• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2001년도 춘계학술대회 논문집
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• pp.177-180
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• 2001

This paper describes the calibration method and the evaluation method of relative expanded uncertainty for a multi-axis force/moment sensor. This sensor should be calibrated to be use in the industry. Now, the confidence of the calibration result is expressed with interference error. But it is no inaccurate, because an interference error, besides, a reproducibility error of the sensor, a error of this six-axis force/moment sensor calibrator, and so on. Thus, in order to accurately evaluate the relative expanded uncertainty of it, the concept of the uncertainty should be induced, and these errors must be contained in the relative expanded uncertainty. In this paper, the calibration method is exhibited and the evaluation method of the relative expanded uncertainty is also exhibited. And, a six-axis force/moment sensor was calibrated and the relative expanded uncertainty was evaluated.

• 한국정보통신학회논문지
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• 제6권2호
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• pp.221-227
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• 2002

본 논문에서는 3GPP(3rd Generation Partnership Project) 비동기(asynchronous) WCDMA(Wide-band CDMA) 시스템에 HIC(Hybrid Interference Cancellation) 기법의 MUD (Multi-User Detector)를 적용하여 Rayleigh 페이딩 채널에서 BER (Bit Error Rate) 성능을 컴퓨터 시뮬레이션을 통해 구하였다. 이 결과를 감산형 간섭제거기법의 대표적인 방식인 SIC(Successive Interference Cancellation) 기법, PIC(Parallel Interference Cancellation) 기법의 BER(Bit Error Rate) 성능과 비교 분석하였다. 분석한 결과, 전송률이 높은 사용자들은 PIC 기법이나 HIC 기법을 사용하여 간섭을 제거하는 것이 효과적이고, 전송률 이 낮은 사용자들은 SIC 기법이나 HIC 기법을 사용하는 게 효과적이라는 것을 알 수 있었다. 또한, 전송률에 의존하지 않고 모든 사용자의 성능을 고루 만족시키기 위해서는 HIC 구조를 사용하는 것이 효과적이었다. 그 이유로서는 페이딩 채널상의 이유에서 또는 원하는 서비스를 만족시키기 위해서 사용자가 전력을 높일지라도 HIC 기법에서는 전단에 사용하는 SIC에 의해 전력이 낮은 사용자들의 성능을 보장해주고 후단에 사용하는 PIC에 의해 SIC 과정에서 전력이 센 사용자가 받는, 전력이 약한 사용자로부터의 간섭이 효과적으로 제거되기 때문이다.

• Journal of Communications and Networks
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• 제5권4호
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• pp.354-364
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• 2003

A general method for the evaluation of the symbol error probability (SER) of ultra wideband (UWB) systems with various kind of modulation schemes (N-PAM, M-PPM, Bi-Orthogonal), in presence of multipath channel, multiuser and strong narrowband interference, is presented. This method is shown to be able to include all the principal multiaccess techniques proposed so far for UWB, time hopping (TH), direct sequence (DS) and optical orthogonal codes (OOC). A comparison between the performance of these multiple access and modulation techniques is given, for both ideal Rake receiver and minimum mean square error (MMSE) equalizer. It is shown that for all the analyzed multiple access schemes, a Rake receiver exhibits a high error floor in presence of narrowband interference (NBI) and that the value of the error floor is in-fluenced by the spectral characteristics of the spreading code. As expected, an MMSE receiver offers better performance, representing a promising candidate for UWB systems. When the multiuser interference is dominant, all multiple access techniques exhibit similar performance under high-load conditions. If the number of users is significantly lower than the spreading factor, then DS outperforms both TH and OOC. Finally 2PPM is shown to offer better performance than the other modulation schemes in presence of multiuser interference; increasing the spreading factor is proposed as a more effective strategy for SER reduction than the use of time diversity.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제14권1호
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• pp.40-52
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• 2020

In this paper, we consider a precoder design problem for multiuser interference channel. Most of the conventional schemes for precoder design utilize a signal-to-interference-plus-noise ratio (SINR) as a cost function. However, since the SINR metric of a desired transmitter-receiver pair is a function of precoding vectors of all transmitters in the multiuser interference channel, an analytic closed-form solution is not available for the precoding vector of a desired transmitter that maximizes the SINR metric. To eliminate coupling between the precoding vectors of all transmitters and to find a closed-form solution for the precoding vector of the desired transmitter, we use a signal-to-leakage-plus-noise ratio (SLNR) instead as a cost function because the SLNR at a transmitter is a function of the precoding vector of the desired transmitter only. In addition, channel estimation errors for undesired links are considered when designing the precoding vector because they are inevitable in a multiuser interference channel. In this case, we propose a design scheme for the precoding vector that is robust to the channel estimation error. In the proposed scheme, the precoding vector is designed to maximize the worst-case SLNR. Through computer simulation, we show that the proposed scheme has better performance than the conventional scheme in terms of SLNR, SINR, and sum rate of all users.

• ETRI Journal
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• 제35권1호
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• pp.166-169
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• 2013

In this letter, we propose a data randomization scheme for endurance and interference mitigation of deeply-scaled multilevel flash memory. We address the relationships between data patterns and the raw bit error rate. An on-chip pseudorandom generator composed of an address-based seed location decoder is developed and evaluated with respect to uniformity. Experiments performed with 2x-nm and 4x-nm NAND flash memory devices illustrate the effectiveness of our scheme. The results show that the error rate is reduced up to 86% compared to that of a conventional cycling scheme. Accordingly, the endurance phenomenon can be mitigated through analysis of interference that causes tech shrinkage.

• Journal of Information Processing Systems
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• 제17권5호
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• pp.933-946
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• 2021

In the non-orthogonal multiple access (NOMA) system, multiple user signals on the single carrier are superimposed in a non-orthogonal manner, which results in the interference between non-orthogonal users and noise interference in the channel. To solve this problem, an improved algorithm combining regularized zero-forcing (RZF) precoding with minimum mean square error-serial interference cancellation (MMSE-SIC) detection is proposed. The algorithm uses RZF precoding combined with successive over-relaxation (SOR) method at the base station to preprocess the source signal, which can balance the effects of non-orthogonal inter-user interference and noise interference, and generate a precoded signal suitable for transmission in the channel. At the receiver, the MMSE-SIC detection algorithm is used to further eliminate the interference in the signal for the received superimposed signal, and reduce the calculation complexity through the QR decomposition of the matrix. The simulation results show that the proposed joint detection algorithm has good applicability to eliminate the interference of non-orthogonal users, and it has low complexity and fast convergence speed. Compared with other traditional method, the improved method has lower error rate under different signal-to-interference and noise ratio (SINR).

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2000년도 추계학술대회 논문집
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• pp.291-294
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• 2000

Free-form surfaces arise in shipbuilding, automotive and aerospace industries. Specially compound free-form surfaces so do. Machining complicated products consist of compound surface, it is very important to avold and remove tool interferences. By the way, in compound surfaces the tool interference can occur not only in the tool path direction but also in the other direction. A new tool interference detection and correction using tool interference conditions is suggested to identify and correct the tool interference in compound surfaces.

• ETRI Journal
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• 제31권4호
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• pp.472-474
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• 2009

In this letter, an ordered successive interference cancellation (OSIC) scheme is applied for multiple-input multiple-output (MIMO) detection in ultra-wideband (UWB) communication systems. The error rate expression of an OSIC receiver on a log-normal multipath fading channel is theoretically derived in a closed form solution. Its bit error rate performance is analytically compared with that of a zero forcing receiver in the UWB MIMO detection scheme followed by RAKE combining.

• International Journal of Precision Engineering and Manufacturing
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• 제3권3호
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• pp.5-11
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• 2002

This paper describes the methods for calibration and evaluation of the relative expanded uncertainty of a multi-axis force/moment sensor. In order to use the sensor in the industry, it should be calibrated and its relative expanded uncertainty should be also evaluated. At present, the confidence of the sensor is shown with only interference error. However, it is not accurate, because the calibrated multi-axis force/moment sensor has an interference error as well as a reproducibility error of the sensor, etc. In this paper, the methods fur calibration and for evaluation of the relative expanded uncertainty of a multi-axis force/moment sensor are newly proposed. Also, a six-axis force/moment sensor is calibrated with the proposed calibration method and the relative expanded uncertainty is evaluated using the proposed uncertainty evaluation method and the calibration results. It is thought that the methods fur calibration and evaluation of the uncertainty can be usually used for calibration and evaluation of the uncertainty of the multi-axis force/moment sensor.

• 한국전자파학회지:전자파기술
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• 제5권3호
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• pp.3-13
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• 1994

간섭과 레일리 페이딩이 함께 존재하는 환경하에서 FH/MFSK 신호의 오류 확률식을 유도하고 유도한 식에 의해 수치 계산 한 결고를 그래프로 나타내고 분석하였다. 선택 합성법고 최대비 합성법의 공간 다이버시티 기법의 채용에 따른 오류 확률의 개선 정도를 알아내었다. 분석 결고 최대비 합성법이 레일리 페이딩과 감섭에 대해 매우 효과적이라는 것을 알 수 있었다.