• Journal of information and communication convergence engineering
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• v.7 no.4
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• pp.561-564
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• 2009

A cryptographic dongle, which is capable of transmitting encrypted voice signals over the CDMA/GSM voice channel, was designed and implemented. The dongle used PIC microcontroller for signals processing including analog to digital conversion and digital to analog conversion, encryption and communicating with the smart phone. A smart phone was used to provide power to the dongle as well as passing the encrypted speech to the smart phone which then transmits the signal to the network. A number of tests were conducted to check the efficiency of the dongle, the firmware programming, the encryption algorithms, and the secret key management system, the interface between the smart phone and the dongle and the noise level.

• Journal of the Korean Institute of Telematics and Electronics S
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• v.35S no.4
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• pp.118-127
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• 1998

In this paper, we propose a voice personality transformation method which makes one person's voice sound like another person's voice. In order to transform the voice personality, vocal tract transfer function is used as a transformation parameter. Comparing with previous methods, the proposed method can obtain high-quality transformed speech with low computational complexity. Conversion between the vocal tract transfer functions is implemented by a linear mapping based on soft clustering. In this process, mean LPC cepstrum coefficients and mean removed LPC cepstrum modeled by the low dimensional vector are used as transformation parameters. To evaluate the performance of the proposed method, mapping rules are generated from 61 Korean words uttered by two male and one female speakers. These rules are then applied to 9 sentences uttered by the same persons, and objective evaluation and subjective listening tests for the transformed speech are performed.

• Proceedings of the KSPS conference
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• 2005.11a
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• pp.67-70
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• 2005

Voice conversion (VC) is a technique for modifying the speech signal of a source speaker so that it sounds as if it is spoken by a target speaker. Most previous VC approaches used a linear transformation function based on GMM to convert the source spectral envelope to the target spectral envelope. In this paper, we propose several nonlinear GMM-based transformation functions in an attempt to deal with the over-smoothing effect of linear transformation. In order to obtain high-quality modifications of speech signals our VC system is implemented using the Harmonic plus Noise Model (HNM)analysis/synthesis framework. Experimental results are reported on the English corpus, MOCHA-TlMlT.

• Proceedings of the IEEK Conference
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• 2003.07d
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• pp.1363-1366
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• 2003

This paper introduces computerized version of Hangout(Korean Language) Standard Pronunciation Rule that can be used in Korean processing systems such as Korean voice synthesis system and Korean voice recognition system. For this purpose, we build Petri net models for each items of the Standard Pronunciation Rule, and then integrate them into the vocal sound conversion table. The reversion of Hangul Standard Pronunciation Rule regulates the way of matching vocal sounds into grammatically correct written characters. This paper presents not only the vocal sound conversion table but also character conversion table obtained by reversely converting the vocal sound conversion table. Making use of these tables, we have implemented a Hangeul character into a vocal sound system and a Korean vocal sound into character conversion system, and tested them with various data sets reflecting all the items of the Standard Pronunciation Rule to verify the soundness and completeness of our tables. The test results shows that the tables improves the process speed in addition to the soundness and completeness.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.41 no.2
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• pp.51-64
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• 2004

The purpose of this paper is to establish the Standard Korean Vocal Sound into Character Conversion Rule (Standard VSCC Rule) by reversely applying the Korean Standard Pronunciation Rule that regulates the way of reading written Hangeul sentences. The Standard VSCC Rule performs a crucially important role in Korean speech recognition. The general method of speech recognition is to find the most similar pattern among the standard voice patterns to the input voice pattern. Each of the standard voice patterns is an average of several sample voice patterns. If the unit of the standard voice pattern is a word, then the number of entries of the standard voice pattern will be greater than a few millions (taking inflection and postpositional particles into account). This many entries require a huge database and an impractically too many comparisons in the process of finding the most similar pattern. Therefore, the unit of the standard voice pattern should be a syllable. In this case, we have to resolve the problem of the difference between the Korean vocal sounds and the writing characters. The process of converting a sequence of Korean vocal sounds into a sequence of characters requires our Standard VSCC Rule. Making use of our Standard VSCC Rule, we have implemented a Korean vocal sounds into Hangeul character conversion system. The Korean Standard Pronunciation Rule consists of 30 items. In order to show soundness and completeness of our Standard VSCC Rule, we have tested the conversion system with various data sets reflecting all the 30 items. The test results will be presented in this paper.

• Journal of the Korea Computer Industry Society
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• v.3 no.5
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• pp.585-594
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• 2002

This paper, describes about creation and implementation of phonetic value- transcription conversion table for postprocessing of the voice recognition. Transcription set generator, which produces transcription set that is pronounced as recognized phonetic value, is designed and implemented to postprocess for the voice recognition system which recognizes syllable unit phonetic value Phonetic value-transcription conversion table is produced with transcription-phonetic value conversion table produced by modeling standard pronunciation on petrinet. To show that phonetic value-transcription conversion table produces correct transcription set, transcription set generator is designed and implemented. This paper proves that correct transcription set is produced, which is including pre-vocalization transcription as a result of experimenting standard pronunciation examples and the words randomly sampled from pronunciation dictionary.

• The Journal of the Acoustical Society of Korea
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• v.20 no.3
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• pp.15-23
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• 2001

This paper presents a voice conversion technique that modifies the utterance of a source speaker as if it were spoken by a target speaker. Feature parameter conversion methods to perform the transformation of vocal tract and prosodic characteristics between the source and target speakers are described. The transformation of vocal tract characteristics is achieved by modifying the LPC cepstral coefficients using Linear Multivariate Regression (LMR). Prosodic transformation is done by changing the average pitch period between speakers, and it is applied to the residual signal using the LP-PSOLA scheme. Experimental results show that transformed speech by LMR and LP-PSOLA synthesis method contains much characteristics of the target speaker.

• Journal of KIISE:Computing Practices and Letters
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• v.7 no.6
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• pp.559-569
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• 2001

It is possible to access web contents by mobile terminals and telephones due to the evolution of voice and VoiceXML technologies. Nevertheless, because these days most of all the web contents are constructed by HTML, it is impossible to access them by using the new technology. Therefore, to access the contents through voices requires the conversion of the web document from HTML to VoiceXML, but its manual conversion process should be involved additional time and expenditure. In this paper, we design and implement HTMLtoVoiceXML converter, suggest a system structure of it and propose a practical identification algorithm of meaningful fragmented group of contents to solve the problem. To test the performance and validity of the converter, we apply it to more than 400 web pages in Korean web sites, it works well except for web pages which involve invalid HTML codes.

• MALSORI
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• no.49
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• pp.77-94
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• 2004

In this paper, new voice message system supporting massive outbound call is proposed. Basic idea of the proposed system is to pre-process all the text-to-speech conversion process, mixing of text and attached music file and to store the results of pre-process in the cache server which is connected to the IVR. New voice message system is optimized for the voice message system supporting massive outbound call by distributing the load of the web server caused by server-side script implementation which is accessing database and generating dynamic Voice XML document over client module and server module of web server. The proposed voice message system was test-deployed in one domestic voice message application service provider and it is shown that proposed voice message system reduced the response latency problem of test-bed voice message system.

• MALSORI
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• no.67
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• pp.167-180
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• 2008

This paper describes a novel spectral envelope conversion method based on Gaussian mixture model (GMM). The core of this paper is rearranging source feature vectors in input space to the transformed feature vectors in feature space for the better modeling of GMM of source and target features. The quality of statistical modeling is dependent on the distribution and the dimension of data. The proposed method transforms both of the distribution and dimension of data and gives us the chance to model the same data with different configuration. Because the converted feature vectors should be on the input space, only source feature vectors are rearranged in the feature space and target feature vectors remain unchanged for the joint pdf of source and target features using KPCA. The experimental result shows that the proposed method outperforms the conventional GMM-based conversion method in various training environment.