• Journal of Broadcast Engineering
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• v.20 no.4
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• pp.580-597
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• 2015

Broadcast encryption system is a cryptographic primitive that enables a sender to broadcast a message to a set of receivers in a secure channel. Out of previous proposed broadcast encryption systems, the most effective is the one that uses the Subset Difference(SD) method in a binary tree structure. The SD method has been realized by two underlying approaches: Pseudo-Random Generator(PRG) and Secret Sharing(SS). 2-SD method is the generalized version of the SD method by which two subsets of revoked receivers can be dealt with by one subset (in an SD-based broadcast encryption system). The primary advantage of the 2-SD method is to further reduce the size of transmission overhead, compared to the SD method. Until now, however, there is no known broadcast encryption system that is based on such a 2-SD technique using either PRG or SS basis. In this paper, we suggest a new 2-SD broadcast encryption system using the SS-based technique that was suggested by Jae Hwan Lee et al. in 2014[9]. The new system can reduce the size of ciphertext by 25% of the one in the previous SS-based broadcast encryption system. Also, on a theoretical note, ours is the first 2-SD broadcast encryption system that is provably secure.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.10A
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• pp.976-981
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• 2006

In this paper, we describe a hybrid ZF-SD method. The method is based on dimensionality reduction via predecoding and cancellation of those symbols that can be quickly and reliably detected by a linear decoder. The proposed method shows BER performance similar to SD but with much lower computational complexity than SD.

• Korean System Dynamics Review
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• v.10 no.4
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• pp.73-83
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• 2009

Systemic Dynamics has been widely used as a method for studies in the areas of education, health care, and behavioral sciences. This paper discussed the SD application in nursing research by illustrating examples of published articles in nursing discipline, which can be classified into physiologic, socio-psychological, and health policy fields. It also identified the limitations of SD use in nursing and suggests strategies in order to facilitate a SD method for nursing research: 1) systematic introduction of SD in nursing research fields; 2) Interest about SD as an innovative research method; 3) researcher's efforts to understand the SD method in academic settings.

• Journal of Broadcast Engineering
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• v.19 no.4
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• pp.502-509
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• 2014

Broadcast encryption is a cryptographic primitive that allows a sender to securely transmit a message to a set of receivers. The most influential broadcast encryption system was proposed in 2001 by Naor, Naor, Lotspiech, based on binary trees and the Subset Difference (SD) method. In 2006, Jang, Nyang, and Song suggested a new broadcast encryption system that can reduce transmission rate by 50% compared to the SD method, by introducing the so-called '2-SD' method. Their result was later given the registration of a patent in Korea (registration number: 100879083). Unfortunately, however, this paper shows that Jang et. al.'s broadcast encryption system is not secure against collusion attacks that are considered as being the basic security requirement in designing broadcast encryption.

• Communications of the Korean Mathematical Society
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• v.9 no.2
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• pp.439-448
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• 1994

It is known that the steepest descent(SD) method and the conjugate gradient(CG) method [1, 2, 5, 6] converge when these methods are applied to solve linear systems of the form Ax = b, where A is symmetric and positive definite. For some finite difference discretizations of elliptic problems, one gets positive definite matrices that are almost symmetric. Practically, the SD method and the CG method work for these matrices. However, the convergence of these methods is not guaranteed theoretically. The SD method is also called Orthores(1) in iterative method papers. Elman [4] states that the convergence proof for Orthores($\kappa$), with $\kappa$ a positive integer, is not heard. In this paper, we prove that the SD method and the CG method converge when the $\iota$$^2$ matrix norm of the non-symmetric part of a positive definite matrix is less than some value related to the smallest and the largest eigenvalues of the symmetric part of the given matrix.(omitted)

• Journal of the Korea institute for structural maintenance and inspection
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• v.16 no.1
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• pp.27-34
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• 2012

The objective of this study is to evaluate the stiffness of mortar-filled sleeve bar splice using estimation method of failure mode in the sleeve reinforcement splice. To attain this goal, we analyzed the test results of 261 actual-sized mortar-filled sleeve splice specimens. The study results showed that the estimation method of the failure mode in mortar-filled sleeve bar splice made an effective estimate of the stiffness in this bar splice with the exception of specimens with SD500 bars and smooth pipe sleeve. Especially, of the specimens with cast sleeve or uneven pipe sleeve in the range of reinforcement fracture using the estimation method of the failure mode in mortar-filled sleeve splice, specimens over 98% with SD400 bars and all specimens with SD500 bars had the stiffness capacity of higher than "A" class of AIJ code in monotonic loading. In addition, of the specimens in the range of reinforcement fracture using the estimation method of the failure mode in mortar-filled sleeve splice, all specimens with SD400 bars and SD500 bars had the stiffness capacity of higher than "A" class of AIJ code in cyclic loading.

• Proceedings of the KIEE Conference
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• 2005.10b
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• pp.201-203
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• 2005

The best method to study language is to talking with a native speaker. A voice recognition technology can be used to develope a language study machine. SD(Speaker dependant) and SI(speaker independant) voice recognition method is used for the language study machine. MP3 Player. FM Radio. Alarm clock functions are added to enhance the value of the product. The machine is designed with a DSP(Digital Signal Processing) chip for voice recognition. MP3 encoder/decoder chip. FM tumer and SD flash memory card. This paper deals with the application of SD ad SD voice recognition. flash memory file system. PC download function using USB ports, English conversation text function by the use of SD flash memory. LCD display control. MP3 encoding and decoding, etc. The study contents are saved in SD flash memory. This machine can be helpful from child to adult by changing the SD flash memory.

• Korean Journal of Construction Engineering and Management
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• v.8 no.2
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• pp.136-145
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• 2007

This study analyzes the current usage of SD500 high-strength re-bar in domestic construction sites. Also, an evaluation method was developed to measure economic efficiency of lap splice and coupler splice, which are most commonly used in connection SD500. The evaluation method was applied to construction sites in Seoul in December 2006, and the result revealed that coupler splice is relatively superior in terms of cost efficiency when the re-bar diameter is bigger and the concrete strength is lower.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2011.05a
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• pp.436-439
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• 2011

As mobile digital devices have come into more widespread use, the demand for mobile storage devices have been increasing rapidly and most of digital cameras and camcorders are using SD memory cards. The SD memory card are generally employing a form of copying data into a personal computer after storing user data based on flash memory. The current paper proposes the SD memory card of being capable of storing photograph and image data through network rather than using a method of storing data in flash memory. By delivering data and memory address values obtained through SD Slave IP to network server without sending them to flash memory, one can store data necessary to be stored in a computer's SD memory in real time in a safe and convenient way.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.05a
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• pp.61-65
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• 2001

The conventional tracking testing as IEC-60587 is widely used in surface aging measurement of outdoor insulator because those testing can carry out very short time in Lab-testing. Also IEC-60587 testing is able to offer the standard judgement of relative degradation level of outdoor HV machine/system. Therefore it is very useful method compare to previous conventional tracking testing method and effective Lab-testing method. But surface discharges(SD) have very complex characteristics of discharge pattern so it is required estimation research to development of precise analysis method. In recent, the study of IRR-camera is carrying out discover of temperature of power equipment through condition diagnosis and system development of degradation diagnosis. In this study, SD occurred from procelain insulator, used 22.9[KV] distribution, is measured with partial temperature distribution in real time, the degradation grade of SD is analyzed through produced patterns in SD concentration according to applied time.