• Journal of the Korean Institute of Telematics and Electronics A
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• v.31A no.6
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• pp.169-176
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• 1994

This paper describes an efficient parallel evaluation algorithm for accelerating fault simulation, which can be applied to combinational circuits. The method is based on a combination of all the advantages in parallel, deductive and concurrent schemes in terms of evaluation and propagation of fautly gates for achieving high performance and handling multi-valued signal. We also propose a new fault grouping procedure to increase parallel operation of fault bits by packing active faults which occur in the same signal line densely into the same fault group. The algorithm has been implemented in C language on a Sun 3/260, and experimental results for ISCAS'85 benchmark circuits have been shown that this algorithm is 2.6 to 8.2 times faster than the conventional cocurrent fault simulation algorithm.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.16 no.2
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• pp.237-245
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• 2012

This paper describes an acoustic echo canceller with double-talk by the blind signal separation. The acoustic echo canceller is deteriorated or diverged in the double-talk period. So we use the blind signal separation to estimate the near-end speech signal and to eliminate the estimated signal from the residual signal. The blind signal separation extracts the near-end signal with dual microphones by the iterative computations using the 2nd order statistical character. Because the mixture model of blind signal separation is multi-channel in the closed reverberation environment, we used the copied coefficients of echo canceller without computing the separation coefficients. By this method, the acoustic echo canceller operates irrespective of double-talking. We verified performances of the proposed acoustic echo canceller by simulations. The results show that the acoustic echo canceller with this algorithm detects the double-talk periods thoroughly, and then operates stably in the normal state without the divergence of coefficients after ending the double-talking. And it shows the ERLE of averagely 20dB higher than the normal LMS algorithm.

• Journal of Korean Society of Steel Construction
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• v.12 no.2 s.45
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• pp.151-165
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• 2000

Since vehicles become large and heavy and traffic volume is increased rapidly, many fatigue damages have been reported in bridge members. In order to prevent fatigue damages of bridge members and maintain safety it is essential to perform rational fatigue check. Only one vehicle is loaded on a bridge deck for the fatigue design. But in reality it is seldom that only one vehicle passes on a bridge deck. Usually more than two vehicles are passing on a bridge deck simultaneously. Therefore, it is necessary to consider the influence of simultaneous loading for a rational fatigue design. In this study, the influence of simultaneous loading is investigated by performing stress variation analysis due to vehicle load on the basis of linear superposition method and Monte-Carlo simulation of traffic flow, and then calculating the measure of fatigue damages.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 1994.04a
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• pp.451-451
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• 1994

• Journal of the Korea Society for Simulation
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• v.20 no.1
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• pp.61-67
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• 2011

Smart TV System will lead to drastic change of communication and media industries as one of the emerging next generation network services. However, when the number of concurrent users increases rapidly, the issue of service quality degradation occurs because providing services to many users simultaneously stresses both the server and the network. The server limitation can be circumvented by deploying server clusters. but the network limitation is far less easy to cope with, due to the difficulty in determining the cause and location of congestion and in provisioning extra resources. In order to alleviate these problems, a number of schemes have been developed. Prior works mostly focus on reducing user-centric performance metrics of individual connection, such as the round-trip time(RTT), downloading time or packet loss rate, but tend to ignore the network loads caused by the concurrent connections or global network load balance. In this work, we make an in-depth investigation on the issue of user grouping for massive Smart TV services through simulations on actual Internet test-bed, PlanetLab.

• Journal of the Korea Society for Simulation
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• v.28 no.4
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• pp.11-20
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• 2019

This paper presents a HILS(Hardware-In-the-Loop Simulation) approach for the verification of the OHT (Overhead Hoist Transport) controller in a semiconductor FAB. Since hundreds of OHTs can run simultaneously on the OHT network of a FAB, the full verification of the OHT controller is very essential to guarantee the stableness of the material handling system. The controller needs to fully consider not only normal situations but also abnormal situations that are difficult to predict. For the verification of the controller, we propose a HILS approach using a virtual environment including OHTs on a rail network, which can generate abnormal situations. The proposed HILS approach has been implemented and tested with various examples.

• Journal of the Korea Society for Simulation
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• v.19 no.4
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• pp.301-308
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• 2010

As a new paradigm called modeling and simulation(M&S) or simulation based acquisition(SBA) has arisen, necessity of applying it to Korea has been increased. Not only rational construction of SBA but development of model which can evaluate driving results and improve relating processes to SBA is needed. Therefore we suggests the framework of capability maturity model for M&S development and SBA. The ultimate purpose of our model is improving processes relating to M&S development and SBA. The last section include detailed model which has practices for improving some SBA processes.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 2005.05a
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• pp.806-813
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• 2005

시계열의 구조를 정확히 파악하기 위해서는 구조변화와 단위근의 존재여부를 가설 검정하는 것이 필요하다. 하지만, 이 두 가지의 가설들은 각각 검정되어 왔고, 이에 따라 단위근도 존재하고 구조변화도 존재하거나, 어느 하나만 존재하는 시계열들을 구분하여 파악하는 데에 있어서는 한계점이 있었다. 이 논문에서는 상태공간모형과 시뮬레이션 방법에 근거하여 두 가지 가설을 동시에 검정하는 절차를 제시하여 논란이 되는 시계열들에 대해 합리적인 해결책을 제시하고자 한다.

• Proceedings of the Korean Information Science Society Conference
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• 2003.04a
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• pp.1-3
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• 2003

프로세서의 효율을 높이기 위한 방법으로 독립적인 쓰레드들을 한 프로세서 사이클에 동시에 실행시킬 수 있는 SMT 기술에 관한 많은 연구가 수행되어왔다［1, 2, 3, 4］. 많은 연구에서 SMT 기술에 대한 성능을 시뮬레이션 수준에서 측정하였기 때문에, 실제 환경에서 SMT 기술의 성능을 측정할 필요가 있다. 본 논문에서는 SMT 기술이 구현된 프로세서에서 각종 벤치마킹을 직접 수행해 봄으로써 실제 환경에서의 성능을 측정해 보았으며, 이를 기존의 SMP와의 비교를 통해 SMT 기술이 실제로 얼마만큼 좋은 성능을 낼 수 있는지 실험을 통해 보였다.

• Proceedings of the Acoustical Society of Korea Conference
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• 1998.06e
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• pp.185-188
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• 1998

본 연구에서는 256(16$\times$16)개의 마이크로폰 정방형 배열에 의한 음향 홀로그래피 시스템을 제작하고, FFT에 의한 음향 홀로그래피법 알고리즘을 이용한 음원 위치 추정에 관하여 기술한다. 본 연구에서 설계한 측정 시스템은 방사된 음들을 동시 수음함으로서 실시간 데이터 처리가 가능하다. 또한 환경 잡음이 존재하는 실음장에서도 계측시간을 단축함과 동시에 고분해능으로 안정하게 음원의 위치를 추정할 수 있다. 본 연구의 타당성을 검증하기 위해 SYSNOISE에 의한 음장해석과 음향 홀로그래피 알고리즘을 이용하여 마이크로폰 간격 및 측정면 크기, 측정거리의 최적 조건을 구한 후 실음장 측정 실험에 적용하였다. 수치 시뮬레이션과 무향실에서 실험 데이터에 의해 음원 위치를 추정한 결과 유사한 결과를 얻었다.