• Journal of the Korea Institute of Information and Communication Engineering
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• v.6 no.5
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• pp.703-717
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• 2002

This paper illustrates the implementation of a scalable shared buffer asynchronous transfer mode (ATM) switch. The designed shared buffer ATM switch has a shared buffet of a pipelined memory which has the access time of 4 ns. The high-speed buffer access time supports a possibility of the implementation of a shared buffer ATM switch which has a large switching capacity. The designed switch architecture provides flexible switching performance and port size scalability with the independence of queue address control from buffer memory control. The switch size and the buffer size of the designed ATM switch can be reconfigured without serious circuit redesign. The designed prototype chip has a shared buffer of 128-cell and 4 ${\times}$ 4 switch size. It is integrated in 0.6um, double-metal, and single-poly CMOS technology. It has 80MHz operating frequency and supports 640Mbps per port.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.19 no.2
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• pp.471-476
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• 2015

In this paper, we propose an energy efficient hybrid MAC protocol for multi-hop wireless sensor networks. The proposed MAC protocol used a hybrid mechanism, in which contention-based MAC protocol and contention free MAC protocol are combined. The sensor nodes located far from the sink node usually send few data packet since they try to send measured data by themselves. So contention-based MAC protocol is useful among them. But other nodes located near sink node usually have lots of data packets since they plays as a relay node. Contention-based MAC protocol among them is not suitable. Using contention-based MAC protocol in heavy data traffic environment, packet collisions and transmission delay may increase. In this paper, slot assignment between sender nodes by sink node is used. The proposed mechanism is efficient in energy and latency. Results showed that our MAC protocol outperformed other protocol in terms of data packet delivery delay and energy consumption.

• Journal of Power Electronics
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• v.17 no.6
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• pp.1658-1671
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• 2017

To address the inaccurate load demand sharing problems among parallel inverter-interfaced voltage-controlled distributed generation (DG) units in islanded microgrids (MGs) with different DG power ratings and mismatched feeder impedances, an enhanced voltage control scheme based on the active compensation of circulating voltage drops is proposed in this paper. Using the proposed strategy, reactive power and harmonic currents are shared accurately and proportionally without knowledge of the feeder impedances. Since the proposed local controller consists of two well-separated fundamental and harmonic voltage control branches, the reactive power and harmonic currents can be independently shared without having a remarkable effect on the amplitude or quality of the DGs voltage, even if nonlinear (harmonic) loads are directly connected at the output terminals of the units. In addition, accurate load sharing can also be attained when the plug-and-play performance of DGs and various loading conditions are applied to MGs. The effects of communication failures and latency on the performance of the proposed strategy are also explored. The design process of the proposed control system is presented in detail and comprehensive simulation studies on a three-phase MG are provided to validate the effectiveness of the proposed control method.

• Journal of KIISE:Databases
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• v.28 no.4
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• pp.715-722
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• 2001

Mobile computing has become a reality thank to the convergence of two technologies :powerful portable computers and the wireless networks. The restrictions of wireless network such as bandwidth and energy limitations make data broadcasting an attractive data communication method. This paper addresses the clustering of wireless broadcast data for multipoint queries. By effective clustering of broadcast data the mobile client can access the data on the air in short latency In the paper we define the data affinity and segment affinity measures. The data affinity is the degree that two data objects are accessed by queries, and the segment affinity is the degree that two sets of data (i.e segments) are accessed by queries Our method clusters data objects based on data and segment affinity measures we show that the performance of our method is scarcely infuenced by the growth of the number of queries.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2009.05a
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• pp.80-83
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• 2009

The most popular communication protocol is those defined by the IEEE 802.11 WLAN to support broadband internet connection. The demand for real-time multimedia service is increasing through WLAN on the road. The Hand-off function of mobile terminal is essential to support mobility. But, the hand-off function of IEEE 802.11 WLANs has the latency up to 300ms, and recent research has focusing on channel scanning and reconnection to AP and certification process of AP. It is also the lack of consideration in related works that hand-off happens frequently when the mobile node is moving. This paper proposed the hand-off algorithm that guarantees high throughput and estimates the point which may occur hand-off using GPS information and RSSI. We implement the proposed hand-off function that achieves the best performance.

• Journal of Convergence for Information Technology
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• v.9 no.7
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• pp.1-7
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• 2019

With the recent commercialization of the next generation of wireless 5G in everyday life, many changes have been made to organizations, industries and businesses of various sizes in various fields. However, although the improved speed and latency of 5G has improved, improvements in encryption, authentication and privacy are still required. In this paper, multiple groups of information management techniques are proposed to efficiently protect users' privacy in the heterogeneous environment of 5G. The proposed technique aims to allow distributed management of users' privacy links by clouding the privacy information generated by different heterogeneous devices to efficiently interface with different groups. Suggestion techniques process user-specific privacy information independently in a virtual space so that users can periodically synchronize their privacy information.

• International Journal of Advanced Culture Technology
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• v.7 no.3
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• pp.111-115
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• 2019

A 5G is 20 times faster than 4G. It also has hyper-connectivity, low latency merit and boundless potentials for medical education, transportation, entertainment and so on. In accordance with this, it is time to quickly look over on the utilization plan for 5G and sensible media in dance field, deal with the issue and its utilization. First of all, this study will review potential of 5G and sensible media in dance and its development plan. It seems like dance is able to communicate in a three-dimensional way. Utilizing sensible media can contribute to inform people of dance, and increase fun and interest which will make three-dimensional mutual communication. Also, in 5G environment, one can select whatever one wants in his or her viewpoint when utilizing sensible media such as VR, AR, hologram and so on. Supposing in a case of dancers and judges, it is possible for them to hire their own style of dancers in their countries. So, both the dancer and the judges have the positive merits. Third, streaming is possible without any installation, buffering is reduced. At the same time high-definition of media is allowed. This allowed collaborated performance of celebrities in dance and it also increased concentration and engagement. Dance field should acknowledge 5G sensible media, look for systemic and detailed method and disseminate and spread professional training and performance. In dance, testing fast developing sensible media due to 5G network, produce systemic dance training environment with various try is required and an effort for the performance situations in which advanced 5G sensible media is used.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.25 no.4
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• pp.581-587
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• 2021

Real-time video streaming scheme for multimedia content delivery and remote conference services is one of technologies that are significantly sensitive to data transmission delay. Recently, because of COVID-19, real-time video streaming contents for the services are significantly increased such as personal broadcasting and remote school class. In order to support the services, there is a growing emphasis on low transmission delay and secure content delivery, respectively. Therefore, our research proposed a packet aggregation algorithm to reduce the transmission delay of selectively encrypted video transmission for real-time video streaming services. Through the application of the proposed algorithm, the selectively encrypted video framework can control the amount of MPEG-2 TS packets for low latency transmission with a consideration of packet priorities. Evaluation results on testbed show that the application of the proposed algorithm to the video framework can reduce approximately 11% of the transmission delay for high and low resolution video.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.24 no.8
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• pp.985-992
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• 2020

Edge computing is a technology that can prepare for a new era of cloud computing. Edge computing is not a remote data center where data is processed and computed, but low-latency/high-speed computing is realized by adding computing power and data processing power to the edge side close to an access point such as a terminal device or a gateway. It is possible. The types of edge computing include mobile edge computing, fog computing, and cloudlet computing. In this article, we describes existing open source platforms for implementing edge computing nodes. By presenting and comparing the structure, features of open source edge platforms, it is possible to acquire knowledge required to select the best edge platform for industrial engineers who want to build an edge node using an actual open source edge computing platform.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.24 no.8
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• pp.1102-1108
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• 2020

Mobile edge computing is a technology that can prepare for a new era of cloud computing and compensate for shortcomings by processing data near the edge of the network where data is generated rather than centralized data processing. It is possible to realize a low-latency/high-speed computing service by locating computing power to the edge and analyzing data, rather than in a data center far from computing and processing data. In this article, we develop a virtual mobile edge computing testbed environment where the cloud and edge nodes divide computing tasks from mobile terminals using the EdgeCloudSim simulator. Performance of offloading techniques for distribution of computing tasks from mobile terminals between the central cloud and mobile edge computing nodes is evaluated and analyzed under the virtual mobile edge computing environment. By providing a virtual mobile edge computing environment and offloading capabilities, we intend to provide prior knowledge to industry engineers for building mobile edge computing nodes that collaborate with the cloud.