 중심으로

김시윤,김준호,박정흠 한국디지털포렌식학회 2023 디지털 포렌식 연구 Vol.17 No.1

With the recent development of technology, the work environment is all digitized, and digital documents are utilized in most of the work. For digital forensic investigators who need to quickly select documents related to a case, numerous digital documents cause a lot of difficulties in investigations. In particular, in eDiscovery, it is important to find meaningful digital evidence by analyzing associations between many documents and files within a limited time. In the case of digital forensic investigation, if documents with similar types are selected among numerous documents by identifying the types of digital documents, only documents created by a specific organization can be grouped. In this paper, we present a method of generating an image that can represent a document among images stored as many as the number of pages of a document for searching similar documents, and a method of searching similar documents using an image hash for similarity analysis between representative images. About 50,000 Microsoft PowerPoint files in the Govdocs1 data set and about 6,000 Microsoft PowerPoint files in the NapierOne data set demonstrate the practicality of the method presented in this paper. 최근 기술이 발전함에 따라 업무 환경이 모두 디지털화되어 업무 대부분에서 디지털 문서를 활용한다. 사건과 관련된 문서를 빠르게 선별해야 하는 디지털 포렌식 수사관들에게 수많은 디지털 문서들은 수사에 많은 어려움을 준다. 특히 전자증거개시제도(eDiscovery)에서는 한정된 시간 내에 많은 문서 및 파일 간의 연관성을 분석하여 의미 있는 디지털 증거를 찾는 것이 중요하다. 디지털 포렌식 수사 시 디지털 문서들의 양식을 식별하여 수많은 문서 중 비슷한 형태를 지닌 문서들을 선별한다면, 특정 조직에서 작성한 문서들만을 그룹화할 수 있다.

사질토의 변형 측정을 위한 최적의 디지털 이미지 해석 기법

장의룡,정영훈,정충기 한국지반공학회 2009 한국지반공학회논문집 Vol.25 No.12

To measure the soil deformation, two common techniques of the digital image analysis—Particle Image Velocimetry (PIV) and Digital Image Correlation (DIC)—have been used. To generally apply these techniques to the soils, the accuracy of these techniques should be evaluated under various conditions. In this study, the influence factors including the image resolution, the degree of displacement and deformation, the size of pixel subsets, and analysis techniques were analyzed. The deformation of an idealized particle assembly using the discrete element method was measured by the digital image analyses, and then the results were compared with the actual deformations. To conduct the optimal digital image analysis, various factors are systematically analyzed in terms of the degree of the displacement and the deformation.

잔디 생육 및 병 평가를 위한 이미지 분석 기술의 적용

장석원(Seog-Won Chang) 한국잡초학회·한국잔디학회 2020 Weed & Turfgrass Science Vol.9 No.1

잔디 연구자나 골프장 현장 관리자들은 잔디의 생육을 평가할 때 많은 경우 시각적 평가에 의존한다. 시각적 평가는 평가자의 경험이나 훈련 정도에 따라 도출 결과에서 큰 차이를 보일 수 있다. 본 연구에서는 보다 정확하고 재현성 있는 잔디 생육 조사를 위하여 촬영한 사진을 대상으로 이미지 분석 프로그램에 적용하여 그린업률, 피복률 및 병반면적률을 평가하였다. 또한 다년간 잔디 평가를 경험한 현역 잔디 전문가들에게 동일한 사진 평가를 의뢰하였고, 그 결과를 이미지 분석 프로그램으로부터 도출된 값과 비교하고 분석하였다. 전문가들이 평가한 그린업률, 피복률 및 병반면적률은 이미지 분석 값과 큰 차이를 보였다. 전문가들 사이에서도 차이를 보였고, 면적률을 계산하기 어려운 사진일수록 개인간의 차이가 컸다. 잔디 연구 경력과 이미지 분석 값과의 관계는 통계적으로 상관관계를 보이지 않았다. 하지만 이미지분석 프로그램을 이용한 잔디 생육 사진 분석은 전문가 평가 값보다 정확하고 재현성이 높았다. 따라서 잔디 연구자나 현장 관리자가 생육 조사에 이미지 분석 프로그램을 이용하면 업무 숙련도에 큰 영향을 받지 않고 정확한 평가에 큰 도움이 될 것으로 기대한다. Turfgrass researchers and golf course superintendents often rely on visual assessments to assess turfgrass growth and disease. Visual evaluation can make a unexpected subjective bias in the outcome of the assessment, depending on the experience of the evaluator or the degree of training. In this study, green up rate, coverage rate and percent diseased area were evaluated by applying image analysis program to photographed turfgrass for more accurate and reproducible investigation. The same photographic evaluation was presented to turfgrass experts who had experienced turfgrass evaluation for many years, and the results were compared with those obtained from the image analysis program. Experts evaluated the green up rate, coverage rate, and percent diseased area of turfgrass significantly different from the results of image analysis. There were also variations in the evaluated values among experts" evaluations, and the more difficult the photographic images are to calculate the acquired area, the greater the variation among individuals. The relationship between turfgrass research experience and image analysis values was not statistically correlated. However, the image analysis of turfgrass growth and disease was more accurate and reproducible than expert evaluation. Therefore, if turfgrass researchers or field managers use image analysis programs, even unskilled researchers expected be of great help in making evaluation.

Digital Image Analysis를 이용한 동적수침시험 평가방법의 개선 연구

손정탄,이진욱,임정혁 한국도로학회 2016 한국도로학회 학술발표회 논문집 Vol.2016 No.06

현재 아스팔트 포장 분야는 최근의 이상기후(집중호우 및 폭설)로 인하여 수분으로 인한 파손(점착력 약화로 인한 박리 및 포트홀)이 증가하고 있는 실정이다. 이에 국토교통부에서는 『아스팔트 혼합물 생산 및 시공 지침(2014)』의 재료 선정 과정에서 동적수침 시험을 통하여 피복잔류율이 50% 미만이면 박리방 지 재료를 사용토록 규정하고 있다. EN 12697-11에 규정되어있는 동적수침 시험은 골재와 아스팔트 사 이의 박리 저항성 평가하고 이 결과를 통해 아스팔트 혼합물의 수분 저항성을 평가하는 시험법으로, 피복 잔류율 평가는 검사자의 주관적인 육안 평가를 통해 이루어지기 때문에 시험결과의 객관성 및 신뢰성이 부족하다고 할 수 있다. 본 연구에서는 동적수침시험의 객관성 및 신뢰성 향상을 위하여, Digital Image Analysis(DIA)를 도입하였으며, Mesh Analysis를 통하여 DIA의 기준값을 선정하였다. Mesh Analysis 를 위하여 시험 후 건조된 시료를 동일한 조건에서 스캔하여 총 400(20×20) 개의 mesh로 나누어 각 셀 에 대한 피복율을 육안조사를 통하여 총 5 단계의 가중치를 적용하여 계산하였다. DIA는 이미지 파일을 화소(Pixel) 값을 기반으로 처리하는 기법으로, Mesh Analysis에 이용된 25비트 컬러 이미지 파일을 그 레이 이미지(화소값 0(검정색)~255(흰색))로 변환한 후 기준값을 바탕으로 변환된 흑백의 이미지를 이용 하여 피복율을 계산하는 분석방법이다. 보다 객관적인 피복율 비교를 위하여 BBS 시험을 수행하여 얻어 진 점착력을 피복율과 비교하였다. Fig. 1(a)는 피복율과 점착력의 비교결과, Fig. 1(b)는 AP-3를 기준으 로 계산된 피복율과 점착력의 재료에 따른 변동비율 결과를 보여준다. Fig. 1에서 육안평가 결과의 경향은 다른 평가방법과 다른 경향을 나타냈으며 즉, 육안평가는 시료 종 류에 따른 피복율 경향 파악에는 적합한 방법이 될 수는 있으나, 객관적인 피복율 평가에는 미흡한 것으 로 판단된다. 반면에 DIA는 Mesh Analysis 및 BBS 결과와 비교적 유사한 경향을 보였으며, 동적수침시 험의 피복율 평가에 DIA를 적용하는 것은 결과의 신뢰성 및 객관성 측면에서 도움이 될 수 있을 것으로 판단된다.

Generating 2D Three-phase Asphalt Mixture Representation Using advanced Digital Image Processing (DIP) techniques

Augusto Cannone Falchetto,KiHoon Moon 한국도로학회 2015 한국도로학회 학술발표회 논문집 Vol.2015 No.10

Analyzing asphalt mixture images can provide crucial information not only for generating advanced geometry structure in several numerical computations (i.e. FEM and/or DEM) codes, but also for numerically evaluating the material microstructure. It is well known that 3D X-Ray Computer Tomography (CT) can provide accurate and realistic microstructure information of asphalt mixtures; however, this technology still presents two limitations: 1) the equipment is very expensive and, therefore, only few pavement agencies can afford it, and 2) the software required to generate realistic image of asphalt mixture with three-phase structure (aggregate, asphalt binder and air-voids) is based on a global thresholding algorithm which cannot be easily accessed and edited by users and practitioners. In this paper, accurate and realistic 2D three-phase asphalt mixture images were generated using an advanced DIP analysis code (implemented on MATLABTM) and a common flatbed scanner, which can be easily purchased at relatively low price. The threshold algorithm was developed based on the computed results of Gmm (maximum specific gravity), Gmb (bulk specific gravity), VMA (voids in mineral aggregates) of given asphalt mixtures which can be experimentally obtained in a laboratory environment. 2D three-phase images of asphalt mixtures were derived from grey scale images (color intensity from 0 to 255) obtained from original RGB (Red-Green-Blue) scale images with a dual-threshold computation techniques (i.e. one step for computing air voids phase, T1, and a second step for computing asphalt binder (and/or mastic) phase, T2). An example of DIP analysis results is shown in Figure 1. Based on the computation results, quite accurate and good visual agreement was observed between RGB scale image and DIP analyzed image. The findings indicate that this advanced DIP analysis technique can provide reliable geometry and microstructural information for several numerical simulations such as finite element method (FEM) and discrete element modeling (DEM). This research work represents a solid base for performing simple 2D microstructure analysis using 2- and 3-point correlation function and for developing the Moon Cannone Falchetto (MCF) model which will be introduced in the next annual KSRE conference.

Digital Image Analysis를 이용한 동적수침시험 평가방법의 개선 연구

손정탄,이진욱,이석근,황성도,임정혁 한국도로학회 2016 한국도로학회논문집 Vol.18 No.4

PURPOSES : The objective of this study was to evaluate the results of the dynamic immersion test (DIT) through digital image analysis (DIA). METHODS : The asphalt binder retained post DIT was inspected visually by more than three investigators. However, because visual observations can be subjective, depending on the inspector’s skills and knowledge, DIA was also performed. The threshold value for the DIA was determined by a mesh analysis, in which the digital image to be analyzed is divided into very small meshes. In addition, the bitumen bond strength (BBS) test was also performed to the compare the visual results with the mechanical values. RESULTS AND CONCLUSIONS : Depending on the materials used, various methods can be used to predict the behavior of retained asphalt. However, the increasing ratio in the trend of retained asphalt shows different behaviors among the evaluation methods. In this study, the results of the visual observations were significantly different from those of the DIA, the mesh analysis, and the BBS tests. Thus, DIA is an appropriate method for evaluating the results of the DIT. However, in order to use this technique in the field, it is necessary to determine a more reasonable threshold value by performing DIA on various materials.

Ground Deformation Evaluation during Vertical Shaft Construction through Digital Image Analysis

Woo, Sang-Kyun,Woo, Sang Inn,Kim, Joonyoung,Chu, Inyeop 한국전력공사 2021 KEPCO Journal on electric power and energy Vol.7 No.2

The construction of underground structures such as power supply lines, communication lines, utility tunnels has significantly increased worldwide for improving urban aesthetics ensuring citizen safety, and efficient use of underground space. Those underground structures are usually constructed along with vertical cylindrical shafts to facilitate their construction and maintenance. When constructing a vertical shaft through the open-cut method, the walls are mostly designed to be flexible, allowing a certain level of displacement. The earth pressure applied to the flexible walls acts as an external force and its accurate estimation is essential for reasonable and economical structure design. The earth pressure applied to the flexible wall is closely interrelated to the displacement of the surrounding ground. This study simulated stepwise excavation for constructing a cylindrical vertical shaft through a centrifugal model experiment. One quadrant of the axisymmetric vertical shaft and the ground were modeled, and ground excavation was simulated by shrinking the vertical shaft. The deformation occurring on the entire ground during the excavation was continuously evaluated through digital image analysis. The digital image analysis evaluated complex ground deformation which varied with wall displacement, distance from the wall, and ground depth. When the ground deformation data accumulate through the method used in this study, they can be used for developing shaft wall models in future for analyzing the earth pressure acting on them.