• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.3
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• pp.1380-1386
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• 2011

The request of interrupt accompanies a context switching. If the interrupt is frequently requested, this overhead of context switching can reduce seriously the performance of embedded systems. In order to reduce processing overhead due to frequently requested communication interrupts at Asynchronous Serial Communication, this paper introduces the method of Expanded Asynchronous Serial Communication with the Interrupt Coalescence(IC) that accumulates a fixed number of interrupts and processes them in one time. we implement the existing Asynchronous Serial Communication that requests communication interrupts by one byte at an LN2440SBC embedded board with a uC/OS-II and compare interrupt processing time for the performance evaluation about proposed method. As a result, the communication interrupt processing time of proposed method appears in case of low speed(9,600 bps), the decline of an average 25.18% at transmission, the decline of an average 41.47% at reception. and in case of hight speed(115,200 bps), the decline of an average 16.67% at transmission, the decline of an average 25.61% at reception.

• The KIPS Transactions:PartD
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• v.15D no.1
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• pp.41-46
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• 2008

In ubiquitous computer environment, by improving the computer's access to context information for dynamic service adaptation, we can increase richness of communication in human computer interaction and make it possible to produce more useful computational services. We need new data structure in order to flexible apply dynamic information to current context information repository and enhance the communication ability between human and computer. In this paper, we proposed to C-A-V (Category-Attribute-Value) context metadata structure required to support dynamic service adaptation for increasing communication ability in user-centric environments. We also classify the context metadata, as well as define its relationship with other context information on the basis of the application services, changes in the external environments.

• Journal of Information Technology Applications and Management
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• v.13 no.3
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• pp.129-143
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• 2006

Diversity of available communication media has increased as the use of Internet and mobile technology increased rapidly. The traditional media tend to transform their roles and functionality. This change brings about the expansion of the span of media to be selected by users. In this study, we examined the characteristics of emerging communication media use based on Niche Theory. Online communication media in this study include Internet messenger, mobile phone, and e-mail. We also analyzed the relationship between the nature of task and the selection of communication media, that is, the effects of communication contexts(formal vs. informal, notification vs. request, superior vs. inferior) where by the communication partners are involved. The result of this study, mobile phone had the highest niche competitive superiority in all communication contexts, and internet messenger and e-mail made difference according to communication contexts. Also, we can notify internet messenger and e-mail have a mutual substitutive relationship by analysis of niche overlap.

• Proceedings of the IEEK Conference
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• 2007.07a
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• pp.153-154
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• 2007

In this paper, we propose context information communication system using RF module to prevent railway cross accident. Since the communication module transmits to the train with high bit rate, OFDM(Orthogonal frequency division multiplexing) modulation method that distributes high speed data and transmits multiple times is applied. And image information is transmitted to the train's transceiver device by using ISM band (2.4GHz frequency band) that is proper to mobile communication. By using this system, we can deal with urgent situations at the railway cross and prevent railway cross accidents in advance.

• The Journal of the Korea institute of electronic communication sciences
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• v.8 no.3
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• pp.397-402
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• 2013

Time variation is the essential component of the context awareness. It is a beneficial way not only including time lapse but also clustering time interval for the context inference using the information from sensor mote. In this study, we proposed a novel way of clustering based multi-sensor data fusion for the context inference. In the time interval, we fused the sensed signal of each time slot, and fused again with the results of th first fusion. We could reach the enhanced context inference with assessing the segmented signal according to the time interval at the Dempster-Shafer evidence theory based multi-sensor data fusion.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.8 no.5
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• pp.211-219
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• 2008

This paper is proposed context-aware based access control, model by extending original access control model. In this paper, we survey the recent researches about security model based context-aware such as xoRBAC and CAAC. For exactly policy evaluation, we make an addition Context Broker and Finder in existing CAAC security model. By this security model, Context information and context decision information is able to be collected easily for more correct policy decision. This paper controlled access of possible every resources that is able to access by user's event and constraint from primitive access resources. In this paper proposed security model can be offer dynamically various security level and access authority method alone with specified policy and constraint adjustment at user's role.

• Journal of Electrical Engineering and Technology
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• v.7 no.1
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• pp.115-123
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• 2012

A video analysis system used to detect events in video streams generally has several processes, including object detection, object trajectories analysis, and recognition of the trajectories by comparison with an a priori trained model. However, these processes do not work well in a complex environment that has many occlusions, mirror effects, and/or shadow effects. We propose a new approach to a context-aware video surveillance system to detect predefined contexts in video streams. The proposed system consists of two modules: a feature extractor and a context recognizer. The feature extractor calculates the moving energy that represents the amount of moving objects in a video stream and the stationary energy that represents the amount of still objects in a video stream. We represent situations and events as motion changes and stationary energy in video streams. The context recognizer determines whether predefined contexts are included in video streams using the extracted moving and stationary energies from a feature extractor. To train each context model and recognize predefined contexts in video streams, we propose and use a new ensemble classifier based on the AdaBoost algorithm, DAdaBoost, which is one of the most famous ensemble classifier algorithms. Our proposed approach is expected to be a robust method in more complex environments that have a mirror effect and/or a shadow effect.

• The Journal of the Korea institute of electronic communication sciences
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• v.16 no.4
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• pp.675-682
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• 2021

In an environment in which a limited type and number of sensors are used, a demand for acquiring various context information may appear. In this study, a new method for acquiring various context information than before was proposed in an environment in which a limited number of sensors are required. To this end, a clue was obtained from the Exon-Intron theory, which is gaining great interest in the field of biology, and a method for acquiring various context information was proposed based on this. By applying Exon-Intron's selective cutting and combining method, events of each sensor were efficiently cut and each event data was combined and utilized, thereby realizing the diversification of the acquired context information.

• Proceedings of the KSRS Conference
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• 2005.10a
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• pp.546-549
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• 2005

It is evident that advancement of ubiquitous technologies in the near future guarantees more convenient and plentiful living. With regarding to car life, we dream of an automatic driving without any effort of operation. This paper touches the realization issue, a convergence of wireless sensor network and Telematics specializing on an information routing mechanism between participating components in Telematics sensor communication network. We list up new requirements of wireless sensor network deployed for Telematics services. Then context-aware routing architecture is proposed in order to solve these constraints, in which a network topology for routing can be dynamically configured according to the combination of context models of network components.

• International Journal of Fuzzy Logic and Intelligent Systems
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• v.14 no.4
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• pp.295-304
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• 2014

Communication infrastructure supports wide variety of mobile services such as photo and file sharing, location tracking, social network services and instant messaging. However, instances like power-loss and natural disasters disrupt these communication infrastructures unable to render support to these mobile services. Delay-tolerant networks (DTNs) offer a solution to these problems at hand. By utilizing mobility and opportunistic contacts among mobile devices, a plausible communication network can be establish and enable support to mobile applications. This paper presents an energy-efficient, reliable message delivery routing scheme with message prioritization rules for DTN. It uses the context information of nodes (mobile devices) such as the contact history (location and time of contact), speed/velocity, moving direction to determine the best forwarders among nodes in the network. The remaining energy of the nodes is also used to determine the message types a node can deliver successfully. The simulation results show that proposed approach outperforms Epidemic and Prophet routing schemes in terms of delivery ratio, overhead ratio, delivered messages per types and remaining energy.