• Journal of IKEEE
• /
• v.5 no.2 s.9
• /
• pp.221-231
• /
• 2001

In this paper, we propose an efficient requantization method for INTRA frames in heterogeneous transcoding from MPEG-1 to MPEG-4 simple profile. The quantizer for MPEG-1 INTRA MB usually uses a quantization weighting matrix while the quantizer for MPEG-4 simple profile doesn't. As a result, the quantization step sizes of the two quantizers may not be the same even for the same quantization parameter. Due to this mismatch in the quantization step site, the transcoded MPEG-4 sequence suffers from serious quality degradation and the number of bits produced by transcoding increases from the original MPEG-1 video sequence. To solve these problems, we propose an efficient method to find a near-optimum reconstruction level in the transcoder. We also present a PDF (probability distribution function) estimation method for the original DCT coefficients of MPEG-1 video sequence, which is required for the proposed requantization. Experimental results show that the proposed method gives $0.3{\sim}0.6dB$ improvement in PSNR over the conventional method, even at the reduced bit-rate about $5{\sim}7%$ from the conventional method.

• Journal of the Korean Geotechnical Society
• /
• v.28 no.2
• /
• pp.43-55
• /
• 2012

In this study, the resistance bias factors are calculated to determine the resistance factor of Gravel Compaction Piles which is one of the soft ground improvement methods. In order to calculate resistance bias factors for gravel compaction piles, two ultimate bearing capacities were analyzed. One is the ultimate bearing capacity in 2.54 cm settlement measured using data of the field loading test on 41 piles and the other is the ultimate bearing capacity calculated using the seven equations concerning bulging failure. The results of analysis show that the probability density function of the calculated ultimate bearing capacities has a lognormal distribution. Resistance bias factor and the coefficient of variation for Greenwood equation are 0.91 and 0.38, respectively, and for those of Hughes & Withers are 1.19 and 0.39. The two equations are suitable for calculating resistance factors for LRFD of soil improvement using gravel compaction piles.

• Journal of the Institute of Electronics Engineers of Korea TC
• /
• v.43 no.8 s.350
• /
• pp.59-68
• /
• 2006

The study on the uniform error property of codes has been restricted to additive white Gaussian noise (AWGN) channel, which is generally referred to as geometrical uniformity. In this paper, we extend the uniform error property to space-time codes in multiple-input multiple-output (MIMO) channel by directly treating the probability density functions fully describing the transmission channel and the receiver. Moreover, we provide the code construction procedure for the geometrically uniform space-time trellis codes in fast MIMO channels, which consider the distance spectrum. Due to the uniform error property, the complexity of code search is extensively reduced. Such reduction makes it possible to obtain the optimal space-time trellis codes with high order states. Simulation results show that new codes offer a better performance in fast MIMO channels than other known codes.

• Proceedings of the KSR Conference
• /
• 2010.06a
• /
• pp.1044-1053
• /
• 2010

Transmitting correct train control information is important in a train control system which demands safety. The train control information includes the maximum speed of trains, position of preceding trains, incline of tracks and curve sections etc. A radio frequency-communication based train control system is influenced by the noise and interference because the train control information is transmitted by wireless between a on-board system and wayside system. The radio frequency-communication based train control system is a mobile communication system due to moving trains. The inter symbol interference(ISI) occurs by the multipath fading in the mobile ommunication system. As signal-to-noise ratio(SNR) is decreased by the ISI, the train control information is not received correctly. In case of tunnel section, numerous reflected waves exist. Therefore, the power density of receiver is decreased by difference among the received times, magnitudes, phases through the multipath. So, the train suddenly is stopped by the fail-safe operation in the train control system on account of decreasing the power density of receiver. In this paper, a line of sight model-(Additive White Gaussian noise(AWGN) channel), rayleigh and rician fading model are presented. Probability density functions which are related to the SNR are derived from the models. The fading phenomenon severely occurs as a result of analyzing the probability density functions. So, the space diversity method is used in order to reduce the fading effect and it is demonstrated by using Matlab program.

• Annual Conference on Human and Language Technology
• /
• 1996.10a
• /
• pp.158-162
• /
• 1996

본 논문에서는 문자출력이 가능한 무선호출기에 음성인식 기술을 접목한, 특성화된 한 음성인식 시스템에 대하여 설명하고자 한다. 시스템 동작 과정은, 일단 호출자가 음성인식 서버와 접속하게 되면 서버는 호출자의 자연스런 입력음성을 인식, 그 결과를 문장 형태로 피호출자의 호출기 단말기에 출력시키는 방식으로 되어 있다. 본 시스템에서는 통계적 음성인식 기법을 도입하여, 각 단어를 연속 HMM으로 모델링하였다. 가우시안 혼합 확률밀도함수를 사용하는 각 모델은 전통적인 HMM 학습법들 중의 하나인 Baum-Welch 알고리듬에 의해 학습되고 인식시에는 이들에 비터비 빔 탐색을 적용하여 최선의 결과를 얻도록 한다. MFCC와 파워를 혼용한 26 차원 특징벡터를 각 프레임으로부터 추출하여, 최종적으로, 83 개의 도메인 어휘들 및 무음과 같은 특수어휘들에 대한 모델링을 완성하게 된다. 여기에 구문론적 기능과 의미론적 기능을 함께 수행하는 FSN을 결합시켜 자연발화음성에 대한 연속음성인식 시스템을 구성한다. 본문에서는 이상의 사항들 외에도 음성 데이터베이스, 레이블링 등과 갈이 시스템 성능과 직결되는 시스템의 외적 요소들에 대해 고찰하고, 시스템에 구현되어 있는 다양한 특성들에 대해 밝히며, 실험 결과 및 앞으로의 개선 방향 등에 대해 논의하기로 한다.

• Journal of the Institute of Electronics Engineers of Korea SC
• /
• v.43 no.4 s.310
• /
• pp.11-20
• /
• 2006

This paper presents a method for detecting tumors on chicken carcasses by fusion of hyperspectral fluorescence and reflectance images. Classification of normal skin and tumor is performed by the image obtain 어 from optimal band ratio which minimizes the overlapping area of PDFs for normal skin and tumor. This method yields four feature images, each of them represents the ratio of two intensity values from a pixel. Classification is achieved by applying ISODATA to each pixel from the feature images. For the analysis of reflectance image, band selection method is proposed based on the information quantity, many effective features are acquired for the classification by defining the linear transformation selecting the projection axis, accordingly, accurate interpretation of images is possible in the reflectance image and automatic feature selection method is realized. Feature images from reflectance images are also classified by ISODATA and combined with the result from fluorescence images. Experimental result indicates that improved performance in term of reducing false detection rate is observed.

• Journal of the Institute of Electronics Engineers of Korea SP
• /
• v.47 no.2
• /
• pp.77-85
• /
• 2010

Fingerprint image quality checking is one of the most important issues in on-line fingerprint recognition because the recognition performance is largely affected by the quality of fingerprint images. In the past, many related fingerprint quality checking methods have typically considered the local quality of fingerprint. However, It is necessary to estimate the global quality of fingerprint to judge whether the fingerprint can be used or not in on-line recognition systems. Therefore, in this paper, we propose both local and global-based methods to calculate the fingerprint quality. Local fingerprint quality checking algorithm considers both the condition of the input fingerprints and orientation estimation errors. The 2D gradients of the fingerprint images were first separated into two sets of 1D gradients. Then，the shapes of the PDFs(Probability Density Functions) of these gradients were measured in order to determine fingerprint quality. And global fingerprint quality checking method uses neural network to estimate the global fingerprint quality based on local quality values. We also analyze the matching performance using FVC2002 database. Experimental results showed that proposed quality check method has better matching performance than NFIQ(NIST Fingerprint Image Quality) method.

• Journal of the Institute of Electronics and Information Engineers
• /
• v.53 no.10
• /
• pp.3-9
• /
• 2016

Current mobile communication systems utilize the multiple-input multiple-output (MIMO) transmission technique as an important means to enhance the bandwidth efficiency. Accurate beamforming via channel estimation contributes to the signal-to-interference-plus-noise ratio (SINR) increase and the system performance improvement when MIMO transmission techniques are employed. Therefore, determination of beamforming vectors as well as the design of appropriate codebooks defining these codevectors play an important role in system operation. In this paper, we statistically analyze the phase difference between the channels corresponding to adjacent antenna elements in order to design an efficient codebook for uniform circular arrays (UCAs). We introduce new parameters which compensate for the additional phase difference observed in its probability density functions (PDFs). The performance of the proposed codebook is tested using the spatial channel model (SCM) to demonstrate its gain over the standard codebooks adopted in the long term evolution (LTE) Releases 8 and 10.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.18 no.3
• /
• pp.156-162
• /
• 2004

In this paper, a technique that estimate the optimal capacity of the solar-wind hybrid power system for minimizing the total monthly electric power expenses is presented. The hybrid power system is assumed to be operated in connection with the utility power system and electric bill be paid for the power not covered by the hybrid system generation. Monthly generation cost is estimated based on total life-cycle cost analysis. The monthly utility power bill is assumed to be increased quadratically in proportion with the net utility power consumption which is the difference between the total monthly load minus the hybrid system generations. Test results demonstrate applications potential of the proposed technique.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.32 no.5B
• /
• pp.287-293
• /
• 2012

This study suggests the topographic index-based methodology which can be used to represent the saturation of soil and thereby change of variable runoff area at basin scale. ${\infty}$-flow direction method is applied to estimate topographic index because of its freedom from the restriction of 8-flow direction method as well as possibility of the minimum flow dispersion. From the comparison of topographic index distribution with the existing result the methodology is shown to be a workable one. It is judged that the representation of variable runoff area may be a systematic tool to investigate the dynamic and non-linear property of rainfall-runoff process because it can provide the explicit way to spatial distribution of basin saturation.