• ETRI Journal
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• 제44권3호
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• pp.512-523
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• 2022

Random delay countermeasures introduce random delays into the execution flow to break the synchronization and increase the complexity of the side channel attack. A novel method for attacking devices with random delay countermeasures has been proposed by using a maximal overlap discrete wavelet transform (MODWT)-based power trace alignment algorithm. Firstly, the random delay in the power traces is sensitized using MODWT to the captured power traces. Secondly, it is detected using the proposed random delay detection algorithm. Thirdly, random delays are removed by circular shifting in the wavelet domain, and finally, the power analysis attack is successfully mounted in the wavelet domain. Experimental validation of the proposed method with the National Institute of Standards and Technology certified Advanced Encryption Standard-128 cryptographic algorithm and the SAKURA-G platform showed a 7.5× reduction in measurements to disclosure and a 3.14× improvement in maximum correlation value when compared with similar works in the literature.

• 대한교통학회지
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• 제10권1호
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• pp.41-54
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• 1992

The purpose of this thesis is to construct a model to estimate the delay that vehicles arriving randomly will be experienced at an isolated singalized intersection. To do this the following objectives are set in this study: (i) An what distance a random arrival pattern occurs after a platoon of vehicles are dis-charged from the stop line; (ii) A model which estimates the average delay per through-vehicle with respect to the de-gree of saturation; and (iii) The relation between the stepped delay and average approach delay per vehicle. The following are the findings of this study: (i) A random arrival pattern on the first second and third lanes occur 300,400 and 300m downstream from stop line rdspectively. A random arrival pattern on lane group occurs 500m downstream from the stop line ; (ii) A model for the estimation of approach delay has been developed in such a way that up to x=0.7 the delay increases linearly and beyond 0.7 the delay increases rapidly in a form of second order polynomial due to high degree of saturation : and (iii) Approach delay equals approximately 1.21 times of stopped delay.

• 대한수학회보
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• 제51권5호
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• pp.1469-1484
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• 2014

In this paper we are concerned with a class of stochastic partial functional differential equations with infinite delay. Supposing that the linear part is a Hille-Yosida operator but not necessarily densely defined and employing the integrated semigroup and random dynamics theory, we present some appropriate conditions to guarantee the existence of a random attractor.

• 반도체디스플레이기술학회지
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• 제10권3호
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• pp.21-28
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• 2011

In recent years, owing to the development of the image processing technology, the research to build control system using a vision sensor is stimulated. However, a random time delay must be considered, because it works of a various time to get a result of an image processing in the system. It can be seen as an obstacle factor to a control of visual tracking in real system. In this paper, implementing two vision controllers each, first one is made up PID controller and the second one is consisted of a Smith Predictor, the possibility was shown to overcome a problem of a random time delay in a visual tracking system. A number of simulations and experiments were done to show the validity of this study.

• 제어로봇시스템학회논문지
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• 제10권7호
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• pp.583-589
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• 2004

Modem control systems often use a communication network to send measurement and control signals between nodes. Communication delays can be time varying. The length of the time delays is often hard to predict and modeled as being random. This paper proposes a combined controller used to compensate network time delay by estimating the delay with the interacting multiple model (IMM). The network delay is modeled as a Markov chain and 3 modes representing heavy, medium, and low network loads are used in the IMM. The proposed method is applied to an optimal control system with double integrators and the results are compared with the existing control methods.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2003년도 ICCAS
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• pp.915-920
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• 2003

Modern control systems often use a communication network to send measurement and control signals between nodes. Communication delays can be time varying. The length of the time delays is often hard to predict and are modeled as being random. This paper proposes a combined controller used to compensate network time delay by estimating the delay with the interacting multiple model (IMM). The network delay is modeled as a Markov chain and 3 modes representing heavy, medium, and low network loads are used in the IMM. The proposed method is applied to an optimal control system with double integrators and the results are compared with the existing control methods.

• 한국통신학회논문지
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• 제37A권10호
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• pp.876-884
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• 2012

본 논문에서는 무선 센서네트워크(wireless sensor network : WSN)에서 발생하는 두 가지 지연 요인인 큐잉 지연(queueing delay)과 랜덤 링크 스케줄링에 의한 지연(delay by random link scheduling)을 소개하고 이를 해결하기 위한 새로운 순차적 스케줄링 기법을 제안한다. 또한 모의 실험을 통하여 이용하여 제안한 다중 홉 전송기법의 성능 평가를 수행하고, 이를 기존의 랜덤 링크 스케줄링 기법의 성능과 종단간 패킷 전송 지연의 관점에서 비교한다. 모의실험 결과에 따르면, 소스 노드(source node)와 목적지 노드(destination node) 사이의 홉 수(hop distance)가 증가할수록 제안한 스케줄링 기법과 기존의 랜덤 링크 스케줄링 기법의 지연 성능 차이가 증가함을 알 수 있었다. 소스 노드와 목적지 노드 사이의 평균 홉 수가 2.66, 4.1, 4.75 및 6.3 일 때, 제안한 스케줄링 기법은 기존의 랜덤 링크 스케줄링 기법에 비해 22%, 36%, 48% 및 55% 까지 지연 시간을 줄일 수 있었다.

• International Journal of Internet, Broadcasting and Communication
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• 제15권3호
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• pp.43-51
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• 2023

Slotted ALOHA (S-ALOHA) is a classical medium access control protocol widely used in multiple access communication networks, supporting distributed random access without the need for a central controller. Although stability and delay have been extensively studied in existing works, most of these studies have assumed ideal channel conditions or independent fading, and the impact of time-correlated wireless channels has been less addressed. In this paper, we investigate the queueing delay performance in S-ALOHA networks under time-correlated channel conditions by utilizing a Gilbert-Elliott model. Through simulation studies, we demonstrate how temporal correlation in the wireless channel affects the queueing delay performance. We find that stronger temporal correlation leads to increased variability in queue length, a larger probability of having queue overflows, and higher congestion levels in the S-ALOHA network. Consequently, there is an increase in the average queueing delay, even under a light traffic load. With these findings, we provide valuable insights into the queueing delay performance of S-ALOHA networks, supplementing the existing understanding of delay in S-ALOHA networks.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2003년도 ICCAS
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• pp.348-353
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• 2003

This paper considers the optimal control problem in real-time control systems with random time-delays. It proposes an algorithm which uses the linear quadratic (LQ) control method and a dedicated technique to compensate for the time-delay effects. Since it is assumed that the time-delays are unknown but the probability distribution of the delays are known a priori, the algorithm considers the mean value of the time-delays as a nominal value for random delay compensation. An example is given to show the performance of the proposed algorithm, where an inverted pendulum system is controlled over a controller-area network (CAN). Simulation results show that the proposed algorithm provides good performance results. It is shown that our algorithm is comparable to existing algorithms in both computation cost and performance.

• 한국통신학회논문지
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• 제30권9A호
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• pp.822-829
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• 2005

본 논문에서는 LBT-Random Searching 방식을 채용한 RFID 시스템의 트래픽 처리시간 및 주파수 채널 용량 분석을 위한 알고리즘을 제시하였다. 서비스 시간, 주파수 채널 탐색시간, 연속적인 주파수 채널 사용에 따른 지연시간, 연속적인 동일 주파수 채널 사용에 따른 지연시간을 고려하여 정상상태에서의 트래픽 처리 지연시간을 산출하였다. 시뮬레이션을 통하여 최대처리 가능한 트래픽 용량 및 주파수 채널수를 평가하고, 제안된 분석 알고리즘 정확성을 입증하였다.