• Journal of Communications and Networks
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• v.17 no.4
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• pp.428-439
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• 2015

In this study, we present an approach for reducing the information inaccuracy of existing star aggregation based on bypass links when there are multi-constraint QoS parameters in asymmetric networks. In our approach, bypass links with low similarity are selected. Links that are not chosen as bypass links are included in each group depending on the star's link characteristics. Moreover, each link group is aggregated differently according to the similarity of the links that make up the group. The selection of a bypass link by using link similarity reduces the existing time complexity of O($N^3$) to O(N) by virtue of the simplification of the selection process. In addition, the adaptive integration according to the characteristics of the links in each group is designed to reduce the information inaccuracy caused by static aggregation. Simulation results show that the proposed method maintains low information distortion; specifically, it is 3.8 times lower than that of the existing method, even when the number of nodes in a network increases.

• The Journal of the Korea Contents Association
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• v.6 no.5
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• pp.1-8
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• 2006

In ubiquitous environments, recommendation service based on multiple contexts is required. The total amount of information is larger due to the greater number of contexts in multiple context environments. This paper proposes a new effective recommendation method adaptive to multiple contexts in ubiquitous environments. A new method of recommendations in multiple context environments is suggested that uses user's preferences and behavior as a weighting factor. This paper describes the recommendation method, scenario and the experimental results. The results verify that the proposed method's recommendation performance is better than other existing method.

• ETRI Journal
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• v.26 no.5
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• pp.391-396
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• 2004

In this paper, we propose a packet scheduling discipline called packet loss fair scheduling, in which the packet loss of each user from different real-time traffic is fairly distributed according to the quality of service requirements. We consider an orthogonal frequency division multiple access (OFDMA) system. The basic frame structure of the system is for the downlink in a cellular packet network, where the time axis is divided into a finite number of slots within a frame, and the frequency axis is segmented into subchannels that consist of multiple subcarriers. In addition, to compensate for fast and slow channel variation, we employ a link adaptation technique such as adaptive modulation and coding. From the simulation results, our proposed packet scheduling scheme can support QoS differentiations while guaranteeing short-term fairness as well as long-term fairness for various real-time traffic.

• JSTS:Journal of Semiconductor Technology and Science
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• v.11 no.1
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• pp.33-39
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• 2011

H.264 decoders usually have pipeline architecture by a macroblock or a 4 ${\times}$ 4 sub-block. The period of the pipeline is usually fixed to guarantee the operation in the worst case which results in many idle cycles and higher data bandwidth. Adaptive pipeline architecture for H.264 decoders has been proposed for efficient decoding and lower the requirement of the bandwidth for the memory bus. However, it requires a controller for the adaptive priority control to utilize the advantage. We propose a smart bus arbiter that replaces the controller. It is introduced to adjust the priority adaptively the QoS (Quality of Service) control of the decoding process. The smart arbiter can be integrated the arbiter of bus systems and it works when certain conditions are met so that it does not affect the original functions of the arbiter. An H.264 decoder using the proposed architecture is designed and implemented to verify the operation using an FPGA.

• Journal of Communications and Networks
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• v.8 no.3
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• pp.297-305
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• 2006

High-rate wireless personal area network (HR-WPAN) has been standardized by the IEEE 802.15.3 task group (TG). To support multimedia services, the IEEE 802.15.3 TG adopts a time-slotted medium access control (MAC) protocol controlled by a central device. In the time division multiple access (TDMA)-based wireless packet networks, the packet scheduling algorithm plays a key role in quality of service (QoS) provisioning for multimedia services. In this paper, we propose an adaptive cross-layer packet scheduling method for the TDMA-based HR-WPAN. Physical channel conditions, MAC protocol, link layer status, random traffic arrival, and QoS requirement are taken into consideration by the proposed packet scheduling method. Performance evaluations are carried out through extensive simulations and significant performance enhancements are observed. Furthermore, the performance of the proposed scheme remains stable regardless of the variable system parameters such as the number of devices (DEVs) and delay bound.

• Annual Conference of KIPS
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• 2008.11a
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• pp.1142-1145
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• 2008

This paper proposes a novel cluster-based lookup service in mobile ad hoc networks. By applying a self-adaptive multi-hop clustering, we avoid the empty region problem of grid system and omit the need of GPS device. The novelty of the proposed scheme is in its exploitation of hashing function for location querying to achieve low communication overhead. By varying different simulation parameters, we show that the proposed scheme is scalable and adaptive to many networks scenarios. Experiment results demonstrate that our scheme reduces the communication overhead significantly.

• International Journal of Computer Science & Network Security
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• v.24 no.3
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• pp.71-82
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• 2024

This paper proposes a new communication system for e-learning applications to mitigate the negative impacts of COVID-19 where the online massive demands impact the current commu-nications systems infrastructures and capabilities. The proposed system utilizes high-altitude platforms (HAPs) for fast and efficient connectivity provision to bridge the communication in-frastructure gap in the current pandemic. The system model is investigated, and its performance is analyzed using adaptive antenna arrays to achieve high quality and high transmission data rates at the student premises. In addition, the single beam and multibeam HAP radio coverage scenarios are examined using tapered uniform concentric circular arrays to achieve feasible communication link requirements.

• Journal of Agricultural Extension & Community Development
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• v.30 no.4
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• pp.213-227
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• 2023

This paper aims to examine the farmers' perceptions of the importance and feasibility of climate change awareness and adaptive measures in agriculture, utilizing paired sample t-tests and Importance-Performance Analysis (IPA). Significant differences were found in farmers' views on the importance and urgency of climate change issues, with specific factors standing out. The IPA analysis identified key issues requiring sustained attention, including climate change magnitude, extreme weather events, livestock damage scale, pest fluctuations, and variability in flowering periods. Additionally, the study revealed significant disparities in farmers' perceptions of the importance and feasibility of adaptive measures, except for specific items related to heat indices.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.1B
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• pp.9-18
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• 2006

Advances in wireless network are enabling the development of ubiquitous multimedia services. These multimedia services need efficient platforms to comply with the requirements of mobile computing. We introduce an adaptive service platform based on mobile agent and grid systems while specifying the challenges of ubiquitous multimedia services and focusing on frequent disconnections and scarce resources. We applied our platform to framework RtoA (Ready-to-Attend) which supports mobile users to access compute-intensive multimedia service, specifically, mobile education and video conferencing. RtoA includes hand-off, speaker and listener service which enable people to attend a conference or a class with satisfying quality of multimedia service. ns-2 based simulation verifies that our scheme is an efficient way to reduce energy consumption of mobile devices and to improve the response time of mobile applications.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.16 no.3
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• pp.929-946
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• 2022

Free viewpoint video (FVV) service is an immersive media service that allows a user to watch it from a desired location or viewpoint. It is composed of various forms according to the direction of the viewpoint of the provided video, and includes zoom in/out in the service. As consumers' demand for active watching is increasing, the importance of FVV services is expected to grow gradually. However, additional considerations are needed to seamlessly stream FVV service. FVV includes a plurality of videos, video changes may occur frequently due to movement of the viewpoint. Frequent occurrence of video switching or re-request another video can cause service delay and it also can lower user's quality of service (QoS). In this case, we assumed that if a video showing an object that the user wants to watch is selected and provided, it is highly likely to meet the needs of the viewer. In particular, it is important to provide an object-oriented FVV service when zooming in. When video zooming in in the usual way, it cannot be guaranteed to zoom in around the object. Zoom function does not consider about video viewing. It only considers the viewing screen size and it crop the video view as fixed screen location. To solve this problem, we propose a zoom in/out method of object-centered dynamic adaptive streaming of FVV in this paper. Through the method proposed in this paper, users can enjoy the optimal video service because they are provided with the desired object-based video.