• Proceedings of the KIEE Conference
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• 2002.11c
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• pp.509-512
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• 2002

We propose a control method for mobile robot system using the bluetooth. The control packet is defined and used for control of the mobile robot. The control packet is composed of behavior components and has reserved packets for future working. The control packet has to be simple and provide commands to the mobile robot, since the bluetooth has a limited bandwidth. The data transmission rate and the distance, which can control the mobile robot in various circumstances, for example, corridor, yard, and room are measured by some experiments.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.32 no.2
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• pp.50-58
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• 1983

In this paper, a field trial of the Korean-made optical fiber communication system is described. This system was installed between Gu-Ro and Ann-Yang telephone offices on November 1981, and carries a 44.7Mb/s NRZ signal(672 voice channel equivalent). For this trial, optical fiber cable, optical terminal equipment, optical repeater, fusion splicer and measurement equipment have been developed. Employing graded index optical fiber at a wave length of $0.85\;\mu\textrm{m}$, average optical attenuation and splicing losses of 3.6 dB/km and 0.4 dB, resectively, were realized. With link margins of 8~20dB and bit error rate of less than $10^{-10}$, this system has been carrying live traffic between Seoul and Ann Yang telephone offices.

• The Transactions of the Korean Institute of Electrical Engineers D
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• v.54 no.2
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• pp.116-123
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• 2005

Chirp spread spectrum method using both time and frequency component is fit to time varying channel such as powerline channel. The used chirp symbol based on the CEBus standard is the unit symbol which sweeps from 100kHz to 380kHz over a 25㎲. To evaluate the performance of between Chirp-SS and DSSS, we measured the bit error rate under Gaussian channel. Simulation result is shown that Chirp-SS has a about 3[dB] gain of SNR than DSSS. To verify the performance of implemented modem, it is made up the powerline channel environment. After adding several noises to it, we examined the receiving status of modem. The implemented modem is able to receive the signal over the powerline channel with having several noises and capacitive loads.

• Proceedings of the KIEE Conference
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• 2002.07d
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• pp.2640-2642
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• 2002

In this paper, we show the channel characteristics measurement system the frequency range up to 30MHz for medium voltage Power Line Grid. Power line channel characteristics are investigated by means of various measurement instruments. Measurement system consists of medium voltage coupler, impedance measurement part, noise measurement part, voltage sensing part and communication part. Measured data will be used for PLC channel modeling and PLC network system design.

• Proceedings of the KIEE Conference
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• 2002.07d
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• pp.2540-2542
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• 2002

In recent years, it is a worldwide trend that many power utilities focus their attention to employ up-to-date communication technology to the automation of their power plants and distribution systems. Automation Systems in Korea was installed using twisted pair cable(TPC), power line carrier(PLC), coaxial cable(CA), wireless network(wireless data, TRS and PCS). Among the communication media only Satellite Communication guarantees the reliable communication in case of emergency such as a flood, a heavy snow and an earthquake. It can integrate two-way satellite systems to existent nationwide SCADA controlling points of electric power transmission & distribution system that enables real time remote monitoring and controlling automatically. This paper presents some of design efforts for the satellite communication network as the media of Automation Systems.

• Proceedings of the KIEE Conference
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• 2002.07d
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• pp.2553-2555
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• 2002

In this paper, we designed the monitoring system by one personal computer which supervise multiple data of multiple system based on the serial communication. This multiple data of multiple system has the merit of the effective data acquisition.

• Proceedings of the KIEE Conference
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• 2002.07d
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• pp.2298-2300
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• 2002

In this paper, we introduced a fault tolerant control system with the aim of achieving higher degree of reliability for a PLC control system in the field network. The system reliability was evaluated by MTBF(Mean Time Between Failure). The design of the fault tolerant system through CC-Link of Mitsubisi's MELSEC network was presented. In addition, the PLC data is transmitted from the field network's PC to the host PC by TCP/IP Window socket.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.25 no.11
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• pp.123-129
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• 2011

In terrestrial wireless optical communication links, atmospheric effects including turbulence, absorption and scattering have significant impact on the system performance. Based on the analysis of transmission in atmospheric channel concerning 830[nm] wavelength diode laser beam, performance of free space optical (FSO) link utilizing Galilean optics as a laser beam transmitting and receving optics, PIN photodiode as a detecting device. In this paper we designed optical link equation for received optical power and we analyze the atmospheric effects on the signal to noise ratio (SNR) and bit error rate (BER) of an terrestrial FSO system. We show that the possible communication distance for BER=$10^{-9}$ in proposed adverse atmospheric conditions.

• Proceedings of the KIEE Conference
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• 2007.10a
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• pp.493-494
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• 2007

RFID (Radio Frequency IDentification) 시스템에서 수동 태그의 낮은 전송 파워 때문에 리더는 태그와의 통신시 많은 에러를 경험하게 된다. 이것은 리더가 태그의 정보를 빠르고 정확하게 인식하는 것을 어렵게 만든다. 따라서, 이러한 문제를 해결하기 위해 에러에 강한 알고리즘을 개발하고 적용할 필요가 있다. 리더가 태그의 정보를 인식하기 위해 사용하는 대표적인 프로토콜에는 ALOHA 기반의 DFSA (Dynamic Framed-Slotted ALOHA) 프로토콜과 트리 기반의 이진트리 프로토콜이 있다. 기존의 두 프로토콜 중 DFSA는 에러가 없을 때 이진트리 보다 성능이 우수하나, 에러가 존재할 때, 이진트리 보다 약 35% 정도 에러의 영향을 많이 받는 성질을 보인다. 본 논문에서는 에러가 있는 환경과 없는 환경에서의 DFSA와 이진트리 프로토콜의 성능을 분석하고, 시뮬레이션을 이용하여 이 논문에서의 성능 분석 방법이 타당함을 증명한다. 그리고 에러가 많은 환경에서는, 빠른 RFID 태그 인식을 위해 DFSA 프로토콜보다 이진트리 프로토콜을 사용할 것을 제안한다.

• 전기의세계
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• v.53 no.7
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• pp.24-30
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• 2004

80년대 후반부터 급속히 발전한 전력용 반도체 기술과 마이크로프로세서에 의한 제어기술은 산업계에 전력전자기기의 보급을 급증시켜 왔으며, 직류모터 구동장치의 경우 싸이리스터 컨버터와 초퍼에 의한 제어가 보편화 되었고, 교류모터 구동장치의 경우 PWM(Pulse Wid Modulation) 인버터에 의한 제어가 보편화 되어 사용 중에 있어 획기적인 생산성 향상과 에너지 절감이 가능하였다. 그러나 이러한 전력전자기기의 사용이 급증하면서 고조파의 발생과 더불어 전체 배전계통의 오염문제가 크게 대두되고 있다. 또한 산업이 고도화하면서 입력전압 변동에 대단히 민감한 정교하고 고신뢰성을 요하는 부하가 많이 등장하였으며, 대표적인 기기로는 컴퓨터, 자동화기기, 통신장비, 의료용장비, 군용장비 등을 들 수 있다. (중략)