• The KIPS Transactions:PartA
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• v.11A no.1
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• pp.67-74
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• 2004

Most of today's parallel numerical schemes use synchronous algorithms, where some processors that have finished their tasks earlier than others must wait at synchronization points for correct computation. Hence overall performance of the system is dependent upon the speed of the slowest processor. In this paper, we det·ise a synchronous/asynchronous hybrid algorithm to accelerate convergence of the solution for finding the dominant eigenpair of a large matrix, by reducing the idle times of faster processors using MPMD programming methodology.

• Bulletin of the Korean Chemical Society
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• v.22 no.8
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• pp.807-815
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• 2001

Two-dimensional (2D) correlation method, which generates the synchronous and the asynchronous 2D spectrum by complex cross correlation of the Fourier transformed spectra, is an analysis method for the changes of the sample spectrum induced by vari ous perturbations. In the present work, the 2D electronic correlation spectra have been simulated for the cases where the sample spectrum composed of two gaussian bands changes linearly. When only the band amplitudes of the sample spectrum change, the synchronous spectrum shows strong peaks at the band centers of the sample spectrum, but the asynchronous spectrum does not make peaks. When the sample spectrum shifts without changing intensity and width, the synchronous spectrum shows peaks around the initial and final positions of the band maximum and the asynchronous spectrum shows long peaks spanning the shifting range. The band width change produces the complex 2D correlation spectra. When the sample spectrum shifts with band broadening, the width change by 50% of full width at half maximum (FWHM) does not give so large an effect on the correlation spectrum as the spectral shift by one half of FWHM of the sample spectrum.

• ETRI Journal
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• v.35 no.3
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• pp.480-490
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• 2013

As technology evolves into the deep submicron level, synchronous circuit designs based on a single global clock have incurred problems in such areas as timing closure and power consumption. An asynchronous circuit design methodology is one of the strong candidates to solve such problems. To verify the feasibility and efficiency of a large-scale asynchronous circuit, we design a fully clockless 32-bit processor. We model the processor using an asynchronous HDL and synthesize it using a tool specialized for asynchronous circuits with a top-down design approach. In this paper, two microarchitectures, basic and enhanced, are explored. The results from a pre-layout simulation utilizing 0.13-${\mu}m$ CMOS technology show that the performance and power consumption of the enhanced microarchitecture are respectively improved by 109% and 30% with respect to the basic architecture. Furthermore, the measured power efficiency is about 238 ${\mu}W$/MHz and is comparable to that of a synchronous counterpart.

• Research in Community and Public Health Nursing
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• v.33 no.3
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• pp.312-320
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• 2022

Purpose: This study was performed to explore the effect of the delivery format on teaching presence, learning presence, and learning outcomes in distance learning of nursing students. Methods: A descriptive survey was conducted to understand teaching presence, learning presence, and learning outcomes depending on the delivery format of distance learning. Quota sampling methodology was used to recruit 295 nursing students from all over the country, and data collection was done from July 27 to September 10, 2020. The first delivery format for distance learning was synchronous learning in which communication between the instructor and students occurred simultaneously. The second delivery format was asynchronous learning in which prerecorded videos were provided and communication did not occur simultaneously. Results: In synchronous learning, teaching presence (especially direct facilitation) and learning presence (especially emotional expression) had a statistical significance that was higher than in asynchronous learning. However, in learning outcomes, there was no statistically significant difference. There were significant positive correlations between teaching presence, learning presence, and learning outcomes, and there were significant positive correlations. Conclusion: It can be suggested that learning outcomes can be improved if presence is improved in the distance learning environment based on the results of this study. It is necessary to add contact with nursing students and instructors to improve teaching presence in the asynchronous learning, and it is necessary to help students express their emotions to improve learning presence.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.6 no.1
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• pp.361-378
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• 2012

Most of the current frequency hopping (FH) based dynamic spectrum access (DSA) methods concern a reactive channel access scheme with synchronous inter-channel spectrum sensing, i.e., FH is reactively triggered by the primary user (PU)'s return reported by spectrum sensing, and the PU channel to be switched to is assumed precisely just sensed or ready to be sensed, as if the inter-channel spectrum sensing moments are synchronous. However, the inter-channel spectrum sensing moments are more likely to be asynchronous, which risks PU suffering more interference. Moreover, the spectrum sensing is usually erroneous, which renders the problem more complex. To address this problem, we propose a proactive FH based DSA method against both erroneous spectrum sensing and asynchronous inter-channel spectrum sensing (moments). We term it as proactive DSA. The optimal FH sequence is obtained by dynamic programming. The complexity is also analyzed. Finally, the simulation results confirm the effectiveness of the proposed method.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.15 no.4
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• pp.1-7
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• 2015

Until now, face to face coaching has been applied almost for completing the goal in various field. Face to face coaching is difficult always to reach each other anywhere, anytime due to the availability of internet and mobile devices. Recently, e-coaching is attempted to expend. But current e-coaching is supporting the secondary role for face to face coaching. E-coaching system has many benefits to use advancement technologies in internet. Therefore, the development of e-coaching system based on horizontal relationships between coach and coachee needs to communication anytime and anywhere in Internet. Usually previous online coaching systems have four types of interactions i.e. electronic mail, video chat, text chat, phone call. Most of the e-coaching approaches are easy to access and provide communication synchronous; video chat is an excellent visibility, whereas e-mail is asynchronous and document-centric. In this paper, we design and implement the integration e-coaching system based on synchronous and asynchronous. This system provides the asynchronous coaching offered by way of e-mail, and the synchronous coaching used P2P (Peer to Peer) video chat and text group chat. This system allows simultaneously asynchronous and synchronous coaching, and supports individual and group communication for periodical or informal coaching.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.11A
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• pp.891-901
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• 2003

This paper presents low-power asynchronous barrel shifters for variable length encoders and decoders useful in portable applications using multimedia standards. Our approach is to create multi-level asynchronous barrel shifters optimized for the skewed shift control statistics often found in these codecs. For common shifts, data passes through one level, whereas for rare shifts, data passes though multiple levels. We compare our optimized designs with the straightforward asynchronous and synchronous designs. Both pre- and Post-layout HSPICE simulation results indicate that, compared to their synchronous counterparts, our designs provide over a 40% savings in average energy consumption for a given average performance.

• Journal of Information Technology Services
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• v.21 no.3
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• pp.73-87
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• 2022

As the COVID-19 pandemic continues to prolong, non face-to-face, online classes has become the new normal in education. To examine the effect of course types and course delivery modes on student course satisfaction, the study analyzed survey data collected from 2,743 students enrolled in a 4-year university located in a metropolitan area. Basic Frequency analysis as well as keyword network analysis were used to analyze student survey data. The main results and implications of the study are as follows. First, the survey results indicated that students preferred asynchronous classes over synchronous online classes. This tendency was consistent regardless of student grades and majors as well as the course type. However, students majoring in more practice-oriented disciplines tend to prefer synchronous online classes and blended classes, and this tendency gets stronger with courses in major. Second, the keyword network analysis results further indicated that interactivity may play an important role in both synchronous and asynchronous online course satisfaction.

• Journal of the Korean Institute of Telematics and Electronics C
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• v.35C no.9
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• pp.38-48
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• 1998

Generating test patterns for asynchronous sequential circuits remains to be a very difficult problem. There are few algorithms for this problem, and previous works cut feedback loops, and insert synchronous flip-flops in the feedback loops during ATPG. The conventional algorithms are similar to the algorithms for synchronous sequential circuits. This means that the conventional algorithms generate test patterns by modeling asynchronous sequential circuits as synchronous sequential circuits. So, test patterns generated by those algorithms nay not detect target faults when the test patterns are applied to the asynchronous sequential circuit under test. In this paper an algorithm is presented to generate test patterns for asynchronous sequential circuits. Test patterns generated by the algorithm can detect target faults for asynchronous sequential circuits with the minimal possibility of critical race problem and oscillation. And it is guaranteed that the test patterns generated by the algorithm will detect target faults.

• Proceedings of the IEEK Conference
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• 2001.06b
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• pp.349-352
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• 2001

As microprocessor and SOC (System On a Chip) performance moves into the GHz speed, the high-speed asynchronous design is becoming challenge due to the disadvantageous power and speed aspects in synchronous designs. The next generation on-chip systems will consist of multiple independently synchronous modules and asynchronous modules for higher performance, so the interface module for data transfer between multiple clocked IPs is designed with Xilinx FPGA and simulated with RISC microprocessor.