• Korean Journal of Remote Sensing
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• v.15 no.3
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• pp.167-175
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• 1999

So far, the remote sensing technology has widely been used in a variety of application areas such as military, medical imaging, environment, geology and so forth. The microwave remote sensing uses the wavelengths ranging from around one centimeter up to a few tens of centimeters and is known to be very effective regardless of the weather conditions and the day/night time as compared with the reflective InfraRed (IR) remote sensing or the thermal IR remote sensing. There are three generic modes of synthetic aperture radar imaging systems depending on its application, that is, stripmap mode, spotlight mode, or inverse mode. In this article we focus on the issue of imaging of flying aircrafts for the inverse mode of a ground - based, fixed radar with moving objects. The imaging of flying aircrafts is considered to be an important step for the automatic target recognition systems, and therefore a great deal of efforts have recently been made on the subject. Here we review the three representative methods including the Fourier transform processing, the time - frequency processing, and the reconstruction from the projection. Some relative merits and drawbacks are also discussed.

• KIPS Transactions on Software and Data Engineering
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• v.12 no.6
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• pp.243-250
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• 2023

Chest X-ray is radiological examination for xeamining the lungs and haert, and is particularly widely used for diagnosing lung disease. Since the quality of these chest X-rays can affect the doctor's diagnosis, the process of evaluating the quality must necessarily go through. This process can involve the subjectivity of radiologists and is manual, so it takes a lot of time and csot. Therefore, in this paper, based on the chest X-ray quality assessment guidelines used in clinical settings, we propose a tool that automates the five quality assessments of artificial shadow, coverage, patient posture, inspiratory level, and permeability. The proposed tool reduces the time and cost required for quality judgment, and can be further utilized in the pre-processing process of selecting high-quality learning data for the development of a learning model for diagnosing chest lesions.

• Proceedings of the Korea Information Processing Society Conference
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• 2001.04a
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• pp.139-142
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• 2001

컴퓨터 이미지처리는 여러 분야에서 응용되고 있는데 어떤 특성을 만족하는 객체들의 계수를 자동으로 분류시키는 생물학분야, 편지봉투나 일반양식에 인쇄되어 있는 글자를 자동으로 검출하고 인식하며 초음파검사 혹은 X-Ray 촬영에서 이미지를 획득하여 향상시키는 의료분야, 지문 및 얼굴인식 등에 이용되고 있다. 최근 몇 년 동안 이미지인식, 형태론, 이미지데이터 압축에 관한 연구가 진전되면서 본 연구에서 형태론적인 기법을 사용하여 문자인식을 위한 전처리 혹은 후처리 단계에서 사용되는 이미지향상을 위해서 침식, 골격화의 2단계를 적용하여 기종의 연구 방법과 비교하여 이미지획득 시간을 줄이고 이미지를 향상시켜 문자를 인식하는 알고리즘을 제안한다.

• Proceedings of the KSLP Conference
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• 1995.11a
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• pp.181-184
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• 1995

일반적으로 의료상에서 방사선 사진 상으로부터 병소 부위를 찾아내어 질병의 유무 및 진단을 해왔으나 명확하지 못한 방사선 사진 자체의 문제점들과 사진 현상시의 문제점들로 인하여 진단의 혼란을 초월할 수 있다. 또한 오래 전부터 컴퓨터의 발달로 인하여 방사선 사진을 입력, 진단하려는 움직임도 있었으나 많은 노력에도 불구하고 입력시키려는 사진이 잡음이 많고 대비가 상당히 안 좋은 상태이므로, 이로 인한 해상도의 문제점으로 이를 기피하고 현상되어 나온 사진자체로 진단을 하려고 하였다. (중략)

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2012.11a
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• pp.172-173
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• 2012

최근 의료산업에서는 동영상 구현이 가능한 직접 방식의 X-선 검측센서에서 X-ray 흡수효율이 좋은 반도체센서와 성숙된 기술. 본 연구에서는 non-alkali 기판에 evaporation 및 RF magnetron sputtering법으로 기판온도를 증가시키며 CdTe막을 증착하였다. 또한, RF magnetron sputtering을 이용하여 상온에서 증착한 CdTe막을 진공 및 대기 중에서 후열처리한 후 미세구조 변화를 관찰하였다.

• Spatial Information Research
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• v.13 no.4 s.35
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• pp.345-354
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• 2005

Super resolution image reconstruction method refers to image processing algorithms that produce a high resolution(HR) image from observed several low resolution(LR) images of the same scene. This method has proven to be useful in many practical cases where multiple frames of the same scene can be obtained, such as satellite imaging, video surveillance, video enhancement and restoration, digital mosaicking, and medical imaging. In this paper, we applied the super resolution reconstruction method in spatial domain to video sequences. Test images are adjacently sampled images from continuous video sequences and are overlapped at high rate. We constructed the observation model between the HR images and LR images applied with the Maximum A Posteriori(MAP) reconstruction method which is one of the major methods in the super resolution grid construction. Based on the MAP method, we reconstructed high resolution images from low resolution images and compared the results with those from other known interpolation methods.

• Proceedings of the Korea Information Processing Society Conference
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• 2014.04a
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• pp.77-80
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• 2014

최근 컴퓨터와 인터넷 이용의 확산, 스마트폰을 포함한 스마트 기기의 보급과 소셜 네트워크 이용의 확대, 위치 기반의 다양한 서비스 확대 등으로 처리해야 할 데이터 크기가 증가하는 추세이다. 이에 따라 대용량 데이터에 대한 처리가 큰 이슈로 떠오르고 있다. 그로 인해 대용량 데이터 처리를 위한 큰 규모의 분산 컴퓨팅 환경을 지원하는 프레임워크인 하둡이 개발되었으며 많은 기업에서 이를 활용하고 있는 추세이다. 하지만 대용량 데이터 중 영상, 의료, 센서 데이터 등 다차원 데이터 처리에 관한 연구는 미비한 상태이다. 기존의 다차원 데이터 처리를 위해 다양한 다차원 인덱스가 제안되었지만, 대용량 다차원 데이터 처리는 단일머신에서는 비효율적인 단점이 있다. 본 논문에서는 다차원 인덱스 기법인 그리드 파일을 하둡의 분산 병렬 처리 모델인 맵리듀스를 기반으로 생성하는 기법을 제안한다. 또한 앞서 생성된 그리드 파일을 가지고 맵리듀스를 이용한 질의처리 방법을 제안 한다. 이로 인해 단일머신에서의 그리드 파일 생성을 병렬처리 함으로써 생성 시간을 단축시키고 질의 처리 또한 맵리듀스를 이용하여 병렬 처리 함으로써 질의 시간 단축을 예상한다.

• Journal of the Korean Society for Nondestructive Testing
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• v.31 no.5
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• pp.479-486
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• 2011

In image-based CFD modeling of carotid bifurcation hemodynamics, it is often not possible (or at least not convenient) to impose measured velocity profiles at the common carotid artery inlet. Instead, fully-developed velocity profiles are usually imposed based on measured flow rates. However, some studies reported a pronounced influence of inflow boundary conditions that were based on actual velocity profiles measured by magnetic resonance imaging which showing the unusual presence of a high velocity band in the middle of the vessel during early diastole inconsistent with a Dean-type velocity profile. We demonstrated that those velocity profiles were induced by the presence of modest secondary curvature of the inlet and set about to test whether such more "realistic" velocity profiles might indeed have a more pronounced influence on the carotid bifurcation hemodynamics. We found that inlet boundary condition with axisymmetric fully-developed velocity profile(Womersley flow) is reasonable as long as sufficient CCA inlet length of realistic geometry is applied.

• Korean Journal of Digital Imaging in Medicine
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• v.13 no.1
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• pp.49-53
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• 2011

Dynamic range on the digital detector can be a representation to the ratio of maximum and minimum of pixel value. Wide dynamic range and post processing ability of the digital detector made difficult to recognize visually to high or low dose images. We were evaluated a change of mean pixel value on the original and processed image, when we controlled the kVp, mA, exposure time on the digital detector. On the kVp of a constant condition, we were acquired an original and processed image by changes of mA, exposure time. According to the thickness of the subject under the same conditions, to determine a relation of pixel value and X-ray intensity, we used an aluminum step wedge. When mA and exposure times were changed under the kVp of a constant condition, the X-ray intensity was decreased by the reduction of the mean pixel value. In addition when kVp was increased in a constant condition of mAs, the mean pixel value was increased according to the increment of the X-ray intensity. Therefore, low kVp, high mA and short exposure time were a way to reduce a patient dose.

• Journal of Broadcast Engineering
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• v.17 no.1
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• pp.73-80
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• 2012

Recently, medical equipments are developed and used for diagnosis or studies. In addition, demand of techniques which automatically deal with three dimensional medical images obtained from the medical equipments is growing. One of the techniques is automatic bone segmentation which is expected to enhance the diagnosis efficiency of osteoporosis, fracture, and other bone diseases. Although various researches have been proposed to solve it, they are unable to be used in practice since a size of the medical data is large and there are many low contrast boundaries with other tissues. In this paper, we present a fast and accurate automatic framework for bone segmentation based on multi-resolutions. On a low resolution step, a position of the bone is roughly detected using constrained branch and mincut which find the optimal template from the training set. Then, the segmentation and the registration are iteratively conducted on the multiple resolutions. To evaluate the performance of the proposed method, we make an experiment with femur and tibia from 50 test knee magnetic resonance images using 100 training set. The proposed method outperformed the constrained branch and mincut in aspect of segmentation accuracy and implementation time.