• The Transactions of the Korea Information Processing Society
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• v.7 no.12
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• pp.3964-3975
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• 2000

There are two policies for maintaining consistency among the multiple processor caches in a multiprocessor system: Write invalidate and Write update. In the write invalidate policy, whenever a processor attempt to write its cached block, it has to invalidate all the same copies of the updated block in the system. As a results of this frequent invalidations, this policy results in high cache miss ratio. On the other hand, the write update policy renew them, instead of invalidating all the same copies. This policy has to transfer the updated contents through interconnection network, whether the updated block is ptivate or not. Therefore the network suffer from heavy transaction traffic. In this paper we present an efficient cache coherence protocol for shared memory multiprocessor system connected by slotted ring. This protocol is based on the write update policy, but the updated contents are transferred only in case of updating the shared block. Otherwise, if the updated block is private, the updated contents are not transferred. We analyze the proposed protocol and enforce simulation to compare it with previous version.

• The Journal of Korean Association of Computer Education
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• v.10 no.5
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• pp.81-88
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• 2007

To support the movement of a mobile network consisting of several mobile nodes, the IETF NEMO working group proposed NEMO basic support protocol using bi-directional tunneling between the home agent and the mobile router. Since NEMO basic support protocol is based on bi-directional tunneling, all communications to and from mobile nodes are suffer from inefficient routing all the cases. To solve the routing inefficiency problem, several proposals are proposed. However, those proposals results in new problems, such as binding update storm and changes in existing protocol. Especially, binding update storm problem may cause the delay in binding update, this subsequently causes the difficulty for a real time service and the handoff delay on the movement of mobile network. In this paper, we propose a new binding update scheme which reduces binding update latency and the handoff delay through the distribution of the transmission time of binding update messages. The performance of the proposed scheme is also evaluated to demonstrate its efficiency. Simulation results show that the proposed scheme can efficiently reduce the binding update latency.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.25 no.3
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• pp.249-255
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• 2007

The building of spatial database such as digital maps has been extensively achieved as a base of geographic information system. However, in the GIS system built by the organizations including local autonomous entities, there are some problems technically and systematically for a promptly updating of GIS DB. This research is to develop the object-oriented database updating system to efficiently update the spatial data at any time for a small area. It could be managed the history of spatial database such as creation, modification and deletion at a object level using the UFID of spatial data. This system could help to modify or update the changed geographical features in an office or in-situ promptly. Finally, it could be made the efficient updating manner of geographic data and the assurance of newest database.

• Journal of KIISE:Databases
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• v.31 no.5
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• pp.505-515
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• 2004

One of the most important issue in location-aware computing is tracking moving objects efficiently. To this end, an efficient protocol which updates location information in a location server is highly needed. In fact, the performance of a location update strategy highly depends on the assumed mobility pattern. In most existing works, however, the mobility issue has been disregarded and too simplified as linear function of time. In this paper, we propose a new mobility model, called state-based mobility model (SMM) to provide more generalized framework for both describing the mobility and updating location information of complexly moving objects. We also introduce the state-based location update protocol (SLUP) based on this mobility model. Using experimental comparison, we illustrate that the proposed technique is many times better in reducing location update cost and the communication bandwidth consumption.

• KIPS Transactions on Software and Data Engineering
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• v.9 no.3
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• pp.77-82
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• 2020

Most of the navigation in the vehicle has been developed based on a complex structure of PSF(Physical Storage Format) files, making it difficult to support incremental map updates. DB-based navigation is drawing attention as a next-generation navigation method to solve this problem. In DB-based navigation that supports incremental map updates, data fragmentation due to continuous map data updates can increase data access costs, which can lead to a decrease in search performance. In this paper, as one of the performance enhancement methods of DB-based navigation that supports incremental map updates, data fragmentation prevention techniques were presented and the performance improvement effect was verified through actual implementation.

• Journal of the Korea Society of Computer and Information
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• v.9 no.2
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• pp.33-40
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• 2004

According as client/server is generalized by development of computer performance and information communication technology, Servers uses local cache for extensibility and early response time, and reduction of limited bandwidth. Consistency of cached data need between server and client this time and much technique are proposed according to this. This Paper improved update frequency cache consistency in old. Existent consistency techniques is disadvantage that response time is late because synchronous declaration or abort step increases because delaying write intention declaration. Techniques that is proposed in this paper did to perform referring update time about object that page request or when complete update operation happens to solve these problem. Therefore, have advantage that response is fast because could run write intention declaration or update by sel_mode electively asynchronously when update operation consists and abort step decreases and clearer selection.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.13 no.4
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• pp.720-726
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• 2009

There are coexisting various kinds of data in the large scale database system, the maintenance problem of freshness of data is emerging important issue that provide correctness and usefulness information to users. Most solution of this problem depends on how execute effectively required refreshing query within timely time. In this paper, we propose the refreshing scheduling algorithm to retain the freshness of data and fairness of starvation of requested refresh queries. Our algorithm recompute a rate of goal refreshing a every period to assign execution time of requested refreshing query so that we can keep the freshness and fairness of data by using proposed algorithm. We implement the web sites to showing the results of refreshing process of dynamic and semi-dynamic and static data.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.10 no.3
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• pp.571-578
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• 2006

To renew the group key securing on the mobile communication needs that it can be not oかy re-shared by all members of the group with the exception of members excluded but also prevented from making a fraudulent use of a terminal's registered key because of a leakage of information from the loss of terminal. In this paper, we propose an efficient renewal mechanism of group key in order for all members of the group to be able to get digital information and to perform the renewal of group key in a small-scale conference employing the Fiat-Shamir method. It can guarantee the security of terminals, since a terminal generates security information needed for key renewal, and then renews the group key for mutual communication.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.17 no.2
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• pp.7-13
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• 2017

Many systems rely on reliable timestamps to determine the time of a particular action or event. This is especially true in digital investigations where investigators are attempting to determine when a suspect actually committed an action. The challenge, however, is that objects are not updated at the exact moment that an event occurs, but within some time-span after the actual event. In this work we define a simple model of digital systems with objects that have associated timestamps. The model is used to predict object update patterns for objects with associated timestamps, and make predictions about these update time-spans. Through empirical studies of digital systems, we show that timestamp update patterns are not instantaneous. We then provide a method for calculating the distribution of timestamp updates on a particular system to determine more accurate action instance times.

• Journal of KIISE:Computing Practices and Letters
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• v.16 no.3
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• pp.324-330
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• 2010

XML schema is widely used as an effective tool for organizing and validating XML data. Although W3C released XQuery and XQuery Update Facility as the standard methods for searching and updating XML data, there is no consideration about providing facilities for updating XML schema itself until now. So users can only update an XML schema file directly by using editors. However, the direct update has several problems: It cannot prevent user's illegal update; it is hard to apply to the XML schemas stored in databases, needs much time to analyze schema, and is likely to make syntactic errors. In this paper, we propose an XML schema update facility, which enables creation, deletion and modification of XML schema by using commands.