• 전자통신동향분석
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• 제36권4호
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• pp.23-33
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• 2021

Wireless communication for train control is an active research field. The World Railway Federation in Europe developed GSM-R, which integrates the GSM-based voice call standard and train control signals. To provide advanced railway services, the LTE-R wireless communication system was developed in Korea for passenger services and wireless image information required by the railroad industry. Recently, direct communication technology for autonomous train driving has been studied to decrease the driving interval, and research is being conducted on a hyperloop train control system that runs at a maximum speed of 1,220km/h in a subvacuum environment of 0.001 atmosphere. In this paper, we summarize the trends in wireless communication technologies used for GSM-R/LTE-R railway systems. For future wireless communication in railway systems, we discuss autonomous train driving and the hyperloop railway control system, define wireless communication technology, and discuss trends in domestic and foreign technologies.

• ETRI Journal
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• 제33권2호
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• pp.279-282
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• 2011

Coexistence analysis is extremely important in examining the possibility for spectrum sharing between orthogonal frequency-division multiplexing (OFDM)-based international mobile telecommunications (IMT)-Advanced and other wireless services. In this letter, a new closed form method is derived based on power spectral density analysis in order to analyze the coexistence of OFDM-based IMT-Advanced systems and broadcasting frequency modulation (FM) systems. The proposed method evaluates more exact interference power of IMT-Advanced systems in FM broadcasting systems than the advanced minimum coupling loss (A-MCL) method. Numerical results show that the interference power is 1.3 dB and 3 dB less than that obtained using the A-MCL method at cochannel and adjacent channel, respectively. This reduces the minimum separation distance between the two systems, which eventually saves spectrum resources.

• 한국전자통신학회논문지
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• 제12권4호
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• pp.555-560
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• 2017

현재 우리나라의 철도 무선통신시스템은 각 지역에 따라 서로 다른 통신방식을 사용하고 있다. 철도 무선통신시스템에서 데이터의 전송률을 높이고 고신뢰성을 확보하기 위해 LTE-R방식의 도입이 연구되고 있다. 본 논문에서는 LTE-R방식을 포함한 다양한 철도통신 방식을 연동하는 기술 개발에 대해 소개한다. 먼저 다양한 철도통신 방식을 연동하는 두 가지방식의 개념 및 표준에 대해 소개한다. 또한 연동방안에 대한 실제 실험결과에 대해서도 일부 소개한다. 본 논문에서 소개하는 연동 기술을 철도 무선통신망에 적용함으로써 끊김 없고 안정적인 철도 무선통신환경이 제공될 것으로 예상된다.

• 대한임베디드공학회논문지
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• 제1권2호
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• pp.82-89
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• 2006

It appears that it is possible for us to make a wireless communication of even home-network system within car by integrating with the Ubiquitous such as mobile phone, wireless Internet, GPS and DMB in the future. If the present wireless surroundings within the car are connected with very high-speed wireless network as measurement system for wireless communication surroundings within this car in the future, it will develop the complicated communication conditions such as safe checkup, communication between systems within car, and wireless communication for user entertainment unlike universal communication conditions. Accordingly, there is the necessity of the device that can measure the interference of electric wave, communication speed and communication quality by a kind of each car. This paper aims at making the real measurement device to raise the reliability of each Application for inquiring into the interference about each other in the frequency band used under Telematics surroundings.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2000년도 제15차 학술회의논문집
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• pp.48-48
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• 2000

We developed a wireless communication system for multiple instrumentation system. The developed system has a function of remote instrumentation and PLC(Programmable Logic Controller) control. The system consists of CC(Control and Communication) protocol, wireless media access and physical media system. For multiple wireless communication, we propose a hub polling protocol based on master-slave control concept. To show the validity of the developed system, several experiments are illustrated.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2006년 학술대회 논문집 정보 및 제어부문
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• pp.117-119
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• 2006

BACnet(Building Automation and Control networks) is a standard data communication protocol designed specifically for building automation and control systems. BACnet provides five options for datalink layer protocols and these five datalink layer options can be applied with various transmission media. Recently wireless technology prevails in automation area. ZigBee is a standard protocol based on IEEE 802.15.4 for low-speed wireless communication network. In this study, we propose a BACnet/ZigBee model that uses ZigBee wireless technology in a BACnet communication network system as a wireless datalink layer protocol. We also applied this model to a lighting control system to evaluate the feasibility of proposed technology. The technology proposed in this paper can extend the application of BACnet not only for building automation but also for home automation by taking the advantages of ZigBee wireless communication technology in BACnet communication network systems.

• 한국항행학회논문지
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• 제26권1호
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• pp.1-8
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• 2022

원격측정 시스템은 비행체의 상태 정보를 계측하여 지상으로 전송하는 시스템이다. 지상에서 수신한 데이터는 비행체의 상태를 모니터링하기 위한 정보로 점검 프로그램을 통해 실시간으로 점검 및 분석이 가능하다. 현재 운용중인 원격측정 자료처리 점검 시스템은 유선 통신을 이용하여 데이터를 전송하고 점검을 수행하도록 구축되어 있다. 계속되는 정보통신기술의 발전으로 스마트 기기가 대중화되면서 무선 통신 네트워크가 중요해지고 있으며, 성능 개선을 위한 기술 개발이 꾸준히 이루어지고 있다. 때문에 본 논문에서는 기존 방식을 탈피하고 미래지향적인 기술을 적용하기 위해 태블릿과 같은 스마트 기기를 통해 점검 가능한 무선 통신(Wi-Fi; Wireless fidelity) 기반의 원격측정 자료처리 지상 점검 시스템을 제안하고 구축하였다. 또한 점검 장비와 점검 프로그램을 연동하여 다양한 환경에서의 테스트를 통해 제안한 점검 시스템의 성능을 확인하였다.

• 반도체디스플레이기술학회지
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• 제3권4호
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• pp.13-17
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• 2004

As the usage of wireless LAN becomes common in working environment, the number of database systems that support both wired and wireless users increases rapidly. The characteristics of wireless LAN that its speed is slow relatively comparing to wired network and the users in its environment connects to different communication points as they moves creates another challenge to be resolved in database systems. In the environment of hybrid communication systems, wired and wireless for voluminous data amount and a number of users, the two layer architecture of the conventional client-server database systems has limitation in the system performance. This is due to that server is the only point of data service in client-server database systems. In this paper, we discuss a new extended database system architecture that data services are distributed among servers and clients based on user database access patterns in order to improve system performance. We analyze the expected system performance by using simulation technique and prove the practical utilization of the system by demonstrating experimental results.

• Journal of Communications and Networks
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• 제11권4호
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• pp.384-389
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• 2009

Optical wireless communication (OWC) systems are rapidly gaining popularity as effective means of transferring data at high rates over short distances. OWC facilitates rapidly deployable, lightweight, high-capacity communication without licensing fees and tariffs. Nevertheless, the performance of this new technology depends strongly on the atmospheric conditions and the characteristics of the link. In this work, we study the influence of these parameters on both the average (ergodic) capacity and the outage capacity of an OWC system over moderate to strong turbulence channels modeled by gamma-gamma distribution. Moreover, we compare the results that we obtain estimating the average and outage capacities.

• Journal of Information Processing Systems
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• 제10권2호
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• pp.215-222
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• 2014

In this paper, we discuss optical encryption and decryption considering wireless communication channels. In wireless communication systems, the wireless channel causes noise and fading effects of the transmitted information. Optical encryption technique such as double-random-phase encryption (DRPE) is used for encrypting transmitted data. When the encrypted data is transmitted, the information may be lost or distorted because there are a lot of factors such as channel noise, propagation fading, etc. Thus, using digital modulation and maximum likelihood (ML) detection, the noise and fading effects are mitigated, and the encrypted data is estimated well at the receiver. To the best of our knowledge, this is the first report that considers the wireless channel characteristics of the optical encryption technique.