• Smart Structures and Systems
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• 제29권1호
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• pp.153-166
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• 2022

Identifying fine cracks in steel bridge facilities is a challenging task of structural health monitoring (SHM). This study proposed an end-to-end crack image segmentation framework based on a one-step Convolutional Neural Network (CNN) for pixel-level object recognition with high accuracy. To particularly address the challenges arising from small object detection in complex background, efforts were made in loss function selection aiming at sample imbalance and module modification in order to improve the generalization ability on complicated images. Specifically, loss functions were compared among alternatives including the Binary Cross Entropy (BCE), Focal, Tversky and Dice loss, with the last three specialized for biased sample distribution. Structural modifications with dilated convolution, Spatial Pyramid Pooling (SPP) and Feature Pyramid Network (FPN) were also performed to form a new backbone termed CrackDet. Models of various loss functions and feature extraction modules were trained on crack images and tested on full-scale images collected on steel box girders. The CNN model incorporated the classic U-Net as its backbone, and Dice loss as its loss function achieved the highest mean Intersection-over-Union (mIoU) of 0.7571 on full-scale pictures. In contrast, the best performance on cropped crack images was achieved by integrating CrackDet with Dice loss at a mIoU of 0.7670.

• 한국지구과학회지
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• 제28권3호
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• pp.277-288
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• 2007

이 연구는 교수요목기부터 7차 교육과정에 이르기까지 '날씨'와 '일기예보'를 다루고 있는 시각적 이미지를 사회-기호학적 관점으로 분석하였다. 연구결과 대부분의 시각적 이미지는 실제 세상의 현상을 묘사하는 '실체형'인 것으로 나타났다. 이는 모든 시기의 초등 과학 교과서의 시각적 이미지는 대부분 학생들에게 친숙하였음을 의미한다. 시각적 이미지와 학생 사이의 의사소통에 대한 주도권 양상은 복잡하게 나타났다. 또한 초등학교 과학 교과서의 시각적 이미지들은 시기에 관계없이 대부분 기하학적 코드나 숫자 문자 등을 사용하지 않는 것으로 나타났다. 이 연구는 시각적 이미지의 정보의 양과 형태, 구조 및 사회적 의미 등을 해석하는 새로운 분석도구를 제안해준다. 또한 차기 과학교과서의 이미지 선택에 사회-기호학적 관점을 도입하는 하나의 전기가 될 것이다.

• Bulletin of the Korean Chemical Society
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• 제32권12호
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• pp.4321-4326
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• 2011

A new series of heteroleptic cyclometalated iridium(III) complexes has been synthesized and characterized by absorption, emission and cyclic voltammetry studies: $(pqx)_2Ir(acac)$ (1), $(dmpqx)_2Ir(acac)$ (2) and $(dfpqx)_2Ir(acac)$ (3) where pqx=2-phenylquinoxalinate, dmpqx=2-(2,4-dimethoxyphenyl)quinoxalinate, dfpqx=2-(2,4-difluorophenyl) quinoxalinate and acac=acetylacetonate anion. The reaction of excess acetylacetone with ${\mu}$-chloride-bridged dimeric iridium complex, $[(C\^N)_2Ir({\mu}-Cl)]_2$, gives a complex 1 and an unusual hydridoiridium(III) complex, $(pqx)IrH(acac)_2$ (4). The complex 1, 2 and 3 show their emissions in an orangered region (${\lambda}_{PL,max}$ = 583-616 nm), and the emission maxima can be tuned by the change of substituent at phenyl ring of 2-phenylquinoxaline ligand. The phosphorescent line shape indicates that the emissions originate predominantly from $^3MLCT$ states with little admixture of ligand-based $^3({\pi}-{\pi}^*)$ excited states. The structures of complex 3 and 4 are additionally characterized by a single crystal X-ray diffraction method. The complex 3 shows a distorted octahedral geometry around iridium(III) metal ion. A strong trans influence of the phenyl ring is examined. In complex 4, there are two discrete molecules which are mirror images each other at the ratio of 1:1 in an unit cell. We propose that the phosphorescent complex 1, 2 and 3 are possible candidates for the phosphors in OLEDs applications.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2003년도 하계종합학술대회 논문집 Ⅲ
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• pp.1291-1294
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• 2003

This paper presents an approach to extract license plates from parking regulation images which is captured in various photographing direction and complex background. first, we search each row at regular intervals starting from the bottom of a license-plate image, and we set up a rough region for a certain zone in which the sign of intensity vector changes frequently enough and color of license plate is detected enough, assuming it as a candidate location of a license plate. And then, we extract an elaborate area of a license plate by horizontally and vertically projecting vertical edges. Here, tar types of the private and the public, are easily classified according to the color of extracted plates. To evaluate proposed method, we used 200 actual regulation images. As a result, the proposed method showed extraction rate of 96%, which is 9% higher than the previous method using only intensity vector.

• 대한의용생체공학회:의공학회지
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• 제9권2호
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• pp.185-194
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• 1988

The dual-energy technique win used to separate the bone-only and tissue-only images from the conventional chest images. The equivalent thickness of the basic materials are estimated from low and high energy images of a given complex materials using the attenuation coefficient of ma serial componens. We showed that the image quality of dual-energy imaging method can be influenced by the ponlinearity and noise components of system and spectrum distributions The quantitative analysis of Calcium component was performed by dual-energy technique and it is shown that the concentration of the Calcium could be accurately estimated within 5% error range.

• 한국멀티미디어학회논문지
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• 제6권4호
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• pp.594-600
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• 2003

In this paper, we propose a detection method for facial features in color images with various backgrounds and face poses. To begin with, the proposed method extracts face candidacy region from images with various backgrounds, which have skin-tone color and complex objects, via the color and edge information of face. And then, by using the elliptical shape property of face, we correct a rotation, scale, and tilt of face region caused by various poses of head. Finally, we verify the face using features of face and detect facial features. In our experimental results, it is shown that accuracy of detection is high and the proposed method can be used in pose-invariant face recognition system effectively

• Maxillofacial Plastic and Reconstructive Surgery
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• 제19권4호
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• pp.343-350
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• 1997

Diagnosis of maxillofacial lesions is very difficult. Recent developments in computed tomography enable the production of three dimnesional images of complex anatomical structures from a series of conventional computed tomographic sections. Methods of three-dimensional analysis of computed tomographic images have recently been described. Mostly, reports have concentrated on applications relative to congenital deformities. In this report, one method of three dimensional reformatting is reviwes. Images formed by this method have solid surface appearance and can be color enhanced and manipulated to isolate anatomic structures of interest. The program allows tissue densitis, volumes, and distances. This report emphasizes maxillofacial applications other than those previously reported in the surgical and radiological literature.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제11권7호
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• pp.3664-3677
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• 2017

Abrupt scene changes generally incur the afterimage effect. So, the unblocked image portion is still viewed by human eyes just after it is blocked by some pattern. Yovo's secure display method utilized this phenomenon and it is systematically analyzed using computational afterimage modeling by replacing the complex afterimage effect via simple low-pass filtering. With this approach, realistic images perceived by the human eye can be computationally generated at every single moment, especially reflecting the afterimage effect. The generated images are compared with the original images to determine the factors that affect the image quality of the secure display method. The simulation results demonstrate that the ratio of the unblocked portion to the blocked portion of an image and the playback rate are two primary factors related to the recognized image quality. We also found that the two factors are still effective for generalized secure display techniques.

• 제어로봇시스템학회논문지
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• 제8권10호
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• pp.874-880
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• 2002

A number of techniques have been proposed for 3D display using view-difference of two eyes. These methods do not express enough reality like real world. The display images have to change according to the position of a viewer to improve reality. In this paper, we present an approach for generating intermediate image between two different view images by applying new image interpolation algorithm The interpolation algorithm is designed to cope with complex shapes. The proposed image interpolation algorithm generates rotated image about vertical axes by any angle from base images. Each base image that was obtained from CCD camera has an view-angle difference of $3^{\circ}C$, $5.5^{\circ}C$, $^{\circ}C$, $22^{\circ}C$, and $45^{\circ}C$. The proposed into mediate image generation method uses the geometric analysis of image and depth information through the block-based matching method.

• International Journal of Contents
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• 제8권4호
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• pp.95-102
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• 2012

In this paper, we present a technique to extract the title areas from book cover images. A typical book cover image may contain text, pictures, diagrams as well as complex and irregular background. In addition, the high variability of character features such as thickness, font, position, background and tilt of the text also makes the text extraction task more complicated. Therefore, we propose a two steps efficient method that uses Histogram of Oriented Gradients and color information to find the title areas. Firstly, text localization is carried out to find the title candidates. Finally, refinement process is performed to find the sufficient components of title areas. To obtain the best result, we also use other constraints about the size, ratio between the length and width of the title. We achieve encouraging results of extracted title regions from book cover images which prove the advantages and efficiency of the proposed method.