• Journal of Information Processing Systems
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• v.4 no.4
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• pp.133-144
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• 2008

Clusters have become a popular alternative for building high-performance parallel computing systems. Today's high-performance system area network (SAN) protocols such as VIA and IBA significantly reduce user-to-user communication latency by implementing protocol stacks outside of operating system kernel. However, emerging parallel applications require a significant improvement in communication latency. Since the time required for transferring data between host memory and network interface (NI) make up a large portion of overall communication latency, the reduction of data transfer time is crucial for achieving low-latency communication. In this paper, Eager Data Transfer (EDT) mechanism is proposed to reduce the time for data transfers between the host and network interface. The EDT employs cache coherence interface hardware to directly transfer data between the host and NI. An EDT-based network interface was modeled and simulated on the Linux-based, complete system simulation environment, Linux/SimOS. Our simulation results show that the EDT approach significantly reduces the data transfer time compared to DMA-based approaches. The EDTbased NI attains 17% to 38% reduction in user-to-user message time compared to the cache-coherent DMA-based NIs for a range of message sizes (64 bytes${\sim}$4 Kbytes) in a SAN environment.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.8 no.11
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• pp.4016-4027
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• 2014

Understanding network latency is important for providing consistent and acceptable levels of services in network-based applications. However, due to the difficulty of estimating applications' network demands and the difficulty of network latency modeling the management of network resources has often been ignored. We expect that, since network latency repeats cycles of congested states, a systematic classification method for network status would be helpful to simplify issues in network resource managements. This paper presents a simple empirical method to classify network status with a real operational network. By observing oscillating behavior of end-to-end latency we determine networks' status in run time. Five typical network statuses are defined based on a long-term stability and a short-term burstiness. By investigating prediction accuracies of several simple numerical models we show the effectiveness of the network status classification. Experimental results show that around 80% reduction in prediction errors depending on network status.

• Annals of Clinical Neurophysiology
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• v.5 no.2
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• pp.187-191
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• 2003

Purpose: MEPs elicited by transmagnetic stimulations of the motor cortex are facilitated by voluntary muscle contraction. We evaluated the effects of the imagination of the movements on latencies of MEPs and reciprocal inhibition by using transmagnetic stimulations. Methods: Twenty two healthy volunteers(eight men and fourteen women) were studied. TMSs were delivered at rest and during imagining abducting or adducting right thumb. A stimulator with a round coil and a fixed intensity of 80% of maximum was used to evoke MEPs. MEPs were evoked by magnetic stimulations over the scalp and cervical spine(C7-T1), and central motor conduction times(CMCT) were calculated by subtracting the latency of compound muscle action potentials(CMAPs) obtained by stimulating over the cervical spine from that obtained by stimulating over the scalp. The motor evoked potentials were recorded from right abductor pollicis brevis muscle(APB) and adductor pollicis muscle(AP) simultaneously. Results: Imagination of abduction resulted in a shortened latency of the CMAPs in APB, and a prolonged latency in AP. Imagination of adduction resulted in a shortened latency in AP, and a prolonged latency in APB. But the imagination caused no significant change in the latency of CMAPs elicited by stimulation over cervical spine. Therefore, the changes of the CMCTs account for these latency changes with imagination of movement. With the imagination of abduction, there are significant reduction of the CMCT's in APB(10.8%) and prolongation in AP(5.8%). On the other hand, with the imagination of adduction, prolongation of the CMCT's in APB(7.3%) and reduction in AP(5.9%) were observed. Conclusion: These findings indicate that imagination of muscle contraction increases the excitability of the human corticospinal system. Reciprocal inhibition may be accountable for the prolonged latency in the antagonist muscle.

• ETRI Journal
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• v.27 no.5
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• pp.525-532
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• 2005

In this paper, we propose and present implementation results of a high-speed turbo decoding algorithm. The latency caused by (de)interleaving and iterative decoding in a conventional maximum a posteriori turbo decoder can be dramatically reduced with the proposed design. The source of the latency reduction is from the combination of the radix-4, center to top, parallel decoding, and early-stop algorithms. This reduced latency enables the use of the turbo decoder as a forward error correction scheme in real-time wireless communication services. The proposed scheme results in a slight degradation in bit error rate performance for large block sizes because the effective interleaver size in a radix-4 implementation is reduced to half, relative to the conventional method. To prove the latency reduction, we implemented the proposed scheme on a field-programmable gate array and compared its decoding speed with that of a conventional decoder. The results show an improvement of at least five fold for a single iteration of turbo decoding.

• Journal of IKEEE
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• v.18 no.3
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• pp.392-397
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• 2014

In this paper, we propose a memory operation system architecture for memory latency penalty reduction in SIMT architecture based stream processor. The proposed architecture applied non-blocking cache architecture to reduce cache miss penalty generated by blocking cache architecture. We verified that the proposed memory operation architecture improve the performance of the stream processor by comparing processing performances of various algorithms. We measured the performance improvement rate that was improved in accordance with the ratio of memory instruction in each algorithm. As a result, we confirmed that the performance of stream processor improves up to minimum 8.2% and maximum 46.5%.

• Environmental and Resource Economics Review
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• v.12 no.1
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• pp.49-74
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• 2003

This study used a slightly modified version of contingent valuation questionnaire designed and developed by Krupnick et al.(2000) to estimate the value of mortality risk reduction for environmental policy. Because that environmental policy, especially air pollution policy with some latency main effect on mortality risk reduction of old people with some latency period, respondents were asked about their current WTP for 5/1,000 mortality risk reduction being to take place beginning at 70 over the course of ten years. The annual mean WTP is 233,370 won (standard error 32,570 won) in spike/continuous/interval data model. The implied VSL is 466 million won. The 95% confidence interval is 339 million won~594 million won.

• KIPS Transactions on Computer and Communication Systems
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• v.2 no.4
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• pp.163-176
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• 2013

Cloud-based streaming game service has numerous merits, but it may suffer from presentation latency in a thin-client. It is an important issue especially for game service which needs instantaneous response to user inputs. This research proposes the methods for reducing the presentation latency between the server unit and the thin-client unit. The approaches proposed to be employed with server unit include the source/sync video format equalization, encoding format configuration according to the media type, and the S/W implementation for transmitting clock periodically. The methods for the thin-client unit include the decreasing the number of instructions, use of light encryption algorithm, and improvement on H/W decoding. The proposed schemes are tested with a commercialized streaming service platform, which reveals the reduction of presentation latency as large as a few hundred milliseconds and reaches the acceptable level (about 100 milliseconds).

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.15 no.7
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• pp.2531-2546
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• 2021

For several years, virtual reality (VR) and augmented reality (AR) technologies have been improving. However, some hurdles remain that slow down the distribution of VR and AR devices, such as head-mounted display (HMD), and related consumer content. One issue is VR motion sickness, which has been experienced by users using 360 degree VR content via HMD. This paper discusses the related international standardization work that classifies the factors causing VR sickness, and proposes the process for VR sickness level evaluation. Among the factors causing VR sickness, many research institutes regard minimizing MTP (Motion-to-Photon) latency as the key enabler to mitigate VR sickness. Thus, this paper introduces research trends of MTP latency measurement and MTP latency mitigation. This paper categorizes the research on MTP latency measurement into 2 categories of hardware-based approach and software code-level approach. The 2 approaches have different pros and cons depending on use-case, purpose, and architecture of each multimedia system. The pros and cons are addressed in this paper. Additionally, the research on mitigating MTP latency with diverse strategies such as proactive computing, caching, and edge server technology is explained, and compared to conventional technologies, shows improved performance.

• The Korean Journal of Pharmacology
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• v.29 no.1
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• pp.33-41
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• 1993

Central analgesic effect of capsaicin was assessed by the tail flick reflex (TFR) test, using male Sprague-Dawley rats under anesthesia with pentobarbital sodium (induction with 40 mg/kg and maintenance with $4{\sim}8\;mg/kg/hr$). Level of norepinephrine in the spinal cord was also measured. Capsaicin, $35{\sim}150\;{\mu}g$, was injected intrathecally, and the TFR latency was measured before, 10, 30, and 60 minutes after the drug administration. TFR latency was increased 100% or more immediately by intrathecal capsaicin, from 2.9 seconds to the maximum of 7.0 seconds at 10 minute after the drug; P<0.01. The increase in TFR latency was maintained during the course of experiment of 2 hours. Concomitant reduction of NE content in the spinal cord was observed; from 16 ng/mg protein to 7 ng/mg protein. On the other hand, subcutaneous injection of capsaicin of 50 mg/kg did not change the TFR latency although the NE content reduced similarly to the case of intrathecal injection. Pretreatment of the animal with 0.5 mg/kg of MK-801 reversed the increase of TFR latency and NE reduction induced by intrathecal capsaicin. These results suggest that capsaicin causes analgesia at the spinal cord level by activating the excitatory amino acid-NE-dorsal horn interneurons axis of the descending inhibitory pain modulation pathway.

• Journal of Sensor Science and Technology
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• v.25 no.5
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• pp.365-370
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• 2016

The study about VR (Virtual Reality) has been done from the 1960s, but technical limits and high cost made VR hard to commercialize. However, in recent, high resolution display, computing power and 3D sensing have developed and hardware has become affordable. Therefore, normal users can get high quality of immersion and interaction. However, HMD devices which offer VR environment have high latency, so it disrupts the VR environment. People are usually sensitive to relative latency over 20ms. In this paper, as adding the Electromyogram (EMG) sensors to typical IMU sensor only system, the latency reduction method is proposed. By changing software and hardware components, some cases the latency was reduced significantly. Hence, this study covers the possibility and the experimental verification about EMG sensors for reducing the latency.