• Journal of Information Processing Systems
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• 제4권3호
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• pp.87-96
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• 2008

This paper analyzes the handover latency of Mobile IP and mobile SCTP over IPv6 networks. The analytical results are compared with the performance by experiment over Linux testbed. For analysis, we consider the two handover scenarios: horizontal handover and vertical handover. From the results, we see that mSCTP can provide smaller handover latency than Mobile IP. Moreover, mSCTP can give much smaller handover latency for vertical handover, compared to horizontal handover.

• 한국콘텐츠학회논문지
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• 제5권3호
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• pp.201-208
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• 2005

사용자가 요청한 서비스의 품질을 보장하기 위해서는 고려해야 할 요소가 많이 있으나, 그 중에서 가장 중요한 요소는 응답시간을 사용자에게 투명하게 제공할 수 있어야 한다. 서비스 응답시간을 측정하기 위해서는 네트워크 지연시간(network latency), 시스템에서의 지연시간(system latency), 소프트웨어 구성요소 지연시간(software component latency)을 측정하여야 한다. 본 논문에서는 네트워크 지연시간에 대하여 모델링을 수행하고, 패킷 손실이 지연시간에 미치는 영향에 대하여 분석을 수행하였다. 또한 NS-2 (Network Simulator)를 이용하여 제시한 수식의 유용성을 제시하기 위해서 시뮬레이션을 수행하였다. 이러한 연구는 서비스제공자와 사용자가 SLA (Service Level Agreement)의 체결 시에 응답시간을 보장해 줄 수 있는 방안의 제시가 가능하다.

• 한국통신학회논문지
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• 제28권12B호
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• pp.1106-1114
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• 2003

지금까지 TCP (transmission control protocol)의 성능을 분석하고 예측하기 위한 많은 모델들이 제시되어 왔다. TCP의 처리율을 모델링을 통해 정확하게 분석하기 위해서는 보다 정확한 TCP의 종단간 전송 지연(latency)을 모델링하는 것이 필요한데, 이를 위해서는 손실 복구 과정에서 발생하는 지연이 필수적으로 고려되어야 한다. 따라서 본 논문에서는 재전송에 의해 복구되는 패킷 손실의 개수를 고려한 손실 복구 확률을 기초로 손실 복구과정에서 발생하는 지연(loss recovery latency)을 모델링을 통해 분석한다. 수학적인 분석과 시뮬레이션을 통해 선택 승인(selective acknowledgement) 옵션을 사용하는 TCP의 성능이 TCP NewReno보다 손실 복구 지연 차원에서 우월하다는 것을 보인다.

• ETRI Journal
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• 제42권5호
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• pp.721-733
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• 2020

Recently, there is an increasing demand for ultra-low-latency (ULL) services such as factory automation, autonomous driving, and telesurgery that must meet an end-to-end latency of less than 10 ms. Fifth-generation (5G) New Radio guarantees 0.5 ms one-way latency, so the feasibility of ULL services is higher than in previous mobile communications. However, this feasibility ensures performance at the radio access network level and requires an innovative 5G network architecture for end-to-end ULL across the entire 5G system. Hence, we survey in detailed two the 3rd Generation Partnership Party (3GPP) standardization activities to ensure low latency at network level. 3GPP standardizes mobile edge computing (MEC), a low-latency solution at the edge network, in Release 15/16 and is standardizing time-sensitive communication in Release 16/17 for interworking 5G systems and IEEE 802.1 time-sensitive networking (TSN), a next-generation industry technology for ensuring low/deterministic latency. We developed a 5G system based on 3GPP Release 15 to support MEC with a potential sub-10 ms end-to-end latency in the edge network. In the near future, to provide ULL services in the external network of a 5G system, we suggest a 5G-IEEE TSN interworking system based on 3GPP Release 16/17 that meets an end-to-end latency of 2 ms.

• 전자공학회논문지S
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• 제34S권10호
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• pp.89-97
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• 1997

To extract time-varying evoked potential (EP), segement latency corrected average method is presented. This method is composed of three steps. First, adaptive filtering for reducing the effect of artifacts and removing background noise is performed. Next, validated intervals of individual segments are aligned, and latency components are detected by cross-correlation between the previously obtained and measured EPs within the intervals. Finally, after the detected latency component, responses of segments are groupe and averaged, the shole corrected EP signal is obtained. In the experiments, the resutls of the conventional methods including simple averaging, Woody's method, and peak component latency corrected averaging are obtained, the results compared with the present method for evaluating performance. Therefore, the presented method confirms that it reflects the latency variations of fundamental peaks and gets the improved EP.

• 전자통신동향분석
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• 제13권3호통권51호
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• pp.61-70
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• 1998

The obvious way to make a computer system more powerful is to make the processor as fast as possible. Furthermore, adopting a large number of such fast processors would be the next step. This multiprocessor system could be useful only if it distributes workload uniformly and if its processors are fully utilized. To achieve a higher processor utilization, memory access latency must be reduced as much as possible and even more the remaining latency must be hidden. The actual latency can be reduced by using fast logic and the effective latency can be reduced by using cache. This article discusses what the memory latency problem is, how serious it is by presenting analytical and simulation results, and existing techniques for coping with it; such as write-buffer, relaxed consistency model, multi-threading, data locality optimization, data forwarding, and data prefetching.

• 수면정신생리
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• 제3권1호
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• pp.79-84
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• 1996

Kleine-Levin syndrome is a disorder characterized by recurrent episodes of hypersomnia, hyperphagia and hypersexuality that typically occur weeks or months apart. A 17-years-old male showed these episodes and took nocturnal polysomnography(NPSG) and multiple sleep latency test(MSLT). As results of NPSG, sleep latency was 82.5min, sleep efficiency was 82.5min, sleep efficiency was 82.5%, latency and percentage of REM sleep were 106.5min and 14.6% and percentage of slow wave sleep was 12.7%. In 4 times MLST, average of sleep latency and REM latency were 8min 7sec and 5min 20sec with 3 times sleep onset REM period(SOREMP). These findings are consistent with these of Keine-Levin syndrome. And the possible causes and classification of this syndrome were discussed.

• 대한임베디드공학회논문지
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• 제14권5호
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• pp.227-237
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• 2019

Ultra-low latency control is one of the characteristics of 5G cellular network services, which means that the control loop is handled in milliseconds. To achieve this, it is necessary to identify time delay factors that occur in all components related to CPS control loop, including new 5G cellular network elements such as MEC, and to optimize CPS control loop in real time. In this paper, a novel CPS architecture for ultra-low latency control of CPS is designed. We first define the ultra-low latency characteristics of CPS and the CPS concept model, and then propose the design of the control loop performance monitor (CLPM) to manage the timing information of CPS control loop. Finally, a case study of MEC-based implementation of ultra-low latency CPS reviews the feasibility of future applications.

• 한국전문물리치료학회지
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• 제25권3호
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• pp.51-59
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• 2018

Background: Despite muscle latency times and patterns were used as broad examination tools to diagnose disease and recovery, previous studies have not compared the dominant arm to the non-dominant arm in muscle latency time and muscle recruitment patterns during reaching and reach-to-grasp movements. Objects: The present study aimed to investigate dominant and non-dominant hand differences in muscle latency time and recruitment pattern during reaching and reach-to-grasp movements. In addition, by manipulating the speed of movement, we examined the effect of movement speed on neuromuscular control of both right and left hands. Methods: A total of 28 right-handed (measured by Edinburgh Handedness Inventory) healthy subjects were recruited. We recorded surface electromyography muscle latency time and muscle recruitment patterns of four upper extremity muscles (i.e., anterior deltoid, triceps brachii, flexor digitorum superficialis, and extensor digitorum) from each left and right arm. Mixed-effect linear regression was used to detect differences between hands, reaching and reach-to-grasp, and the fast and preferred speed conditions. Results: There were no significant differences in muscle latency time between dominant and non-dominant hands or reaching and reach-to-grasp tasks (p>.05). However, there was a significantly longer muscle latency time in the preferred speed condition than the fast speed condition on both reaching and reach-to-grasp tasks (p<.05). Conclusion: These findings showed similar muscle latency time and muscle activation patterns with respect to movement speeds and tasks. Our findings hope to provide normative muscle physiology data for both right and left hands, thus aiding the understanding of the abnormal movements from patients and to develop appropriate rehabilitation strategies specific to dominant and non-dominant hands.

• IEIE Transactions on Smart Processing and Computing
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• 제3권1호
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• pp.1-9
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• 2014

This paper proposes a low-latency Sample Adaptive Offset filter (SAO) architecture and its Single Instruction Multiple Data (SIMD) optimization scheme to achieve fast High Efficiency Video Coding (HEVC) decoding in a multi-core environment. According to the HEVC standard and its Test Model (HM), SAO operation is performed only at the picture level. Most realtime decoders, however, execute their sub-modules on a Coding Tree Unit (CTU) basis to reduce the latency and memory bandwidth. The proposed low-latency SAO architecture has the following advantages over picture-based SAO: 1) significantly less memory requirements, and 2) low-latency property enabling efficient pipelined multi-core decoding. In addition, SIMD optimization of SAO filtering can reduce the SAO filtering time significantly. The simulation results showed that the proposed low-latency SAO architecture with significantly less memory usage, produces a similar decoding time as a picture-based SAO in single-core decoding. Furthermore, the SIMD optimization scheme reduces the SAO filtering time by approximately 509% and increases the total decoding speed by approximately 7% compared to the existing look-up table approach of HM.