• Journal of Digital Convergence
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• v.19 no.7
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• pp.209-215
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• 2021

This study is a system development for voice information protection equipment in major meetings and places requiring security. Security performance and stability were secured with information leakage prevention technology through generation of false noise and ultrasonic waves. The cutoff frequency band for blocking the leakage of voice information, which has strong straightness due to the nature of the radio wave to the recording prevention module, blocks the wideband frequency of 20~20,000Hz, and the deception jamming technology is applied to block the leakage of voice information, greatly improving the security. To solve this problem, we developed a system that blocks the recording of a portable smartphone using a battery, and made the installation of a separate device smaller and lighter so that customers do not recognize it. In addition, it is necessary to continuously study measures and countermeasures for efficiently using the output of the anti-recording speaker for long-distance recording prevention.

• Journal of KIISE:Computing Practices and Letters
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• v.10 no.3
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• pp.243-250
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• 2004

We describe a practical implementation of DVR (Digital Video Recording) system. And we propose a new image compression algorithm, that input video signal is divided into two parts, a moving target and a non-moving background part to achieve efficient compression of image sequences. This algorithm reorganizes a target area and a back-ground area by use of Macro Block(MB) unit on encoding scheme. The proposed algorithm allows high quality image reconstruction at low bit rates.

• Proceedings of the KOSOMBE Conference
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• v.1993 no.05
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• pp.109-113
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• 1993

In this paper, we devised a simple portable digital recorder for a day life ECG signal recording. The system are consisted of ECG amp. part, signal conditioning part. A/D converter, data compression part and digital memory part. An ADPCM algorithm used at data compress part for 50% of data reduction. The maximum lengths of recording times take 3 hours in 1 mega byte memory.

• 한국해양학회지
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• v.30 no.2
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• pp.116-124
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• 1995

Marine, shallow seismic data have been acquired and processed by newly developed multi-channel(6 channel), PC-based digital recording and processing system. The digital processing system includes pre-processing, swell-compensation filter, frequency filter, gain correction, deconvolution, stacking, migration, and plotting. The quality of processed sections is greatly enhanced in terms of signal-to-noise ratio and vertical/horizontal resolution. The multi-channel, digital recording, acquisition and processing system proved to be and economical, efficient and easy-to-use marine shallow seismic tool.

• Journal of Digital Forensics
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• v.13 no.4
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• pp.257-270
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• 2019

Recently, due to the popularization of smart devices such as smartphones and the like, photography and video recording audio recordings are frequently and efficiently performed. Thus the use of digital files of those types is increasing. For these digital files to be legally valid as digital evidence, the proof of origin for digital evidence was essential. Mainly, due to the characteristics of the digital audio file, it is possible to make a sophisticated forgery and falsification through the mass copying and digital editing program from the original record. In this way, it has been increasing more and more cases of manipulating digital audio files. In this paper, we propose the procedure of analyzing the file format of digital audio files and the audio signal after the analysis of various actual cases. As a result, it has confirmed that the digital audio files can be not original through traces generated during the manipulation of the digital audio file in case of the manipulated data. Moreover, it has confirmed that the proposed authentication analysis procedure may not clarify whether or not the digital audio file has been a forgery in some specific condition.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.63 no.7
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• pp.940-944
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• 2014

In this research, we designed representative motion patterns that possibly occurred in sleep situation and evaluated the feasibility of the smartphone based movement recording technique. For this, we designed 7 motions such as posture change, head movement, arm movement (vertical, horizontal), leg movement and hand movement (flipping, folding). Movement was recorded by using the smartphone and the actimetry device simultaneously for comparing the feasibility of smartphone based recording. As a result of experiment, we found that the smartphone based movement recording well reflects the body movement, however, it shows the limitation in recording the small local movement such as hand motion compared with the reference actimetry device, Actiwatch.

• Journal of the Korean Institute of Telematics and Electronics B
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• v.31B no.11
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• pp.27-35
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• 1994

In this paper, a modified version of PRML is discussed to reduce nonlinearity in digital high-density storage devices. We propose a PRML with a nonlinear compensator which can reduce nonlinear interaction between the stored flux regions on the storage channel, and apply it to recording channels with three different densities. By comparing its performance with the existing PRML through computer simulation, we confirm that the nonlinear intersymbol interference increasing with high-density recording channels can be reduced effectively by the PRML with a nonlinear compensator.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.27 no.1A
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• pp.13-17
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• 2002

For elimination DC component, the optical recording systems generally exploit WRDS (word-end running digital sum) criterion. However, its performance is degraded if the lengths of the control bits and codewords are increased. Another criterion is MSW (mean-square weight) method. Whereas MSW criterion has the complexity, this hs optimal performance. In this paper, we have proposed a new dc-component suppression method (MPRDS, minimum peak RDS) of the modulation codes for high density optical recording system. This method requires less complexity than MSW's, and the performance is near to MSW's even if the lengths of the control bits and codewords are increased.

• Transactions of the Society of Information Storage Systems
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• v.8 no.2
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• pp.50-55
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• 2012

Optical disks are widely used in libraries and archives as digital data media due to their long-term storage stability. Though archive-grade optical disks are already available on the market, there is a relative less focusing on the reliable recording conditions. Commercial BD-R media were recorded at various recording speeds with the maximum speed of 6X, and tested at the acceleration aging conditions. Through the evaluation of long-term storage features by the data stability test, lower recording speed of 2x resulted in better long-term storage stability. In addition, degradation aspects of unstable long-term storage feature at outer region of disk were discussed.

• Journal of the Korean Institute of Telematics and Electronics B
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• v.33B no.6
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• pp.45-53
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• 1996

In this paper, the convergence behavior of timing phase when an adaptive partial response equalizer and decision-directed type of a PLL work together in a digital recording channel is described. The phenomena of getting biased in timing phase when the convergence parameter of an adaptive partial response equalizer and timing recovery constant of a PLL are not selected properly is introduced. The phenomena, occurring due to perturbation of timing phase, are analyzed, by computer simulation and the region of ocnvergence for timing phase is discussed. Also, a method to overcome the phenomena using a variable step-size parameter is described.