• Journal of the Korean Institute of Telematics and Electronics A
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• v.31A no.1
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• pp.17-25
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• 1994

We analyze risks andd present the requirements of digital multisignature in electronic contract systems where several persons contract a digital document electronically. We also apply a few digital multisignature schemes that have been developed so far, to the electronic contract system and propose a new digital multisignature scheme based on the Fiat-Shamir scheme. We investigate how these schemes satisfy with the requirements and evaluate their efficiency in terms of processing speed. communication complexity, and message length Owing to the high processing speed and the high degree of satisfaction to the requirements, the proposed scheme is suitable for electronic contract systems.

• Proceedings of the Korean Institute of Communication Sciences Conference
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• 2004.07a
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• pp.227-227
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• 2004

• Journal of the Korea Institute of Information Security & Cryptology
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• v.21 no.2
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• pp.49-60
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• 2011

Instant Messenger is one of the most popular communication service when translating message or data each other through Internet. For digital crime investigation, therefore, it is obviously important to obtain communication trace and contents derived from Instant Messenger. This is because that gathering traditional communication histories also have been important until now. However, extracting communication trace and contents are not easy because they are generally encrypted or obfuscated in local system, futhermore, sometimes they are located at server computer for Instant Messenger. This paper researches on extracting communication histories against NateOn, BuddyBuddy, Yahoo! messenger and Mi3 messenger, and obtaining user password or bypassing authentication system to Instant Messenger Service when a user use auto-login option.

• Asia pacific journal of information systems
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• v.32 no.3
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• pp.537-563
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• 2022

This study investigates the adoption and application of digital transformation in the financial sector and analyzes the process and outcomes of digitization and digitalization in the field of the finance industry of South Korea and overseas, in order to seek both managerial and strategic implications for successful implementation of digital transformation in the future. The findings show that, for successful digital transformation, it is necessary to maximize active and systematic use of advanced online and digital technologies that form the basis of business and create an open, horizontal organizational culture and communication system to equally share and distribute advanced technologies and competencies through the entire organization. Furthermore, this study also discovers the legitimacy to concentrate the organizational competencies and know-how in providing technical training for members, expanding customer experience, and improving customer satisfaction services to contribute to improving the quality of life for members of the organization and creating and improving social and public infrastructures, instead of using digital transformation only to improve productivity of organizations or firms. As such, it is necessary to concentrate corporate competencies in establishing and supplying digital transformation that is not just human-centered but also has productivity, innovativeness, and reliability at the same time.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.32 no.1
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• pp.49-66
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• 2022

The COVID-19 pandemic has led many countries around the world to introduce and employ a digital certificate system to prevent infectious diseases, however, there are difficulties in using the compatible digital certificate between countries in that the international standards of the system have not been developed. Accordingly, we propose an improved system, comparing two methods of presenting a certificate, existing QR code-based and a short-range wireless communication-based certificates. The proposed system is a digital certificate system against the spread of infectious disease by storing verification information of the certificate using decentralized identity-based technology on the blockchain. Blockchain-based trust anchor improves security by solving the problem of forgery and alteration of certificates and guaranteeing the identity of certificate issuers and presenters. This system is also expected to enhance usability providing concurrent verification of a number of certificates(vaccination certificates, recovery certificates, test results, identity certificates, etc.) in a single certificate presentation.

• Journal of Digital Convergence
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• v.12 no.3
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• pp.7-16
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• 2014

This study aims to analyze the key logic of the current C-P-N-D ICT ecological system, to find out the shortcomings of the current system, and then to offer policy suggestions for the establishment of a new creative contents industry ecological system; that is, ICCT (Information, Communication, Contents and Technology) System.

• 제어로봇시스템학회:학술대회논문집
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• 2001.10a
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• pp.113.3-113
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• 2001

In this paper, we have designed the VHDL module of DS/SS QPSK wireless modem processor for digital data communication. The spread spectrum method is used for modern processor, because this method guarantees good frequency efficiency and higher security. Also, it guarantees good performance in digital communication system under multi-path interferences. The differential encoder and decoder are used for simple circuit composition in the signal detection. For the synchronization of receiver, matched filter and power detector are used. And the IF modulation/demodulation of QPSK method is used in the digital level. The transmitter of VHDL modem processor consists of differential encoder, PN code generator, and QPSK ...

• ETRI Journal
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• v.29 no.5
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• pp.607-613
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• 2007

Most signal-to-noise ratio (SNR) estimation techniques in digital communication channels derive the SNR estimates solely from samples of the received signal after the matched filter. They are based on symbol SNR and assume perfect synchronization and intersymbol interference (ISI)-free symbols. In severe channel distortion where ISI is significant, the performance of these estimators badly deteriorates. We propose an SNR estimator which can operate on data samples collected at the front-end of a receiver or at the input to the decision device. This will relax the restrictions over channel distortions and help extend the application of SNR estimators beyond system monitoring. The proposed estimator uses the characteristics of the second order moments of the additive white Gaussian noise digital communication channel and a linear predictor based on the modified-covariance algorithm in estimating the SNR value. The performance of the proposed technique is investigated and compared with other in-service SNR estimators in digital communication channels. The simulated performance is also compared to the Cram$\acute{e}$r-Rao bound as derived at the input of the decision circuit.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.33A no.7
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• pp.76-91
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• 1996

In this paper, we proposed the new medium access control protocol for the virtual token bus netowrk. The network is applied to inter-processor communication network of large capacity digital switching system and digital mobile system with distributed control architecture. in the virtual token bus netowrk, the existing medium access control protocols hav ea switchove rtime overhead when traffic load is light or asymmetric according ot arbitration address of node that has message to send. The proposed protocol optimized average message delay using cyclic bus access chain to exclude switchover time of node that do not have message to send. Therefore it enhanced bus tuilization and average message delay that degrades the performance of real time communication netowrks. It showed that the proposed protocol is more enhacned than virtual token medium access control protocol and virtual token medium access control protocol iwth reservation through performance analysis.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.1 no.1
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• pp.55-64
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• 1997

Spread Spectrum Communication is a core technique in CDMA system, but the problem for SS Communication schemes is synchronous method. There are DLL, Tau-dither, SO etc, in the synchronous method. But since there are analog operations, the settling is difficult and size is large. In this paper we realized Digital Delay Lock Loop (DDLL) and estimated it's performance through the Power line experiment.