• Journal of information and communication convergence engineering
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• v.5 no.4
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• pp.382-388
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• 2007

Indoor location system using wireless sensor network technology was applied for the status evaluation and activity monitoring of elderly person or chronic invalid at home. Location awareness application is transparent to the daily activities, while providing the embedded computing infrastructure with an awareness of what is happening in this space. To locate an object, the active ceiling-mounted reference beacons were placed throughout the building. Reference beacons periodically publish location information on RF and ultrasonic signals to allow application running on mobile or static nodes to study and determine their physical location. Once object-carried passive listener receives the information, it subsequently determines it's location from reference beacons. By using only the sensor nodes without any external network infrastructure the cost of the system was reduced while the accuracy in our experiments. was fairly good and fine grained between 7 and 15 cm for location awareness in indoor environments. Passive architecture used here provides the security of the user privacy while at the server the privacy was secured by providing the authentication using Geopriv approach. This information from sensor nodes is further forwarded to base station where further computation is performed to determine the current position of object and several applications are enabled for context awareness.

• Journal of Digital Contents Society
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• v.14 no.3
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• pp.313-321
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• 2013

In recent, proliferation of mobile smart devices have led to big-data era, the importance of location-based services is increasing due to the exponential growth of trajectory related data. In order to process trajectory data, parallel processing platforms such as cloud computing and MapReduce are necessary. Currently, the researches based on MapReduce are on progress, but due to the MapReduce's properties in using batch processing and simple key-value structure, applying MapReduce framework for real time LBS is difficult. Therefore, in this research we propose a suitable system design on efficient indexing and search techniques for real time service based on detailed analysis on the properties of MapReduce.

• Journal of Computing Science and Engineering
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• v.12 no.1
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• pp.12-23
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• 2018

The Internet of Things (IoT) ecosystem potentially includes heterogeneous devices with different processing mechanisms as well as very complicated network and communication models. Thus, analysis of data associated with adverse conditions is much more complicated. Moreover, mobile things in the IoT lead to dynamic alteration of environments and developments of a dynamic and ultra-large-scale (ULS) environment. Also, IoT and the services provided by that are mostly based on devices with limited resources or things that may not be capable of hosting conventional controls. Finally, the dynamic and heterogeneous and ULS environment of the IoT will lead to the emergence of new security requirements. The conventional preventive and diagnostic security controls cannot sufficiently protect it against increasing complication of threats. The counteractions provided by these methods are mostly dependent on insufficient static data that cannot sufficiently protect systems against sophisticated and dynamically evolved attacks. Accordingly, this paper investigates the current security approaches employed in the IoT architectures. Moreover, we define the dynamic security based on dynamic event analysis, dynamic engineering of new security requirements, context awareness and adaptability, clarify the need for employment of new security mechanism, and delineate further works that need to be conducted to achieve a secure IoT.

• Journal of Internet Computing and Services
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• v.8 no.6
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• pp.127-133
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• 2007

The u-learning environment has been developed through a number of iterations, and has now been formally evaluated, through analysis of student learning results and the use of quantitative and qualitative measures, Generally, for advance learning effect and analysis of student learning results, the most learning system be use to the item analysis method. But, nowadays, it has using the IRT(Item Response Theory) instead of the item analysis method, The IRT adopts explicit models for the probability of each possible response to a test. Therefore, I proposed the lightweight component based u-learning system using the IRT. Applied device of u-learning is PDA which is in Windows mobile 5.0 environments.

• The KIPS Transactions:PartC
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• v.16C no.1
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• pp.109-116
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• 2009

Recently, there are many researches to realize context-awareness service that recognizes surrounding environments as context and provide the citizens with pervasive convenience based on ubiquitous computing technology. In the u-City, various sensors collect information as context, and citizens will receive various context-awareness service, making use of their wireless and mobile devices and the infrastructures of the u-City. We designed ontology that is useful to structure information of sensor or device that is linked to networks and use OWL (Web Ontology Language) that can express information of mutual relation and partial situation. And we propose a context-aware reasoning system for personalized u-City services based on collected context information and user's intention.

• Journal of KIISE:Databases
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• v.29 no.5
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• pp.404-415
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• 2002

In this paper, we address the issue of ensuring consistency of multiple data items requested in a certain order by read-only transactions in a wireless data broadcast environment. To handle the inherent property in a data broadcast environment that data can only be accessed strictly sequential by users, we explore a predeclaration-based query optimization and devise two practical transaction processing methods in the context of local caching. We also evaluate the performance of the proposed methods by an analytical study Evaluation results show that the predeclaration technique we introduce reduces response time significantly and adapts to dynamic changes in workload.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2019.05a
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• pp.243-246
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• 2019

In cognitive radio networks, secondary transmitters should cease its transmission immediately under the detection of primary transmission in the spectrum they are using. Then they need to exploit another idle spectrums and resynchronize to the newly found idle spectrums. Most of related work presume the existence of separate control channel used by secondary users commonly for exchanging the information of idle spectrums. However, this presumption is not feasible in real world cognitive radio scenario. Therefore we address a proactive spectrum synchronization scheme with no need of separate control channel. Our scheme lets secondary users exchange the spectrum information periodically during normal communication process and determine the next spectrum band in advance of detecting primary transmission. We evaluate our scheme in a real world cognitive radio environments set up with USRPs.

• Journal of KIISE:Computing Practices and Letters
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• v.15 no.11
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• pp.861-865
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• 2009

As the hospital environment has been increasingly changed into a ubiquitous environment, the application services for the hospital environment are also faced with new requirements. In particular, the emergence of various mobile devices and the introduction of a wireless sensor network technology have accelerated the realization of the u-healthcare. The multi-agent paradigm has been introduced for satisfying both the integration of information and the various application scenarios established from various environments. This paper describes the software structure and u-applications for u-hospital information system based on ubiquitous environments. And it suggested the construction of a multi agent based distributed framework for supporting u-hospital information system. The suggested framework includes the JADE and distributed object group framework. And it implemented u-application services for supporting doctors and nurses, which provides the patient's health information and ward environment information. Especially, it is using a dynamic security mechanism on the security situation, which has not been emphasized in existing researches, and this paper shows the results for each user through the GUI.

• Journal of Internet Computing and Services
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• v.9 no.1
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• pp.159-170
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• 2008

The ubiquitous network revolution is beginning with the onset of digital convergence, whereby computers, horne appliances, and communications and broadcast media are being unified into digital media with the founding of the information super high speed. This technical advancement is creating a new culture and a new space and accelerating society's transition to the new and unique social paradigm of a 'ubiquitous society'. In particular, studies on ubiquitous communications are well underway. Lately, the focus has been on the Bluetooth technology due to its applicability in various environments. Applying Bluetooth connectivity to new environments such as ubiquitous or sensor networks requires finding new ways of using it. Thus, the scalable Bluetooth piconet scheme with independent slave device is proposed. It follows from work by Sea et al. But extended scatternet is not considered is Kiisc05 paper. Therefore, we propose secure bridge connection scheme for scalable Bluetooth scatternet.

• Journal of the Korea Convergence Society
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• v.10 no.3
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• pp.395-400
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• 2019

The Web environment of the frontend domain is increasingly competitive to preempt the new standard of presentation layer. N-Screen, a service that enables users to seamlessly use one content in various devices in Korea, is competing for market preemption by recognizing it as a core service of the future. In the cloud computing, N-screen is a typical service type. However, most of the frontend research required for groupware in enterprise environments has been limited to responsive web design for the web and native apps for mobile. Gradually, the need for MVC design patterns is increasingly widening in enterprise environments to overcome the cultural differences of companies and to support one source multi-use strategy supporting multiple devices and development productivity. Therefore, in this study, we will analyze and design JPetStore with hybrid application design based on Spring MVC, e-government standard framework environment of next generation web standard, and provide reference model of frontend hybrid apps design in future enterprise environment.