• Journal of the Korean Professional Engineers Association
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• v.23 no.1
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• pp.49-63
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• 1990

A signalling system generally designates electrical conditions and transmissionㆍreceiving programs of exchange control use signals concerning the establishmentㆍreleaseㆍtariff etc of calls between telephone subscribers and an exchange office or inter-exchange offices. In signalling system, different systems are being used according as communication service for control. With the development of exchange and transmission technique and higher functional advance, there exist many kinds of signalling systems. As for the signalling system used in international communication, an international standardization is specially important for the exchange of each country to operate properly and execute a smooth exchange connection. A term "signalling system" is chiefly used in telephone exchange system, while in telex exchange system "signalling condition, " and in data exchange system "protocol" is used. "protocol" is used.; is used.

• Journal of the Korean Professional Engineers Association
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• v.24 no.1
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• pp.95-103
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• 1991

The communication transmission engineering plays the most important role in electrical communications engineering. Recently, it has been making remarkable progress as an infrastructure supporting informationaged society. Specially, the start of television conference and service of high speed digital transmission can be said it is announcing a raising curtain of high speed broad band age. Together with high speed broad band service needs a capacity as much as several or several hundred times of telephone with one circuit, various kinds of service forms are anticipated to emerge, it is anticipated to give a big impact to the way of future communications newtork. At present, telecommunication network is transforming telephone voice information by analog technology into a flexible higher system disposable of a variety of information such as pictures or data other than telephone by the introduction of digital technology. Consequently, the development of hereafter for the following respective technologies is desired.

• Journal of the Korean Professional Engineers Association
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• v.24 no.2
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• pp.127-136
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• 1991

The communication transmission engineering plays the most important role in electrical communications engineering. Recently, it has been making remarkable progress as an infrastructure supporting informationaged society. Specially, the start of television conference and service of high speed digital transmission can be said it is announcing a raising curtain of high speed broad band age. Together with high speed broad band service needs a capacity as much as several or several hundred times of telephone with one circuit, various kinds of service forms are anticipated to emerge, it is anticipated to give a big impact to the way of future communications network. At present, telecommunication network is transforming telephone voice information by analog technology into a flexible higher system disposable of a variety of information such as pictures or data other than telephone by the introduction of digital technology. Consequently, the development of the hereafter for the following respective technologies is desired.

• Journal of Biomedical Engineering Research
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• v.7 no.1
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• pp.21-34
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• 1986

In this paper, we described the ECG telemetry system via the Public Telephone Line. The system consist of a signal acquisition and measurement section, a signal processing section, and a signal transmission section. It used 8 bits microprocessor. The transmission section is composed of 3 ch. analog modulators and 1 ct. digital modem. Especially, using the digital modem, signal is transmitted with about 50n data reduction ratio by the TP (Turning Point) algorithm. The acoustic coupler or inductive coil for linking the public telephone line are used. The speed of the digital modem is 300 baud rate. The MCBS (Multi Channel Biotelemetry System) is tested and evaluated through the experiment.

• Proceedings of the Acoustical Society of Korea Conference
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• 1994.06a
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• pp.1070-1075
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• 1994

This paper describes the method for designing loudness ratings as transmission quality for ISDN telephone connected to fully digital network. To design the desirable loudness ratings for ISDN telephone, the model system of digital speech communication for subjective test is developed and opinion tests for establishing the optimal CODEC input level, the range of overall loudness rating, and sidetone masking rating are performed. As the results, the desirable ranges of loudness ratings are proposed as 6 to 8dB for sending, 0 to 2dB for receiving, and 10 to 14dB for sidetone masking rating.

• Proceedings of the IEEK Conference
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• 2002.06d
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• pp.191-194
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• 2002

The final purpose of this paper is the enhancement of speech recognition rate under the matched telephone environment between training data and test data. To analyze the effect by the distortion of the changing telephone channel on every call, MFCC is used as the feature parameter and CMN, RTCN, and RASTA are used as channel compensation techniques. For each case, the variation of feature parameters of all phones is analyzed. And, we find recognition rates according to each compensation method using the continuous HMM recognizer, and examine the relationship between variation and recognition rate.

• Survey Research
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• v.1 no.1
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• pp.21-43
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• 2000

Although telephone surveys are an attractive alternative to household interviews it is important to determine whether the data collected by the two methods are comparable. To answer this question, findings from the telephone survey literatures are examined in the view point of i) direct effect which means expressions of preference of the interview detail of answers on open questions and item missing data rates ii) statistical estimates and iii) differences of interviewers and data collection modes. Differences are explained by social desirability effects on the telephone, cognitive ability of the survey question, and mode effects and interviewer effects.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.27 no.7C
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• pp.723-727
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• 2002

In this paper a new remote control system for operating indoor gas(LPG) range safely based on PLM(Power Line Modem) and telephone is developed because it would make disasters of properties and lives by user's carelessness or worker's bad installation, etc. The system includes the following elements: a telephone line interface system for user to call from the outdoors to the indoors, a communication system using the power line as a communication media, a system of cutting off gas and a alarm system.

• Proceedings of the KSPS conference
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• 2003.05a
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• pp.119-122
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• 2003

In general, triangular shape filters are used in the filter bank when we get the MFCCs from the spectrum of speech signal. In [1], a new feature extraction approach is proposed, which uses specific filter shapes in the filter bank that are obtained from the spectrum of training speech data. In this approach, principal component analysis technique is applied to the spectrum of the training data to get the filter coefficients. In this paper, we carry out speech recognition experiments, using the new approach given in [1], for a large amount of telephone speech data, that is, the telephone speech database of Korean connected digit released by SITEC. Experimental results are discussed with our findings.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.12 no.6
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• pp.1006-1009
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• 2008

We suggest the digital voice encryption module using the pseudo random number generator and design the security device of a telephone using the module. The proposed method provides encryption method of the telephone against the third party. This encryption method uses pseudo random number generator which computes the encryption key using the shared secret key and the current time value.