• Title/Summary/Keyword: Delay effects

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Design of Adaptive Disturbance Observer for the Time Delay System Control (시간지연 시스템 제어를 위한 적응외란관측자 설계)

  • Lee, Soon-Young
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.56 no.9
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    • pp.1676-1679
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    • 2007
  • In control of the time delay systems, if the disturbance information can be estimated exactly, the ideal response for the disturbance can be achieved. Therefore, in this paper, a new adaptive disturbance observer for the time delay system control is proposed. The disturbance observer is designed and adaptive laws for adjusting the observer are proposed. The new Smith predictor controller to eliminate the effects of the disturbance can be achieved by adding an estimated disturbance to the Smith model. The improved performances of the proposed system and the adaptive disturbance observer are verified by computer simulation.

Evaluation of Packet Loss Rate in Optical Burst Switching equipped with Optic Delay Lines Buffer

  • To, Hoang-Linh;Bui, Dang-Quang;Hwang, Won-Joo
    • Proceedings of the Korea Multimedia Society Conference
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    • 2012.05a
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    • pp.166-167
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    • 2012
  • High packet loss rate and impatience of messages passing through optical switches are essential characteristics in Optical Burst Switching system equipped with Optic Delay Lines buffer, which have not been solved efficiently yet by current existing models. In order to capture both effects, this paper introduces an analytical model from the viewpoint of classical queuing theory with impatient customers. We then apply it to evaluate and compare two wavelength-sharing cases, (1) all delay lines share a common wavelength resource and (2) each wavelength is associated with a number of delay lines. Our numerical results suggest to implement the first case because of lower packet loss rate for a fairly broad range of traffic load.

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Comparisons of Diversity Techniques for OFDM Systems in Interference-Limited Environments (간섭 제한적인 환경에서의 OFDM 시스템의 다이버시티 기술의 비교)

  • Rim, Min-Joong;Kim, Hong-Seog
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.33 no.11A
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    • pp.1043-1052
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    • 2008
  • This paper compares the performances with space time coding and cyclic delay diversity techniques for OFDM systems in interference-limited environments. While a communication system usually use a diversity technique to improve its own performance, it is also necessary to consider the interference effects to other users as well if the system is operated in interference-limited environments. When there is no interference from or to other users, space time coding technique results in better performance than cyclic delay diversity. However, cyclic delay diversity can be better than space time coding if interferences to other users are considered.

A New Implementation of the LMS Algorithm as a Decision-directed Adaptive Equalizer with Decoding Delay

  • Ahn, Sang-Sik
    • The Journal of the Acoustical Society of Korea
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    • v.15 no.1E
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    • pp.89-94
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    • 1996
  • This paper deals with the application of the LMS algorithm as a decision-directed adaptive equalizer in a communication receiver which also employs a sophisticated decoding scheme such as the Viterbi algorithm, in which the desired signal, hence the error, is not available until several symbol intervals later because of decoding delay. In such applications the implemented weight updating algorithm becomes DLMS and major penalty is reduced convergence speed. Therefore, every effort should by made to keep the delay as small as possible if it is not avoidable. In this paper we present a modified implementation in which the effects of the decoding delay can be avioded and perform some computer simulations to check the validity and the performance of the new implementation.

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Time-Delay Estimation using Wavelet Theory and Higher-Order Statistics (웨이블릿 이론과 고차통계 처리기법을 이용한 시간지연 추정)

  • 차용철;김용남;정지현;남상원
    • Journal of Institute of Control, Robotics and Systems
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    • v.4 no.5
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    • pp.630-635
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    • 1998
  • The objective of this paper is to propose a new efficient technique for the estimation of time-delay parameters using wavelet theory and third-order cumulants, yielding good performance even in the case of low SNR. In particular, band-limited non-Gaussian signals with non-zero skewness and spatially correlated Gaussian noises are considered here. The approach is based on the fact that the effects of spatially correlated Gaussian noises on time-delay estimation can be reduced by using the projection sequences (based on the redundant wavelet decomposition) of given measurements in the higher-order cumulant domain. Finally, the performance of the proposed approach is demonstrated using simulations.

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Experimental study of solid fuel ignition in a confined enclosure (밀폐공간내 복사에 의한 고체연료 점화의 실험적 연구)

  • Kim, Yeong-Gwan;Baek, Seung-Uk
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.20 no.11
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    • pp.3630-3638
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    • 1996
  • An experimental study has been conducted to explore the behaviors of the radiative ignition of polymethylmetacrylate(PMMA) in a confined enclosure such as the ignition delay time, PMMA surface temperature, the ignition location and the ignition process. In addition, the effects of hot wall orientation on the ignition delay and PMMA surface temperature were studied. When the hot wall is located at the bottom, ignition delay time is the shortest. Ignition surface temperature becomes the lowest for the hot top wall case. These are due to buoyancy effect. Since the radiative heat flux of hot wall is rather lower than laser source, the ignition is considered to be controlled by the mixing process. Therefore, the ignition location, where appropriate mixture of fuel and oxygen exists, occurs near the hot wall. The flame propagates along the hot wall where there exists sufficient oxygen.

Useful Characteristics for Controlling the Cancellation Performance and Center Frequency of a Linearization Loop

  • Kang, Sang-Gee;Hong, Sung-Yong
    • ETRI Journal
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    • v.28 no.2
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    • pp.231-234
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    • 2006
  • The cancellation performance of a linearization loop is limited by the degree of an amplitude imbalance and a phase imbalance. A delay mismatch causes a phase variation as a function of frequency. Therefore, the cancellation performance and linearization bandwidth are limited by a delay mismatch. The expression for the effects of an amplitude imbalance, a phase imbalance, and a delay mismatch on the characteristics of a linearization loop is derived and analyzed. The simulation results are compared with the results obtained by means of using a commercial simulation tool and the exact agreement is reported. The derived equation could be used in designing a linearization loop and predicting the cancellation performance of the linearization loop usefully. Some useful characteristics, known from the simulation results obtained by using the derived equation, of a linearization loop for designing and implementing feedforward amplifiers are described in detail.

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On the Application of Cyclic Delay Diversity to Distributed SC-FDMA Systems (분산할당 SC-FDMA 시스템에서의 순환지연 다이버시티의 적용)

  • Rim, Min-Joong
    • Journal of the Institute of Electronics Engineers of Korea TC
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    • v.45 no.12
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    • pp.49-57
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    • 2008
  • In distributed-allocation OFDMA systems, cyclic delay diversify can improve the system performance by increasing frequency diversity. However, applying cyclic delay diversify to distributed-allocation SC-FDMA systems can affect the performance in two contrary ways: positive effect due to increased frequency diversity and negative effect caused by increased frequency selective channels. This paper addresses these two contrary effects and discusses about when cyclic delay diversity is useful and when it is not very useful for distributed-allocation SC-FDMA systems.

A Study on the Traffic Flow Characteristic Analysis and Applicability of Work Zones (도로 공사중의 교통류 특성분석과 적용성에 관한 연구 -고속도로를 중심으로-)

  • Lim, Chae-Moon;Lee, Ju-Ho;Lee, Young-Woo
    • Journal of the Korean Society of Industry Convergence
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    • v.5 no.4
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    • pp.329-337
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    • 2002
  • It is the actual condition that the increasing traffic delay and accident caused by inefficient management on various construction by occupying the roadways. Since almost roadway improvements are for the public convenient, negative effects by them are ignored. But now due to the increase of traffics demand and limitation of road supply, the positive management scheme and treatment plan on the constructions must be considered. Thus, to the extent of this study divides uninterrupted flow into freeways and the Highway, yielding the time spread between under construction and not, that is delay time, we build capacity and delay model in the change of traffic volume and occupying length.

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A Study on Implementation Delay Factors of the Block-unit Housing Renewal Project - Focused on the Incheon Metropolitan City - (가로주택정비사업의 사업시행 지연요인에 관한 연구 - 인천광역시 사례를 중심으로 -)

  • Han, Young Hoon;Na, In Su
    • Journal of KIBIM
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    • v.12 no.4
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    • pp.32-40
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    • 2022
  • The block-unit housing renewal project was presented as an alternative method to overcome the side effects of large-scale renewal projects while improving poor residential conditions. However, projects implementation is prolonged and even the pace of projects, which was considered an various incentives, is being delayed for the most part. In this study, delay factors are drawn by eight; conflict among association members, contract delay of joint implementation, participation paucity of constructor, inadequate project guidelines, alteration of project plan, lack of renewal project professionals, stricter loan restriction of HUG, lack of capacity of project operator. We categorized those eight factors to three aspects such as implementation, participants and proposition and suggested improvement alternatives according to three aspects.