• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• v.9 no.2
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• pp.223-226
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• 2005

본 논문에서는 지능형 교통망 시스템 서비스에 사용하는 5.8GHz 대역에서 OFDM을 이용한 단거리 전용 통신 시스템의 성능을 분석하였다. 현재의 DSRC 시스템은 1Mbps 이상의 데이터 서비스가 어려울 것으로 예상되므로 개선도니 변복조방식이 요구된다. OFDM(orthogonal frequency division multiplexing) 방식은 보호구간의 삽입을 통하여 ISI를 방지할 수 있으므로 고속 데이터 전송에 적합하다. 따라서, 본 논문에서는 데이터 변조 방식으로는 IEEE 802.11a에 근거한 부 반송파의 수가 64개인 QPSK변조 방식을 사용하는 OFDM 시스템을 모델링 하고, 도플러 천이 효과를 고려한 Clark & Gans 페이딩 환경에서 성능을 분석하였다. 또한 페이딩 환경에서는 성능의 열화 정도가 크기 때문에 이를 극복하기 위해 채널 예측기를 사용하여 채널 응답을 근사적으로 예측${\cdot}$보상하였다.

• Proceedings of the KIEE Conference
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• 2004.05b
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• pp.66-72
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• 2004

본 연구는 접지저감제의 성분으로 수용성 고분자의 유기물과 층상형 점토의 무기재료를 주재료하여 새롭게 개발한 새로운 형태의 접지저감제의 성능비교에 관한 것이다. 신개발의 접지저감제는 수분을 흡습하여 수분에 용해된 수용성고분자가 수분과 함께 층상형점토의 층으로 삽입되어 접지저감 성능을 발휘하게 된다. 본 연구의 유 무기 복합재료형 접지저감제는 함수율과 팽창률이 매우 우수할 뿐 아니라 300wt%의 수분을 공급 후 측정한 전기전도도도 매우 뛰어나다. 또한 환경친화적인 천연재료들이므로 인체나 환경에 매우 안전하며, 접지전극의 부식과 전식을 방지하는 기능이 매우 뛰어나 염해나 화학적으로 부식성이 높은 토양에서 큰 장점을 갖는다. 본 논문에서는 신개발의 접지저감제와 기존의 여러 접지저감의 성능을 비교 분석하였다. 이를 위해 현장의 대지저항율을 측정 분석하여 각각의 접지저감제의 접지설계에 적용하여 시뮬레이션하였으며, 시뮬레이션 결과와 현장에서 실제 시공한 측정 결과와 비교 분석하였다.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.11 no.1
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• pp.28-33
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• 2007

In spite of the large interest in the 802.15.4 standard, no realistic experimental research of its behaviour exists to date except a few works by simulations and analytical modeling. In this paper, we have established realistic environment of IEEE 802.15.4 network and analyze its behaviour under various conditions as like 1) maximum throughput of 802.15.4 MAC, 2) MAC fairness. and 3) throughput and m rate under co-existence of 802.11 Wi-Fi wireless networks.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.39C no.3
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• pp.291-297
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• 2014

Due to the rapid increase in demand for transportation of human and freight in modern railway systems, the CBTC system has been proposed, which is the solution for improvement of the line capacity that has been limited by the conventional track circuit based train control system. In the CBTC system, higher reliability of the communication system should be guaranteed for the safety of passengers and trains. However, due to the inherent characteristics of the wireless channel environment, performance degradations are inevitable. The diversity techniques can increase the reliability of data transmission using multiple antennas. In this paper, we investigate the performance of the STBC in the railway channel environment. Rician fading model is used for the viaduct scenarios which take important roles in the railway system. Also, considered is the Doppler effect which is an important factor in the mobile communication system. Simulations are performed to analyze the performance of the STBC in various channel environments. Results show that the performance degradation due to the phase error in viaduct scenarios is independent of the diversity order but is affected by the constellation of the modulation.

• Journal of Advanced Navigation Technology
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• v.8 no.2
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• pp.169-175
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• 2004

We analyzed about digital watermarking embedded transmission of still image in wireless multimedia communication environment. Also, we proposed improved watermark techniques. It effects that get in original image than method to use conventional image is less and shows robust watermark restoration ability from outside attack. Performance analysis achieved about still image and restoration of watermark information using OFDM/QPSK still image transmission system in wireless channel environment. Analysis result, VI watermark performance that influence in original image is very small. And it could know that show high restoration performance. Also, It showed superior copyright information extraction performance than image watermark in wireless channel environment of same transmission error condition.

• Journal of the Korea Society of Computer and Information
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• v.14 no.6
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• pp.11-16
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• 2009

The queuing theory was adopted by Erlang to predict the availability of telephone lines in 1917 and had not been used for computer system performance analysis until late 1960s when Scherr published a performance analysis of time-shared computer system. In 2000s, the explosive Internet usage and the development of IT technology made the business environment speed-centric and analysts should react swiftly to the ever-changing situation to satisfy the user requirement. It's tempting to solve the performance problem by purchasing new devices because the price of computers and peripherals are rapidly decreasing along with their increasing performance. But this scheme not only makes it difficult to understand the overall performance of the system but also wastes money. A coarse performance model that is gotten quickly is sometimes preferred to a complex and precise one that takes longer time to get. This paper examines an analytic model suggested by Menasce based on the measured data and suggests a simulation model using ARENA that takes a short time to build.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.29 no.6
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• pp.1305-1317
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• 2019

Although encryption for data protection is essential in the big data platform environment of public institutions and corporations, much performance verification studies on encryption algorithms considering actual big data workloads have not been conducted. In this paper, we analyzed the performance change of AES, ARIA, and 3DES for each of six workloads of big data by adding data and nodes in MongoDB environment. This enables us to identify the optimal block-based cryptographic algorithm for each workload in the big data platform environment, and test the performance of MongoDB by testing various workloads in data and node configurations using the NoSQL Database Benchmark (YCSB). We propose an optimized architecture that takes into account.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.45 no.6
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• pp.10-15
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• 2008

This paper describes virtual environment and sensor modeling to analyze and verify the performance of autonomous navigation system. Virtual synthetic environment is constructed with 6 subgroups which cover from virtual environment construction to virtual sensor modeling of real systems. This research is applied to validate and assess performance of concerned algorithms and complex functions for autonomous navigation system based on virtual environment.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.5B
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• pp.449-454
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• 2009

In this paper, we analyze the hardware and software platform for constructing the USN in the vessel environment. Specifically, we analyze the mote technology based on the CC2420 in the hardware platform and analyze the TinyOS platform in the software platform. We also analyze the physical layer of IEEE802.15.4 which is the standard of the USN communication. In the simulation, we evaluate the performance in the physical layer of ZigBee/IEEE 802.15.4 by using the MATLAB and verify the validity of constructing the USN in the vessel environment based on the simulation results.

• Proceedings of the Korean Information Science Society Conference
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• 2000.04a
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• pp.651-653
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• 2000

WWW의 급격한 발전은 고성능 웹 서버의 구축을 필요로 하게 하였다. 특히 프로세스와 오버헤드를 줄이기 위해 도입된 멀티 쓰레드 기법을 이용한 병행 웹 서버들이 많이 연구되었는데 본 논문에서는 이런 웹 서버들을 리눅스가 탑재되어 있는 다중 처리가상에서 구현하였으며, 다양한 환경 하에서 성능을 비교, 분석하였다. 실험을 통하여 Thread Pool 구조 웹 서버가 가장 좋은 성능을 보임을 알 수 있었고, 작업 기반 웹 서버와 요구 기반 웹 서버의 성능은 환경에 따라 차이가 있음을 알 수 있었다. 이와 같은 실험 결과는 다중 처리기를 이용한 고성능 웹 서버를 구축하는 데 있어서 이용될 수 있을 것이다.