• Title/Summary/Keyword: Performance Technique

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Vibration Data Denoising and Performance Comparison Using Denoising Auto Encoder Method (Denoising Auto Encoder 기법을 활용한 진동 데이터 전처리 및 성능비교)

  • Jang, Jun-gyo;Noh, Chun-myoung;Kim, Sung-soo;Lee, Soon-sup;Lee, Jae-chul
    • Journal of the Korean Society of Marine Environment & Safety
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    • v.27 no.7
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    • pp.1088-1097
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    • 2021
  • Vibration data of mechanical equipment inevitably have noise. This noise adversely af ects the maintenance of mechanical equipment. Accordingly, the performance of a learning model depends on how effectively the noise of the data is removed. In this study, the noise of the data was removed using the Denoising Auto Encoder (DAE) technique which does not include the characteristic extraction process in preprocessing time series data. In addition, the performance was compared with that of the Wavelet Transform, which is widely used for machine signal processing. The performance comparison was conducted by calculating the failure detection rate. For a more accurate comparison, a classification performance evaluation criterion, the F-1 Score, was calculated. Failure data were detected using the One-Class SVM technique. The performance comparison, revealed that the DAE technique performed better than the Wavelet Transform technique in terms of failure diagnosis and error rate.

SDL-OPNET Co-Simulation Technique for the Development of Communication Protocols with an Integrated Approach to Functional Verification and Performance Evaluation (기능 검증 및 성능 평가 통합 접근 방법을 통한 통신 프로토콜 개발을 위한 SDL-OPNET 코-시뮬레이션 기법)

  • Yang, Qi-Ping;Kim, Tae-Hyong
    • Journal of the Korea Society for Simulation
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    • v.19 no.2
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    • pp.157-164
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    • 2010
  • While both functional verification and performance evaluation of a system are necessary for the development of effective and reliable communication systems, they have been usually performed individually through functional modeling with formal language tools and performance modeling with professional network performance evaluation tools, respectively. However, separate and duplicated modeling of a system may cause increase of the cost and inconsistency between the models. In order to overcome this problem, this paper proposes an integrated design technique that estimates the performance of a communication protocol designed in SDL with SDL-OPNET co-simulation. The proposed technique presents how to design a co-simulation system with the environment functions of Tau and the external system module of OPNET. InRes protocol was used as an example to show the applicability and usefulness of the proposed technique.

Dynamic Fractional Frequency Reuse based on an Improved Water-Filling for Network MIMO

  • M.K, Noor Shahida;Nordin, Rosdiadee;Ismail, Mahamod
    • KSII Transactions on Internet and Information Systems (TIIS)
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    • v.10 no.5
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    • pp.2124-2143
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    • 2016
  • In Long Term Evolution-Advanced (LTE-A) systems, Inter-cell Interference (ICI) is a prominent limiting factor that affects the performance of the systems, especially at the cell edges. Based on the literature, Fractional Frequency Reuse (FFR) methods are known as efficient interference management techniques. In this report, the proposed Dynamic Fractional Frequency Reuse (DFFR) technique improved the capacity and cell edge coverage performance by 70% compared to the Fractional Frequency Reuse (FFR) technique. In this study, an improved power allocation method was adopted into the DFFR technique to reach the goal of not only reducing the ICI mitigation at the cell edges, but also improving the overall capacity of the LTE-A systems. Hence, an improved water-filling algorithm was proposed, and its performance was compared with that of other methods that were considered. Through the simulation results and comparisons with other frequency reuse techniques, it was shown that the proposed method significantly improved the performance of the cell edge throughput by 42%, the capacity by 75%, and the coverage by 80%. Based on the analysis and numerical expressions, it was concluded that the proposed DFFR method provides significant performance improvements, especially for cell edge users.

Selection of Voltage Vectors in Three-Level Five-Phase Direct Torque Control for Performance Improvement

  • Tatte, Yogesh N.;Aware, Mohan V.
    • Journal of Power Electronics
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    • v.16 no.6
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    • pp.2162-2172
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    • 2016
  • This paper presents a Direct Torque Control (DTC) strategy for the five-phase induction motor driven by a three-level five-phase inverter in order to improve the performance of the five-phase induction motor. In the proposed DTC technique, only 22 voltage vectors out of 243 available voltage vectors in a three-level five-phase inverter are selected and are divided in 10 sectors each with a width of $36^{\circ}$. The four different DTC combinations (DTC-I, II, III and IV) for a three-level five-phase induction motor drive are investigated for improving the performance of five-phase induction motor. All four of the DTC strategies utilize a combination of the same large and zero voltage vectors, but with different medium voltage vectors. Out of these four techniques, DTC-II gives the best performance when compared to the others. This DTC-II technique is analyzed in detail for improvements in the performance of five-phase induction motor in terms of torque ripple, x-y stator flux and Total Harmonics Distortion (THD) of the stator phase current when compared to its two-level counterparts. To verify the effectiveness of the proposed three-level five-phase DTC control strategy, a DSP based experimental system is build. Simulation and experimental results are provided in order to validate the proposed DTC technique.

Performance Analysis of Trellis Coded OFDM/M-ary PSK Systems in the presence of tarrier Frequency Offset (반송파 주파수 오프셋의 존재하에서 Trellis Coded OFDM/M-ary PSK 시스템의 성능 분석)

  • 조성언;박기식;오원근
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.5 no.4
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    • pp.684-691
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    • 2001
  • In this paper, the BER performance of OFDM/M-ary PSK systems is analyzed with considering carrier-frequency offset and TCM technique, which encodes and modulations simultaneously, is adopted to OFDWM-ary PSK systems for compensation of performance degradation according to carrier-frequency offset. As a result of analysis, the error performance of OFDM/M-ary PSK systems is degraded as the frequency offset is increased. And the frequency offset should be below 0.025 in order to achieve $BER= 10^{-3}$ with $E_b/N_o$ of 10 dB. Especially, when the TCM technique is adopted to OFDM/M-ary PSK systems, the performance improvement of about 4 dB is obtained in terms of $E_b/N_o$.

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An AHP Approach to Select the Technique to Improve the Manufacturing Performance in Shipbuilding Enterprise (AHP에 의한 조선기업의 생산성과 향상기법의 선택)

  • Kim, Tae-Soo;Lee, Kang-Woo
    • Journal of Korean Society of Industrial and Systems Engineering
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    • v.29 no.4
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    • pp.43-50
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    • 2006
  • The objective of this research is to select the most effective technique from AMT (Advanced Manufacturing Technologies) and IMP (Innovative Management Practices) for improving manufacturing performance in shipbuilding enterprises. The research consists of several principal steps. The first step is to design critical criteria in evaluating manufacturing performance in shipbuilding enterprises. The second step is to develop sub-criteria of the critical criteria. The third step is to develop a four level AHP (Analytic Hierarchy Process) structure using the critical criteria, sub-criteria and techniques from AMT and IMP. The fourth step is to develope the pairwise comparison matrix by each level of AHP structure, which was based on survey data collected at the H heavy industry. And the last step is to select the most effective technique from AMT and IMP by using AHP analysis. The results of AHP analysis did not show clear difference in priority between techniques of AMT and IMP in terms of manufacturing performance of the shipbuilding enterprise. Thus, each critical criterion was assigned modified weights and examined the priority change of techniques by conducting performance sensitivity analysis.

Performance Improvement of Robust Speaker Verification According to Various Standard Deviations of a Reference Distribution in Histogram Transformation (히스토그램 변환에서 기준분포의 표준편차 변경에 따른 강인한 화자인증 성능 개선)

  • Kwon, Chul-Hong
    • Phonetics and Speech Sciences
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    • v.2 no.3
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    • pp.127-134
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    • 2010
  • Additive noise and channel mismatch strongly degrade the performance of speaker verification systems, as they distort the features of speech. In this paper a histogram transformation technique is presented to improve the robustness of text-independent speaker verification systems. The technique transforms the features extracted from speech such that their histogram is conformed to a reference distribution. The effect of different standard deviations for the reference distribution is investigated. Experimental results indicate that, in channel mismatched environments, the proposed technique offers significant improvements over existing techniques. We also verify performance improvement of the proposed method using statistics.

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A Study on the Improvement of Performance for High Speed Cutting Tool using Magnetic Fluid Polishing Technique (자기연마기술을 이용한 고속절삭공구의 성능향상에 관한 연구)

  • Cho, Jong-Rae;Yang, Sun-Cheul;Jung, Yoon-Gyo
    • Transactions of the Korean Society of Machine Tool Engineers
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    • v.15 no.1
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    • pp.32-38
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    • 2006
  • The magnetic fluid polishing technique can polish the tool of complex shape, because the polishing method which polishes as compress the workpiece by the magnetism abrasives to arrange to the linear according to the line of magnetic force. Therefore, we producted the magnetic fluid polishing device in order that mirror like finishing processes the tool surface. In order to a polishing condition selection, polishing characteristic was estimated by polishing conditions which are magnetic flux density, polishing speed, grain size, magnetic fluid. The tool was polished to the selected polishing condition. The result to evaluate the polished tool's performance with the cutting force and tool wear, the polished tool's performance was improved compared with the tool not to polish.

Determination of Regulator Parameters and Transient Analysis of Modified Self-commutating CSI-fed IM Drive

  • Pandey, A.K.;Tripathi, S.M.
    • Journal of Electrical Engineering and Technology
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    • v.6 no.1
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    • pp.48-58
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    • 2011
  • In this paper, an attempt has been made to design the current and speed proportional and integral (PI) regulators of self-commutating current source inverter-fed induction motor drive having capacitors at the machine end and to investigate the transient performance of the same for step changes in reference speed. The mathematical model of the complete drive system is developed in closed loop, and the characteristic equations of the systems are derived using perturbation about steady-state operating point in order to develop the characteristic equations. The D-partition technique is used for finding the stable region in the parametric plane. Frequency scanning technique is used to confirm the stability region. Final selection of the regulator parameters is done by comparing the transient response of the current and speed loops for step variations in reference. The performance of the drive is observed analytically through MATLAB simulation.

Optimizing Caching in a Patch Streaming Multimedia-on-Demand System

  • Bulti, Dinkisa Aga;Raimond, Kumudha
    • Journal of Computing Science and Engineering
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    • v.9 no.3
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    • pp.134-141
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    • 2015
  • In on-demand multimedia streaming systems, streaming techniques are usually combined with proxy caching to obtain better performance. The patch streaming technique has no start-up latency inherent to it, but requires extra bandwidth to deliver the media data in patch streams. This paper proposes a proxy caching technique which aims at reducing the bandwidth cost of the patch streaming technique. The proposed approach determines media prefixes with high patching cost and caches the appropriate media prefix at the proxy/local server. Herein the scheme is evaluated using a synthetically generated media access workload and its performance is compared with that of the popularity and prefix-aware interval caching scheme (the prefix part) and with that of patch streaming with no caching. The bandwidth saving, hit ratio and concurrent number of clients are used to compare the performance, and the proposed scheme is found to perform better for different caching capacities of the proxy server.