• 핵의학기술
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• 제16권2호
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• pp.99-105
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• 2012

Purpose : This study is designed to compare two parameters reflecting $^{18}F$-FDG uptake, SUV and radioactivity, for diagnosis of thyroid cancer in dual time $^{18}F$-FDG PET/CT imaging and to find which parameter is more useful to decide whether the tumor is malignant or not. Materials and Methods : We performed retrospective study for 40 patients. All patients are diagnosed as primary thyroid cancer and examined $^{18}F$-FDG PET/CT. First, we got the dispersion of scattering beam of neck and lung apex to set a background and compared each dispersion, mean value, standard deviation of maxSUV and radioactivity. Also, mean maxSUV, ${\Delta}maxSUV$, ${\Delta}maxBq$/ml(%) and radioactivity between groups according to lesion's size based on biopsy are compared with independent-sample t-test. Results : the values that were from maxSUV and radioactivity measurement technique were compensated and calculated to practical values for mean comparison and patients were divided to two groups based on tumor size, Group1 ($size{\leq}1$ cm, n=21), Group2 (size>1 cm, n=19) for accurate comparison. In Group1, maxSUV (semi-quantitative analysis) was increased from $5.64{\pm}5.85$ (1.89~17.84) at first image to $5.90{\pm}5.01$ (1.95~18.22) at second image and radioactivity (Bq/ml) (quantitative analysis) showed similar increase from $5.93{\pm}6.38$ (2.50~16.75) at first image to $6.01{\pm}5.25$ (2.66~16.58) at second image. In Group2, TFmaxSUV was $10.54{\pm}14.36$ (2.54~33.89) in true first image, TSmaxSUV was $9.85{\pm}12.88$ (2.62~26.20) in true second image separately. The maxSUV showed a significant difference in the mean comparison between the two groups (p=0.035) But, mean radioactivity (Bq/ml) was $5.93{\pm}6.38$ (4.81~40.99) in true first image, $6.01{\pm}5.25$ (4.51~36.93) in true second image and didn't show a significant difference statistically (p=0.126) Conclusion : In diagnosis of thyroid tumor, SUV and radioactivity depending on $^{18}F$-FDG uptake showed high similarity with coefficient of determination (R2=0.939) and malignant evaluation results using dual time also showed similar aspect. Radioactivity for evaluation of malignant tumor didn't show better specificity or sensitivity than maxSUV.

• Korean Journal of Radiology
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• 제22권6호
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• pp.951-958
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• 2021

Objective: To evaluate the usefulness of virtual monochromatic images (VMIs) obtained using dual-layer dual-energy CT (DL-DECT) for evaluating brain tumors. Materials and Methods: This retrospective study included 32 patients with brain tumors who had undergone non-contrast head CT using DL-DECT. Among them, 15 had glioblastoma (GBM), 7 had malignant lymphoma, 5 had high-grade glioma other than GBM, 3 had low-grade glioma, and 2 had metastatic tumors. Conventional polychromatic images and VMIs (40-200 keV at 10 keV intervals) were generated. We compared CT attenuation, image noise, contrast, and contrast-to-noise ratio (CNR) between tumor and white matter (WM) or grey matter (GM) between VMIs showing the highest CNR (optimized VMI) and conventional CT images using the paired t test. Two radiologists subjectively assessed the contrast, margin, noise, artifact, and diagnostic confidence of optimized VMIs and conventional images on a 4-point scale. Results: The image noise of VMIs at all energy levels tested was significantly lower than that of conventional CT images (p < 0.05). The 40-keV VMIs yielded the best CNR. Furthermore, both contrast and CNR between the tumor and WM were significantly higher in the 40 keV images than in the conventional CT images (p < 0.001); however, the contrast and CNR between tumor and GM were not significantly different (p = 0.47 and p = 0.31, respectively). The subjective scores assigned to contrast, margin, and diagnostic confidence were significantly higher for 40 keV images than for conventional CT images (p < 0.01). Conclusion: In head CT for patients with brain tumors, compared with conventional CT images, 40 keV VMIs from DL-DECT yielded superior tumor contrast and diagnostic confidence, especially for brain tumors located in the WM.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2007년도 Proceedings of ISRS 2007
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• pp.203-206
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• 2007

The Space-borne electro-optical camera system has panchromatic redundant image channel as well as primary channel in order to increase reliability of satellite system. In most case redundant channel never been used during the whole mission period. Staggered array configuration using redundant image channel and new operation mode proposed which operates primary and redundant channel simultaneously. Without new hardware design, fast electronics and system complexity, we can get 1.414 times more fine GSD image of original system or we can get 1.414 times more SNR or High dynamic range imaging mode. In this paper we deal with several image quality improvement methods using dual panchromatic channel.

• 한국방사선학회논문지
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• 제17권6호
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• pp.809-817
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• 2023

뇌출혈 진단 방법 중 CT는 비침습적으로 피사체의 3차원 영상을 제공할 수 있다. 그래서 응급실에서 급성인 환자 상대로 많이 사용되고 중요한 역할을 담당하고 있다. 뇌혈관 CT는 다른 혈관 CT에 비해 비교적 촬영 빈도가 높으며 뇌혈관 CT 검사 시 적절한 SNR, 합리적인 유효선량으로 검사를 해야한다. 뇌혈관 CT 검사 시 이중에너지와 단일에너지를 이용하였을 때 실질적으로 어느 것이 유효선량이 적으며, SNR이 차이가 없는지 환자영상과 Phantom영상을 같이 비교하였다. SNR과 CNR의 P값이 0.05이상일 때 통계적으로 차이가 없다고 보았고, 유효선량은 0.05미만일 경우 통계적으로 차이가 있다고 보았다. 실험에서는 병원영상의 환자선량을 비교하였을 때 이중에너지의 유효선량이 53.53% 적게, Phantom의 OLSD 이중에너지 유효선량이 57.94% 적게, Phantom의 Dose Report의 이중에너지 유효선량이 56.04% 적었다. 그래서 뇌혈관조영 CT는 이중에너지를 권장한다.

• 한국광학회지
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• 제23권6호
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• pp.251-254
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• 2012

이 파장 디지털 홀로그래피는 단파장 디지털 홀로그래피에 비해 보다 큰 단차를 얻는데 사용할 수 있다. 이파장 홀로그래피 방법을 이용하기 위해서는 각각의 파장에서 얻은 홀로그램으로부터 재생된 위상 이미지 크기가 동일하여야하는데, 위상 이미지 크기는 재생거리와 파장에 의존한다. 이러한 문제점을 해결하기 위하여 프레즈렐-불루스타인 변환법이 제안되었다. 이변환법은 재생상의 크기를 재생거리와 파장에 의존하지 않고 자유롭게 만들 수 있다. 본 연구에서는 프레즈렐-불루스타인 변환법을 이파장 홀로그래피에 적용하여 파장에 의존하지 않는 동일한 위상 재생상을 얻을 수 있음을 실험적으로 확인하였다.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2005년도 ICCAS
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• pp.610-615
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• 2005

Visual servoing is the fusion of results from many elemental areas including high-speed image processing, kinematics, dynamics, control theory, and real-time computing. It has much in common with research into active vision and structure from motion, but is quite different from the often described use of vision in hierarchical task-level robot control systems. We present a new approach to visual feedback control using image-based visual servoing with the stereo vision in this paper. In order to control the position and orientation of a robot with respect to an object, a new technique is proposed using a binocular stereo vision. The stereo vision enables us to calculate an exact image Jacobian not only at around a desired location but also at the other locations. The suggested technique can guide a robot manipulator to the desired location without giving such priori knowledge as the relative distance to the desired location or the model of an object even if the initial positioning error is large. This paper describes a model of stereo vision and how to generate feedback commands. The performance of the proposed visual servoing system is illustrated by the simulation and experimental results and compared with the case of conventional method for dual-arm robot made in Samsung Electronics Co., Ltd.

• 대한의용생체공학회:학술대회논문집
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• 대한의용생체공학회 1997년도 추계학술대회
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• pp.294-298
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• 1997

In the magnetic resonance imaging, the fast spin echo imaging technique is a widely used clinical imaging method, since its scanning time is much shorter than the conventional spin echo imaging and it gives the almost same image quality. However, the fast spin echo technique has two times longer imaging time or the dual echo acquisition which can obtain a spin density image and a $T_2$-weighted image simultaneously. To overcome such a drawback, this paper proposes a new fast dual echo imaging technique which can give the same quality images at the single echo imaging time. The proposed technique reduces the imaging time by overlapping most of echo train data for each image reconstruction. In order to verify its validity and usability the human head experimental results which were obtained at the 0.3T permanent MRI system are presented.

• 전자공학회논문지
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• 제51권9호
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• pp.139-147
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• 2014

본 논문에서는 다중객체 검출과 동시에 추적을 수행하는 이중계층구조의 파티클 샘플링을 제안한다. 제안된 방법은 다중 객체 검출을 위한 상위 계층 파티클 샘플링과 검출된 객체의 추적을 위한 하위 계층 파티클 샘플링으로 구성된다. 상위 계층에서는 빠른 객체 검출을 위해 슬라이딩 윈도우 대신 움직임 추정 기반의 부모 파티클 (parent particles; PP) 윈도우를 사용하여, 이동 객체 주위로 리샘플링된 파티클을 통해 객체를 검출한다. 하위 계층에서는 상위 계층에서 검출한 객체의 객체영역에 자식 파티클 (child particles; CP)을 생성하여 해당 객체를 추적한다. 실험결과를 통해 비디오 시스템에서 기존 객체 검출 방법보다 빠른 검출이 가능하고, 다중 객체를 효과적으로 추적할 수 있음을 확인하였다.

• Journal of Advanced Marine Engineering and Technology
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• 제32권8호
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• pp.1231-1239
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• 2008

The characteristics of flow on unventilated dual jets was experimentally investigated. The two nozzles each with an aspect ratio of 20 were separated by 6 nozzle widths. Reynolds number based on nozzle width was set to 5,000 by nozzle exit velocity. All measurements were made over a range of nozzle-to-nozzle angles from $0^{\circ}$ to $25^{\circ}$. The particle image velocimetry and pressure transducer were employed to measure turbulent velocity components and mean static pressure, respectively. It was shown that a recirculation zone with sub-atmospheric static pressure was bounded by the inner shear layers of the individual jets and the nozzles plated. As nozzle-to-nozzle inclined angles were decreased, it was found that the spanwise turbulent intensity is greater than the streamwise turbulent intensity in the merging region. In the combined region, the velocity of dual jets agree well with that of single jet, but the turbulence intensity of dual jets not agree with that of single jet.

• 대한전자공학회논문지SP
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• 제49권4호
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• pp.1-9
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• 2012

출력 장치로 널리 이용되는 LCD(Liquid Crystal Display)는 CRT(Cathod-ray tube)에 비해 그 반응 속도가 느린 단점을 가진다. 이러한 단점으로 인해 시간방향으로 급격한 밝기 변화가 발생하는 영상에서 출력되는 영상이 흐려지는 문제점을 가진다. 반응 속도의 문제점을 극복하기 위해 LCD에서는 오버드라이빙 기술을 TCON에 적용하여 사용하고 있다. 이러한 오버드라이빙을 위해서는 화면에 출력된 이전 영상에 대한 정보를 압축 저장해야 한다. 기존의 8bit HD급을 위한 TCON에서는 TCON의 칩면적과 실시간성을 고려하여 AM-BTC(Absolute Moment Block Truncation Coding)기법을 적용하여 이러한 목적을 달성하고 있다. 하지만 최근에 많은 수요가 예상되는 10 bit Full HD급 대형 LCD에서는 기존에 비교하여 영상 데이터의 양이 많기 때문에 기존의 방법이 적합하지 않다. 기존의 방법을 10 bit Full HD급 대형 LCD에 적용하면 TCON의 칩면적의 증가로 인한 비용이 발생하거나, 화질의 열화를 야기하는 문제점이 있다. 본 논문에서는 이러한 문제점을 개선하기 위해 샘플 블록 내의 형태학적 정보에 적응적인 이원적 구조를 가지는 Dual BTC기법을 제안한다. 실험을 통해 제안된 Dual BTC기법이 기존의 AM-BTC기법 보다 정량적 측면과 정성적 측면에서 성능이 우수함을 확인하였다.