• Structural Engineering and Mechanics
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• 제31권5호
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• pp.621-624
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• 2009

The time delay in active and semi-active controls is an important research subject. Many researches on the time-delay control for deterministic systems have been made (Hu and Wang 2002, Yang et al. 1990, Abdel-Mooty and Roorda 1991, Pu 1998, Cai and Huang 2002), while the study on that for stochastic systems is very limited. The effects of the time delay on the control of nonlinear systems under Gaussian white noise excitations have been studied by Bilello et al. (2002). The controlled linear systems with deterministic and random time delay subjected to Gaussian white noise excitations have been treated by Grigoriu (1997). Recently, a stochastic averaging method for quasi-integrable Hamiltonian systems with time delay has been proposed (Liu and Zhu 2007). In the present paper, a stochastic optimal time-delay control method for stochastically excited nonlinear structural systems is proposed based on the stochastic averaging method for quasi Hamiltonian systems with time delay and the stochastic dynamical programming principle. An example of stochastically excited and controlled hysteretic column is given to illustrate the proposed control method.

• Wind and Structures
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• 제16권5호
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• pp.433-455
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• 2013

A phase delay spectrum model towards the representation of spatial coherence of stochastic wind fields is proposed. Different from the classical coherence functions used in the spectral representation methods, the model is derived from the comprehensive description of coherence of fluctuating wind speeds and from the thorough analysis of physical accounts of random factors affecting phase delay, building up a consistent mapping between the simulated fluctuating wind speeds and the basic random variables. It thus includes complete probabilistic information of spatial stochastic wind fields. This treatment prompts a ready and succinct scheme for the simulation of fluctuating wind speeds, and provides a new perspective to the accurate assessment of dynamic reliability of wind-induced structures. Numerical investigations and comparative studies indicate that the developed model is of rationality and of applicability which matches well with the measured data at spatial points of wind fields, whereby the phase spectra at defined datum mark and objective point are feasibly obtained using the numerical scheme associated with the starting-time of phase evolution. In conjunction with the stochastic Fourier amplitude spectrum that we developed previously, the time history of fluctuating wind speeds at any spatial points of wind fields can be readily simulated.

• 한국정보처리학회논문지
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• 제7권2호
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• pp.536-541
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• 2000

터보코드는 인터리버의 크기가 클수록 반복 복호횟수가 많을수록 복호 성능은 우수하지만 시스템이 복잡해져 한 개의 정보비트를 복호할 때 많은 시간지연을 발생시켜 실시간 통신에는 부적합하다는 단점이 있다. 따라서 본 논문에서는 터보코드 부$\cdot$복호기에 사용되는 인터리버의 크기를 감소시켜 한 개의 정보비트를 복호할 때 소요되는 시간지연을 줄이는 새로운 세미 랜덤(Semi-Random) 인터리버 알고리즘을 제안하였다. 세미 랜덤 인터리버 알고리즘은 입력 데이터 길이의 1/2 크기만큼 인터리버를 구성하고, 인터리버 내에 쓸때는 블록 인터리버처럼 행으로 쓰고, 읽을 때는 랜덤하게 읽음과 동시에 다음 데이터가 그 주소 번지에 위치하게 된다. 따라서 기존의 블록, 대각, 랜덤 인터리버와 알고리즘의 복잡도를 비교할 시 그 복잡도를 1/2로 감소시킬 수 있게 된다.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2000년도 제15차 학술회의논문집
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• pp.433-433
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• 2000

In this paper, we propose a development of internet teleoperation method applying QoS model, which has the real time control capability and the time-delay predicting capability, The QoS model gives a constant bandwidth to a specified application and makes the dynamically irregular time-delay to be predictable and fined so that it can have real-time capability.

• 한국산학기술학회논문지
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• 제13권3호
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• pp.1147-1152
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• 2012

본 논문은 의학 분야에서 사용되는 하드웨어 발생기 디지털 난수 출력열의 특성 처리 분석을 주요 이슈로 한다. 하드웨어 이진 난수를 기반으로 하는 난수발생기의 출력열은 지연, 지터, 온도 등의 요소로부터 영향을 받는다. 본 논문에서는 하드웨어 출력 난수열에 영향을 주는 주요 요소에 대해 살펴보고, 출력열과 암호알고리즘, 부호알고리즘이 결합된 출력열의 난수성을 분석하였다. 분석된 결과는 난수성 주요 검증 항목에 의해 평가되었다.

• Journal of information and communication convergence engineering
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• 제15권1호
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• pp.28-36
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• 2017

The medium access control (MAC) protocol based on dynamic time division multiple access/time division duplex (TDMA/TDD) is responsible for random access control and radio resource allocation in dynamic traffic environments. These functions of random access and resource allocation are very important to prevent wastage of resources and improve MAC performance according to various network conditions. In this paper, we propose new random access and resource allocation schemes to guarantee quality of service (QoS) and provide priority services in a dynamic TDMA/TDD system. First, for the QoS guarantee, we propose an adaptive random access and resource allocation scheme by introducing an access probability. Second, for providing priority service, we propose a priority-based random access and resource allocation scheme by extending the first adaptive scheme in both a centralized and a distributed manner. The analysis and simulation results show that the proposed MAC protocol outperforms the legacy MAC protocol using a simple binary exponential backoff algorithm, and provides good differential performance according to priorities with respect to the throughput and delay.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2004년도 춘계학술대회논문집
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• pp.228-232
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• 2004

This paper is to identify the position of random disturbance on flexible dynamic system, and the position of the piezo ceramic actuator 0 minimize tip response. Correlation of the output signals from each parts on flexible system is used to identify the position of random disturbance. Except the correlation with an output signal from the position of random disturbance, other correlations have time delay. This is a base idea to identify the position on this study.

• 한국통신학회논문지
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• 제36권1A호
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• pp.49-57
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• 2011

Random access method for Wibro system is proposed using the Bayesian Technique, which can estimate the number of bandwidth request messages in a frame only based on the number of successful slots. The performance measures such as the maximum average throughput, the mean delay time and the collision ratio are investigated to evaluate the performance of the proposed method. The proposed method shows better performance than the binary exponential backoff algorithm used currently.

• Journal of Communications and Networks
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• 제8권1호
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• pp.21-27
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• 2006

We present and analyze a class of limited sensing random access algorithms with powerful properties. The algorithms are implementable in wireless mobile environments and their operational properties are simple. Their throughput in the worst case of the limit Poisson user model is 0.4297, while this throughput degrades gracefully in the presence of channel feedback errors.

• 전자공학회논문지A
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• 제33A권2호
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• pp.205-216
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• 1996

In this paper we propose an efficient robust path delay fault test genration algorithm for detection of path delay faluts in combinational ligic circuits. In the proposed robust test genration approach, the testability measure is computed for all gates in the circuit under test and these computed values are used to genrate weighted random delay test vetors for detection of path delay faults. For genrated robust test vectors, we perform fault simulation on ISCAS '85 benchmark circuits using parallel pattern technqieus. The results indicate that the proposed test genration method not only increases the number of detected robust path delay faults but also reduces the time taen to genrate robust tests.