• Journal of KIISE:Databases
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• v.30 no.2
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• pp.184-196
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• 2003

Mobile transactions updating spatial objects are long transactions that can update independently local objects of mobile clients during disconnection. Validation based protocols that are well known to be appropriate for mobile transactions are required to abort a conflicted transaction in order to keep data consistent. Since abortion leads to cancel of all of tile updates, it is not desirable to use the abortion for resolving conflicts of mobile transactions. In this paper, we propose a reprocessing transaction model to resolve the update conflicts between mobile transactions without aborting them. We also design a mobile transaction server to support the reprocessing transaction and build a prototype of a mobile field system. The reprocessing transaction is a subtransaction of a newly committed mobile transaction and re-executes only conflicted objects with foreign conflicted objects. We also introduce a progressive reprocessing scheme to expose non-conflicted objects of the mobile transaction to other transactions in order to reduce starvation of reprocessing transactions.

• The Journal of Korean Association of Computer Education
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• v.6 no.4
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• pp.49-59
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• 2003

In order to index exactly moving objects(vehicle, mobile phone, PDA, etc.) in a mobile database, continuous updates of their locations arc inevitable as well as time-consuming. In this paper, we propose a spatial indexing method of moving objects for the efficient mobile map services. In detail, we analyze the characteristics of both the method to re-index all the objects after each time period and the method to update immediately the locations on reporting their locations. We also newly propose a bucket split method using the properties of moving objects in order to minimize the number of database updates. The experiments conducted on the environments of moving object show that the proposed indexing method is appropriate to map services for mobile devices.

• Journal of Internet Computing and Services
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• v.7 no.2
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• pp.81-92
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• 2006

Recently, the number of mobile phone and PDA users has been rapidly increased. Such monitoring and control applications as geographical and traffic information systems are being used widely with wireless devices. In this paper, we introduce the mobile M/VC application framework that supports the rapid constructions of mobile monitoring and control (M/VC) applications. The mobile M/VC application framework uses the mobile Observer/Observable pattern that extends the Java's Observer/Observable for automatic interactions of server and client objects in wireless environments. It also provides the Multiplexer and Demultiplexer classes that supports the assembly feature of Observer and Observable objects. To construct an application using the framework, developers just need to create necessary objects from the Observable and MobileObserver classes and inter-connect them structurally(like the plug-and-play style) through the Multiplexer and Demultiplexer objects. Then, the state change of Observable objects is notified to the connected Observer objects and user's input with Observer objects is propagated to Observable objects. These mechanism is the main process for monitoring and control applications. Therefore, the mobile M/VC application framework can improve the productivity of mobile applications and enhance the reusability of such components as Observer and Observable objects in wireless environments.

• Korean Journal of Remote Sensing
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• v.22 no.3
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• pp.221-228
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• 2006

In this study, an integrated 3D modeling and rendering system dealing with 3D urban landscape features such as terrain, building, road and user-defined geometric ones was designed and implemented using $OPENGL\;{|}\;ES$ (Embedded System) API for mobile devices of PDA. In this system, the authoring functions are composed of several parts handling urban landscape features: vertex-based geometry modeling, editing and manipulating 3D landscape objects, generating geometrically complex type features with attributes for 3D objects, and texture mapping of complex types using image library. It is a kind of feature-based system, linked with 3D geo-based spatial feature attributes. As for the rendering process, some functions are provided: optimizing of integrated multiple 3D landscape objects, and rendering of texture-mapped 3D landscape objects. By the active-synchronized process among desktop system, OPENGL-based 3D visualization system, and mobile system, it is possible to transfer and disseminate 3D feature models through both systems. In this mobile 3D urban processing system, the main graphical user interface and core components is implemented under EVC 4.0 MFC and tested at PDA running on windows mobile and Pocket Pc. It is expected that the mobile 3D geo-spatial information systems supporting registration, modeling, and rendering functions can be effectively utilized for real time 3D urban planning and 3D mobile mapping on the site.

• Korean Management Science Review
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• v.28 no.1
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• pp.1-10
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• 2011

One of the fundamental roles of web object navigation is to support what the user wants precisely and efficiently from the enormous web database to the web browser. As long as the web search results are a set of individual lists, it is all right to display each and every web result for the web browser to display a web object one by one. However, in case the search results are a collection of multiple interrelated web objects, then there is a need to represent for a new mechanism for linked web objects at a time. We define a unit of web objects derived from a Steiner tree where the web objects include a set of specific keywords calculated by the weight from which the solutions are extracted. Even if a web object does not include all the keywords, then the related hypertext linked web objects are derived and displayed onto the mobile web browser with meta data in one shot. In this paper, it is applied for the mobile browser that the web contents can dynamically be displayed with Steiner trees until each renewal of the navigation request may be issued. In this paper, a new synchronized mobile browsing method is developed so that the navigating time can drastically be reduced and the web navigating efficiency can be dramatically enhanced without sacrificing memory consumption.

• 제어로봇시스템학회:학술대회논문집
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• 2001.10a
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• pp.91.2-91
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• 2001

This paper describes the path planning of an autonomous mobile robot using one camera-based sequence image processing. As an assumption, all objects in front of the mobile robot are located on the same plane where robot moves. Using the moving camera grounded on the autonomous mobile robot, the robot extracts the angular points of obstacle objects, calculates the height using the assumption and discrepancy between two consecutive images. In the image processing, angular points of objects must correspond so that they deliver the size of objects. Thus, the robot passes through if the object has not the height, like the paper or the shadow projected. Otherwise, the robot passes aside if ...

• 제어로봇시스템학회:학술대회논문집
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• 2000.10a
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• pp.363-363
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• 2000

The conventional algorithms which identify and follow a moving target using a camera located at a fixed position are not appropriate for applying to the cases o( using mobile robots, due to their long processing time. This paper proposes a new tracking algorithm based on the sensing system which uses a line light with a single camera. The algorithm categirizes the motion patterns of a pair of mobile objects into parallel, branching, and merging motion, to decide of which objects the trajectories should be calculated to follow the reference object. Kalman Filter is used to estimate the trajectories of selected objects. The proposed algorithm has shown in the experiments that the mobile robot does not miss the target in most cases.

• The KIPS Transactions:PartD
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• v.10D no.2
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• pp.175-186
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• 2003

Mobile clients like a PDA need a cache and a spatial index to search and access map data efficiently. When a server transmits spatial objects to a mobile client which has a low storage capacity, some of them can be duplicated in a cache of the mobile client. Moreover, the cost for strong added data in the cache and reconfiguring spatial index is very high in the mobile client with low computing power. The scheme for processing duplicated objects and disturbing tasks of the mobile client which has low computing power is needed. In this paper, we classfy the method for strorng duplicated objects and present the scheme for the both caching objects and reconfiguring a spatial index of cached objects using the clipping technique. We propose the caching system based on an agent in order to distribute the overhead of a mobile client as well as to provide efficiently map services. We design and implement it, and evaluate the performance.

• 제어로봇시스템학회:학술대회논문집
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• 1997.10a
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• pp.815-818
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• 1997

In this paper, an intelligent control strategy for a mobile vehicle, based on the technology of the artificial neural network in a Neurocomputer, is presented. The mobile vehicle learned recognizing and driving knowledge by a neurocomputer. Moment Invariants computation was used to extract the shape of objects. The technologies of both neurocomputer and Neumann-type computer are applied into the control system, and make the mobile vehicle be capable of tracking designated objects and avoiding obstacles.

• Journal of Information Processing Systems
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• v.13 no.5
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• pp.1410-1429
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• 2017

Mobility arises naturally in the Internet of Things networks, since the location of mobile objects, e.g., mobile agents, mobile software, mobile things, or users with wireless hardware, changes as they move. Tracking their current location is essential to mobile computing. To overcome the scalability problem, hierarchical architectures of location databases have been proposed. When location updates and lookups for mobile objects are localized, these architectures become effective. However, the network signaling costs and the execution number of database operations increase particularly when the scale of the architectures and the numbers of databases becomes large to accommodate a great number of objects. This disadvantage can be alleviated by a location caching scheme which exploits the spatial and temporal locality in location lookup. In this paper, we propose a hierarchical location caching scheme, which acclimates the existing location caching scheme to a hierarchical architecture of location databases. The performance analysis indicates that the adjustment of such thresholds has an impact on cost reduction in the proposed scheme.