• Proceedings of the KAIS Fall Conference
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• 2009.05a
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• pp.768-771
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• 2009

현재 음성인식에서 가장 많이 사용하고 있는 특징벡터는 MFCC(Mel-Frequency Cepstral Coefficients)이다. 그러나 MFCC도 잡음이 존재하는 환경에서는 인식 성능이 저하된다. 이러한 MFCC의 단점을 해결하기 위해 mel sub-band 스펙트럼 차감법과 신호대잡음비에 따른 에너지 압축을 이용하는 CMSBS(Compression and Mel Sub-Band Spectral subtraction) 방법을 사용한다. 본 논문에서는 CMSBS 방법 적용 시 음성이 발성되는 구간과 묵음 구간에서 mel sub-band 스펙트럼 차감법이 동일한 조건으로 이루어져 발생하는 중요한 음성정보의 손실을 보완하기 위하여 신호의 주기성을 이용하여 spectral flooring 파라미터를 변형하는 방법을 제안한다. 제안한 방법으로 실험을 한 결과 잡음이 거의 없는 음성신호에 대해서는 기존의 방법과 비슷한 인식률을 가지고, 잡음성분이 많을수록 변형된 mel sub-band 스펙트럼 차감법을 적용한 방법이 인식률에서 보다 높은 성능 향상을 가져왔다.

• Journal of the Korean Institute of Telematics and Electronics B
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• v.33B no.8
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• pp.42-49
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• 1996

In this paper, we propose a satellite multispectral image data compression method using classified vector quantization. This method classifies each pixel vector considering band characteristics of multispectral images. For each class, we perform both intraband and interband vector quantization to romove spatial and spectral redundancy, respectively. And residual vector quantization for error images is performed to reduce error of interband vector quantization. Thus, this method improves compression efficiency because of removing both intraband(spatial) and interband (spectral) redundancy in multispectral images, effectively. Experiments on landsat TM multispectral image show that compression efficiency of proposed method is better than that of conventional method.

• Proceedings of the IEEK Conference
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• 2006.06a
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• pp.333-334
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• 2006

In this study, information compression based on the wavelet technique is described. The principle of signal or image compression is performed by optimization of quantization, that is the bit allocation taking advantage of their energy concentration in low frequency components. The wavelet transform is one of frequency decomposition, such as the discrete cosine transform or sub-band filtering, and it is also implemented as a filter bank. Wavelet transform with use of spatially localized basis function can reduce several drawbacks in conventional methods. The benifit of wavelet based compression method is described as comparing the transform method to another ones.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.42 no.1
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• pp.1-7
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• 2005

We propose an effective Landsat TM image compression method using the classified bidirectional prediction (CBP), the classified KLT and the SPIHT. The SPIHT is used to exploit the spatial redundancy of feature bands selected in the visible range and the infrared range separately. Regions of the prediction bands are classified into three classes in the wavelet domain, and then the CBP is performed to exploit the spectral redundancy. Residual bands that consist of difference values between the original band and the predicted band are decorrelated by the spectral KLT Finally, the three dimensional (3-D) SPIHT is used to encode the decorrelated coefficients. Experiment results show that the proposed method reconstructs higher quality Landsat TM image than conventional methods at the same bit rate.

• KCI Concrete Journal
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• v.12 no.1
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• pp.57-68
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• 2000

The effect of structure size on the nominal strength of unidirectional fiber-polymer composites, failing by propagation of a kink band with fiber microbuckling, is analyzed experimentally and theoretically. Tests of novel geometrically similar carbon-PEEK specimens, with notches slanted so as to lead to a pure kink band (without shear or splitting cracks), are conducted. The specimens are rectangular strips of widths 15.875, 31.75. and 63.5 mm (0.625, 1.25 and 2.5 in and gage lengths 39.7, 79.375 and 158.75 mm (1.563, 3.125 and 6.25 in.). They reveal the existence of a strong (deterministic. non-statistical) size effect. The doubly logarithmic plot of the nominal strength (load divided by size and thickness) versus the characteristic size agrees with the approximate size effect law proposed for quasibrittle failures in 1983 by Bazant This law represents a gradual transition from a horizontal asymptote, representing the case of no size effect (characteristic of plasticity or strength criteria), to an asymptote of slope -1/2 (characteristic of linear elastic fracture mechanics. LEFM) . The size effect law for notched specimens permits easy identification of the fracture energy of the kink bandand the length of the fracture process zone at the front of the band solely from the measurements of maximum loads. Optimum fits of the test results by the size effect law are obtained, and the size effect law parameters are then used to identify the material fracture characteristics, Particularly the fracture energy and the effective length of the fracture process zone. The results suggest that composite size effect must be considered in strengthening existing concrete structural members such as bridge columns and beams using a composite retrofitting technique.

• The Journal of the Korea institute of electronic communication sciences
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• v.16 no.6
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• pp.1053-1058
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• 2021

This paper presents the multi-band mixer which converts a X-, K- and Ka-band adaptively by adjusting the gate-bias voltage of an active device. The proposed mixer presented a conversion loss of -10 dB at -0.8 V gate-bias voltage for X-band, a conversion loss of -9 dB at -0.3 V gate-bias voltage for K-band and for Ka-band, a conversion loss of -7 dB at -0.2 V gate-bias voltage under the LO power of +6.0 dBm. The 1dB compression point (P1dB) is +0.5 dBm for all band.

• The Research Journal of the Costume Culture
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• v.20 no.4
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• pp.549-559
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• 2012

The purpose of this study was to analyze the comfort of sports bras by style and bra cup size. The comfort of wear was measured with compression level. The displacement of breast points (BP) after wearing a sports bra was measured. Study subjects evaluated the comfort level of the compression type and encapsulation type sports bras after walking and running. The results showed that all types of experimental sports bras provided more coverage than everyday bras. The compression type bra placed more pressure on the breast, chest, and under-bust than the encapsulation type bra. The BP distance decreased for all types. The C cup subjects' breasts were raised after wearing the sports bras. The B cup subjects had less comfort with the compression style bra than C cup subjects. The racer back style bra with high neckline and small band girth placed more pressure than others. They were difficult to don and doff and the least comfortable. These results imply that the racer back compression style sports bra was uncomfortable for women with large breast, while the encapsulation style bra with the compressing panel at upper chest was the most comfortable. The bras that shortened BP distance placed more pressure on the breast. But the bra that raised and shorted the distance of BP provided better comfort for large-breasted subjects.

• Journal of Korea Multimedia Society
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• v.6 no.1
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• pp.28-39
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• 2003

This paper is an overview of research contributions by the authors to the use of compression techniques to handle high resolution, multi-spectral images. Originally developed in the remote sensing context, the same techniques are here applied to food and medical images. The objective is to point out the potential of this kind of processing in different contexts such as remote sensing, food monitoring, and medical imaging and to stimulate new research exploitations. Compression is based on the simple assumption that it is possible to find out a relationship between pixels close one each other in multi-spectral images it translates to the possibility to say that there is a certain degree of correlation within pixels belonging to the same band in a close neighbourhood. Once found a correlation based on certain coefficient on one band, the coefficients of this relationship are, in turn, quite probably, similar to the ones calculated in one of the other bands. Based upon this second observation, an algorithm was developed, able to reduce the number of bit/pixel from 16 to 4 in satellite remote sensed multi-spectral images. A comparison is carried out between different methods about their speed and compression ratio. As reference it was taken the behaviour of three common algorithms, LZW (Lempel-Ziv-Welch), Huffman and RLE (Run Length Encoding), as they are used in common graphic format such as GIF, JPEG and PCX. The Presented methods have similar results in both speed and compression ratio to the commonly used programs and are to be preferred when the decompression must be carried out on line, inside a main program or when there is the need of a custom made compression algorithm.

• Proceedings of the KIEE Conference
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• 1993.11a
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• pp.346-349
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• 1993

A method for image compression based on decomposition is presented. We design the efficient coding technique for upper band image signals. This coding technique with directive 1-D DPCM is based on the statistical properties of upper bands. Lower band image signals is encoded using 2-D DPCM. The directive 1-D DPCM is performed, scanning upper bands according to edge direction. And then the predicted error signals of upper band sis coded using B1 and Huffman code, and the predicted error signals of lower band is coded using Huffman code. The proposed system shows improved performance when compared with other existing methods with respect to peak signal to noise ratio(PSMR) and human visual system(HVS) properties.

• Journal of electromagnetic engineering and science
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• v.6 no.1
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• pp.18-23
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• 2006

In this paper, we demonstrate a fully integrated X-band image rejection down converter, which was developed using InGaP/GaAs HBT MMIC technology, consists of two single-balanced mixers, a differential buffer amplifier, a differential YCO, an LO quadratue generator, a three-stage polyphase filter, and a differential intermediate frequency(IF) amplifier. The X-band image rejection downconverter yields an image rejection ratio of over 25 dB, a conversion gain of over 2.5 dB, and an output-referred 1-dB compression power$(P_{1dB,OUT})$ of - 10 dBm. This downconverter achieves broadband image rejection characteristics over a frequency range of 1.1 GHz with a current consumption of 60 mA from a 3-V supply.