• Journal of the Korea Institute of Information and Communication Engineering
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• v.4 no.2
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• pp.371-378
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• 2000

In this study, we proposed pathological pattern detection system for X-ray chest image using artificial neural network. In a physical examination, radiologists have checked on the chest image projected the view box by a magnifying glass and found out what the disease is. Here, the detection of X-ray fluoroscopy is tedious and time-consuming for human doing. Lowering of efficiency for chest diagnosis is caused by lots mistakes of radiologist because of detecting the micro pathology from the film of small size. So, we proposed the method for disease detection using artificial neural network and digital image processing on a X-ray chest image. This method composes the function of image sampling, median filter, image equalizer used neural network and pattern recognition used neural network. We confirm this method has improved the problem of a conventional method.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.37 no.7C
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• pp.601-609
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• 2012

In this paper, a limited-view CT image reconstruction method was studied to reduce the scan times and the X-ray dose for the patients. To reduce streak artifacts which is caused by insufficient number of views, we introduce a sinogram interpolation method based on image matching. Image matching is achieved using the characteristics of the neighboring views including intensity, gradient and distance between the pixels. Interpolation is performed using the image matching results.. A numerical phantom and Al-acryl phantom were used for evaluating the effectiveness of the proposed interpolation method. The results showed that streak artifacts were reduced in the reconstructed images while the details of the images were preserved. Moreover, maximum 5% improvements in terms of PSNR were observed.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.5 no.4
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• pp.829-840
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• 2001

In this study, we propose a method for quantifying the degree of advance of pulmonary emphysema by using chest X-ray images. With this method, we devise two schemes for this purpose. One is for detecting blood vessels by using a deformable model with the tree-like structure and using an evaluation function specialized by knowledge about blood vessels appeared in chest X-ray images, and the other is for quantifying the degree of advance by using several features, which were extracted from blood vessels, and the equation of quantitative evaluation. In order to evaluate the performance, we applied the proposed method to 189 ROIs(Regions of Interest) of ten chest X-ray images and compared the values by the proposed method with those by a medical doctor.

• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.1933_1934
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• 2009

This research is about the remote control of the infra-ray signal producer and the received signal memory-type control unit. Also by using the infra-ray signal from the remote control, reduction of malfunctions due to infra-ray signal from other devices are presented. Applications on various electric and electronic items to improve the convenience are also shown.

• Proceedings of the KIEE Conference
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• 1987.07b
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• pp.1073-1076
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• 1987

In this paper, a new ray tracing algorithm which uses space subdivision method is introduced. In order to reduce huge number of ray-surface intersection calculation, the space is subdivided as lattice that contains minimum number of objects. With lattice structure, the process that calculates unnecessary ray-surface intersection is eliminated.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.3C
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• pp.157-170
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• 2006

Downhole method is considered as giving a little unreliable Vs profile when the signal to noise ratio(S/N) is low and the travel time information is erroneous although it is economical and ease of operation. Direct method has been applied for obtaining adequate result in this case. But it is difficult to determine optimum result by using direct method which is subjective and considering straight ray path. Therefore, in this paper, Mean Refracted Ray Path Method(MRM) was proposed, which is automated and considering refracted ray path. Artificial travel time data adding some travel time error was generated by forward modeling based on Snell's Law and travel time data was also obtained from numerical signal traces using FEM modelling. Using these travel time data, reliability of MRM was verified in the manner of comparing the results determined by MRM with the model. Finally, proposed method was applied to the real field data and it was considered as improved method for obtaining the optimum result in downhole seismic method.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.05a
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• pp.52-55
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• 2002

In this research, the modification method of spherical aberration, and aspherical lens shape design method were investigated. Spherical aberration affects lens's performance directly. Many studies have attempted to remove spherical aberration with a lot of methods in order to reduce the bad effect of spherical aberration. The approach to lens shape design was base on the ray tracing method. From the result, it was confirmed that ray reverse-tracing method was convenient to remove spherical aberration, and could be used very effectively and usefully for aberration-free aspherical lens design.

• The Journal of Korea Robotics Society
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• v.5 no.4
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• pp.302-308
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• 2010

A gradient method can provide a global optimal path in indoor environments. However, the optimal path can be often generated in narrow areas despite a sufficient wide area which lead to safe navigation. This paper presents a novel approach to path planning for safe navigation of a mobile robot. The proposed algorithm extracts empty regions using a ray-casting method and then generates temporary waypoints in wider regions in order to reach the goal fast and safely. The experimental results show that the proposed method can generate paths in the wide regions in most cases and the robot can reach the goal safely at high speeds.

• Current Optics and Photonics
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• v.4 no.1
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• pp.23-30
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• 2020

This paper presents a new method for designing a lens system stable against chromatic variation at a specified wavelength. Conventional lenses are corrected for chromatic aberration, but the new method suppresses chromatic changes of the marginal ray in the image-side. By doing so, paraxial properties of the lens system are stabilized against chromatic variation. Since the new method is based on paraxial ray tracing, the stabilizing conditions against chromatic variation are given by recurrence formulas. However, there is an analytic solution for the case of a cemented doublet in the air. A stable doublet at 405 nm wavelength is designed and analyzed.

• Proceedings of the KSR Conference
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• 2000.11a
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• pp.157-164
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• 2000

This study is about predicting the interior pressure level of the korean high speed train using ray acoustic method. The motor car and the motor and passenger cabin are investigated under the environment of passing open countryside and inside tunnel of 350 km/hr. Calculated sound levels are compared with the proposed sound levels and suggestions about the transmission Joss values of isolating panels inside motor car and the guide lines of allowed sound power limit of motor equipments are provided. Results of TPI car show calculated interior sound level is below the proposed values for both cases of open countryside running and inside tunnel. Since ray acoustic method calculated only air borne noise component, real sound level of the motor car may be higher than prediction. Passenger cabins of TMI, TM5 show higher sound level than the proposed values, so window method was carried out to find the contribution of each panel components and point out the remedy of transmission path. Reduction of sound power of motor equipments should be condisered at the same time.