• The Journal of Korean Institute of Communications and Information Sciences
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• v.40 no.7
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• pp.1420-1423
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• 2015

This letter considers a ship-to-ship communication system in which two ships exchange their information with the help of multiple relay ships. For the system, we propose a novel relay scheme that allows relay ships to select a method between analog network coding (ANC) and digital network coding (DNC) adaptively based on channel state information. We also provide a relay selection criterion in supporting the proposed adaptive network coding. The simulation results show that the proposed scheme outperforms the conventional scheme employing only the ANC or only the DNC.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.60 no.12
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• pp.2361-2367
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• 2011

In this paper survey and analysis of recent trends in noise barriers and noise measurements and assessments were conducted for providing design basis of ANC barriers. Looking at the results, transparent barrier(glass) has received the most attention in domestic and foreign countries, because it has a harmony with the surrounding environment and easy installation in a small space. For optimal barrier design using computer simulation, reliability of simulation has been verified and classified into 5 groups, according to barrier's upper cross section. Evaluation results of barrier's performance and design using computer simulation are as follows : In the case of the "B-type" barrier, it has improved maximum 2.5dB(A) at each point(R1~R6) and have a good workability. Therefore, "B-type" Barriers applied to the next active noise barrier system will be possible.

• Proceedings of the Korea Society for Simulation Conference
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• 2000.04a
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• pp.168-173
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• 2000

지금까지 국내에서 설치되어 있는 원전 시뮬레이터용 노심 (Neutronics) 모델 프로그램은 주로 전산기 성능이 오늘날 비해 낮은 환경에서 실시간으로 노물리 계산을 위해 중성자 확산(Diffusion)현상을 미리 반영한 곡선을 사용하는 등 빠른 계산을 위해 많은 가정과 간략화가 있었다. 본 논문에서는 중성자 물리 계산을 2 Group 3-D로 계산이 가능한 최신의 노심코드(REMARK)를 이용하여, WH사가 공급한 900Mw의 3 Loop PWR인 영광 1호기 12주기를 기준으로 한 시뮬레이터의 노심모델 개발하기 위한 핵설계 전산체계인 APA(ALPHA-PHOENIX-ANC) 시스템의 출력으로부터 자동으로 REMAR 입력데이타를 생성하기 위한 GUI툴 개발과 개발된 노심모델의 자체 검증 및 원자력발전소 사고해석에 쓰이는 최적평가코드(RETRAN)를 기반으로 하는 최신 실시간 열수력 시뷸레이션(ARTS) 모델과 결합(Integration)되어 원자로 냉각재 펌프 1대 정지 및 터빈정지 시험등 과도시험한 결과를 기술하였으며 개발된 노심 모델은 원자력 교육원 2호기 시뮤레이터에 적용될 예정이다.

• The Journal of the Acoustical Society of Korea
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• v.32 no.5
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• pp.408-414
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• 2013

The famous filtered-x least mean square (FxLMS) algorithm for active noise control (ANC) systems may become unstable in non-stationary noise environment. To solve this problem, Sun's algorithm and Akhtar's algorithm are developed based on modifying the reference signal in update of FxLMS algorithm, but these two algorithms have dissatisfactory stability in dealing with sustaining impulsive noise. In proposed algorithm, probability estimation and zero-crossing rate (ZCR) control are used to improve the stability and performance, at the same time, an optimal parameter selection based on fuzzy system is utilized. Computer simulation results prove the proposed algorithm has faster convergence and better stability in non-stationary noise environment.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.8 no.1
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• pp.45-50
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• 2015

In this paper, we confirm the effective adaptive algorithm for tha active noise contorl (ANC) though the performance comparison between adaptive algorithms. Generally, the normalized least mean square (NLMS) algorithm has been widely used for an adaptive algorithm thanks to its simplicity and having a fast convergence speed. However, the convergence performance of the NLMS algorithms is often deteriorated by colored input signals. To overcome this problem, the affine pojection (AP) algorithm that updates the weight vector based on a number of recent input vectors can be used for allowing a higher convergence speed than the NLMS algorithm, but it is computationally complex. Thus, the proper algorithm were determined by the comparison between NLMS and AP algorithms regarding as the convergence performance and complexity. Simulation results confirmed that the noise reduction performance of NLMS algorithm was comparable to AP algorithm with low complexity. Therefore the NLMS algorithm is more effective for ANC system.

• Journal of the korean Society of Automotive Engineers
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• v.14 no.5
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• pp.83-94
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• 1992

There has been a suggestion of many techniques as the methods of diagnosis for rotational machinery. In this study, HFRT was used as the analysis method for ball bearing of automobile and was compared with the conventional ANC technique. And this paper presented the computer simulation process about fault types and noise for the validity of the algorithm and identification of the physical meanings of HFRT. Also, experiment was performed using ball bearing and the results showed that HFRT was much more effective than the conventional methods in diagnostic process.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.22 no.10
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• pp.2339-2347
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• 1997

The performance of the adaptive noise canceller using LMS algorithm is degraded by the gradient noise due to target speech signals. An adaptive noise canceller with speech detector was proposed to reduce this performande degradation. The speech detector utilized the adaptive prediction-error filter adapted by the NLMS algorithm. This paper discusses to enhance the performance of the adaptive noise canceller forthecorlored noise. The affine projection algorithm, which is known as faster than NLMS algorithm for correlated signals, is used to adapt the adaptive filter and the adaptive prediction error filter. When the voice signals are detected by the speech detector, coefficients of adaptive filter are adapted by the sign-error afine projection algorithm which is modified to reduce the miaslignment of adaptive filter coefficients. Otherwirse, they are adapted by affine projection algorithm. To obtain better performance, the proper step size of sign-error affine projection algorithm is discussed. As resutls of computer simulation, it is shown that the performance of the proposed ANC is better than that of conventional one.

• Journal of Industrial Technology
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• v.18
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• pp.317-322
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• 1998

The purpose of this present experiments was to simulate the Active noise control system using MATLAB Tool kit. The Least-Mean-Square algorithm is the most applicable one to optimize the ANC systems, even it has tight limitation. This paper shows the influence of choosing step size to the performance of the LMS adaptive filters. In addition to the simulation, this paper describes the method to design the filtered LMS algorithm to get the better performance in Active noise control. It contains the secondary-path modeling to realize the real Active noise control system in the requesting fields.

• Proceedings of the KIEE Conference
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• 1996.07b
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• pp.993-995
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• 1996

This paper proposes an adaptive Filtered-X LMS algorithm with robustness. The proposed system updates filter parameters to keep the performance even if the conventional Active Noise Control (ANC) system well does not work. As a result of the computer simulation, the proposed system has all the advantage of the system using the conventional Filtered-X LMS algorithm. Also some results from the proposed algorithm present that the system is stable when the Adaptive filter does not work. Therefore, the proposed system using the Adaptive Filtered-X LMS algorithm must have much advantage than the system using the conventional algorithm in the side of the stability and performance.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.11a
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• pp.737-742
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• 2007

The method of the reducing duct noise can be classified by passive and active control techniques. However, passive control has a limited effect of noise reduction at low frequencies (below 500Hz) and is limited by the space. On the other hand, active control can overcome these passive control limitations. The active control technique mostly uses the Least-Mean-Square (LMS) algorithm, because the LMS algorithm can easily obtain the complex transfer function in real-time particularly when the Filtered-X LMS (FXLMS) algorithm is applied to an active noise control (ANC) system. However, the convergence performance of the LMS algorithm decreases slightly so it may delay the convergence time when the FXLMS algorithm is applied to the active control of duct noise. Thus the Co-FXLMS algorithm was developed to improve the control performance in order to solve this problem. The Co-FXLMS algorithm is realized by using an estimate of the cross correlation between the adaptation error and the filtered input signal to control the step size. In this paper, the performance of the Co-FXLMS algorithm is presented in comparison with the FXLMS algorithm. Simulation results show that active noise control using Co-FXLMS is effective in reducing duct noise.