• Journal of international Conference on Electrical Machines and Systems
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• v.2 no.4
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• pp.405-412
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• 2013

This paper includes new protection concepts and practices to avoid mechanical damage of three-phase transformer by asynchronous operation of synchronous generator. this failure is often caused just after synchronous generator was connected to the grid because of a malfunction of the controller or misconnections of the synchronous devices. The results of the studies on the analyzing the phenomenon of asynchronous operation experienced in Korea and rapidly detecting asynchronous state are descrived.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.40 no.5
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• pp.321-334
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• 2003

Globally-Asynchronous Locally-Synchronous (GALS) systems are worthy of notice as an adequate architecture for a large scaled chip design with guaranteeing easy designs and functional confidence. In this paper, we suggest an advanced structure of the interface unit which is indispensable for GALS systems by using stoppable clocks. The proposed interface unit is composed of a sender module and a receiver module. The sender module can carry out data transmission partially without the relation to an internal clock. We have designed it with 0.25${\mu}{\textrm}{m}$ standard cell library at the gate level and simulated its operation to show performance improvement. Finally, we constructed all example circuit with the interface unit and proved the correct operation of it.

• Proceedings of the Korean Information Science Society Conference
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• 2004.04a
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• pp.931-933
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• 2004

In a SoC environment, asynchronous design techniques offer solutions for problems of synchronous design techniques. Asynchronous FIFOs have the advantages of easier interconnection methods and higher throughput than synchronous ones. Low latency and high throughput are two imp ortant standards in asynchronous FIFOs. We present low latency asynchronous FIFO in the paper, which optimizes GasP[6]. Pre-layout of HSPICE simulations of a 8-stage FIFO on 1-bit datapath using Anam's 0.25$\mu\textrm{m}$ technology indicates 17% lower latency than GasP.

• Journal of Korea Society of Industrial Information Systems
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• v.19 no.1
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• pp.61-67
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• 2014

Conventional synchronous circuits in low power required systems such as sensor systems cannot only satisfy the timing requirement of the low voltage digital systems, but also they may generate wrong outputs under the influence of PVT variations and aging effects. Therefore, in the reliable ultra-low power design, asynchronous circuits have recently been reconsidered as a solution for scaling issues. However, it is not easy to totally replace synchronous circuits with asynchronous circuits in the digital systems, so the interfacing between the synchronous and asynchronous circuits is indispensable for the digital systems. This paper presents a new design for interfacing between asynchronous circuits and synchronous circuits, and the interface circuits are applied to a $4{\times}4$ multiplier logic designed using 0.11um technology.

• Journal of The Korean Society of Integrative Medicine
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• v.9 no.2
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• pp.53-61
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• 2021

Purpose : The purpose of this study is to explore the effectiveness of online blended learning(asynchronous online learning class 1+synchronous online learning class 2) method and discuss the applicability of online blended learning. In this study, we will analyze the differences in class satisfaction and academic achievement between asynchronous online learning and online blended learning classes, and discuss the strengths, weaknesses, and satisfactions of online blended learning. Methods : The subjects of this study were 39 of the occupational therapy students who took the 'child development' course. Asynchronous online learning class was applied for 1-6 weeks and online blended learning was applied for 9~14 weeks. The online blended learning class consisted of 1 hours synchronous online learning and 2 hours asynchronous online learning. For the asynchronous online learning, the screen recording program of OBS Studio was used, and for the synchronous online learning, the Zoom program was used. The results of course evaluation and academic achievement of students according to the type of lecture were compared, and a survey was conducted on the satisfaction of online blended learning. Results : The results of this study are as follows. First, satisfaction(A class: t=-4.19, p=.001, B class: t=-7.94, p=.00) with online blended learning classes was significantly higher than asynchronous online learning. Second, when applying online blended learning class, academic achievement(t=-10.58, p=.00) was significantly higher. Third, the online blended learning class showed the highest satisfaction in improving the interest in the subject, and it was found to be helpful in online class management, professor-student interaction, and class content understanding. Conclusion : We have found that online blended learning can compensate for the shortcomings of online lectures and increase the quality of the lectures and the satisfaction of students. The application of online blended learning should be supplemented according to the characteristics of each class, and I hope that blended online teaching methods can be developed based on new ideas in the future.

• Proceedings of the IEEK Conference
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• 1999.11a
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• pp.771-774
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• 1999

This paper presents a new timing structure for real time communications and its performance analysis. The cycle time consists of several "one time slot" which may be an interval defined by a synchronous traffic part followed by an asynchronous traffic part. If a station receives a token within a synchronous interval, it transmits its synchronous message if any, otherwise it may transmit an asynchronous message. This scheme is different from usual allocation schemes which divide one cycle into alternating synchronous and asynchronous subslots. This protocol is designed to prevent low priority messages from delaying too much due to lots of high priority messages. We propose the algorithm and show its justification by simulation.

• International Journal of Fluid Machinery and Systems
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• v.10 no.2
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• pp.164-175
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• 2017

Francis turbines are often operated over a wide load range due to high flexibility in electricity demand and penetration of other renewable energies. This has raised significant concerns about the existing designing criteria. Hydraulic turbines are not designed to withstand large dynamic pressure loadings on the stationary and rotating parts during such conditions. Previous investigations on transient operating conditions of turbine were mainly focused on the pressure fluctuations due to the rotor-stator interaction. This study characterizes the synchronous and asynchronous pressure and velocity fluctuations due to rotor-stator interaction and rotating vortex rope during load variation, i.e. best efficiency point to part load and vice versa. The measurements were performed on the Francis-99 test case. The repeatability of the measurements was estimated by providing similar movement to guide vanes twenty times for both load rejection and load acceptance operations. Synchronized two dimensional particle image velocimetry and pressure measurements were performed to investigate the dominant frequencies of fluctuations, vortex rope formation, and modes (rotating and plunging) of the rotating vortex rope. The time of appearance and disappearance of rotating and plunging modes of vortex rope was investigated simultaneously in the pressure and velocity data. The asynchronous mode was observed to dominate over the synchronous mode in both velocity and pressure measurements.

• Journal of Digital Convergence
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• v.15 no.4
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• pp.27-34
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• 2017

As information technology has been developed in a rapid way, a lot of users get to be familiar with social media. Accordingly, the possibility of social media for educational use has increased. From the view point of learning, social media help learners make communities of practice that can lead to collective intelligence. In this study, two different types of social media, synchronous and asynchronous, were compared in terms of usage patterns in the e-learning settings of college level. Content analysis has figured out four factors: learning content, tasks and assignments, emotional communications, and chatting. There found to be a statistical differences in the postings in all of the factors except tasks and assignments. In the qualitative interviews, the participants told various usage patterns of synchronous and asynchronous social media. In sum, the learners generally preferred synchronous social media. Rather, asynchronous social media were mainly used for deep thinking and summarizing. Last, suggestions were made to improve educational environments for the learners in the digital and social media age.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.24 no.7A
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• pp.996-1004
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• 1999

In this paper, we evaluate the performance of reverse link synchronous CDMA with orthogonal spreading and Rake combining, and compare this to that of an asynchronous transmission under Rayleigh multipath fading environments. The link performance is evaluated in terms of average bit error rate (BER) and capacity, assuming ideal BPSK data modulation. The focus of this paper is on the impact that the multipath intensity profile (MIP) shape and number of taps in Rake receiver have on the performance of synchronous transmission. The results show the reverse link synchronous transmission can always achieve smaller BER than the asynchronous transmission even if inter-path interference exists.

• Journal of Korea Society of Digital Industry and Information Management
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• v.5 no.2
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• pp.39-49
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• 2009

In this paper, we classify web-based social network into two types: open and community, and model user behavior in social activities. After that, we also propose the combination of instant messaging and web system as the method of support asynchronous/synchronous social activities. Furthermore, we introduce ImCoWeb prototype system that supports both asynchronous social activities (ex. social bookmark, comment, rate, and data share) and synchronous ones (ex. real-time communication, file transfer, co-browsing, and co-work). Because it is built on the existing instant messaging, it reduces costs by reusing the facilities such as session management, user management, and security of instant messaging.