• Journal of Korea Society of Digital Industry and Information Management
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• v.6 no.3
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• pp.179-190
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• 2010

With science and technology getting more and more advanced, the scope of digital product is expanding and the new products continuously are introduced on the market. On the basis of consumers' attachment to products, we investigated the consumers' behaviors towards the product when a digital product is extended. As a result of an empirical analysis, it turned out that a consumer tended to have higher trust and a positive emotion about relevant goods if he or she had a strong attachment to digital products. However, even though one had a strong attachment to digital products, the emotion about the corresponding brands did not necessarily appeared to be positive. In the event that a brand of digital products was extended to other new products, only the trust in the brand exerted significant influence on the consumers' behaviors towards the extended products. Finally, this study suggests some theoretical and managerial implications for effective strategies in response to customers' attachment to digital product.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.20 no.12
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• pp.1252-1263
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• 2009

In this paper, in order to improve a service quality and to broaden the service coverage in the mobile communication system a study on a digital RF repeater employed with an Interference Cancellation System(ICS) is performed. The digital RF repeater employed with an ICS is implemented to remove interference and feedback signals which are disadvantages of a conventional(or general) RF repeater. This thesis presents the design and experiments of the new wireless repeater. The proposed wireless repeater consists of a RF repeater mounted with digital engine. The digital ICS engine consists of a DSP and FPGA. The digital engine and RF circuit are designed into a one-piece. After developing hardware through the digital platform they are also designed and fabricated into a one-piece in order to apply a best performance repeater system. The method of removing interference and feedback signals is an adaptive IF technique employed with a LMS algorithm. The powerful performance and fast convergence speed is obtained by using this method.

• Journal of Korea Society of Digital Industry and Information Management
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• v.5 no.2
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• pp.109-121
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• 2009

As our society is changed to the information & digital society based on the internet, the requirement that the analog certificate of Korean residence is changed to digital one is increased. The Korean Government selected the smart card of 72 KB for the digital certificate of Korean residence and try to insert the personnel information of 41 items to it. The method that the numerous personnel information is stored in one smart card is convenience to use. If the certificate of residence is lost, the number of personnel information is misused or spreaded thorough the Internet by the hacking. In this paper, we analyze the problem about the digital certificate of Korean residence and propose the countermeasure about the problem. In the proposal, the digital certificate of residence have only the certificate. Therefore, the size of the smart card is minimized and can be canceled at the loss of the certificate of residence. And the exposure worry of personnel information will be decreased.

• Proceedings of the IEEK Conference
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• 2000.11d
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• pp.127-130
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• 2000

This paper proposes a low-Power DDC(Digital Down Converters) architecture for IF(Intermediate frequency) signal processing. It is shown that concept of conventional interpolated FIR filters can be expanded to IIR filters for DDC applications. Also in the paper, power dissipations for the proposed architecture and conventional ones are estimated.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.9 no.2
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• pp.13-24
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• 1999

Electronic cash is a digital signature issued by bank. If the concept of the distributed secret sharing and magic ink signature is introduced in the existing electronic cash system we can increase the security level and the availability of electronic cash system and trace the electronic cash itself and the owner of electronic cash which was issued anonymously to a user in case of illegal usage of electronic cash by users. If the trust is concentrated on one bank system. the problem of misuse of bank can be occurred. To solve this problem, the distributed secrete sharing scheme need to be introduced in electronic cash system. In this paper We propose a DSS(Digital Signature Standard) distributed magic ink signature scheme and a KCDSA(Korea Certificate-based Digital Signature Algorithm) distributed magic ink signature scheme using a verifiable secret sharing method. and we compare two methods with respect to the required computation amount for the generation of magic-ink signature.

• Journal of Broadcast Engineering
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• v.21 no.5
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• pp.803-815
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• 2016

In this paper, we design a direct radio frequency (RF) sampling receiver for multiband GNSS signals and demonstrate its performance. The direct RF sampling is a technique that does not use an analog mixer, but samples the passband signal directly, and all receiver processes are done in digital domain, whereas the conventional intermediate frequency (IF) receiver samples the IF band signals. In contrast to the IF sampling receiver, the RF sampling receiver is less complex in hardware, reconfigurable, and simultaneously converts multiband signals to digital signals with an analog-to-digital (AD) converter. The reconfigurability and simultaneous reception are very important in military applications where rapid change to other system is needed when a system is jammed by an enemy. For simultaneous reception of multiband signals, the sampling frequency should be selected with caution by considering the carrier frequencies, bandwidths, desired intermediate frequencies, and guard bands. In this paper, we select a sampling frequency and design a direct RF sampling receiver to receive multiband global navigation satellite system (GNSS) signals such as GPS L1, GLONASS G1 and G2 signals. The receiver is implemented with a commercial AD converter and software. The receiver performance is demonstrated by receiving the real signals.

• Journal of Korea Society of Digital Industry and Information Management
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• v.10 no.3
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• pp.119-125
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• 2014

Echo cancellation is required for a dual-duplex high speed communication such as digital subscriber line(DSL), in order to allow each individual loop to operate in a full duplex fashion. Echo cancellation was one of the most difficult aspects of DSL design, requiring high linearity and total echo return loss in excess of 70 dB. For a long and rapidly changing echo response, if the echo is cancelled by an adaptive echo canceller, the echo canceller needs more taps and its performance is decreased. But if the response is divided into several responses, which response is estimated by a adaptive digital filter and combined, the computation complexities are decreased and the performance is increased. Therefore, the adaptive multi-stage echo canceller is proposed to decrease the computation complexity and increase the performance of echo return loss, in which the echo canceller is composed of several stage echo canceller estimating each divided echo response. Through computer simulations, this multi-stage echo canceller is verified to have merits for high speed communications such as DSL application.

• JSTS:Journal of Semiconductor Technology and Science
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• v.5 no.4
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• pp.276-281
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• 2005

This paper presents a low voltage operating IF QPSK receiver block which is consisted of programmable gain amplifier (PGA) and analog to digital converter. This PGA has 6 bit control and 250MHz bandwidth, $0{\sim}20\;dB$ gain range. Using the proposed PGA architecture (low distortion gain control switch block), we can process the continuous fully differential $0.2{\sim}2.5Vpp$ input/output range and 44MHz carrier with 2 MHz bandwidth signal at 1.8V supply voltage. Using the sub-sampling technique (input freq. is $44{\sim}46MHz$, sampling freq. is 25MHz), we can process the IF QPSK signal ($44{\sim}46MHz$) which is the output of the 6 bit PGA. We can get the SNDR 35dB, which is the result of PGA and ADC at full gain mode. We fabricated the PGA and ADC and the digital signal processing block of the IF QPSK with the 0.18um CMOS MIM process 1.8V Supply.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2009.01a
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• pp.508-511
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• 2009

The infringement of the copyright is a problem by the distribution of digital contents copied illegally. The digital watermark is expected as a thing preventing unjust copying by burying information in digital data such as image, animation, the sound, TV, radio and movies. [1] [2]But a noise is included in a digital watermark reproduction image. So there is the case that the certification of the reproduction image has difficulty with. If a computer cannot recognize the information reproduced from digital watermarking, the information does not have a meaning. This paper aimed at improvement of the proof of a digital-watermarking reproduction image. And it is verified whether the difference of the form of a character affects the degree of correlation.

• Proceedings of the KIEE Conference
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• 2000.07d
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• pp.3112-3114
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• 2000

Recently. internet applications for efficient cyber education have drawn much interests. The world-wide web provides new opportunities for cyber education over the internet. In this paper, we developed the internet-based educational simulator for design and virtual experiment of the digital logic circuits. The proposed simulator provides the improved learning methods which can enhance the educational efficiency in digital theory. If the students execute the Digital simulator on the web. they can simulate in digital circuits through simple mouse manipulation. The proposed digital simulator can be used so that the students can easily understand the well-known digital principles.