• 한국가시화정보학회:학술대회논문집
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• 2001.12a
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• pp.123-137
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• 2001

PIV (particle image velocimetry) systems use a camera to take snapshots of particles carried by a fluid at some precise instants. Signal processing methods are then used to compute the flow velocity field. In this paper, the design of the camera objective (optics) is addressed. The optimization is done in order to maximize the signal-to-noise ratio of in-focus particles. Four different kinds of noise are considered: photon shot noise, thermal and read noise, background glow shot noise, and noise made by the other particles. A semi-empirical model for the lens aberrations of a two-doublet objective is first addressed, since further, it is shown that lens aberrations (low f-value $f_{\#}$) should be used instead of the Fraunhofer diffraction (high f-value) for the fitting of the particle image size with the pixel size. Other important conclusions of the paper include the expression of optimum values for the magnification M, for the exposure period $\tau$ and for the pixel size $\xi$.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.61 no.6
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• pp.872-878
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• 2012

It is quite important to improve the visual acuity of a medical image by suppressing noisy parts and simultaneously keeping the details of signal components to draw the accurate diagnostics. With this aim, we suggest a novel method to generate Rotational Kernel Transformation (RKT) filter mask with applying Bresenham's algorithm and implement an nonlinear filtering algorithm to eliminate noises. As a result, we can find the fact that RKT filter mask can be automatically created and the visual acuity of a corrupted image can be elevated in terms of the signal-to-noise ratio (SNR) with applying the RKT filter.

• Proceedings of the KOSOMBE Conference
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• v.1998 no.11
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• pp.305-306
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• 1998

In this paper, we infer the onset of the brain infarction from the MR image using evaluate signal intensities on diffusion weighted and turbo spin echo T2-weighted and FLAIR images. Infarcts were divided into four stages (hyperacute, acute, subacute, chronic) depending on period of onset. DWI is useful for the detection of early ischemic infarct, and stages of ischemic infarctions can be estimated by evaluating CR(conspicuity ratio) and CNR(contrast to noise ratio) on DW, T2, FLAIR images Hyperacute infarcts were visualized DWI. Acute infarcts were visualialized both DWI and T2 Weighted image.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.17 no.2 s.119
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• pp.160-167
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• 2007

In this study, the influences of environmentally friendly visual and auditory information on traffic noise perception were surveyed by the using electroencephalogram. Green rural region image and CBD (central business district) image in urban city were used as visual informations. And traffic noise, signal and environmental music were used to detect the impact on electroencephalogram variance. It was revealed that green rural region image caused ${\alpha}-wave$ ratio increase about 10% and environmental music increased ${\alpha}-wave$ ratio approximately $40{\sim}50%$. The results of this study improved that environmentally friendly visual and auditory information had an effect on decreasing traffic noise loudness to some extents.

• Journal of Biomedical Engineering Research
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• v.17 no.4
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• pp.545-552
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• 1996

Researches on chromosome are very significant in cytogenetics since a gene of the chromosome controls revelation of the inheritance plasma The human chromosome analysis is widely used to diagnose genetic disease and various congenital anomalies. Many researches on automated chromosome karyotype analysis has been carried out, some of which produced commercial systems. However, there still remains much room for improving the accuracy of chromosome classification. In this paper, we propose an algorithm for reconstruction of the chromosDme image to improve the chromosome classification accuracy. Morphological feature parameters are extracted from the reconstructed chromosome images. The reconstruction method from chromosome image is the 32 direction line algorithm. We extract three morphological feature parameters, centromeric index(C.I.), relative length ratio(R.L.), and relative area ratio(R.A.), by preprocessing ten human chromosDme images. The experimental results show that proposed algorithm is better than that of other researchers'comparing by feature parameter errors.

• Proceedings of the KOSOMBE Conference
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• v.1996 no.11
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• pp.169-172
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• 1996

In this paper, we present the evaluation of signal to noise ratio(SNR) and images of Magnetic resonance imaging system which is underdevelopement. For the evaluation of such parameters, we used two different phantoms, one for SNR and image homogeneity, and the other is for the slice thickness measurement. Further, comparison with other leading MR systems may be needed for the better image quality assessment.

• Journal of the Korean Society of Industry Convergence
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• v.3 no.4
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• pp.369-378
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• 2000

Conventional fractal image compression methods have many problems in searching time for matching domain block. Proposed method is an improved method of Fisher's Quadtree Decomposition in terms of time, compression ratio, and PSNR. This method determines range block in advance using QR algorithm. First, input image is partitioned to $4{\times}4$ range block and then recomposition is performed from bottom level to specified level. As a result, this proposed method achieves high encoding and decoding speed, high compression ratio, and high PSNR than Fisher's Quadtree Decomposition method.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.15 no.4
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• pp.1-7
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• 2006

Injection molding is a very important industrial process for the manufacturing of plastics objects. During an injection molding process of composites, the fiber-matrix separation and fiber orientation are caused by the flow of molten polymer/fiber mixture. As a result, the product tends to be nonhomogeneous and anisotropic. Hence, it is very important to clarify the relations between separation orientation and injection molding conditions. So far, there is no research on the measurement of fiber orientation using image processing. In this study, the effects of fiber content ratio and molding condition on the fiber orientation-angle distributions are studied experimentally. Using the image processing method, the fiber orientation distribution of weld-line in injection-molded products is assessed. And the effects of fiber content and injection mold-gate conditions on the fiber orientation are also discussed.

• Journal of the Optical Society of Korea
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• v.18 no.1
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• pp.89-94
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• 2014

It is established that the perceived image contrast is affected by surround luminance. In order to get the same perceived image contrast, the optimum surround compensation ratios for those surround conditions is needed. Much research has been performed for dark, dim, and average surrounds. In this study, a wide range of surround luminance from dark up to $2087cd/m^2$ was considered. Using magnitude estimation method, the change in perceived brightness of six test stimuli was measured under seven surround conditions; dark, dim, 2 levels of average, bright, and 2 levels of over-bright surrounds. To drive the perceived image contrast from the perceived brightness, two different definitions of contrast were tested. Their calculated results were compared with the visual data of our previous work. And to conclude, the perceived contrast compensation ratios were 1:1.11:1.2 for average, dim and dark surrounds. These were close to CIECAM02 model (1:1.17:1.31). Besides, for average, bright, over-bright1 and over-bright2 surrounds the ratios 1:1.17:1.42:1.69 were determined. For intermediate or more extreme surround conditions, the compensation ratio was obtained from the linear interpolation or extrapolation.

• Journal of the Korean Society of Visualization
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• v.20 no.1
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• pp.11-17
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• 2022

Among the various factors that cause the performance decrease of heat exchangers used in many industries, flow path blocking is one of the important and serious factor. In order to solve this problem, proper maintenance and management of the heat exchanger is important and emphasized. In this study, we developed and algorithm that can quantitatively determine and diagnose the normal and blocked areas of fin-tube heat exchanger using pattern analysis, Gaussian Edge Detection, Image Processing and Affine Transformation techniques. The developed algorithms was applied to the actual heat exchanger and the performance was evaluated by comparing with the manual results. From these results, it was proved that the developed algorithm is effective in evaluating the pollution ratio of the fin-tube heat exchanger.