• 대한전자공학회논문지SD
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• 제45권6호
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• pp.89-95
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• 2008

본 논문에서는 필터방식 얼굴검출 하드웨어를 저전력 설계하고 그에 따른 전력 소모량을 분석하였다. 얼굴검출 하드웨어는 입력되는 영상에서 얼굴의 위치를 검출하며 내부적으로 6개 모듈과 11개의 모듈 간 버퍼가 삽입되어 각 모듈이 순환 연산한다. 따라서 저전력 설계를 위해 SLEEP 모드와 ACTIVE 모드를 적용하였고, 해당 하드웨어에 모듈별 그리고 레지스터별 클럭게이팅(Clock Gating) 기술을 적용하였다. 추가적으로 모듈간 버퍼는 메모리 파티션을 통해 메모리에서 소비하는 전력양을 줄였으며 게이트 레벨에서도 저전력 설계 기술(Gate level power optimization)을 적용하였다. 이는 삼성 0.18um 공정의 STD130 라이브러리를 사용하여 Synopsis(사)의 Power-Compiler를 통해 구현되었으며 동사의 Prime-Power에 의해 소비 전력량을 측정하였다. 그 결과 저전력 설계 기술을 적용하기 전과 비교하여 ACTIVE 모드일 경우 약 68%의 전력 소모를 줄였다.

• Investigative Magnetic Resonance Imaging
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• 제21권4호
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• pp.223-232
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• 2017

Purpose: To report the use of multiband accelerated echo-planar imaging (EPI) for resting-state functional MRI (rs-fMRI) to achieve rapid high temporal resolution at 3T compared to conventional EPI. Materials and Methods: rs-fMRI data were acquired from 20 healthy right-handed volunteers by using three methods: conventional single-band gradient-echo EPI acquisition (Data 1), multiband gradient-echo EPI acquisition with 240 volumes (Data 2) and 480 volumes (Data 3). Temporal signal-to-noise ratio (tSNR) maps were obtained by dividing the mean of the time course of each voxel by its temporal standard deviation. The resting-state sensorimotor network (SMN) and default mode network (DMN) were estimated using independent component analysis (ICA) and a seed-based method. One-way analysis of variance (ANOVA) was performed between the tSNR map, SMN, and DMN from the three data sets for between-group analysis. P < 0.05 with a family-wise error (FWE) correction for multiple comparisons was considered statistically significant. Results: One-way ANOVA and post-hoc two-sample t-tests showed that the tSNR was higher in Data 1 than Data 2 and 3 in white matter structures such as the striatum and medial and superior longitudinal fasciculus. One-way ANOVA revealed no differences in SMN or DMN across the three data sets. Conclusion: Within the adapted metrics estimated under specific imaging conditions employed in this study, multiband accelerated EPI, which substantially reduced scan times, provides the same quality image of functional connectivity as rs-fMRI by using conventional EPI at 3T. Under employed imaging conditions, this technique shows strong potential for clinical acceptance and translation of rs-fMRI protocols with potential advantages in spatial and/or temporal resolution. However, further study is warranted to evaluate whether the current findings can be generalized in diverse settings.

• 비파괴검사학회지
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• 제29권1호
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• pp.1-9
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• 2009

본 연구에서는 균열선단 주위의 응력장을 균열선단으로부터 멀리 떨어진 직선상에서 위상이동 광탄성법과 멱급수형 등각사상 맵핑함수를 이용하여 해석하였다. 해석된 광탄성 응력장을 실제의 광탄성프린지와 비교하였다. 정성적인 비교가 용이하도록 디지털 영상처리에 의해 등색프린지 패턴을 2배로 증식시키고, 증식된 프린지를 다시 세선 처리하여 서로 비교하였다. 정량적인 분석을 위하여 각각의 광탄성 측정 데이터와 계산된 프린지에 대한 퍼센트 오차와 멱급수형 응력함수의 항의 수에 따른 퍼센트 오차에 대한 표준편차를 비교하였다. 응력함수의 항의 수를 변화시켰을 때 표준편차를 계산하였다. 해석 결과 모드I 응력확대계수는 유한요소법과 경험식으로 계산한 값과 2% 이내로 근접하였다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제14권8호
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• pp.3295-3311
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• 2020

With the wide application of hyperspectral images, it becomes more and more important to compress hyperspectral images. Conventional recursive least squares (CRLS) algorithm has great potentiality in lossless compression for hyperspectral images. The prediction accuracy of CRLS is closely related to the correlations between the reference bands and the current band, and the similarity between pixels in prediction context. According to this characteristic, we present an improved CRLS with adaptive band selection and adaptive predictor selection (CRLS-ABS-APS). Firstly, a spectral vector correlation coefficient-based k-means clustering algorithm is employed to generate clustering map. Afterwards, an adaptive band selection strategy based on inter-spectral correlation coefficient is adopted to select the reference bands for each band. Then, an adaptive predictor selection strategy based on clustering map is adopted to select the optimal CRLS predictor for each pixel. In addition, a double snake scan mode is used to further improve the similarity of prediction context, and a recursive average estimation method is used to accelerate the local average calculation. Finally, the prediction residuals are entropy encoded by arithmetic encoder. Experiments on the Airborne Visible Infrared Imaging Spectrometer (AVIRIS) 2006 data set show that the CRLS-ABS-APS achieves average bit rates of 3.28 bpp, 5.55 bpp and 2.39 bpp on the three subsets, respectively. The results indicate that the CRLS-ABS-APS effectively improves the compression effect with lower computation complexity, and outperforms to the current state-of-the-art methods.

• Asian Pacific Journal of Cancer Prevention
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• 제16권9호
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• pp.4109-4114
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• 2015

Background: Full-field digital mammography (FFDM) with dense breasts has a high rate of missed diagnosis, and digital breast tomosynthesis (DBT) could reduce organization overlapping and provide more reliable images for BI-RADS classification. This study aims to explore application of COMBO (FFDM+DBT) for effect and significance of BI-RADS classification of breast cancer. Materials and Methods: In this study, we selected 832 patients who had been treated from May 2013 to November 2013. Classify FFDM and COMBO examination according to BI-RADS separately and compare the differences for glands in the image of the same patient in judgment, mass characteristics display and indirect signs. Employ Paired Wilcoxon rank sum test was used in 79 breast cancer patients to find differences between two examine methods. Results: The results indicated that COMBO pattern is able to observe more details in distribution of glands when estimating content. Paired Wilcoxon rank sum test showed that overall classification level of COMBO is higher significantly compared to FFDM to BI-RADS diagnosis and classification of breast (P<0.05). The area under FFDM ROC curve is 0.805, while that is 0.941 in COMBO pattern. COMBO shows relation of mass with the surrounding tissues, the calcification in the mass, and multiple foci clearly in breast cancer tissues. The optimal sensitivity of cut-off value in COMBO pattern is 82.9%, which is higher than that in FFDM (60%). They share the same specificity which is both 93.2%. Conclusions: Digital Breast Tomosynthesis (DBT) could be used for the BI-RADS classification in breast cancer in clinical.

• 대한조선학회논문집
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• 제47권1호
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• pp.20-29
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• 2010

The complicated flow characteristics of upper propeller wake influenced by hull wake are investigated in detail in the present study. A two-frame PIV (particle image velocimetry) technique was employed to visualize the upper propeller wake region. As the upper hull wake affects strongly propeller inflow, upper propeller wake shows much unstable vortical behavior, especially in the tip vortices. Velocity field measurements were conducted in a cavitation tunnel with a simulated hull wake. Generally, the hull wake generated by the hull of a marine ship may cause different loading distributions on the propeller blade in both upper and lower propeller planes. The unstable upper propeller wake caused by the ship's hull is expressed in terms of turbulent kinetic energy (TKE) and is identified by using the proper orthogonal decomposition (POD) method to characterize the coherent flow structure in it. Instabilities appeared in the eigen functions higher than the second one, giving unsteadiness to the downstream flow characteristics. The first eigen mode would be useful to find out the tip vortex positions immersed in the unstable downstream region.

• Nuclear Engineering and Technology
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• 제44권1호
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• pp.53-60
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• 2012

The aim of this study was to explore the spatial and energy resolutions of a PET scanner that we have recently developed. The scanner, which consists of six detector modules with 1-layer LGSO crystals, has a hexagonal configuration with a faceto- face distance of 86.4 mm between two opposite PET modules; such properties facilitate the imaging of small animals. A $^{22}Na$ point source was employed to estimate horizontal and vertical spatial resolutions. To assess the energy resolution, a uniform $^{18}F$ cylindrical phantom was scanned. A software-based spectrum analysis of list-mode data was used to assign a local energy window centered on the photopeak position for every single crystal. For the image reconstruction, an ML-EM algorithm was used. The spatial resolutions at the center of the scanner were 0.99 mm in the horizontal direction and 1.13 mm in the vertical direction. The energy resolution averaged over each PMT ranged from 13.3%-14.3%, which gave an average value of 13.8%. These results show that this simple system is promising for small animal imaging with excellent spatial and energy resolutions.

• 한국작물학회지
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• 제49권1호
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• pp.36-40
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• 2004

To observe and analysis ultra-microscopically barley aleurone cell surface, atomic force microscope (AFM) was used. Seed coat of early maturing germplasm, eam9, was dehulled and scanned by non-contact mode. We have obtained the high resolution topographic 3-dimensional image of barley aleurone layer with high resolution. These images showed the membrane proteins in barley aleurone cell. One channel protein and numerous peripheral or integral proteins were detected in a area of 100 $\mu\textrm{m}^2$. Furthermore, we found that their widths were ranged from 50 to 750nm and lengths from 0 to 66 $\mu\textrm{m}$. The thickness of aleurone layer was measured by scanning electron microscope. The thickness at early developmental stage was about 16 and then the aleurone cell enlarged upto 57 $\mu\textrm{m}$${\mu}{\textrm}{m}$ at least until 42 days after anthesis. In this study, we firstly reported on the ultrastructural AFM analysis of living aleurone cell as a biological specimen. It was clearly suggested that AFM will become an powerful tool for probing both the structural properties of biological samples.

• International Journal of Vascular Biomedical Engineering
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• 제4권2호
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• pp.25-30
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• 2006

We intended to measure the IT, MT, and the IMT of carotid artery separately and tried to analyze the clinical significance. Two hundred and fifty consecutive patients (125 males, 125 females) underwent carotid artery scanning using high-resolution ultrasound. The images were off-line analyzed using B-mode ultrasound image processing, devised in our research. We measured the IT, MT, and IMT semi-automatically at the far wall of designated 1cm length of the right common carotid and calculated the average values over the 200 points. The IT (p < 0.05), MT (p < 0.05) as well as IMT (p < 0.01) of patients with atherosclerotic disease were significantly thicker than that of the patients without atherosclerotic disease. Patients with hypertension showed significantly thicker IT (p < 0.05), MT (p < 0.01), and IMT (p < 0.01) than that of the patients without hypertension. However, only IT was thicker in patients with smoking (p < 0.05) than that of the patients without smoking. Smoking was associated only with intima while hypertension was associated with the all three layer's thickness. This result suggests the atherosclerotic process can be different by cardiovascular risk factors.

• 대한전자공학회논문지SP
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• 제42권2호
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• pp.151-160
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• 2005

본 논문에서는 연속제거 알고리즘(successive elimination algerian)을 기반으로 하여 H.264 부호화기의 복잡도에서 가장 큰 비중을 차지하는 가변 블록에 대한 움직임 추정을 효율적으로 생략함으로써 고속으로 움직임 벡터를 탐색하는 기법을 제안한다. 제안된 기법은 7가지 모드의 가변 블록에 대하여 기존의 SEA를 계층적으로 적용한다. 즉, SEA를 사용해서 $4\times4$ 블록 단위로 SAD 또는 sum norm을 조합하고 이것을 각 모드의 최소 SAD 값과 비교 검색함으로써 불필요한 SAD 계산을 줄이는 방식이다. 그러므로 SEA의 SAD와 sum norm의 부등 관계에서 경계범위를 좁게 만들 수 있다. 단위 블록의 크기를 $4\times4$ 이하로 할 경우에는 경계 범위를 더욱 좁게 만들 수 있으나 계산량이 증가하는 단점이 있다. 제안된 기법을 적용했을 때에 각 실험영상에 따른 전체적인 계산량은 H.264의 고속 전역 탐색 방식에 비하여 약 $60\%\~70\%$의 일관된 감소가 있었다.