• Proceedings of the Korea Society of Information Technology Applications Conference
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• 2005.11a
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• pp.225-228
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• 2005

A context-aware services platform supporting mobile agents consists of sensor nodes and a sensor coordinator. Sensor nodes collect environmental information and transmit the collected information to the sensor coordinator through wireless sensor networks. The sensor coordinator passes the information to the context-aware service module, and the mobile agent. The context-aware service module or the mobile agent performs services suitable for a user's situation based on the environmental information and a service actuation message is delivered to an actuation node through the sensor coordinator. In this paper, we present a context-aware services platform structure employed in our project, and describe context-aware services platform interfaces with a context-aware service module and mobile agents.

• Journal of the Korea Society of Computer and Information
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• v.4 no.2
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• pp.70-79
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• 1999

In mobile database system, transactions processing schemes address in ones using a static coordinator and coordinator migration. This apply coordinator migration mechanism which perform the transaction in new database server when posed to be the transaction service handoff. That apply static coordinator mechanism which perform the transaction in database server to begin the transaction when posed to be the transaction service handoff. In this paper, a scheme-independent simulation model has been developed in order to support comparative performance studies of mobile transaction processing schemes. And this paper describes the model in detail and presents simulation results which were obtained for what it believe to be the performance evaluation of the mobile transaction processing schemes. Finally, the mobile transaction processing schemes will improve system performance by minimizing the transmission of message for processing the transactions in mobile database system.

• The KIPS Transactions:PartA
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• v.11A no.4
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• pp.285-296
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• 2004

The rapid progress of IT technologies promoted the foundation to offer users 'Any Time, Any Where, Any Service', and wireless internet services made it possible to use wired internet services while traveling. The previous academic administration management system having migrated from wired to wireless was dependent on mobile equipments' platform because of not being constructed on standard surroundings. And in the aspect of faculty system, course coordinator plays an significant role in building curricula and manage them, and finally counseling students with regard to them. But the course coordinator can't afford to advise students on which fields of their faculty fit them and which courses they have to take. We propose a mobile course coordinator system to help students learn profound courses of their major fields. Also the proposed system is implemented by using JAVA and WIPI technology, so that it is platform-independent. A mobile course coordinator system has an inference engine considering not only course trees which tell informations about the courses in every fields, but also personal courses that students have taken. The inference engine calculates three weights, representing the significance of each course considering every fields, the score of prerequisite courses which a student have taken, and the suitability in which department each student fits. When students apply for taking lectures, a mobile course coordinator system recommends them the most suitable courses. A mobile course coordinator system is able to substitute for the course coordinator who is counseling students. And the students with personal cellular phone are able to keep tracking their courses, and improve their knowledge about major with taking courses which the system's inference engine will advice.

• International Journal of Advanced Culture Technology
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• v.5 no.2
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• pp.90-97
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• 2017

The Internet of Things(IoT) market is expected to grow from 15.5billion to 75.4 billion by 2015-2025. As the number of IoT devices increases, the amount of data that is sent to the cloud is increasing. Today's Cloud Computing models are not suited to handle the vast amount of data generated by IoT devices. In this paper, we propose a Cooperation Coordinator System that reduces server load and improved real-time processing capability under specific circumstances by using Band-Cloud. The cooperation coordinator system dynamically forms the cloud when cooperation is needed between mobile devices located near. It is called Band-Cloud. Band-Cloud provides services entrusted by Central Cloud. This paper describes the proposed system and shows the cooperation process using the Android-based mobile devices and Wi-Fi Direct technology. Such a system can be applied to cases where real-time processing is required in a narrow area such as a hospital ward or a school classroom.

• The Journal of Korean Association of Computer Education
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• v.8 no.5
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• pp.51-62
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• 2005

In the aspect of the faculty, a course coordinator plays an significant role in managing the curriculum and counseling students on academic matters and fostering their progress in the course. However, the course coordinator cannot afford to advise students on which fields of their faculty fit them and which courses they have to take. This paper proposes a mobile course coordinator system to help students learn courses of their major fields deeply. Also the proposed system is implemented by using WIPI technology, so that it is platform-independent and it is able to assist the course coordinator who is counseling students. And the students with personal cellular phones are able to keep tracking their courses, and improve their knowledge about major subjects by taking courses which the system's inference engine will advise.

• Journal of Internet Computing and Services
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• v.4 no.4
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• pp.15-25
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• 2003

Wireless ad-hoc networks are only composed with mobile devices. Unlike the traditional wired networks, those devices are mostly operated with battery power. Since the battery-operated power is limited, the efficient energy resource managements becomes an important issue in wireless ad-hoc networks and various studies that considered these characteristics are progressed. One of those studies is an energy efficient routing using coordinators. In this method. only devices elected as coordinator participate in data transmissions in ad-hoc networks, while other devices remain in sleep node. The overall energy consumption of a system can be reduced. In order to minimize energy consumption of a total network, previous results try to maximize the number of nodes in sleep mode. However, minimizing the number of coordinators does not ensure to increase the system lifetime. In this thesis, we propose an algorithm that can elect coordinators with considering the amount of necessary energy to transmit assigned data and a connectivity of nodes in the networks. The result of proposed coordinator election algorithm can increase the system lifetime of an Ad-hoc network from the results of existing coordinator election algorithms.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.11
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• pp.4543-4552
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• 2010

A leader is a special process who roles as the coordinator within multiple processes of a group. In a distributed system, leader election is the procedure of electing a coordinator. This is a very important issue for building fault-tolerant distributed systems. When two normal mobile ad hoc networks are merged, there are two leaders. This violates the safety property, so a mechanism to detect and handle are required. In mobile ad hoc distributed computing system, we propose a leader competition protocol and to prove the temporal logic to it. This solution is based on the group membership detection algorithm.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.14 no.2
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• pp.321-328
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• 2010

This paper presents a coordinator-based TDMA reader protocol that can avoid the reader collision in a passive RFID system. In the proposed protocol, the coordinator can not only minimize the number of empty slots by efficiently allocating slots to readers incoming in Poisson distribution, but reduce latency time through the limited frame size. The proposed protocol can be implemented in either mobile or fixed mode through the slot structure to be described in the context. The simulation results show it works as suggested and the frame size limitation as well as the statistical distribution of incoming readers has a great impact on the overall slots and the average latency time.

• Journal of KIISE:Information Networking
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• v.28 no.3
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• pp.289-296
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• 2001

The Election protocol can be used as a building block in many practical problems such as group communication, atomic commit and replicated data management where a protocol coordinator might be useful. The problem has been widely studied in the research community since one reason for this wide interest is that many distributed protocols need an election protocol. However, despite its usefulness, to our knowledge there is no work that has been devoted to this problem in a mobile computing environment. Mobile systems are more prone to failures than conventional distributed system. Solving election in such an environment requires from a set of mobile hosts to choose a mobile host or a fixed host based on the their priority despite failures of both mobile computing and/or fixed hosts. In this paper, we describe a solution to the election problem from mobile computing systems. This solution is based on the Garcia Molina\\`s Bully algorithm.

• The Journal of the Korea Contents Association
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• v.8 no.12
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• pp.53-62
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• 2008

The Election paradigm can be used as a building block in many practical problems such as group communication, atomic commit and replicated data management where a protocol coordinator might be useful. The problem has been widely studied in the research community since one reason for this wide interest is that many distributed protocols need an election protocol. However, despite its usefulness, to our knowledge there is no work that has been devoted to this problem in a mobile ad hoc computing environment. Mobile ad hoc systems are more prone to failures than conventional distributed systems. Solving election in such an environment requires from a set of mobile nodes to choose a unique node as a leader based on its priority despite failures or disconnections of mobile nodes. In this paper, we describe a solution to the election problem from mobile ad hoc computing systems. This solution is based on the Group Membership Detection algorithm.