• Proceedings of the KIEE Conference
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• 2007.04a
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• pp.451-453
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• 2007

This paper describes the design of an asynchronous implementation of a sensor network processor. The main purpose of this work is the reduction of power consumption in sensor network node processors and the research presented here tries to explore the suitability of asynchronous circuits for this purpose. The Handshake Solutions toolkit is used to implement an asynchronous version of a sensor processor. The design is made compact, trading area and leakage power savings with dynamic power costs, targeting the typical sparse operating characteristics of sensor node processors. It is then compared with a synchronous version of the same processor. Both versions are then compared with existing commercial processors in terms of power consumption.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.27 no.7A
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• pp.635-640
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• 2002

We investigate optimal and suboptimal decision rules for parallel code acquisition in chip asynchronous direct-sequence spread-spectrum systems. The conventional decision rule for parallel acquisition is to choose the largest correlator output of a receiver. However, such a scheme is optimum only for chip synchronous models. In this paper, an optimal decision rule is derived based on the maximum-likehood criterion for chip asynchronous models. A simpler suboptimal decision rule is also discussed. The performance of the optimum and suboptimum decision rules is compared to that of the conventional decision rule. Numerical results show that, for chip asynchronous models, both the optimal and suboptimal decision rules outperform the conventional decision rule.

• The KIPS Transactions:PartA
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• v.8A no.4
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• pp.439-446
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• 2001

The main stream of parallel programming today is using synchronous algorithms, where processor synchronization for correct computation and workload balance are essential. Overall performance of the whole system is dependent upon the performance of the slowest processor, if workload is not well-balanced or heterogeneous clusters are used. Asynchronous iteration is a way to mitigate such problems, but most of the works done so far are for shared memory systems. In this paper, we suggest and implement a parallel large sparse linear system solver that improves performance on distributed memory systems like clusters by reducing processor idle times as much as possible by asynchronous iterations.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.5
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• pp.2457-2464
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• 2013

In this paper, we design and analyze a mutual exclusion algorithm, based on the Token and Failure detector, in asynchronous distributed systems. A Failure Detector is an independent module that detects and reports crashes of other processes. There are some of advantages in rewriting the Token-based ME algorithm using a Failure Detector. We show that the Token-based ME algorithm, when using Failure Detector, is more effectively implemented than the classic Token-based ME algorithm for synchronous distributed systems.

• English Language & Literature Teaching
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• v.13 no.4
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• pp.33-58
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• 2007

The present paper aims at comparing the two modes of CMC - synchronous and asynchronous - in terms of discourse markers used in turn-initial positions. It further attempts to examine the viability and limitations of these two modes of CMC in fostering EFL learners' face-to-face conversation skills. For these purposes, the present study analyzed 33 Korean EFL learners' Web chat and E-mail exchange data. Discourse markers in the participants' Web chat transcripts and those in their E-mail transcripts were identified and then compared in terms of their frequency and functions. The analysis revealed that the participants show difference in their preference for discourse markers depending on the modes of CMC. Also, the functions of discourse markers used for Web chat showed were strikingly different from those for e-mail. Especially, e-mail discourse markers revealed greater discrepancy from the markers in face-to-face conversation. The differences were found to be attributable to the time factor involved with the turn-taking systems of the two modes of CMC, especially the degree of instantaneousness in their turn-taking. Findings suggest that the turn taking skills and discourse marker use in CMC is not applicable to face-to-face conversation contexts. Pedagogical implications are discussed.

• Journal of the Korean Operations Research and Management Science Society
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• v.28 no.2
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• pp.75-89
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• 2003

Media Access Control (MAC) Protocol in IEEE 802.11 Wireless LAN standard supports two types of services, synchronous and asynchronous. Synchronous real-time traffic is served by Point Coordination Function (PCF) that implements polling access method. Asynchronous nonreal-time traffic is provided by Distributed Coordination Function (DCF) based on Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA) protocol. Since real-time traffic is sensitive to delay, and nonreal-time traffic to error and throughput, proper traffic scheduling algorithm needs to be designed. But it is known that the standard IEEE 802.11 scheme is insufficient to serve real-time traffic. In this paper, real-time traffic scheduling and admission control algorithm is proposed. To satisfy the deadline violation probability of the real time traffic the downlink traffic is scheduled before the uplink by Earliest Due Date (EDD) rule. Admission of real-time connection is controlled to satisfy the minimum throughput of nonreal-time traffic which is estimated by exponential smoothing. Simulation is performed to have proper system capacity that satisfies the Quality of Service (QoS) requirement. Tradeoff between real-time and nonreal-time stations is demonstrated. The admission control and the EDD with downlink-first scheduling are illustrated to be effective for the real-time traffic in the wireless LAN.

• Journal of Information Science Theory and Practice
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• v.6 no.1
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• pp.45-64
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• 2018

The global information economy is transforming the way people connect with each other, learn new things, and contribute to the knowledge society. With the online platform, library services have also expanded beyond face to face interaction. Although studies of virtual reference services have been made in different parts of the world, a case study discussing various forms of online reference engagement in Kazakhstan has not been written. While most of the theories on connectivism emphasize the context of instruction, the researchers of this paper discussed the tenets as they relate to online engagement. Applying the theory of connectivism, this paper explores through a mixed method the use of various online platforms to enhance engagement connecting library users to information. Findings revealed that differences in patterns of interactions as to platforms, types of queries, and users reveal that students, faculty, and other members of the academic community served by the library have various preferences for communication. The case study further showed that respondents have not maximized the use of VLS but interest in using both synchronous and asynchronous services is clear. Finding connections between sources of information, creating useful information patterns, is essential in learning. Amplifying awareness on the use of VLS giving emphasis to the unique features of each service is useful in order to enable students to see how this platform facilitates learning.

• Nuclear Engineering and Technology
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• v.52 no.5
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• pp.1066-1078
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• 2020

The present paper describes an analytic solution procedure for flexural vibration of a rotationally restrained hinged-hinged Timoshenko beam at the supports during an earthquake. Focusing on maximal magnitudes of internal loads such as bending moment and shearing force under wide variations of two parameters, kL/EI and kGAL²/EI, various beams under synchronous and asynchronous support motions are simulated. The simulations under asynchronous support motions show the following facts. The variations of the maximal magnitudes of internal loads of stocky beams due to the variation of kL/EI from zero to infinity show much wider variations than those of slender beams as kGAL²/EI decreases. The maximal magnitudes of internal loads of a beam tend to be governed by their static components as kL/EI increases and kGAL²/EI decreases. When the internal loads are governed by their static components, maximal magnitudes of internal loads of the stocky tend to increase monotonically as the value of kL/EI increases. However, the simulations under synchronous support motions show the static components of the internal loads vanish and the internal loads are governed by dynamic components irrespective of the two parameters.

• The Journal of the Convergence on Culture Technology
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• v.7 no.4
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• pp.35-42
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• 2021

The college English teaching-learning model in this study is intended to effectively apply dictogloss activities to enhance competencies such as communication, self-directedness, and cooperation by upgrading the utilization of various online platform functions. Dictogloss is a language teaching and learning activity that combines four functions (listening, speaking, reading, and writing) of communication. College English classes in this study focus on communication-oriented integrated English education. In this study, the teaching and learning is an online-based English integrated teaching-learning method based on constructivism theory. The model presented the roles of learners and teachers according to the seven procedures.

• Journal of Electrical Engineering and Technology
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• v.12 no.3
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• pp.1090-1100
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• 2017

This paper presents the comparison of starting current characteristics of a three-phase induction motor fed by two types of soft starters. The first soft starter under investigation is a conventional AC voltage controller on the basis of a phase-control technique. The other is the proposed asynchronous PWM AC chopper which is developed from the conventional synchronous PWM AC chopper. In this paper, the proposed asynchronous PWM AC chopper control scheme is developed by generating only two asynchronous PWM signals for a three-phase main power circuit (6 switching devices) from a single voltage control signal which is compared with a single sawtooth carrier signal. By this approach, the PWM signals are independent and easy to implement since the PWM signals do not need to be synchronized with a three-phase voltage source. Details of both soft starters are discussed. The experimental and simulation results of the starting currents are shown. It is found that the asynchronous PWM AC chopper efficiently works as a suitable soft starter for the three-phase induction motor due to that the starting currents are reduced and are sinusoidal with less harmonic contents, when being compared with the starting current waveforms using the conventional phase-control starting technique. Also the proposed soft starter offers low starting electromagnetic torque pulsation.