• Journal of Digital Convergence
• /
• v.10 no.10
• /
• pp.277-282
• /
• 2012

The speech recognition system can not quickly adapt to varied environmental noise factors that degrade the performance of recognition. In this paper, the echo noise robust HMM learning model using average estimator LMS algorithm is proposed. To be able to adapt to the changing echo noise HMM learning model consists of the recognition performance is evaluated. As a results, SNR of speech obtained by removing Changing environment noise is improved as average 3.1dB, recognition rate improved as 3.9%.

• Proceedings of the IEEK Conference
• /
• 1998.10a
• /
• pp.1273-1276
• /
• 1998

The HMM-Net is an architecture for a neural network that implements a hidden Markov model (HMM). The architecture is developed for the purpose of combining the discriminant power of neural networks with the time-domain modeling capability of HMMs. Criteria used for learning HMM-Net classifiers are maximum likelihood (ML), maximum mutual information (MMI), and minimization of mean squared error(MMSE). In this paper we propose an efficient learning method of HMM-Net classifiers using hybrid criteria, ML/MMSE and MMI/MMSE, and report the results of an experimental study comparing the performance of HMM-Net classifiers trained by the gradient descent algorithm with the above criteria. Experimental results for the isolated numeric digits from /0/ to /9/ show that the performance of the proposed method is better than the others in the respects of learning and recognition rates.

• Proceedings of the Korean Information Science Society Conference
• /
• 2002.04b
• /
• pp.328-330
• /
• 2002

본 논문에서는 패턴이나 음성데이터와 같이 순차적 데이터론 인식하는데 널리 사용되어온 모델로서, 일련의 순차적인 성질을 내포하고있는 데이터를 다루는 문제에 적합하다고 할 수 있는 HMM을 이용하여 정보추출 문제를 다룬다. 기본적으로는 통상적인 HMM 사용법을 따르나 모델의 구조를 정함에 있어서 HMM을 사용할 때는 주로 목적에 맞는 HMM의 구조를 수동으로 구성하고 모델 내부의 확률 파라미터 값을 학습시켰던 데 반해, 본 논문에서는 데이터의 전처리 정보를 이용하여 초기에 추상적으로 설정한 모델이 학습을 통해서 점차 구체화되어 가는 자기 구성 은닉마르코프 모델(5-HMM)을 제시하여 사용한다. 제시된 방법은 CFP(Call for Paper)등의 텍스트 데이터에 더만 실험에서 기존 방식을 사용한 HMM보다 향상된 결과를 보여준다.

• Journal of Korea Multimedia Society
• /
• v.19 no.1
• /
• pp.22-29
• /
• 2016

Hidden Markov Model is one of the most successful and popular tools for modeling real world sequential data. Real world signals come in a variety of shapes and variabilities, among which temporal and spectral ones are the prime targets that the HMM aims at. A new problem that is gaining increasing attention is characterizing missing observations in incomplete data sequences. They are incomplete in that there are holes or omitted measurements. The standard HMM algorithms have been developed for complete data with a measurements at each regular point in time. This paper presents a modified algorithm for a discrete HMM that allows substantial amount of omissions in the input sequence. Basically it is a variant of Baum-Welch which explicitly considers the case of isolated or a number of omissions in succession. The algorithm has been tested on online handwriting samples expressed in direction codes. An extensive set of experiments show that the HMM so modeled are highly flexible showing a consistent and robust performance regardless of the amount of omissions.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.5 no.3
• /
• pp.443-449
• /
• 2001

This paper is simulation research to improve speech recognition rates under the noisy environment. We examines recognition ratio based on frequency-weighted HMM together with spectral subtraction. As results, frequency-weighted HMM with scaling coefficients is trained as a minimum error classification criterion, and is presents a higher recognition rates in noisy condition than a conventional method. Furthermore, spectral subtraction method gives 11 to 28% improvements for this frequency-weighted HMM in low SNR, and gives recognition rates of 81.7% at 6dB SNR of noisy speech.

• Proceedings of the IEEK Conference
• /
• 1998.06a
• /
• pp.933-935
• /
• 1998

The HMM-Net is an architecture for a neural network that implements a hidden markov model (HMM). The architecture is developed for the purpose of combining the discriminant power of neural networks with the time-domain modeling capability of HMMs. Criteria used for learning HMM-Net classifiers are maximum likelihood(ML) and minimization of mean squared error(MMSE). In this paper we propose an efficient learning method of HMM_Net classifiers using a ML-MMSE hybrid criterion and report the results of an experimental study comparing the performance of HMM_Net classifiers trained by the gradient descent algorithm with the above criteria. Experimental results for the isolated numeric digits from /0/ to /9/ show that the performance of the proposed method is better than the others in the repects of learning and recognition rates.

• Proceedings of the Acoustical Society of Korea Conference
• /
• spring
• /
• pp.36-39
• /
• 1999

본 논문에서는 기존의 반연속 HMM과 신경망 알고리즘인 RBF(Radial Basis Function)를 혼합한 형태를 음성인식에 적용한다. 기존의 반연속 HMM은 학습 과정에서 모든 모델과 상태에서 공유되는 L개의 가우시안 확률 밀도들과 각가우시안 확률 밀도들의 가중치를 결정하는 흔합 밀도계수 의해 입력 음성의 특징을 확률적으로 모델링하는 혼합 확률을 얻고 또 Maximum likelihood와 Baum-Welch 알고리즘을 이용해 초기확률, 전이확률, 관측확률, 평균벡터 $\mu$, 공분산 행렬 $\Sigma$을 학습해 나간다. 그러나 제안한 RBF/반연속 HMM 혼합형태는 RBF의 변형된 방식을 첨가해 반연속 HMM 관측 파라미터를 RBF에 의해 결정함으로써 보단 분별릭 있는 화자독립 인식 시스템이 된다. 그래서 인식 실험결과 인식률에 있어서 기존의 반연속 HMM보다 향상된 인식률을 얻는다.

• Journal of the Institute of Electronics Engineers of Korea TE
• /
• v.37 no.3
• /
• pp.16-20
• /
• 2000

Most of speech recognition systems are using Hidden Markov Model based on statistical modelling frequently. In Korean isolated telephone digit speech recognition, high recognition rate is gained by using HMM if many training data are given. But in Korean continuous telephone digit speech recognition, HMM has some limitations for similar telephone digits. In this paper we suggest a way to overcome some limitations of HMM by using discriminant learning based on minimal classification error criterion in Korean continuous telephone digit speech recognition. The experimental results show our method has high recognition rate for similar telephone digits.

• Journal of the Korean Society of Clothing and Textiles
• /
• v.24 no.1
• /
• pp.15-23
• /
• 2000

Effect of fixation methods on the flame retardant(FR) and performance properties of MDPPA/HMM treated cotton fabrics were studied. Combination of three different fixation methods - premercerization, swelling agent treatment, pad dry cure fixation, and wet fixation - were applied to flame retardant finish of cotton with MDPPA/HMM. As a result, an increase in internal volume of cotton fiber by pre-mercerization and addition of swelling agent, and wet fixation increased %add-on of FR agent improving FR efficiency and wash fastness. Tensile strength of MDPPA/HMM treated cotton fabrics by wet fixation and swelling agent were slightly decreased, but that of premercerized cotton was improved. Wet fixated fabric showed lower bending rigidity and better compressional properties which improved fabric hand. Retention of swelling ability of cotton treated with MDPPA/HMM improved moisture absorption properties.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.27 no.11
• /
• pp.1864-1872
• /
• 2003

Hidden Markov Model(HMM) has been widely used in speech recognition, however, its use in machine condition monitoring has been very limited despite its good potential. In this paper, HMM is used to recognize rotor fault pattern. First, we set up rotor kit under unbalance and oil whirl conditions. Time signals of two failure conditions were sampled and translated to auto power spectrums. Using filter bank, feature vectors were calculated from these auto power spectrums. Next, continuous HMM and discrete HMM were trained with scaled forward/backward variables and diagonal covariance matrix. Finally, each HMM was applied to all sampled data to prove fault recognition ability. It was found that HMM has good recognition ability despite of small number of training data set in rotor fault pattern recognition.