• Journal of the Institute of Electronics Engineers of Korea TC
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• v.41 no.6 s.324
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• pp.93-99
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• 2004

According to rapid increment of demand for wireless Local Area Network (LAN), the HyperLAN of 5.1-533GHz and 5.725-5.825GHz is newly allocated for wireless LAM in many regions over the world. Also, because most of mobile communication equipments are small, the size of antenna is important factor of effective design. In this paper, the compacted and wide bandwidth antenna is designed for wireless LAN at 5GHz band. Although the structure of U-shaped slot antenna is simple, It has large bandwidth of $10-40\%$. Also, the U-slot antenna has good radiation pattern. However, in general, the size of U-slot antenna is large. Therefore, it is difficult to apply to wireless equipment such as PDA and Notebook. This proposed antenna has a wide bandwidth by U-shaped slot in rectangular patch and is compacted by using two layered dielectric substrates and foam. For the design of U-slot antenna, the Finite Difference Time Domain method is applied. Also, the method of MPI parallel program is used for the enhancement of the analyzing speed of the FDTD method.

• The Journal of the Korea Contents Association
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• v.11 no.2
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• pp.135-141
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• 2011

Mobile communication technology in the field of ubiquitous computing is one of important technologies. The development of GPS technology in mobile communications technology and PDA, the vast majority of mobile devices such as smart phones also being equipped with GPS functionality. This user where they are located where they are based on the number of through services were able to receive information. In this paper, mounted on a mobile device user's location using GPS capabilities to track the migration routes and the accumulated user to determine the migratory path of the system used to recommend the proposed route of the proposed method and system Designs. The services offered by tracking the location of the user to move the user to route data to create and upload to the server. Upload a migration path to move data from where they currently reside to the user is recommended to go to your destination. The services offered by the users do not know where to travel or go to your destination, etc. If you do not remember the path can be useful.

• Journal of Korea Spatial Information System Society
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• v.7 no.3 s.15
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• pp.45-53
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• 2005

Nowadays, using the mobile communication devices, such as a mobile phone, PDA, telematics device, and so forth, are increasing. The large parts of the services with these mobile devices are the position tracking and the route planning. For offering these services, it is increasing the use of the spatial data on the mobile environment. Although the storage of mobile device expands more than before, it still lacks the necessary storage on the spatial data. In this paper, lossy compression technique on the spatial data is suggested, and then it is analyzed the compression ratio and the amount of loss data by the test. Suggested compression technique on the spatial data at this paper is applied to the real-data, and others methods, suggested at the previous studies, is applied to same data. According as the results from both are compared and analyzed, compression technique suggested at this study shows better performance when the compression result is demanded the high position accuracy.

• Convergence Security Journal
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• v.7 no.2
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• pp.81-89
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• 2007

Mobile computing environment that support so that can offer employees inside information that enterprise has always improves business productivity and fetches efficiency enlargement. In this paper, limit model that can process ERP information by real-time as easy and convenient always utilizing radio network and PDA, Mobile camera based on Mobile vision concept. Calculable information between seller and customer is supplied supplying real-time brand image and information by practical use of Enterprise Resource Planning doing based on Mobile. Technical development and commercialization that utilize mobility, enforcement stronghold, portability etc. that is advantage of Mobile communication are required. In this paper, mobility of precious metals.jewel field that use portable terminal equipment taking advantage of a Mobile technology is secured. Constructed Mobile vision system that satisfy photography and bar-code scan at the same time from Mobile camera.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.14 no.12
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• pp.2737-2746
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• 2010

Recently, Logistics industry has emerged a new u-logistics paradigm combines USN / RFID technology. In this paper offers a vehicle history Web-based logistics management system based on the u-logistics paradigm. The design of this system is considered all events processes as a form of recycling and entire system is to modeling based UML of object oriented. Also It was undergone some process to make sure by logistics vehicles identified that RFID based was identified vehicle logistics. To identify logistics vehicle based RFID, identified the logistics vehicles is a process that will determine. The implementation method designed the interface based web which uses in the manager to C/S methods, consideration of the mobility of the system user implements the user GUI based PDA. As well as, In this paper was separated customer, manufacturer, distributor, administrator, drivers, respectively and focuses to raise a system reusability which is implementation by separately for each feature.

• The KIPS Transactions:PartA
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• v.15A no.2
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• pp.101-110
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• 2008

Ubiquitous computing has extended the computer system into the whole physical space and has ushered the emergence of more dynamic distributed systems. This environment require unique QoS parameters for various devices, resources and user requirements. In this paper, we propose a new hybrid QoS management model which defines a static-dynamic QoS parameter that is more appropriate to the ubiquitous computing environment. This model consists of the QoS Control Management Module(QoS CMM) in the client side and the Resource QoS Management Module (RQoS MM) in the server side. The RQoS MM deals with the static QoS parameters and the whole QoS control of the distributed control(QoS CMM) in order to minimize server load in cases of multiple communication. Finally, we present the experimental result of our location based application using a graphical user interface that shows the multimedia service execution of selected client device types such as desktop PC, notebook and PDA.

• Spatial Information Research
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• v.20 no.5
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• pp.57-66
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• 2012

Recent development in wireless communication technology like GPS as well as mobile equipments like PDA and cellular phone makes location-based services (LBSs) popular. However, because users request a query to LBS servers by using their exact locations while moving on the road network, users' privacy may not be protected in the LBSs. Therefore, a mechanism for users' privacy protection is required for the safe and comfortable use of LBSs by mobile users. For this, we, in this paper, propose a road network distance based cloaking scheme supporting user privacy protection in location-based services. The proposed scheme creates a cloaking area by considering road network distance, in order to support the efficient and safe LBSs on the road network. Finally, we show from our performance analysis that our cloaking scheme outperforms the existing cloaking scheme in terms of cloaking area and service time.

• Journal of the Korea Society of Computer and Information
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• v.17 no.6
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• pp.119-130
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• 2012

In this paper, we propose ubiquitous tree management system based on GIS and smart-phone using the object-oriented design modeling to maximize the efficiency of tree management. For this, proposed system is implemented in the form of client/server (C/S). The spot tree management system as the client is based on the mobile(PDA, Smart-Phone), whereas the tree management system based on PC as the server makes use of GIS. Also, Web service method instead of CDMA used in exist studies is used for tree data communication among C/S. And problems of existing studies, that is excessive maintenance costs, accessibility shortage of variety users, connectivity shortage of geographic information system will be settled through the convergence of the proposed system development methods, GIS system, smart devices. Therefore, we verify proposed system by using the systemic unit test and qualitative assessment respectively and prove to be more excellent than the existing system based on the mobile, in terms of systemic effectiveness and extendability.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.14 no.2
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• pp.507-512
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• 2010

Many learning methods are recently being proposed for web-based remote education and a method commonly applied to web-based learning is learning through questions. In the existing methods, the difficulty of questions is chosen by learners in accordance with their level or questions are selected dynamically. As these methods are simply based on difference among questions presented, however, it is hardly possible for learners to study according to their abilities. To solve the problem, we adjusted the difficulty of questions presented based on information on individuals' weak points for different types of questions. Under the system individuals can learn by applying information on their abilities with regard to the type and difficulty of questions repeatedly, so the system can provide more effective distance learning. To overcome space restrictions in learning, also, we design and implement a mobile study system on the top of PDA platforms.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.12 no.6
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• pp.1120-1127
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• 2008

This paper presents implementation of localization system using UWB (Ultra-Wide Band) sensors and its experimental results along with development of context-aware services. In order for precise measurement of position, we experimented various conditions of pitch angles, yaw angles, number of sensors, height of tags along with measuring errors at each installation. As an application examples of the location tracking system, we developed an intelligent health training management system based on context-aware technology. The system provides appropriate training schedule to a trainee by recognizing position of the trainee and current status of gymnastic equipments and note the usage of the equipment through a personal digital assistant (PDA). Error compensation on position data and moving direction of the trainee was necessary for context-aware service. Hence, we proposed an error compensation algorithm using velocity of the trainee. Experimental results showed that proposed algorithm had made error data reduce by 30% comparing with the data without applying the algorithm.