• Journal of the Korean Geotechnical Society
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• v.27 no.7
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• pp.5-16
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• 2011

Digital image analysis techniques have been developed and utilized in the field of solid mechanics and fluid mechanics to measure the deformation and velocity of a target object. The deformation measurement systems based on Particle Image Velocimetry (PIV) and Digital Image Correlation (DIC) have been attempted in geotechnical testings (e.g., physical model tests) for observing the deformation of soils. The digital image analysis is influenced by image pattern of test materials, resolution of the used digital camera, target area, image analysis techniques, and analysis conditions. Therefore, optimal analysis conditions should be determined to obtain high quality results on soil deformations. In the present study, various influence factors on the digital image analysis were described and summarized. The optimizing procedure for high accurate results was then proposed. Finally, the applicability of the developed procedure was examined.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.38 no.3
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• pp.247-257
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• 2001

New methods are proposed for printing a full resolution image on a limited output device. The proposed algorithm uses a dot-pattern database that models overlapping phenomena among neighbor printing dots. To solve the problem of dot-overlap, the gray levels of dot-pattern sets were calculated using a circular dot-overlap model and then measured by a spectrometer. Thereafter, in order to improve the visual quality of the color dithering, the contrast sensitivity function of the human visual system was used. As a result, the optimal dot-pattern can be selected from the database. Consequently, the proposed algorithm can produce high quality images while using low-cost color devices.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.41 no.4
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• pp.176-180
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• 2015

Objectives: The increased prevalence of antibiotic resistance is an outcome of evolution. Most patients presenting with odontogenic space infections also have associated systemic co-morbidities such as diabetes mellitus resulting in impaired host defense. The present study aims to compare the odontogenic spaces involved, antibiotic susceptibility of microorganisms, length of hospital stay, and the influence of systemic comorbidities on treatment outcome in diabetic patients. Materials and Methods: A 2-year prospective study from January 2012 to January 2014 was conducted on patients with odontogenic maxillofacial space infections. The patients were divided into two groups based on their glycemic levels. The data were compiled and statistically analyzed. Results: A total of 188 patients were included in the study that underwent surgical incision and drainage, removal of infection source, specimen collection for culture-sensitivity, and evaluation of diabetic status. Sixty-one out of 188 patients were found to be diabetic. The submandibular space was the most commonly involved space, and the most prevalent microorganism was Klebsiella pneumoniae in diabetics and group D Streptococcus in the nondiabetic group. Conclusion: The submandibular space was found to be the most commonly involved space, irrespective of glycemic control. Empiric antibiotic therapy with amoxicillin plus clavulanic acid combined with metronidazole with optimal glycemic control and surgical drainage of infection led to resolution of infection in diabetic as well as nondiabetic patients. The average length of hospital stay was found to be relatively longer in diabetic individuals.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.49 no.4
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• pp.36-44
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• 2012

Electrical impedance tomography is a relatively new imaging modality in which the internal conductivity (or resistivity) distribution of a object is reconstructed based on the injected currents and measured voltages through the electrodes placed on the surface of the object. In this paper, it is assumed that the relationship between the resistivity distribution and the resistance of electrodes is linear. From this linear relation, the weighting matrix can be obtained and modified iterative Landweber method is applied to estimate the internal resistivity distribution. Additionally, to accelerate the convergence rate and improve the spatial resolution of the reconstructed image, optimal step lengths for the iterative Landweber method are computed from the objective function in the least-square sense. The numerical experiments have been performed to illustrate the superior reconstruction performance of the proposed scheme.

• Journal of radiological science and technology
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• v.43 no.4
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• pp.251-257
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• 2020

This study was purpose to quantitative evaluation of edge method of modulation transfer function(MTF) and physical image characteristics of by obtain the optimal edge image by using magnetic resonance imaging(MRI). The MRI equipment was used (MAGNETOM Vida 3.0T MRI, Siemense healthcare system, Germany) and the head/neck matrix shim MR coil were 20 channels(elements) receive coil. The MTF results of showed the best value of 0.294 based on the T2 Nyquist frequency of 1.0 mm^-1. The MTF results of showed that the T1 image is 0.160, the T1 CE image is 0.250, T1 Conca2 image is 0.043, and the T1 CE (Concatenation) Conca2 image is 0.190. The T2 image highest quantitatively value for MTF. The physical image characteristics of this study were to that can be used efficiently of the MRI and to present the quantitative evaluation method and physical image characteristics of 3.0T MRI.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.15 no.2
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• pp.137-146
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• 1990

A series of images whose sized and resolutions differ by a constant factor are called an image pyramid. Because the images at high levels are small, large object can be detected on high levels of the pyramid at low cost, But in this way, the boundaries of objects are not accurately localized. Therefore the pyramid algorithms extracte the objects by segmentation the constructed image using bottom-up method and description it in an original resolution using inverse bottom-up method. In this paper, we can project an object down to the next lower level of the pyramid and apply to the boundary adjustment algorithm at that level to localize it more precisely. We repeat the process at successively lower levels. In this paper, we present a method of boundary adjustment using an image pyramid to obtain optimal boundary. The performance of the proposed algorithm is compared to those of the conventional method in term of subjective quality of object boundary.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.2
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• pp.829-834
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• 2011

Exposure process is the most important technology to fabricate highly integrated circuit. Up to now, mask type lithography process has been generally used. However, it is not efficient for small quantity and/or frequently changing products. Therefore, maskless lithography technology is raised in exposure process. In this study, relations between multi-beam energy and overlay were analyzed. Exposure experiment of generating pattern was performed. It was from presented scan line by multi- beam simulation. As a result, optimal scan line distance was proposed by simulation, and micro pattern accuracy could be improved by exposure experiment using laser direct imaging system.

• The Journal of Engineering Geology
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• v.14 no.1
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• pp.21-28
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• 2004

Three-dimensional (3-D) resistivity inversion including a topographic effect can be considered theoretically to be the technique of acquiring the most accurate image in the interpretation of resistivity data, because it includes characteristic image that the actual subsurface structure is 3-D. In this study, a finite-element method was used as the numerical method in modeling, and the efficiency of Jacobian calculation has been maximized with sensitivity analysis for the destination block in inversion process. Also, during the iterative inversion, the resolution of inversion can be improved with the method of selecting the optimal value of Lagrange multiplier yielding minimum RMS(root mean square) error in the parabolic equation. In this paper, we present synthetic examples to compare the difference between the case which has the toprographic effect and the other case which has not the effect in the inversion process.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.18 no.2
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• pp.329-334
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• 2014

This paper proposes the hardware architecture of high performance multi-mode 2D forward transform for HEVC which has same number of cycles for processing any type of four TUs and yield high throughput. In order to make the original image which has high pixel and high resolution into highly compressed image effectively, the transform technique of HEVC supports 4 kinds of pixel units, TUs and it finds the optimal mode after performs each transform computation. As the proposed transform engine uses the common computation operator which is produced by analyzing the relationship among transform matrix coefficients, it can process every 4 kinds of TU mode matrix operation with 35cycles equally. The proposed transform block was designed by Verilog HDL and synthesized by using TSMC 0.18um CMOS processing technology. From the results of logic synthesis, the maximum operating frequency was 400MHz and total gate count was 214k gates which has the throughput of 10-Gpels/cycle with the $4k(3840{\times}2160)@30fps$ image.

• Journal of radiological science and technology
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• v.33 no.4
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• pp.355-362
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• 2010

This study determines a range of CT parameter values in Brain CT which are minimizing patient absorption dose without compromising the image quality and optimal exposure condition. We measured dose and image noise using conventional CT parameters in Brain CT. In additon, we evaluated dose, SNR and PSNR of head phantom images while changing kVp and rotation time. In this study, effectiveness of dose that was achieved from dose reproducible experiments in conventional head CT condition is determined by changing kVp and rotation time. Dose and PSNR is related to low dose-high resolution condition. In conclusion, we suggest that using proposed conditions is effective for imaging to compare with conditions proposed by the manufacturer.