• The Journal of the Korea institute of electronic communication sciences
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• v.7 no.4
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• pp.873-879
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• 2012

Recently the cloud computing paradigm has been widely accepting in various applications. Data management system of cloud computing requires ability to manage tremendous data and supporting scalability. The former can be achieved by weaken consistency and limitation of transactions, and the latter needs expand or shrink of components. In this paper, we propose a transaction processing model and a scalable module management algorithm when transaction is executed in the cloud. Transaction processing model consists of a transaction management module and a data management module. Scalable module management algorithm has no redistribution of components and may alleviates loads of existed modules. With simulation results, we can see the improvement of response time and decrease abort ratio of transactions.

• Proceedings of the Korea Information Processing Society Conference
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• 2011.04a
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• pp.11-13
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• 2011

최근 스마트 폰, 타블렛 PC 등 고성능 모바일 기기에 대한 시장수요가 증가함에 따라 임베디드 프로세서에 대한 성능 최적화가 활발히 이루어지고 있다. 고성능 멀티미디어 시스템을 대상으로 설계된 Empress 프로세서는 다수의 기능 유닛을 포함하고 있어 명령어 스케줄링을 통해 성능 향상을 기대할 수 있으나 기존의 컴파일러는 이를 지원하지 않고 있다. 본 연구에서는 GNU C 컴파일러를 이용하여 Empress 프로세서를 위한 DFA 기반의 명령어 스케줄링 최적화를 구현하였다. 그 결과 EEMBC 벤치마크를 이용한 성능 분석에서 실행시간 기준 평균 8%의 향상이 있음을 확인하였다.

• Proceedings of the IEEK Conference
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• 2003.07c
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• pp.2795-2798
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• 2003

본 논문에서는 국내에서 개발하고 있는 과학로켓용 발사통제시스템(FCS, Fire Control System)의 시퀀스제어의 처리 영역을 PLC 시스템을 사용하여 구현하였다. 프로세서의 이중화를 통하여 Hot Backup 시스템을 구축하고 ControlNet 네트워크［l］［2］를 기반으로 하는 프로세서와 I/O 간의 통신을 이용하였다. 먼저 로켓 발사통제시스템의 개요 및 주요 임무에 대하여 설명하고 기존에 사용된 발사통제시스템 구성을 분석하였다. PLC 시스템의 개요와 CPU 동작 내용 그리고 ControlNet 통신방식에 대하여 설명하고 프로세서를 이중화한 시스템을 제안하였다. 또한 이중화된 프로세서의 Switchover［2］방법을 알아보고 이러한 조건에 따른 PLC 시스템을 응용한 발사 통제시스템을 구성하여 이를 위해 작성된 시스템 운용 Ladder Diagram 프로그램에 대한 기술을 논하였다. 개발된 PLC 시스템의 구성을 제시하고 발사체 및 각종 지원시설과 연계한 시험을 통하여 성능을 검증하였다.

• The Journal of the Korea institute of electronic communication sciences
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• v.12 no.5
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• pp.817-828
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• 2017

It is very hard to find the system which processes single 10Gbps stream, and the related application is also rare. But in the field of science such as physics and astronomy, these high speed systems have been widely used and now more upgraded performance is expected. For this reason, high speed network based storage which captures and records 10Gbps level of packets was developed for the support of small astronomical company in KASI. But for the use of the system in research, system performance should be not only evaluated but also optimized. In this paper, we first implement system environment for the performance evaluation and discuss the experiment procedure and solution to acquire numerical results.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.43 no.4 s.310
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• pp.123-132
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• 2006

In this paper, the digital video and audio system is improved so that various digital video data formats in DVD disc, and digital audio data formats through the S/PDIF ports may be decoded. It is not easy to implement all decoding functions of video and audio by a DVD processor. The special structure in audio decoding circuit is proposed in this system so as to have simultaneously almost same video and audio performance in quality. By dividing the decoding circuit separately into video and audio part, the audio quality can be dramatically improved together with supporting several audio formats and with several effects. In order to satisfy the perfect audio system to support to audio decoding formats, it is just enough to get the expensive, complicated decoder. However, it may be not easy to get this expensive decoder in near future. Therefore it is rather to adopt the downloading method by which the host should download the appropriate code into memory by detecting the corresponding audio bit streams. It is proved that this method may be efficient in the point of sharing resource of audio data for video decoding.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.37 no.5
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• pp.13-21
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• 2000

In this paper, we investigate the performance improvement by applying flow control to LonWorks-based network systems which support various communication media together with interpretable class of systems. To this end, we introduce a circular queue at each node of industrial network systems usually operated in open loop. Then we utilize the feedback information of the number of data in a queue, the data arriving interval in a queue and channel error to make the overall industrial network system in closed loop. We verify the improved performance of the network systems in view of throughput and fairness measures via the experimental results conducted in several field situation.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.48 no.4
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• pp.77-83
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• 2011

In this paper, we study the throughput-delay tradeoff of OFDMA systems in context of 2-dimensional resource allocation, and analyze the effect of frequency diversity and user-multiplexing in time domain that has on delay QoS performance. Based on the analysis results, we investigate the impacts of delay QoS on spectral efficiency. In high SNR regime, the optimal DoM (degree of multiplexing) maximizing the spectral efficiency is identified. The results of the high SNR analysis can give us an intuition on an efficient resource allocation policy. Finally, through the simulation results, we verify that our approach with its optimal DoM yields substantial capacity gain.

• Journal of the Institute of Electronics and Information Engineers
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• v.54 no.2
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• pp.3-8
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• 2017

This paper considers an application of distributed antenna system (DAS) to a system of intra-vehicle wireless energy transfer (WET). The intra-vehicle WET system has features such as limited mobility of energy receiver, static channel environment and short distance between transmitter and human body. Under these conditions, location of transmitter highly affects the amount of energy received by human body and the energy received by energy receiving devices. We compare centralized antenna system (CAS) and the DAS in intra-vehicle WET system by simulation. The results show the DAS has superior performance to the CAS.

• The Journal of the Korea institute of electronic communication sciences
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• v.13 no.6
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• pp.1223-1228
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• 2018

LTE-R(Long Term Evolution - Railway), as a mobile communication technology to support safety operation of train on high speed railway system, have to be equipped appropriately by hand-over method for high moving environment of train. In this paper, hand-over performance of LTE-R network, which is used in railway communication system, is analyzed and hand-over implementation condition is suggested with this analysis. The performance analysis of this study is carried out with computer simulation with NS(Network Simulator)-3. SINR(Signal to Interference and Noise Ratio) and RSRP(Reference Signal Received Power), and Data Rate is used for hand-over performance parameter.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.48 no.3
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• pp.82-90
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• 2011

Multi-core system is becoming more general with development of microprocessors. Due to this change in performance improvement paradigm, switching conventional single thread applications with multi thread applications. Performance monitoring tools are used to optimize application performance because of complexity in development of multi thread applications. Conventional performance monitoring tools are focused on performance itself rather than user friendliness or real-time support. Real-time performance monitor identify the problem while multi-threaded applications should be performed as well as check real-time operating status of the application. So it can be used as an effective tool compared to non-real-time performance monitor that only with simple performance indicators to find the cause of the problem. In this paper, we propose RMPM(Real-time Multi-core Performance Monitor) which is real-time performance monitoring tool for multi-core system. Observation period is optimized by comparing relation between overhead due to performance evaluation period and accuracy. Our performance monitor shows not only amount of CPU usage of whole system, memory usage, network usage but also aspect of overhead distribution per thread of an application.