• Proceedings of the KIEE Conference
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• 1996.07a
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• pp.107-111
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• 1996

In this paper, the voltage monitoring system is designed to monitor the outage and voltage fluctuation by using a dial-up telephone. The master station receives tire outage signal-such as interruption and voltage sag etc. - from the remote in on-line of real-time. The SCC(Serial Communication Controller) is adapted to monitor voltages multiple clients(about 256 clients) simultaneously. The voltage fluctuation in a normal range shall be transmitted to the master station, at early morning the clients use the telephone less frequently. The operating system shall be "window 95" and the database is programmed in Visual-basic for a easy analysis of voltage fluctuation.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.5 no.6
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• pp.1151-1156
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• 2001

In this paper, the electric field distribution and directivity on human head caused by portable phone is analyzed. An analysis model is composed of a human head model and the antenna mounted on the same ground plane as portable telephone size. The QMSA to load a capacitor without limitation of the electric force is used In the computational model to apply to the antenna mounted on portable phone. This antenna is designed to operate in the near of frequency 2.0㎓, is observed the radiation characteristics of the antenna and their variations as a function of distance from the human head.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.22 no.11
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• pp.2381-2387
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• 1997

The Communication Processing Systems(CPS) is a gateway that supports 01410 hitel service by connecting the public switched telephone network(PSTN) with the public switched data network(PSDN). The CPS is made the meausred rate accounting method for the biling after extracting the originating numbers from the nearest local PSTN. In this paper, a numerical simulation is carried out on the offered traffic per user on the telephone access part of the CPS according to change of call loss probability and also propose the proper number of channels based on the simulation results.

• Journal of information and communication convergence engineering
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• v.6 no.1
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• pp.68-72
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• 2008

The VoIP(Voice over IP) has been worldwide used and already put to practical use in many fields. However, it is needed to ensure secret of VoIP call in a special situation. It is relatively difficult to eaves-drop the commonly used PSTN in that it is connected with 1:1 circuit. However, it is difficult to ensure the secret of call on Internet because many users can connect to the Internet at the same time. Therefore, this paper suggests a new model of Internet telephone for eavesdrop prevention enabling VoIP(using SIP protocol) to use the VPN protocol and establish the probability of practical use comparing it with Internet telephone.

• ETRI Journal
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• v.5 no.1
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• pp.3-9
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• 1983

The pathsearching method in switchingmatrix of an electronic switching system depends upon the structure and function of the system. In this paper, an efficient way to construct the switching matrix and a pathsearching method under the full distributed traffic theory in an wideband switching system, which can control not only normal telephone call, but also TV telephone, data communication, videotex and sound, is proposed. And the effectiveness of the method is shown through an example of the pathsearching simulation program.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2013.10a
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• pp.801-804
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• 2013

Automatic dialing function of the telephone is to support communication such as emergency call, public relations and guidance service by automatic dialling of individual phone number. In this paper, we analyze the relevant provisions of each country and discuss the direction of institutional maintenance related to automatic dialling function.

• Proceedings of the IEEK Conference
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• 2002.07c
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• pp.1819-1822
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• 2002

The authors propose a robust symbol timing recovery (STR) for telephone line modems supporting data rates up to 32 Mbps. The STR is initialized by a start signal from carrier sensor, and the novel method is proposed which resolves the difference between the frequency of the transmitter's clock and the receiver's clock, called baud frequency offset. The proposed method is applied on digital receiver in a 16 frequency diverse quadrature amplitude modulation (FDQAM) system.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.3 no.1
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• pp.175-183
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• 1999

This paper describes the network configuration, No. 7 signaling IS-41.A protocol and basic operations for the RFC(Remote Feature Control) service which is one of the supplementary services provided in the mobile telephone network. In order to solve the protocol error occurred while providing the RFC service for analog system, this paper suggests three schemes and analyse detail signal algorithm for the proposed schemes. Through the simulations, it is verified the best choice of the proposed schemes without the signaling procedure error.

• Proceedings of the IEEK Conference
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• 1998.06a
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• pp.557-560
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• 1998

In this paper, we presetn the WWW (world-wide-web) base dtelePACS, which uses the communication network as asymmetric satellite data communication system (ASDCS). Web-based telePACS is imple-mented with JAVA language. Through the internet, web-based TelePACS can make it possible for remote hospital or doctor to access PACS data and information easily and cheaply. The ASDCS uses receive-only satellite links for data delivery and PSTN (Public switched telephone Network) modem or N-ISDN (narrow band integrate services digital network) for communication. The satellite communication linking shows the very high-seed performance such as 10-30 times faster than the modem linking.To solve the speed limits of internet, JPEG and wavelet compression methods were adapted in WWW-based TelePACS and were evaluated by PSNR (peak signal-to-noise ratio) and by radiological experts that 10:1 or less JPEG and wavelet compression may be acceptable for diagnostic purposes. Consequently, we get the conslusion that our system is suitable for tele-radiology and telemedicine world widely.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1997.04a
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• pp.708-713
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• 1997

A remote data communication system for monitoring of NC machine fault diagnosis and status is developed. This system communicates with host PC by using dial-up communication method on PSTN. The developed system consists of (1)remote communication module among NC's and host PC using PSTN, (2) 8 channels analog data sensing module, (3) digital I/O module for control of NC machine, (4) communication module between NC machine and remote data communication system using RS-232c, and (5) Software man-machine interface. This system may be applied for remote sensing of the status in Fms. To show the veridity of the developed system, several examples are illustrated.