• 제어로봇시스템학회:학술대회논문집
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• 1987.10b
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• pp.684-689
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• 1987

Digital Subtraction Angiography(DSA) technique has been widely used to detect vascular diseases and hemodynamic parameters noninvasively. However, there are few quantitative studies on the factors in fluencing the resultant DSA image quality. In this paper, several important factors are suggested to improved the DSA image quality based on mathematical analysis. Experimental DSA images for different filters are shown and also discussed the difference between original and processed image quality.

• Proceedings of the Korea Institutes of Information Security and Cryptology Conference
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• 2002.11a
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• pp.261-265
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• 2002

본 논문에서는 XTR에 기반한 블라인드 서명인 블라인드 XTR-DSA 스킴을 이용하여 전자화폐 시스템에서 블랙메일링 공격을 막는 방법을 제안한다. 인출과정에서 은행이 블라인드 XTR-DSA 스킴을 이용하여 서명을 하면 효과적으로 블랙메일러에게 표시된 화폐를 발행할 수 있다. 기존의 방법에서는 블랙메일러에게 표시된 화폐를 발행하기 위해 사용자의 개인키를 은행에 전달해야했으나 본 논문에서 제안하는 블라인드 XTR-DSA 스킴을 이용할 경우 사용자의 개인키 전달이 필요 없게 되어 기존의 방법보다 더욱 효율적이다.

• Journal of the Institute of Convergence Signal Processing
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• v.13 no.2
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• pp.99-105
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• 2012

The focus of this paper is a proposal for a computationally efficient dynamic subcarrier allocation (DSA) algorithm for orthogonal frequency-division multiple access (OFDMA) systems. The proposed DSA algorithm considerably reduces the computational complexity and the amount of channel quality information (CQI) compared to amplitude craving greedy (ACG) algorithms, which use full CQI. At the same time, the performance of the proposed algorithm closely appear to ACG algorithms. Moreover, the authors present a new bandwidth-assignment algorithm produced by modifying bandwidth assignment based on the signal-to-noise ratio (BABS). This modified BABS algorithm enables the proposed DSA algorithm to produce a strong outage performance gain over the conventional scheme.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.12 no.6
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• pp.125-135
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• 2002

The electronic payment system based on blind signature is susceptible to the blackmailing attack as opposed to keep the lifestyle of users private. In this paper. we suggest an efficient electronic cash system using a blind XTR-DSA scheme, which improves the method of defeating blackmailing in online electronic cash systems of ［6,9］. In case of blackmailing, to issue the marked coins we use the blind XTR-DSA scheme at withdrawal. In ［6,9］, to cheat the blackmailer who takes the marked coins the decryption key of a user had to be transferred to the Bank. But in our proposed method the delivery of the decryption key is not required. Also, in the most serious attack of blackmailing. kidnapping, we can defeat blackmailing with a relatively high probability of 13/18 compared with 1/2 in ［9］ and 2/3 in ［6］. If an optimal extension field of XTR suggested in ［7］ is used, then we can implement our system more efficiently.

• Journal of the Korean Electrochemical Society
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• v.13 no.2
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• pp.123-127
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• 2010

An assembled-graphite/DSA(Dimensionally Stable Anode) was prepared using graphite powder to increase durability and energy efficiency of redox flow battery and investigated its electrochemical properties in vanadium-based electrolyte. The cyclic voltammetry (CV) was carried out in the voltage range of -0.7V and 1.6V vs. SCE at 5 mV/sec scan rate to analyze vanadium redox reaction. From the CV results, the assembled-graphite/DSA electrode showed a fast couple reaction and good reversibility in 2M $VOSO_4$ + 2.5 M $H_2SO_4$ electrolyte. Therefore, it has been expected that this electrode increases power density as well as energy density of redox flow battery.

• Journal of the Korean Society of Radiology
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• v.8 no.1
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• pp.43-49
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• 2014

PACS is needed medical imaging with large-capacity storage device. Slower transmission degrades the performance of the PACS. Thus, the image read by the reading of the long-term stored image without compromising the quality of the video, which does not affect future readings in the range will be compressed and stored. Compression and video storage, and video transport Noise generated during storage and transmission of medical images and the resulting loss of information that occurs when the monitor output from many problems. The study estimates server display monitor and client display monitor of philips DSA system, and suggests that the evaluation and improvement about PSNR, process from server display signal obtaining to client display monitor. P company DSA is used in the test. Two monitors that are $1280{\times}1024$ pixel monitor of P company and 1536x2048 pixel monitor of Wide are used displaying angiography picture. MARO-view is taken in PACS program, and Visual $C^{++}$ is taken as accomplishing PSNR measurement program. As a result of experiment, no change in No 1, 3 of PSNR appear that there is no error in telephotograph and display. In terms of compressibility, low compressibility has small change of definition, and there was not remarkable drawback of compressibility which has little change in definition.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.8
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• pp.3045-3052
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• 2010

The international standard signature algorithm DSA has been guaranteed its security based on discrete logarithm problem. Recently, the DSA was known to be vulnerable to some fault analysis attacks in which the secret key stored inside of the device can be extracted by occurring some faults when the device performs signature algorithm. After analyzing an existing fault attack presented by Bao et al., this paper proposed a new fault analysis attack by disturbing the random number. Furthermore, we presented a countermeasure to compute DSA signature that has its immunity in the two types of fault attacks. The security and efficiency of the proposed countermeasure were verified by computer simulations.

• Journal of the Korea Society for Simulation
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• v.11 no.3
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• pp.23-34
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• 2002

Dynamic storage allocation (DSA) is a field fairly well studied for a long time as a basic problem of system software area. Due to memory fragmentation problem of DSA and its unpredictable worst case execution time, real-time system designers have believed that DSA may not be promising for real-time application service. Recently, the need for an efficient DSA algorithm is widely discussed and the algorithm is considered to be very important in the real-time system. This paper proposes an efficient DSA algorithm called QSB (quick semi-buddy) which is designed to be suitable for real-time environment. QSB scheme effectively maintains free lists based on quick-fit approach to quickly accommodate small and frequent memory requests, and the other free lists devised with adaptation upon a typical binary buddy mechanism for bigger requests in harmony for the .improved performance. Comprehensive simulation results show that the proposed scheme outperforms QHF which is known to be effective in terms of memory fragmentation up to about 16%. Furthermore, the memory allocation failure ratio is significantly decreased and the worst case execution time is predictable.

• 제어로봇시스템학회:학술대회논문집
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• 1997.10a
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• pp.1528-1535
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• 1997

Many radiological modalities has been applied to medicine as a basic fundamental diagnosis and therapy recently. The prevalence of computer systems affect most images to be digitized. However conventional X-ray film images are not digital images eventhough they covers 70% of all radiologica images. This is the hinderacne of building PACS. In this paper all radiological digital imaging parts such as DSA. CR. MRI. SPECT. PET and ultrasonography were briefly introduced and the applications were described. In brief digital radiography contribute to enhance the medical service quality. And the digital substituition of conventional X-ray film image is inevitable.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.13 no.5
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• pp.39-48
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• 2003

AAA(Authentication, Authorization, Accounting) protocol is a framework that propose functions of AAA on multiple networks and platforms. AAA protocol is extending from previous RADIUS protocol to Diameter protocol. There are some Diameter applications for variety purpose. Diameter CMS Application makes Diameter messages more secure by using PKI. Diameter CMS Application establish DSA(Diameter Security Association) for end to end security. However the Application has some problems to establish DSA(Diameter Security Association), which can make Diameter system unstable. If one system lose DSA information for some system error - for example, reboot -, the secure communication between two nodes may not be possible. At the application such as MIP, even user registration can't be done. In this paper, we propose a mechannism for DSA re-establishment, and also show the result of the implementation.