• 한국HCI학회:학술대회논문집
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• 2006.02a
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• pp.400-405
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• 2006

In this paper, we present effective methods for music summarization which summarize music automatically. It could be used for sample music of on-line digital music provider or some music retrieval technology. When summarizing music, we use different two methods according to music length. First method is for finding sabi or chorus part of music which can be regarded as the most important part of music and the second method is for extracting several parts which are in different structure or have different mood in the music. Our proposed music summarization system is better than conventional system when structure of target music is explicit. The proposed method could generate just one important segment of music or several segments which have different mood in the music. Thus, this scheme will be effective for summarizing music in several applications such as online music streaming service and sample music for Tcommerce.

• Proceedings of the IEEK Conference
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• 2002.07b
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• pp.872-875
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• 2002

A digital watermarking technique applying psychoacoustic model for audio signal is proposed in this paper. In the watermarking scheme, the pseudo-random bit stream used as a watermark signal is embedded into the audio signal in both speech and music. The strength of the embedded signal is subject to the human auditory system in such a way that the disturbances on host audio signal are beyond the sensing of human ears. The experimental results show that the quality of the watermarked audio signal, in term of signal to noise ratio, can be improved up to 3.2 dB.

• Journal of Advanced Navigation Technology
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• v.16 no.2
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• pp.190-196
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• 2012

In this paper, we propose an improved error correction code in order to improve the performance of digital modems for HF data communications and verify the performance of the proposed scheme. The proposed scheme employs outer Reed-Solomon codes concatenated with inner convolutional codes. Numerical results show that the proposed system significantly improves the bit error rate performance compared to the conventional PACTOR-III modems. Hence, the proposed system can improve the bandwidth efficiency of digital modems for HF data communications.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.12B
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• pp.1013-1021
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• 2004

Recently, there have been the rapid increasing needs to integrate high-speed communications and digital TV in home network. To realize the integration of those services, the MIC formulated the broadband convergence network (BcN) plan as one of the new growth engines. The BcN will be implemented by FTTH solutions and these solutions are designed to support digital home network. To develop and promote the BcN, we need to find the bandwidth requirements for home network. This paper will examine the bandwidth requirements in detail to accommodate data traffics for high-speed communications and TV at building intra network and home intra network.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.11 no.2
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• pp.122-136
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• 1986

In this paper, the new modulation system, the digital phase-frequency hybrid modulation system is proposed for mobile radio communications. The error rate and the outage equation of PFSK(Phase-Frequency Shift Keying) signal transmitted through the fading channel has been derived considiering deversity techniques. The error rate and the outgae rate performances of PFSK system have been evaluated and shown in figures in terms of carrier-to-noise power ratio(CNR), fading figure, numbers of diversity branches, correlation coefficient among the diversity branches. And the performance of PFSK system is superior to that of QDPSK system. And by using diversity techniques, system performances can be improved 13dB above in CNR.

• Journal of information and communication convergence engineering
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• v.22 no.2
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• pp.89-97
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• 2024

This research conducted a comparative analysis of two communication systems. The first system utilizes a conventional series configuration consisting of a symbol-rate least mean square (LMS) equalizer followed by a timing recovery loop. The second system introduces an innovative approach that integrates a symbol-rate LMS equalizer and a timing recovery component within a single loop, allowing mutual feedback between the two blocks. In this integrated system, the equalizer also provides timing error information, thereby eliminating the requirement for a separate threshold error detector. This study examines the performance curves of both system configurations. The simulation results revealed that the integrated system may offer improved stability in terms of multiple transmission challenges, including phase and frequency offsets and intersymbol interference. Further analysis and discussion highlight the significant insights and implications of the proposed architecture. Overall, the present findings provide an alternative perspective on the joint implementation of equalization and timing recovery in communication systems.

• 제어로봇시스템학회:학술대회논문집
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• 2004.08a
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• pp.788-793
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• 2004

Internet-based distribution of digital contents provides great opportunities for producers, distributors and consumers, but it may seriously threaten users' privacy. The Digital Rights Management (DRM) systems which one of the major issues, concern the protection of the ownership/copyright of digital content. However, the most recent DRM systems do not support the protection of the user's personal information. This paper examines the lack of privacy in DRM systems. We describe a privacy policy and user's privacy preferences model that protect each user's personal information from privacy violation by DRM systems. We allow DRM privacy agent to automatically negotiate between the DRM system policy and user's privacy preferences to be disclosed on behalf of the user. We propose an effective negotiation algorithm for the DRM system. Privacy rules are created following the negotiation process to control access of the user's personal information in the DRM system. The proposed privacy negotiation algorithm can be adapted appropriately to the existing DRM systems to solve the privacy problem effectively.

• Journal of the Korea Institute of Military Science and Technology
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• v.20 no.3
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• pp.431-440
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• 2017

HF communications are used as a last means of long distance communications without any relay node in NLOS (Non Line-Of-Sight) environment. Conventional analog voice communication in the HF band is vulnerable to security as well as severe background noise. To overcome these shortcoming, digital voice was introduced into HF radios in the early 1980s. In this paper, we analyze avaliable digital voice communication ground wave range of HF radios that applied MELPe CODEC and MIL-STD-188-110B physical layer standard using GRWAVE program. And we evaluate usefulness of digital voice communication in HF band.

• 제어로봇시스템학회:학술대회논문집
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• 2004.08a
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• pp.232-237
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• 2004

In many application of DC-DC converters, loads cannot be specified in advance, i.e., their amplitudes are suddenly changed from the zero to the maximum rating. Generally, design conditions are changed for each load and then each controller is re-designed. Then, a so-called robust DC-DC converter which can cover such extensive load changes and also input voltage changes with one controller is needed. Analog control IC is used usually for the controller of DC-DC converter. Simple integral control etc. are performed with the analog control IC. However it is difficult to retain sufficient robustness of DC-DC converter by these techniques. The authors proposed the method of designing an approximate 2-degree-of-freedom (2DOF) controller of DC-AC converter. This controller has an ability to attain sufficient robustness against extensive load and DC power supply changes. For applying this approximate 2DOF controller to DC-DC converter, it is necessary to improve the degree of approximation for better robustness. In this paper, we propose a method of designing good approximate 2DOF digital controller which makes the control bandwidth wider, and at the same time makes a variation of the output voltage very small at a sudden change of resistive load. The proposed good approximate 2DOF digital controller is actually implemented on a DSP and is connected to a DC-DC converter. Experimental studies demonstrate that this type digital controller can satisfy given specifications.

• Journal of Communications and Networks
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• v.5 no.4
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• pp.374-385
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• 2003

The growing interest towards ultra-wideband (UWB) communications stems from its unique features such as baseband operation, ample multipath diversity, and the potential of enhanced user capacity. But since UWB has to overlay existing narrowband systems, multiple access has to be achieved in the presence of narrowband interference (NBI). However, existing baseband spreading codes for UWB multiple access are not flexible in handling NBI. In this paper, we introduce two novel spreading codes that not only enable baseband UWB multiple access, but also facilitate flexible NBI cancellation. We construct our codes using a single carrier or multiple carriers (SC or MC), which can be implemented with standard discrete-cosine transform (DCT) circuits. With our SC/MC codes, NBI can be avoided by simply nulling undesired digital carriers. Being digital, these SC/MC codes give rise to multiband UWB systems, without invoking analog carriers. In addition, our SC/MC codes enable full multipath diversity, and maximum coding gains. Equally attractive is their capability to reduce the number of interfering users, with simple matched filter operations. Comprehensive simulations are also carried out to corroborate our analysis.