• Composites Research
• /
• v.23 no.1
• /
• pp.17-22
• /
• 2010

The compressive and dynamic properties of magnetorheological elastomers were investigated as functions of magnetizable particle volume fraction, alignment of the embedded particle and magnetic force. The specimens consisted of pure and filled silicons with randomly dispersed, longitudinal and transverse aligned magnetizable particle chains. To align the embedded particles in the elastomer, the cross-linking of the elastomer composites took place in a magnetic field. The compression and dynamic tests in the absence and the presence of different magnetic forces were carried out. The modulus and loss factor of the elastomer composites increase with increasing volume fraction at the same magnetic force. The case of longitudinal alignment shows a high modulus and loss factor when compared to the case of transverse alignment or random dispersion.

• The Journal of the Acoustical Society of Korea
• /
• v.15 no.2
• /
• pp.55-60
• /
• 1996

This paper describes the subjective assessment of the multi-channel audio quality according to the bitrate changing and evaluates the predistortion effect to avoid the unmasked noise after matrixing/dematrxing process in transmission and regeneration of the multi-channel audio. The simulation is processed by the perceptual coding that is MPEG-2 Audio layer II algorithm. We evaluate the quality improvement about predistortion using or not by 384, 320, 256, 128kbps. As the result of the double blind subjective assessment, 5 Grade-Impairment Scale is scored under minus one to 320kbps and so audio quality is evaluated to be perceptible, but not annoying in 3/2 channel. The effect of the predistortion is improved one level in 128kbps and especially speech test material I better improved than music test materials.

• Journal of the Korean GEO-environmental Society
• /
• v.9 no.7
• /
• pp.37-43
• /
• 2008

The unconfined compressive strength of soil-cement mixed with red mud, an industrial by-product of alumina production, was investigated in the laboratory. The investigation involved laboratory tests under the various conditions such as red mud content, cement content, fly ash content and ratio of soil replacement with sands. The unconfined compressive strength tests were performed at 7, 14 and 21 days after specimen preparation. Results of the study show that the unconfined compressive strength increased as red mud and fly ash content decreased and cement content increased. Increasing the soil replacement ratio with sands had an insignificant effect on compressive strength because the soil had a similar particle size as the replacement sands.

• Journal of KIISE:Computing Practices and Letters
• /
• v.9 no.5
• /
• pp.509-520
• /
• 2003

In this paper, we developed a new and robust algorithm for a practical and very efficient MPEG-4 video coding. The MPEG-4 video group has developed the video Verification Model(VM) which evolved through time by means of core experiments. And in the standardization process, MS-FDAM was developed based on the standard document of ISO/IEC 14496-2 and VM as a reference MPEG-4 coding system. But MS -FDAM has drawbacks in practical MPEG-4 coding and it does not have the VOP extraction functionality. In this research, we implemented a preprocessing system for a real-time input and the VOP extraction for a practical content-based MPEG-4 video coding and also implemented the motion detection to achieve the high compression rate of 180:1.

• Journal of Astronomy and Space Sciences
• /
• v.13 no.2
• /
• pp.198-209
• /
• 1996

In this paper, we present an image compression algorithm that is capable of significantly reducing the vast mount of information contained in multispectral images. The developed algorithm exploits the spectral and spatial correlations found in multispectral images. The scheme encodes the difference between images after contrast/brightness equalization to remove the spectral redundancy, and utilizes a two-dimensional wavelet trans-form to remove the spatial redundancy. The transformed images are than encoded by hilbert-curve scanning and run-length-encoding, followed by huffman coding. We also present the performance of the proposed algorithm with KITSAT-1 image as well as the LANDSAT MultiSpectral Scanner data. The loss of information is evaluated by peak signal to noise ratio (PSNR) and classification capability.

• Annual Conference on Human and Language Technology
• /
• 1989.10a
• /
• pp.168-173
• /
• 1989

데이터의 압축은 화일의 저장공간과 전송시간을 줄이는 중요한 이점을 제공한다. 국내에는 많은 경우 데이터 화일에 2 바이트로 구성된 표준한글부호를 포함하고 있다. 본 논문에서는 2 바이트로 부호화 된 한글을 포함한 데이터 화일을 허프만 부호화 방식에 의해 압축 할때 한글을 한 바이트 단위로 인식하여 압축하는 경우와 두 바이트 단위로 인식하여 압축하는 경우의 여러가지 압축 특성을 비교하였다. 아울러 사전에 조사된 한글의 찾기 순서에 따라 고정된 압축 부호를 사용하는 경우와 앞에서 제시된 방법들을 비교하였다. 비교 결과 두 바이트 단위로 인식하여 압축하는 방법이 더 좋은 압축율을 보이었다.

• The Journal of the Acoustical Society of Korea
• /
• v.21 no.6
• /
• pp.566-575
• /
• 2002

Low-titrate audio coding enables a number of Internet and mobile multimedia streaming service more efficiently. For the help of next-generation mobile telephone technologies and digital audio/video compression algorithm, we can enjoy the real-time multimedia contents on our mobile devices (cellular phone, PDA notebook, etc). But the limited available bandwidth of mobile communication network prohibits transmitting high-qualify AV contents. In addition, most bandwidth is assigned to transmit video contents. In this paper, we design a novel and simple method for reproducing high frequency components. The spectrum of high frequency components, which are lost by down-sampling, are modeled by the energy rate with low frequency band in Bark scale, and these values are multiplexed with conventional coded bitstream. At the decoder side, the high frequency components are reconstructed by duplicating with low frequency band spectrum at a rate of decoded energy rates. As a result of segmental SNR and MOS test, we convinced that our proposed method enhances the subjective sound quality only 10%∼20% additional bits. In addition, this proposed method can apply all kinds of frequency domain audio compression algorithms, such as MPEG-1/2, AAC, AC-3, and etc.

• The magazine of the Korean Society for Advanced Composite Structures
• /
• v.5 no.4
• /
• pp.21-28
• /
• 2014

최근 증가하는 현무암 석분슬러지를 건설재료로 재활용하기 위한 방안으로, 시멘트 몰탈에서 잔골재의 일부를 현무암석분슬러지로 대체한 후, 기능성 마감재로서의 성능을 검증한 결과 다음과 같은 결과를 얻었다. 1. 현무암 석분슬러지를 포함한 몰탈의 휨인장강도와 압축강도는, 대체율 21%에 도달할 때까지 압축 및 휨인장강도는 일반 시벤트몰탈 대비 각각 47%와 35% 증가하였다. 2. 원적외선 방사율에 있어서도 기존몰탈보다 높은 0.933까지 이르렀으며, 이 수치는 기타 기능성 마감재보다 우수한 원적외선 방사율을 나타내는 것이다. 3. 음이온 방사량은 현무암석분의 대체율에 따른 일관된 경향을 보이지는 않았으나, 일반 시멘트몰탈 보다는 5% ~ 12% 증가효과가 나타났다. 4. 기존 시멘트몰탈의 잔골재의 21%를 현무암석분슬러지로 대체할 경우, 시멘트 몰탈보다 물리적 성질이 증가 함과 동시에, 기능성몰탈로서의 원적외선 방사율, 음이온 방사량의 증진효과가 있었다. 또한 새로운 건축자재의 생산을 통한 경제적 이득은 물론, 산업폐기물의 양을 줄일 수 있다.

• Fire Science and Engineering
• /
• v.25 no.1
• /
• pp.42-49
• /
• 2011

In the high temperature situation like in a fire, the high strength of concrete (HSC) has extreme danger named explosive spalling. It is assumed that the major cause of explosive spalling is water vapour pressure inside concrete. This paper examines the effect of the compressive strength and the moisture content on the initial occurrence of explosive spalling. For the effective experiment of the initial explosive spalling, the curve of ISO834 temperature profile is applied on the basis of 15 minute and 30 minute. As a result, the more increase the compressive strength and the moisture content, the more increase the occurrence and phenomenon of explosive spalling. This paper analyzes the territory of explosive spalling depending the compressive strength and the moisture content. The explosive spalling is not examined in the case of the compressive strength 50~100 MPa and the moisture content below 3% and the compressive strength over 100 MPa and the moisture content below 1%. Also, due to the HSC, which makes it more difficult to transport vapour and moisture, very high vapour-pressure may occur close to the surface, there is a greater risk that HSC spalls compared with normal strength concrete (NSC).

• Journal of the Institute of Electronics Engineers of Korea SP
• /
• v.39 no.6
• /
• pp.565-574
• /
• 2002

We propose an algorithm for the robust transmission of video in error prone environment based on multiple description (MD) scheme and simple rate-distortion operators. The redundancy rate-distortion (RRD) criteria is used to split a one-layer compressed video stream into two correlated descriptions. The proposed algorithm can find more candidate points on the RRD curve than the conventional RRD based methods. A new distortion measure is also defined in this paper, which considers more realistic error environments. Since the proposed MD video coder is based on the standard H.263 coder, each description can be decoded independently by the standard H.263 decoder. Also, several descriptions can be decoded into a single stream by additional merge stage and the H.263 decoder. Simulation results show that the proposed MD video coder yields better performance than the conventional MD splitting algorithm at all bitrates both in single and two description cases.