• The Journal of Engineering Research
• /
• v.2 no.1
• /
• pp.57-62
• /
• 1997

Two psychoacoustic models used in MPEG-1 employ different masking patterns, different masking indexes, and different computational procedures. As a result, Model 1 is inferior to Model 2 due to its worst case approach in computing the SMR even though it determines tonality and masking levels accurately. In this study, we investigate the performances of psychoacoustic models when we modify the MPEG-1 audio coder for variable bitrates. Simulation results show that Model 2 has a gain of 30 kbps in the dual channel mode and 20 kbps in the joint stereo mode. It is generally known that the joint stereo mode has a gain in bitrate compare to the dual channel mode. For signals with frequent attacks, this gain becomes larger in Model 1 than in Model 2. This is due to the fact that Model 1 uses the worst case approach in computing the SMR to reduce pre-echo

• The Journal of the Acoustical Society of Korea
• /
• v.18 no.2
• /
• pp.77-82
• /
• 1999

A sinusoidal model has been widely used in the analysis and synthesis of speech and audio signals, and becomes one of the efficient candidates for high quality low bit rate audio coders. One of the crucial steps in the analysis and synthesis using a sinusoidal model is the detection of tonal components. This paper proposes an efficient method for the analysis and synthesis of audio signals using a sinusoidal model, which uses psychoacoustic criteria such as masking effect, masking index, and JNDf(Just Noticeable Difference in Frequency). Simulation results show that the proposed method reduces the number of sinusoids significantly without degrading the quality of the synthesized audio signals.

• The Korean Journal of Applied Statistics
• /
• v.29 no.6
• /
• pp.1041-1059
• /
• 2016

The increasing demand from researchers and policy makers for microdata has also increased related privacy and security concerns. During the past two decades, a large volume of literature on statistical disclosure control (SDC) has been published in international journals. This review paper introduces relatively recent SDC approaches to the communities of Korean statisticians and statistical agencies. In addition to the traditional masking techniques (such as microaggregation and noise addition), we introduce an online analytic system, differential privacy, and synthetic data. For each approach, the application example (with pros and cons, as well as methodology) is highlighted, so that the paper can assist statical agencies that seek a practical SDC approach.

• The Journal of the Acoustical Society of Korea
• /
• v.20 no.3
• /
• pp.48-55
• /
• 2001

A novel method to reduce additive non-stationary noise is proposed. The method requires neither the information about noise nor the estimate of the noise statistics from any pause regions. The enhancement is performed on a band-by-band basis for each time frame. Based on both the decision on whether a particular band in a frame is speech or noise dominant and the masking property of the human auditory system, an appropriate amount of noise is reduced using spectral subtraction. The proposed method was tested on various noisy conditions (car noise, Fl6 noise, white Gaussian noise, pink noise, tank noise and babble noise) and on the basis of comparing segmental SNR with spectral subtraction method and visually inspecting the enhanced spectrograms and listening to the enhanced speech, the method was able to effectively reduce various noise while minimizing distortion to speech.

• Proceedings of the Korean Society of Broadcast Engineers Conference
• /
• 2016.11a
• /
• pp.27-30
• /
• 2016

본 논문에서는 기존에 쓰이던 주파수차감법과 다른 새로운 방법을 제안한다. 본 논문에서 다루는 방법은, 특정한 주파수의 대역에서 음성과 잡음의 우세도를 결정하고, 인간의 청각기와 관련된 매스킹 성질을 기반으로 하여 주파수 차감법을 이용해 제거한다. 이에 대하여 다양한 성능 평가를 하였고, 기존의 일반적인 주파수차감법과 비교하여 보다 효과적으로 잡음처리를 할 수 있음을 알 수 있다.

• Proceedings of the KIEE Conference
• /
• 2002.11a
• /
• pp.77-78
• /
• 2002

본 논문은 Pt/Ti 박막을 HF-ethanol 혼합 용액에 대한 매스킹 물질과 오믹 전극으로 사용하였다. 다공질 실리콘 층에 정공과 전자의 주입을 용이하게 하기 위해 이온 주입 공정으로 애노드(anode)와 캐소드(cathode) 전극을 실리콘 다이어프램에 구성하였다. 실리콘 다이어프램 영역에 정전압을 인가하여, 전기화학적 방법으로 관통된 PSi 층을 다이어프램 영역에 성장시켰다. 또한, 제작된 소자를 UV에 대한 광 특성을 고찰하였다.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2005.05a
• /
• pp.603-606
• /
• 2005

This study is to make good acoustic environment around Gwang-ju riverside and performed survey and measurement of soundscape. The survey was focused on the types of sound producing. The results of measurement and analysis are as follows: 1) The types of sound at reverside were twenty and the Leq(equivalent noise level) was ranging from 50 dB(A) to 76 dB(A). The dominant sound was road traffic noise. 2) In the upperstream and the downstream, the sound of wind, bird and water was observed. 3) In the inner city, the water sound was produced by the difference of the height of the weir to mask the road traffic noise.

• Journal of KIISE:Computing Practices and Letters
• /
• v.10 no.2
• /
• pp.189-198
• /
• 2004

As display devices evolve, computer-based work environments are also becoming better suited to actual application tasks. This paper discusses the development of an architectural design system using the virtual table, which is a table-type projection system. It consists of the interactive VR modeler, the hybrid tracker and the architectural interpreter. The interactive VR modeler offers visual and tactile guide such as grid interaction, a tangible transparent prop and reference objects, so that a user can design architectural 3D models more easily and intuitively on the virtual table. The hybrid tracker includes two types of tracking methods for viewpoint according to the user's view and hand interaction: namely, vision-based tracking and magnetic tracking. The architectural interpreter automatically transforms simple 3D masses into a basic construction form that has architectural knowledge. The proposed system has advantage in the sense that it is suitable for collaboration among several users, allowing them to view graphical objects in stereoscopic view with direct 3D manipulation. Thus, it can be effectively used for architectural simulation and user-participated design.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.21 no.7
• /
• pp.1276-1284
• /
• 2017

Lightweight Encryption Algorithm (LEA) that was standardized as a lightweight block cipher was implemented with 8-bit data path, and the vulnerability of LEA encryption processor to correlation power analysis (CPA) attack was analyzed. The CPA used in this paper detects correct round keys by analyzing correlation coefficient between the Hamming distance of the computed data by applying hypothesized keys and the power dissipated in LEA crypto-processor. As a result of CPA attack, correct round keys were detected, which have maximum correlation coefficients of 0.6937, 0.5507, and this experimental result shows that block cipher LEA is vulnerable to power analysis attacks. A masking method based on TRNG was proposed as a countermeasure to CPA attack. By applying masking method that adds random values obtained from TRNG to the intermediate data of encryption, incorrect round keys having maximum correlation coefficients of 0.1293, 0.1190 were analyzed. It means that the proposed masking method is an effective countermeasure to CPA attack.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.19 no.5
• /
• pp.822-832
• /
• 1994

DSC-HDTV image compression algorithm removes spatial, temporal, and amplitude redundancies of an image by using transform coding, motion-compensated predictive coding, and adaptive quantization, respectively. In this paper, leak processing method which is used to recover image quality quickly from scene change and transmission error and adaptive quantization using perceptual weighting factor obtained by HVS are proposed. Perceptual weighting factor is calculated by contrast sensitivity, spatio-temporal masking and frequency sensitivity. Adaptive quantization uses the perceptual weighting factor and global distortion level from buffer history state. Redundant bits according to adaptation of HVS are used for the next image coding. In the case of scene change, DFD using motion compensated predictive coding has high value, large bit rate and unstabilized buffer states since reconstructed image has large quantization noise. Thus, leak factor is set to 0 for scene change frame and leak factor to 15/16 for next frame, and global distortion level is calculated by using standard deviation. Experimental results show that image quality of the proposed method is recovered after several frames and then buffer status is stabilized.