• Progress in Medical Physics
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• v.12 no.1
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• pp.51-58
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• 2001

Synchrotron radiation (SR) has several advantages over convetional x-rays, including its phase, collimation, and high flux. A synchrotron radiation beamline 5C1 at Pohang Light Source (PLS) was recently built for imaging applications. We have shown that a SR imaging system is useful in imaging microscopic structures. SR with broad-band energy spectrum were adjusted to an object by Si wafers and their energy were approximately ranging from 6 keV to 30 keV. SR were passed through an object and finally transformed into visible lights by CdWO$_4$ scintillator screen. The visible lights which were reflected at an angle of 90 degrees by gold plated mirror were detected by a CCD camera and the image data were acquired using image acquisition system. A high-resolution phantom, capacitor, adult tooth, child tooth, cancerous breast tissue, and mouse lumbar vertebra were imaged with SR imaging system. The Objects were rotated within the field of view of the CCD detector, and their projection image data were obtained at 250 steps over 180 degrees rotation. Image reconstructions were carried out in a PC by using IDLTM(Research systems, Inc., US) program. The spatial resolution of the images acquired by the SR imaging system was measured with a high-resolution chart manufactured for several micrometer resolution. The specimens were also imaged with conventional x-ray radiography system to compare the image quality of radiography obtained with the SR imaging system. The results showed more structural details and high contrast images with SR imaging system than conventional x-ray radiography system. The SR imaging system may have a potential for imaging in biological researches, material applications, and clinical radiography.

• Journal of Dental Rehabilitation and Applied Science
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• v.26 no.1
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• pp.21-32
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• 2010

The convergence angle of a prepared tooth is a very important factor in the retention and resistance of a crown restoration. But various intraoral environments and clinician's techniques make it difficult to obtain the ideal inclination. Therefore, in this study, clinical convergence angle of a prepared tooth was investigated. The data was collected from the patient models of prosthodontic residents and the patient models of general practitioners. The images of mesiodistal and buccolingual surfaces were taken with a digital camera to evaluate the convergence angle on 'ImageJ' program. The images were classified according to the criteria (1. Clinician group, 2. Position in the dental arch, 3. The purpose of abutment preparation)and then analyzed. The mean convergence angle of a prepared tooth for Korean clinicians was $15.02^{\circ}$ (${\pm}10.13^{\circ}$). 1. It was significant in the convergence angle between the general practitioner group and the prosthodontic resident group(p<0.05). 2. It was significant between the mesiodistal and buccolingual surface in the the prosthodontic resident group(p<0.05). 3. For the general practitioner group, it was significant when anteriors and premolars were compared with molars(p<0.05). For the prosthodontic resident group, it was significant when anteriors and premolars were compared with molars (p<0.05). 4. When divided into upper and lower arches, for the general practitioner group, it showed significant difference in the buccolingual aspect(p<0.05). Also in the prosthodontic resident group, it showed significant difference in the buccolingual aspect(p<0.05). 5. Dividing left and right sides of the arches, there was no significant difference in the general practitioner group and the prosthodontic resident group(p>0.05). 6. In the general practitioner group, it was significant in the mesiodistal axial convergence angle of single crown abutment and 3 unit bridge abutment(p<0.05). In the prosthodontic resident group, it was significant in the mesiodistal and overall axial convergence angle of single crown abutment and 3 unit bridge abutment(p<0.05). Clinical convergence angle of prepared tooth in Korea was included in agreement with other studies investigating convergence angle that ranged from 10 to 22 degrees, achieved in clinical practice.

• Journal of the Korean Society of Clothing and Textiles
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• v.27 no.12
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• pp.1397-1404
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• 2003

2002년 월드컵 전야제에서는 한국문화를 소개해 세계인의 환호를 받았는데 그 중에는 칠석동 민속축제인 고싸움놀이가 펼쳐졌다. 칠석동 민속축제는 일반 서민복식의 전통복 형태를 보여주는 복식(服飾)을 실제 착용하고 축제를 행하고 있으므로, 점차 사라져 가는 전통복식을 놀이문화를 통해 직접 확인할 수 있다는 점에서 연구가치를 갖는다. 본 연구의 목적은 국제화 시대에 우리 전통문화에 대한 정체성 확립을 위해 시대적 변화에 따라 변해 가는 민속복식을 무형문화재로 지정되어 있는 칠석동 고싸움놀이를 중심으로 시대적 흐름을 통한 고싸움놀이의 전수과정에서 형성되어 온 민속축제복식의 구성과 특성을 살펴보는데 있다. 연구방법은 광주지역인 광산구 칠석동 마을을 중심으로 자료조사와 현장조사를 병행하였다. 자료조사는 민속에 관련된 전공서적과 무형문화재 조사보고서, 행사팜플렛 등을 참고하였고, 현장조사는 고싸움 축제에 참가하여 복식 전반에 대한사진촬영과 마을축제 참여하는 마을사람들을 중심으로 축제복식에 관한 면담조사를 하였다. 칠석동 고싸움 축제복식은 행사가 진행되는 내용에 따라 크게 4가지로 분류할 수 있는데 본격적인 고싸움이 시작되기 전날 밤에 당산나무에 제를 지내는 당산제 복식, 마을의 평안과 고싸움의 흥을 돋우기 위한 농악복식, 고싸움이 시작되기 전에 아낙네들이 손과 손을 맞잡고 둥글게 돌며 화합을 다짐하는 강강수월래 복식, 한해 풍년을 기원하는 고싸움복식이 있다. 칠석동 고싸움 축제복식의 특성을 요약하면 다음과 같다. 첫째, 구성면에서는 농경제의(農耕祭衣)와 안택축원(安宅祝願的)을 기원하는 민속놀이축제복식으로 일상생활에 착용하는 복식을 이용한 농경 의례복의 다(多)기능성이 강조된 것으로 나타났다. 둘째, 색상은 우리조상의 백의(白衣)의 상징인 일상복인 백색 위에 오방색을 사용하여 화려하고도 강렬한 원색의 색상조화가 특징적으로 나타났다. 셋째, 형태면에서는 양쪽어깨와 허리선의 면 분할이나 비례를 통해 허리부분의 동작에 따른 유동적인 선이 부각되고 있다. 특히, 평면구성의 단조로움은 흔들리는 몸동작에 따른 고름의 율동미와 축제복식의 착장 방법에 따른 한국복식의 형태미를 보여주었다.

• The Journal of the Korea Contents Association
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• v.12 no.8
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• pp.87-95
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• 2012

We propose that a subjective image quality assessment based on objective image quality factors in order to evaluate objectively preference of consumers. In other words, we define objective image quality factors which are easy to accept by manufacturers and they are composed of subjective image quality assessment questionnaires. Also, portrait image is selected by stimulus in order to persue easiness of evaluation for the general subjects. Throughout a subjective image quality assessment model, we evaluate recognition of image quality by consumers and analyze the effectiveness of correlation in terms of the final image quality preference. Analyzing the relationship between image quality factors, we can figure out the preferable image quality and confirm the positive effects on consumers' recognition of image quality. In the results, there are strong relationship between preference and color reproduction, dynamic range, noise, and resolution respectively. especially, the characteristic of portrait, there is high correlation between color reproduction and preference.

• Journal of Digital Convergence
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• v.12 no.8
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• pp.295-302
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• 2014

Essential to the establishment of such 3D spatial information are the laser scanning technology to obtain high-precision 3D point group data and the photography-metric camera to obtain high-resolution multispectral image information. The photography-metric camera, however, lacks in usability for its broad scope of utilization due to the high purchase price, difficult purchase channel, and low applicability. This study thus set out to investigate a technique to establish multi-dimensional ortho-image data with a single lens reflex digital camera of high speed and easy accessibility for general users. That is, the study remodeled a single lens reflex digital camera and calibrated the remodeled camera to establish 3D multispectral image information, which is the essential data of 3D spatial information. Multi-dimensional ortho-image data were collected by surveying the reference points for stereo photos, taking multispectral shots of the objects, and converting them into ortho-images.

• Aerospace Engineering and Technology
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• v.13 no.1
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• pp.63-69
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• 2014

The oxidizer-rich preburner's combustion tests were fulfilled in the development process of staged combustion cycle rocket engines. The exhaust plume from an oxidizer-rich preburner is relatively transparent because combustion takes place in oxidizer rich state. During hot fire tests a still and infrared images were captured to visualize the plume structure, temperature distribution and so on. In addition, the exhaust plume was numerically investigated to figure out the detailed characteristics. The combustion was not considered for the numerical modeling, but the mixing of exhaust plume with circumstantial air was modeled by species transport model with several turbulence models. The inner structure of plume was configured out by the comparison of numerical results with experimental results, and the validity of applied numerical models was verified.

• Journal of Korean Society for Geospatial Information Science
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• v.21 no.4
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• pp.101-107
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• 2013

Generally the commercial high-resolution images have their coordinates, but the locations are locally different according to the pose of sensors at the acquisition time and relief displacement of terrain. Therefore, a process of image co-registration has to be applied to use the multi-temporal images together. However, co-registration is interrupted especially when images include the cloud-covered regions because of the difficulties of extracting matching points and lots of false-matched points. This paper proposes an automatic co-registration method for the cloud-covered high-resolution images. A scale-invariant feature transform (SIFT), which is one of the representative feature-based matching method, is used, and only features of the target (cloud-covered) images within a circular buffer from each feature of reference image are used for the candidate of the matching process. Study sites composed of multi-temporal KOMPSAT-2 images including cloud-covered regions were employed to apply the proposed algorithm. The result showed that the proposed method presented a higher correct-match rate than original SIFT method and acceptable registration accuracies in all sites.

• Korean Journal of Remote Sensing
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• v.28 no.5
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• pp.561-571
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• 2012

The MTF(Modulation Transfer Function) is one of quality assesment factors to evaluate the performance of satellite images. Image restoration is needed for MTF compensation, but it is an ill-posed problem and doesn't have a certain solution. Lots of filters were suggested to solve this problem, such as Inverse Filter(IF), Pseudo Inverse Filter(PIF) and Wiener Filter(WF). The most commonly used filter is a WF, but it has a limitation on distinguishing signal and noise. The L-curve-based Modified Wiener Filter(MWF) is a solution technique using a Tikhonov regularization method. The L-curve is used for estimating an optimal regularization parameter. The image restoration was performed with Dubaisat-1 images for PIF, WF, and MWF. It is found that the image restored with MWF results in more improved MTF by 20.93% and 10.85% than PIF and WF, respectively.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.19 no.3
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• pp.129-136
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• 2020

In this paper, we propose a thermal imagery-based object detection algorithm for low-light level nighttime surveillance system. Many features selected by Haar-like feature selection algorithm and existing Adaboost algorithm are often vulnerable to noise and problems with similar or overlapping feature set for learning samples. It also removes noise from the feature set from the surveillance image of the low-light night environment, and implements it using the lightweight extended Haar feature and adaboost learning algorithm to enable fast and efficient real-time feature selection. Experiments use extended Haar feature points to recognize non-predictive objects with motion in nighttime low-light environments. The Adaboost learning algorithm with video frame 800*600 thermal image as input is implemented with CUDA 9.0 platform for simulation. As a result, the results of object detection confirmed that the success rate was about 90% or more, and the processing speed was about 30% faster than the computational results obtained through histogram equalization operations in general images.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.37 no.6
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• pp.465-472
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• 2019

The SPR (Single Photo Resection) is widely used as a method of estimating the EOPs (Exterior Orientation parameters) at the time of taking a photograph, but it requires an initial value and has a disadvantage of being sensitive to the initial value. In this study, we introduce quaternion-based single photo resection and PnP (Perspective-n-Point) algorithm that do not require initial values and compare the results. Photos were taken using a general smartphone, and the ground control point acquisition was based on the hybrid MMS (Mobile Mapping System) point cloud data possessed by the researchers. As a result, when the collinear condition based SPR is true value, quaternion-based SPR has higher attitude angle estimation accuracy than PnP algorithm. In case of camera position estimation, both algorithms showed accuracy within 0.8m when compared with ground control points.