• The Journal of Korean Institute of Communications and Information Sciences
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• v.27 no.6B
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• pp.638-644
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• 2002

In this paper, we implemented a three dimensional image display system using stereogram and holographic optical memory techniques which can store many images and reconstruct them automatically. In this system, to store and reconstruct stereo images, incident angle of reference beam must be controlled in real time, so we used BPH(binary phase hologram) and LCD(liquid crystal display) for controlling reference beam. The reference beams are acquired by Fourier transform of BPHs which designed with SA(simulated annealing)algorithm, and the BPHs are represented on the LCD with the 0.05 seconds time interval using application software for reconstructing the stereo images. And input images are represented on the LCD without polarizer/analyzer for maintaining uniform beam intensities regardless of the brightness of input images. The input images and BPHs are edited using application software(Photoshop) with having the same recording scheduled time interval in storing. The reconstructed stereo images are acquired by capturing the output images with CCD camera at the behind of the analyzer which transforms phase information into brightness information of images. In output plane, we used a LCD shutter that is synchronized to a monitor that display alternate left and right eye images for depth perception. We demonstrated optical experiment which store and reconstruct four stereo images in BaTiO$_3$ repeatedly using the proposed holographic optical memory techniques.

• Korean Journal of Materials Research
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• v.8 no.8
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• pp.720-725
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• 1998

As a basic study on the production of $Sm_{2}Fe_{17}N_{x}$ system rare earth permanent magnet by the reduction and diffusion(R- D) process, firstly the reduction reaction of $Sm_2O_3$ by metallic Ca and diffusion of Sm into Fe powder was investigated for the production the $Sm_{2}Fe_{17}$intermetallic compound. We concluded that the former case was very rapidly completed under the high temperature greater than 100$0^{\circ}C$ and the latter case of completion of diffusion reaction of Sm into the center of Fe powder(perfect homogenization condition) was required through 3h R- D reaction at 110$0^{\circ}C$ and identified as a rate determining step(RDS) on the whole reaction. Though $SmFe_2,SmFe_3$, and $Sm_{2}Fe_{17}$phases in the growth of phases of intermetallic compound in the Sm - Fe binary system were obseved below 100$0^{\circ}C$, but only $Sm_{2}Fe_{17}$phase was observed at lIOO$^{\circ}C$. Oxygen and Ca contents of the final sample in this work were 0.72wt% and O. 11 wt% respectively.

• The KIPS Transactions:PartB
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• v.12B no.7 s.103
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• pp.729-736
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• 2005

In this paper. the proposed method for the digital watermarking is based on the multiresolution wavelet transform. The 1-level Discrete Wavelet Transform(DWT) coefficients of a $2N_{wx}{\times}2N_{wy}$ binary logo image used as a watermarks. The LL band and middle frequency band of the host image that the 3-level DWT has been performed are divided into $N_{wx}{\times}N_{wy}$ size and we use large coefficients at the divided blocks to make threshold. we set the thresholds that completely insert the watermark in each frequency of the host image. The thresholds in each frequency of the host image differ each other. The watermarks where is the same positions are added to the larger coefficients than threshold in the blocks at LL band and middle frequency band in order to prevent the quality deterioration of the host image. The watermarks are inserted in LL band and middle frequency band of the host image. In order to be invisibility of the watermark, the Human Visual System(HVS) is applied to the watermark. We prove the proper embedding method by experiment. We rapidly detect the watermark using this watermarking method. And because the small size watermarks are inserted by HVS, the results confirm the superiority of the proposed method on invisibility and robustness.

• Journal of radiological science and technology
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• v.33 no.2
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• pp.97-107
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• 2010

The objectives of this study is to figure out the unknown image processing methods of commercial CR system. We have implemented the processing curve of each Look up table(LUT) in REGIUS 150 CR system by using virtual digital test pattern method. The characteristic of Dry Imager was measured also. First of all, we have generated the virtual digital test pattern file with binary file editor. This file was used as an input data of CR system (REGIUS 150 CR system, KONICA MINOLTA). The DICOM files which were automatically generated output files by the CR system, were used to figure out the processing curves of each LUT modes (THX, ST, STM, LUM, BONE, LIN). The gradation curves of Dry Imager were also measured to figure out the characteristics of hard copy image. According to the results of each parameters, we identified the characteristics of image processing parameter in CR system. The processing curves which were measured by this proposed method showed the characteristics of CR system. And we found the linearity of Dry Imager in the middle area of processing curves. With these results, we found that the relationships between the curves and each parameters. The G value is related to the slope and the S value is related to the shift in x-axis of processing curves. In conclusion, the image processing method of the each commercial CR systems are different, and they are concealed. This proposed method which uses virtual digital test pattern can measure the characteristics of parameters for the image processing patterns in the CR system. We expect that the proposed method is useful to analogize the image processing means not only for this CR system, but also for the other commercial CR systems.

• Journal of KIISE:Databases
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• v.31 no.5
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• pp.527-539
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• 2004

As more and more documents are published in XML, generating relational schemas to store XML documents in a relational database is also getting important. This paper describes a technique as well as its implementation to produce a relational schema from the XML Schema, a standard recently recommended by W3C. The DTD-based inlining technique cannot be applied to the XML Schema, because the XML Schema has many new features, which don't exist in the DTD. Various built-in data types, inheritance, and polymorphism, for example, strengthen the XML Schema, but make the generation of a relational schema from an XML Schema more difficult. We propose an XML Schema Inlining Technique, based on the previous work. The technique first maps various data types in the XML Schema to those of the relational database. After that, it construct the schema graph and the type graph from types and elements defined in the XML Schema. The relational schema is generated while traversing the type graphs. Besides, we describe techniques for handling xsi：type, used for the polymorphism, and the anon#moos type. We also propose a couple of heuristic methods for enhancing the performance of the system. Finally, we conducted experiments to show that our technique is better than the binary table approach.

• Journal of the Korean institute of surface engineering
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• v.41 no.5
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• pp.181-188
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• 2008

A.C. impedance properties of HA/Ti compound layer coated Ti-30Ta-($3{\sim}15$)Nb alloys have been studied by electrochemical method. Ti-30Ta binary alloys contained 3, 7, 10 and 15 wt% Nb were manufactured by the vacuum furnace system. And then specimen was homogenized at $1000^{\circ}C$ for 24 hrs. The sample was cut and polished for corrosion test and coating. It was coated with HA/Ti compound layer by magnetron sputter. The non-coated and coated morphology of Ti alloy were analyzed by X-ray diffractometer (XRD), energy X-ray dispersive spectroscopy (EDX) and filed emission scanning electron microscope (FE-SEM). The corrosion behaviors were investigated using A.C. impedance test (PARSTAT 2273, USA) in 0.9% NaCl solution at $36.5{\pm}1^{\circ}C$. Ti-30Ta-($3{\sim}15\;wt%$)Nb alloys showed the ${\alpha}+{\beta}$ phase, and $\beta$ phase peak was predominantly appeared in the case of increasingly Nb contents. The microstructures of Ti alloy were transformed from needle-like structure to equiaxed structure as Nb content increased. From the analysis of coating surface, HA/Ti composite surface uniformed coating layer with 750 nm thickness. The growth directions of film were (211), (112), (300) and (202) for HA/Ti composite coating on the surface after heat treatment at $550^{\circ}C$, whereas, the growth direction of film was (110) for Ti coating. The polarization resistance ($R_p$) of HA/Ti composite coated Ti-alloys were higher than those of the Ti and HA coated samples in 0.9% NaCl solution at $36.5{\pm}1^{\circ}C$. Especially, corrosion resistance of Ti-Ta-Nb system increased as Nb content increased.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.27 no.9C
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• pp.861-870
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• 2002

In this paper, with targeting on the drawback of RSA of operation speed, a new 1024-bit RSA cryptosystem has been proposed and implemented in hardware to increase the operational speed and perform the variable-length encryption. The proposed cryptosystem mainly consists of the modular exponentiation part and the modular multiplication part. For the modular exponentiation, the RL-binary method, which performs squaring and modular multiplying in parallel, was improved, and then applied. And 4-stage CSA structure and radix-4 booth algorithm were applied to enhance the variable-length operation and reduce the number of partial product in modular multiplication arithmetic. The proposed RSA cryptosystem which can calculate at most 1024 bits at a tittle was mapped into the integrated circuit using the Hynix Phantom Cell Library for Hynix 0.35㎛ 2-Poly 4-Metal CMOS process. Also, the result of software implementation, which had been programmed prior to the hardware research, has been used to verify the operation of the hardware system. The size of the result from the hardware implementation was about 190k gate count and the operational clock frequency was 150㎒. By considering a variable-length of modulus number, the baud rate of the proposed scheme is one and half times faster than the previous works. Therefore, the proposed high speed variable-length RSA cryptosystem should be able to be used in various information security system which requires high speed operation.

• Journal of the Korean Chemical Society
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• v.12 no.2
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• pp.65-80
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• 1968

The physico-chemical properties of nine selected thallium borosilicate glasses and other 21 supplementary compositions were investigated. Their composition-property curves are found to be in many respects analogous to those of other borosilicate glasses containing lithia, soda, and lead oxide. It is indicated that certain minima found in the composition-property curves of thallium borosilicate glasses might be caused by a change in boron coordination as has been observed to occur in the $Na_2O-B_2O_3-SiO_2$ glasses. Typical effects of thallium ions on the borosilicate glass are summarized as follows: 1) Addition of thallium ions increased density, refractive index, water solubility, linear coefficient of thermal expansion, and dielectric constant. 2) Increased concentration of thallium decreased the softening point of the glasses, caused fluorescence under ultraviolet radiation and smeared out the absorption edges up to $15{\mu}$ in the infrared region. An extensive liquid immiscibility was found by replication electron microscope technique in the $Tl_2O-B_2O_3-SiO_2$ system. The immiscibility covers a composition range roughly from 55 wt. % Tl2O to the binary system $B_2O_3-SiO_2.$ By acid treatment, it was found that the immiscible glass consists of separate silica-rich and boron-rich phases.

• Journal of Radiation Protection and Research
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• v.26 no.2
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• pp.93-99
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• 2001

Voxel head phantom for overcoming the limitation of mathematical phantom in depleting anatomical details was constructed and example dose calculation for BNCT was performed. The repeated structure algorithm of the general purpose Monte Carlo code, MCNP4B was applied for yokel Monte Carlo calculation. Simple binary yokel phantom and combinatorial geometry phantom composed of two materials were constructed for validating the voxel Monte Carlo calculation system. The tomographic images of VHP man provided by NLM(National Library of Medicine) were segmented and indexed to construct yokel head phantom. Comparison of doses for broad parallel gamma and neutron beams in AP and PA directions showed decrease of brain dose due to the attenuation of neutron in eye balls in case of yokel head phantom. The spherical tumor volume with diameter, 5cm was defined in the center of brain for BNCT dose calculation in which accurate 3 dimensional dose calculation is essential. As a result of BNCT dose calculation for downward neutron beam of 10keV and 40keV, the tumor dose is about doubled when boron concentration ratio between the tumor to the normal tissue is $30{\mu}g/g$ to $3{\mu}g/g$. This study established the voxel Monte Carlo calculation system and suggested the feasibility of precise dose calculation in therapeutic radiology.

• Journal of Korea Spatial Information System Society
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• v.11 no.1
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• pp.127-136
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• 2009

This paper proposes an on-line mining algorithm of moving trajectory patterns in RFID data streams considering changing characteristics over time and constraints of single-pass data scan. Since RFID, sensor, and mobile network technology have been rapidly developed, many researchers have been recently focused on the study of real-time data gathering from real-world and mining the useful patterns from them. Previous researches for sequential patterns or moving trajectory patterns based on stream data have an extremely time-consum ing problem because of multi-pass database scan and tree traversal, and they also did not consider the time-changing characteristics of stream data. The proposed method preserves the sequential strength of 2-lengths frequent patterns in binary relationship table using the time-evolving graph to exactly reflect changes of RFID data stream from time to time. In addition, in order to solve the problem of the repetitive data scans, the proposed algorithm infers candidate k-lengths moving trajectory patterns beforehand at a time point t, and then extracts the patterns after screening the candidate patterns by only one-pass at a time point t+1. Through the experiment, the proposed method shows the superior performance in respect of time and space complexity than the Apriori-like method according as the reduction ratio of candidate sets is about 7 percent.