• Journal of Korea Society of Industrial Information Systems
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• v.14 no.4
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• pp.8-15
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• 2009

Relay-assisted multi-input multi-output (MIMO) technique has become a promising candidate for next generation broadband wireless communications for high speed access. In this paper, we propose channel selective relay-based MIMO transmission system. The performance of relay-based system can be improved by using the subcarriers selectively based on the channel condition between relay and mobile station. Simulation results show that the proposed relay-based system considerably outperforms the conventional relay-based system.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.25 no.1
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• pp.124-133
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• 2021

Smart factory is a future factory that collects, analyzes, and monitors various data in real time by attaching sensors to equipment in the factory. In a smart factory, it is very important to inquire and generate the status and history of equipment in real time, and the emergence of various smart devices enables this to be performed more efficiently. This paper proposes a multi device-based system that can create, search, and delete equipment status and history in real time. The proposed system uses the Android system and the smart glass system at the same time in consideration of the special environment of the factory. The smart glass system uses a QR code for equipment recognition and provides a more efficient work environment by using a voice recognition function. We designed a system structure for real time equipment monitoring based on multi devices, and we show practicality by implementing and Android system, a smart glass system, and a web application server.

• Proceedings of the Korean Information Science Society Conference
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• 2008.06b
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• pp.400-404
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• 2008

무인항공기를 이용한 실시간 공중 모니터링은 재난 재해, 테러 등의 위기상황을 사전에 대비하고, 사고 발생 시 피해상황을 신속하게 파악할 수 있는 효율적인 관리 시스템이다. 실시간 공중 모니터링을 위해 무인항공부문에서는 고성능의 카메라, 관성항법장치, 레이저 스캐너, GPS 수신기 등의 다중 센서들을 장착하고, 제어하며 각 센서들로부터 입력받은 데이터 처리 및 지상국으로 데이터 전송이 실시간으로 가능해야 한다. 기존 무인 모니터링 시스템들은 카메라와 같이 단일 센서의 운용을 목적으로 설계되었으나, 본 연구에서는 레이져 스캐너, 적외선카메라를 포함하는 다중센서를 위한 컴퓨터를 설계하였다. 최근 다중센서를 장착한 관측시스템에 관한 연구가 미국 및 유럽에서 수행되고 있으나, 아직 개발이 완료되지 않은 상태이다. 본 논문에서는 고성능 다중 센서 데이터 처리를 위해 실시간 소프트웨어, 고속 대용량 데이터처리 기술, 고속 압축 기술, 이기종 다중 센서들 간의 시각 동기화 기능을 제공하는 탑재컴퓨터의 설계결과를 소개하였다.

• Journal of the Korea Society of Computer and Information
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• v.14 no.12
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• pp.33-40
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• 2009

We study Interpreted Systems, ATL, and ATEL to capture the notion of time, knowledge, and strategy which are important in the analysis of multi-agent systems and propose strategic constraints based on subgame perfect Nash equilibrium of game theory as one of the solutions for the issues of ATEL which an agent can access the current state of the whole system when making up his strategy even when he should be uncertain about the state, and no explicit representation of actions in ATEL models makes some natural situations harder to model. Also, we present strategic constraints-based Interpreted Systems for model checking of multi-agent systems.

• Journal of Korea Multimedia Society
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• v.9 no.1
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• pp.51-58
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• 2006

In this paper, we evaluated Ultra Wideband MC-CDMA system which is the combination of DS-CDMA and OFDM systems, which have been drafting in current standardization for IEEE802.15.3a. Too many Rake Fingers are demanded in the DS-CDMA system to detect multi-path signals, which results in high system complexity. OFDM system fails to qualify for FCC certification unless frequency hopping is off. MC-CDMA has lower complexity compared to DS-CDMA and shows good performance against frequency selective fading. In addition, for a wide-band communication, less radio power per spectrum is allowed in the MC-CDMA system than in an OFDM system. The MC-CDMA system is analyzed by a numerical formula and compared with DS-CDMA and OFDM by a computer simulation.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.8B
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• pp.1003-1011
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• 2011

In this paper, a real-time multi-source sensor data management system based on wireless sensor network is proposed and implemented. The proposed management system is designed to transmit the wireless data to the server in order to monitor and control the multi-source target's status efficiently by analyzing them. The proposed system is implemented to make it possible to control and transmit the wireless sensor data by classifying them, of which data are issued from the clustered sources composed of a number of the remote multiple sensors. In order to evaluate the performance of the proposed system, we measure and analyze both the transmission delay time according to the distance and the data loss rate issued from multiple data sources. From these results, it is verified that the proposed system has a good performance.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2005.11a
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• pp.135-138
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• 2005

최근 지상파 DMB 서비스를 위한 다중화 사업자들이 선정되어 이동 시에도 동영상을 포함하는 멀티미디어 방송 서비스를 위한 본방송을 준비하고 있다. 이러한 시점에서 다중화 사업자들은 송출되고 있는 방송의 상태를 확인하는 것이 필요하다. 더욱이, 지상파 DMB와 관련된 제품 및 서비스 개발자들은 필드 단위까지 방송 스트림을 상세하게 검토하려고 한다. 그러나, 현재 지상파 DMB 방송 스트림의 검증을 위한 방법이 제시되고 있지 않으며, 이를 위한 제품도 개발되어 있지 않다. 본 논문에서는 지상파 DMB 서비스를 위한 방송 상태를 검증하고 방송 스트림의 상세 정보를 분석하기 위한 방법을 제안하고, 이를 구현한 ETI 프레임 검증 시스템을 개발하여 상용 지상파 DMB 전송 시스템에 적용하여 실험하였다.

• Journal of Korea Society of Industrial Information Systems
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• v.14 no.5
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• pp.1-9
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• 2009

Relay-assisted multiple input technique has become a promising candidate for next generation broadband wireless communications. In this paper, we propose channel selective relay-based multiple input transmission system. In the proposed system, single carrier frequency division multiple access (SC-FDMA) and orthogonal frequency division multiple access (OFDMA) are adopted for uplink and downlink transmissions, respectively. The performance of relay-based system can be improved by using the subcarriers selectively based on the channel condition between relay station (RS) and mobile station, or between RS and base station. Simulation results show that the proposed relay-based system considerably outperforms the conventional relay-based system.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.17 no.7
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• pp.1597-1601
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• 2013

Multiple antenna technique is attracting attention as a core technology for next-generation mobile communication systems to accommodate explosively increasing mobile data traffic. Especially, recent researches focus on multi-user multiple input multiple output (MU-MIMO) system where base stations are equipped with several tens of transmit antennas and transmit data to multiple terminals (users) simultaneously. To enhance the performance of MU-MIMO systems, we, in this paper, propose an adaptive user selection algorithm which adaptively selects a user set according to varying channel states. According to Monte-Carlo based computer simulations, the performance of proposed scheme is significantly improved compared to the conventional scheme without user selection and approaches that of exhaustive search-based optimal scheme. On the other hand, the proposed scheme can reduce the computational complexity to $K/(2^K-1)$ compared to the optimal scheme where K denotes the number of total users.

• Journal of Digital Convergence
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• v.12 no.11
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• pp.265-272
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• 2014

This study suggests a system for preventing and coping with diverse industrial accidents available for taking place in the industrial field by designing a context-aware system of the solar cell equipment with the use of multi-sensor. It installs multi-sensor in the surrounding and major positions of the solar cell equipment, acquires data on the surrounding situations and solar cell equipment from this device, and then save it into the local memory and transmits it to the server. The saved data recognizes a situation based on the context-aware algorithm and judges depending on the perceived result. An administrator comes to have environment available for monitoring the status on the production field and equipments with real time according to the judged outcome through the context-aware algorithm. The context-aware system in the industrial field, which is put today in the ubiquitous environment, will become a service of offering appropriate information for dealing with industrial accidents through real-time inspection.