• Journal of KIISE:Databases
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• v.37 no.4
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• pp.185-196
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• 2010

Existing methods to compute reverse skyline queries are not correct to process the queries in dataset with region objects which have conditions like a price is 5~7 dollars and a distance to beach is 1km~2km, since they consider datasets with only point objects. To solve the problem, we propose a novel method to process reverse skyline queries for region objects in this paper. It has advantages. First, it is expected to get a good performance, because it is extended from efficient reverse skyline (ERSL) algorithm which is a best algorithm to computing reverse skyline queries in datasets with point objects. Second, it can give a right of choice unlike the others to a person requesting the query. That is because results of reverse skyline have a difference preference according to proposed pruning methods and overlap relations. This algorithm is a first for supporting region objects. Therefore there are not any other algorithms to compare their performance. For that reason, our experiment to prove the efficiency of proposed algorithm is focused what conditions give an effect to its performance and result and how much time it needs to process the query.

• The KIPS Transactions:PartA
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• v.15A no.5
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• pp.287-294
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• 2008

A tag collision arbitration algorithm for RFID passive tags is one of the important issues for fast tag identification, since reader and tag have a shared wireless channel in RFID system. This paper suggests Hyper-Hybrid Query Tree algorithm to prevent the tag-collisions. The suggested algorithms determine the specified point in time for tag to transfer ID to reader by using value 1 of the upper 3 bit based on Query Tree. Also, because the transferred upper 3 bits of tag is different depending on the time of transfer, it is possible to predict in the suggested Algorithm. In the performance evaluation through simulation, it shows the suggested algorithm has higher performance in the number of queries compared to other Tree-based protocols.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.4A
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• pp.431-439
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• 2006

RFID Anti-Collision technique is needed to avoid collision problem caused by Radio interference between tags in the same RFID Reader area. It affects the performance and reliability of the RFID System. This paper propose the QT-CBP(Query Tree with Collision-Bit Positioning) Algorithm based on the QT(Query Tree) algorithm. QT-CBP Algorithm use precise collision bit position to improve the performance. We demonstrated the proposed algorithm by simulation. Our algorithm outperformed when each tag bit streams are the more duplicate and the number of tags is increased, compared with QT.

• ETRI Journal
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• v.38 no.6
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• pp.1197-1206
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• 2016

Performing continuous skyline queries of dynamic data sets is now more challenging as the sizes of data sets increase and as they become more volatile due to the increase in dynamic updates. Although previous work proposed support for such queries, their efficiency was restricted to small data sets or uniformly distributed data sets. In a production database with many concurrent queries, the execution of continuous skyline queries impacts query performance due to update requirements to acquire exclusive locks, possibly blocking other query threads. Thus, the computational costs increase. In order to minimize computational requirements, we propose a method based on a multi-layer grid structure. First, relational data object, elements of an initial data set, are processed to obtain the corresponding multi-layer grid structure and the skyline influence regions over the data. Then, the dynamic data are processed only when they are identified within the skyline influence regions. Therefore, a large amount of computation can be pruned by adopting the proposed multi-layer grid structure. Using a variety of datasets, the performance evaluation confirms the efficiency of the proposed method.

• KIISE Transactions on Computing Practices
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• v.23 no.11
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• pp.611-616
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• 2017

In the area of Information Retrieval, Query Expansion is a well-known technique that uses external knowledge to increase an inquiry generated by users. However, ambiguous words used in the query decrease the performance of search tools. In this paper, we propose a solution to the above problem, by using domain knowledge which identifies the meaning of words in the query. In particular, we present a domain centered query expansion technique that magnifies a query using domains. By comparing with various query expansion models, we demonstrate that the proposed model performs better than the other models.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.15 no.5
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• pp.75-84
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• 2015

A data allocation technique is essential to improve the performance of data broadcast systems. This paper explores the issues for allocating data items on broadcast channels to process multiple-data queries in the environment where query profiles and query request rates are given, and proposes a new data allocation scheme named IDAS. The proposed scheme employs the strategy that the broadcast frequency of each data is determined by the square root value of its relative access probability. IDAS could enhance the performance of query response time since it can process queries of high request rate fast and show a resonable degree of query data adjacency. Simulation is performed to evaluate the performance of the proposed scheme. The simulation results show that IDAS outperforms other schemes in terms of the average response time.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.9 no.6
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• pp.2078-2094
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• 2015

Now a days, Efficient processing of Broadcast Queries is of critical importance with the ever-increasing deployment and use of mobile technologies. BQs have certain unique characteristics that the traditional spatial query processing in centralized databases does not address. In novel query processing technique, by maintaining high scalability and accuracy, latency is reduced considerably in answering BQs. Novel approach is based on peer-to-peer sharing, which enables us to process queries without delay at a mobile host by using query results cached in its neighboring mobile peers. We design and evaluate cooperative caching techniques to efficiently support data access in ad hoc networks. We first propose two schemes: Cache Data, which caches the data, and Cache Path, which caches the data path. After analyzing the performance of those two schemes, we propose a hybrid approach (Hybrid Cache), which can further improve the performance by taking advantage of Cache Data and Cache Path while avoiding their weaknesses. Cache replacement policies are also studied to further improve the performance. Simulation results show that the proposed schemes can significantly reduce the query delay and message complexity when compared to other caching schemes.

• International Journal of Computer Science & Network Security
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• v.24 no.1
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• pp.140-150
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• 2024

Database-as-a-Service is one of the prime services provided by Cloud Computing. It provides data storage and management services to individuals, enterprises and organizations on pay and uses basis. In which any enterprise or organization can outsource its databases to the Cloud Service Provider (CSP) and query the data whenever and wherever required through any devices connected to the internet. The advantage of this service is that enterprises or organizations can reduce the cost of establishing and maintaining infrastructure locally. However, there exist some database security, privacychallenges and query performance issues to access data, to overcome these issues, in our recent research, developed a database security model using a deterministic encryption scheme, which improved query execution performance and database security level.As this model is implemented using a deterministic encryption scheme, it may suffer from chosen plain text attack, to overcome this issue. In this paper, we proposed a new model for cloud database security using nondeterministic encryption, order preserving encryption, homomorphic encryptionand database distribution schemes, andour proposed model supports execution of queries with equality check, range condition and aggregate operations on encrypted cloud database without decryption. This model is more secure with optimal query execution performance.

• Journal of the Korean Operations Research and Management Science Society
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• v.27 no.4
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• pp.29-39
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• 2002

The transaction tables of the existing association algorithms have two column attributes : It is composed of transaction identifier (Transaction_id) and an item identifier (item). In this kind of structure, as the volume of data becomes larger, the performance for the SQL query statements came applicable decreases. Therefore, we propose advanced association rules algorithm of n-items which can transact multiple items (Transaction_id, Item 1, Item 2…, Item n). In this structure, performance hours can be contracted more than the single item structures, because count can be computed by query of the input transaction tables. Our experimental results indicate that performance of the n items structure is up to 2 times better than the single item. As a result of this paper, the proposed algorithm can be applied to internet shopping, searching engine and etc.

• International Journal of Advanced Culture Technology
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• v.5 no.1
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• pp.76-82
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• 2017

An image hash, a discriminative and robust summary of an image, should be robust against quality-preserving signal processing steps, while being pairwise independent for perceptually different inputs. In order to improve the hash matching performance, this paper proposes a probabilistic dissimilarity matching. Instead of extracting the binary hash from the query image, we compute the probability that the intermediate hash vector of the query image belongs to each quantization bin, which is referred to as soft quantization binning. The probability is used as a weight in comparing the binary hash of the query with that stored in a database. A performance evaluation over sets of image distortions shows that the proposed probabilistic matching method effectively improves the hash matching performance as compared with the conventional Hamming distance.