• The KIPS Transactions:PartD
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• v.17D no.5
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• pp.353-358
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• 2010

Unlike the traditional databases, queries on XML streams are restricted to a real time processing and memory usage. In this paper, a robust labeling scheme is proposed, which quickly identifies structural relationship between XML fragments. The proposed labeling scheme provides an effective query processing by removing many redundant operations and minimizing the number of fragments being processed. In experimental results, the proposed labeling scheme efficiently processes query processing and optimizes memory usage.

• Journal of KIISE:Databases
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• v.32 no.4
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• pp.416-428
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• 2005

In the paper we propose an index method for XML streaming services, where a server broadcasts XML data to a lot of clients in wireless information systems. In order to control the access and tuning time of mobile clients, the proposed method constructs the XML stream through replicating partial index intermixed with parts of data. For this purpose, we propose a two-level tree structure for separating index and XML data into two parts: replicated vs. non-replicated. We analyze the performance of the proposed method with respect to access time and tuning time. With the analysis result, we derive the optimal level value.

• Journal of Digital Contents Society
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• v.8 no.4
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• pp.541-546
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• 2007

Traditional query processing method is not efficient for continuous queries with large continuous stream data. This paper proposes a data-driven query processing method for stream data. The structure of query plan and query execution method are presented. With the proposed method, multiple query processing and sharing among queries can be achieved. Also query execution time can be reduced by storing partial results of query execution. This paper showed an example of query processing with XML data and XQuery query.

• Journal of KIISE:Databases
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• v.35 no.1
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• pp.67-83
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• 2008

In order to realize ubiquitous computing, it is essential to efficiently use the resources and the computing power of mobile devices. Among others, memory efficiency, energy efficiency, and processing efficiency are required in executing the softwares embedded in mobile devices. In this paper, query processing over XML data in a mobile device where resources are limited is addressed. In a device with limited amount of memory, the techniques of XML. stream query processing need to be employed to process queries over a large volume of XML data Recently, a technique Galled XFrag was proposed whereby XML data is fragmented with the hole-filler model and streamed in fragments for processing. With XFrag, query processing is possible in the mobile device with limited memory without reconstructing the XML data out of its fragment stream. With the hole-filler model, however, memory efficiency is not high because the additional information on holes and fillers needs to be stored. In this paper, we propose a new technique called XFLab whereby XML data is fragmented with the XML labeling scheme which is for representing the structural relationship in XML data, and streamed in fragments for processing. Through implementation and experiments, XML showed that our XFLab outperformed XFrag both in memory usage and processing time.

• The KIPS Transactions:PartD
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• v.15D no.1
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• pp.1-14
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• 2008

This paper is on query processing in the mobile devices where memory capacity is limited. In case that a query against a large volume of XML data is processed in such a mobile device, techniques of fragmenting the XML data into chunks and of streaming and processing them are required. Such techniques make it possible to process queries without materializing the XML data in its entirety. The previous schemes such as XFrag[4], XFPro[5], XFLab[6] are not scalable with respect to the increase of the size of the XML data because they lack proper memory management capability. After some information on XML fragments necessary for query processing is stored, it is not deleted even after it becomes of no use. As such, when the XML fragments are dynamically generated and infinitely streamed, there could be no guarantee of normal completion of query processing. In this paper, we address scalability of query processing over dynamic XML fragment stream, proposing techniques of deleting information on XML fragments accumulated during query processing in order to extend the previous schemes. The performance experiments through implementation showed that our extended schemes considerably outperformed the previous ones in memory efficiency and scalability with respect to the size of the XML data.

• Proceedings of the Korean Institute of Communication Sciences Conference
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• 2006.07a
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• pp.600-600
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• 2006

• Proceedings of the Korean Information Science Society Conference
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• 2006.10c
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• pp.113-117
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• 2006

유비쿼터스 컴퓨팅의 실현을 위해서는 이동 단말기의 자원 및 컴퓨팅 파워의 효율적 사용이 필수적이다. 특히, 이동 단말기에 내장된 소프트웨어의 수행에 있어 메모리 효율성, 에너지 효율성, 그리고 처리 효율성이 요구된다. 본 논문은 자원이 제약되어 있는 이동 단말기에서의 XML 데이터에 대한 질의 처리 기술에 관한 것이다. 메모리 용량이 크지 않은 단말기의 경우 대량의 XML 데이터에 대한 질의 처리를 수행하기 위해서는 XML 스트림 질의 처리 기술이 활용되어야 한다. 최근에 제시된 XFrag 기법은 홀-필러(hole-filler) 모델을 이용하여 XML 데이터를 XML 조각(fragment)으로 분할(fragmentation)하여 스트림으로 전송하고 처리할 수 있는 기법이다. 이는 메모리 효율성이 요구되는 이동 단말기에서 전체 XML 문서를 재구성하지 않고 XML 데이터에 대한 질의 처리를 가능하게 한다. 그러나 홀-필러 모델을 사용할 경우 홀과 필러에 대한 부가적인 정보를 저장해야 하므로 메모리 효율성이 높지 못하다. 본 논문에서는 XML 데이터의 구조 정보를 표현하는 XML 레이블링(labelling) 기법을 이용하여 XML 데이터를 조각으로 분할하여 조각 스트림에 대한 질의 처리를 수행하는 기법을 제시한다. 구현 및 성능 실험 결과 본 논문에서 제시한 기법이 기존의 XFrag 기법보다 메모리 사용량과 처리 시간 양면 모두에서 우수한 것으로 나타났다.

• Proceedings of the Korean Information Science Society Conference
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• 2007.06a
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• pp.1-2
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• 2007

• Journal of KIISE:Databases
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• v.33 no.6
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• pp.578-589
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• 2006

Owing to the proliferation of Radio Frequency Identification (RFID) technologies which is being watched as a core technology of ubiquitous computing, applications which offer convenience to people using RFID technologies are more and more increased. To easily develop these applications, a middleware system which acts as a bridge between RFID hardware and application is essential. In this paper, we propose a novel XML-based RFID middleware system called UbiCore (Ubiquitous Core). UbiCore has following features: First, UbiCore employs its own query language called XQueryStream (XQuery for Stream Data) which is originated from XQuery. Second, UbiCore has the preprocessing phase called pre-filtering prior to query evaluation and reuses the intermediate result of previous evaluation to speed up the processing of RFID tag data stream. Third, UbiCore supports query on both continuously generated stream data and archived historical data. And last, UbiCore offers a distinct markup language called Context-driven Service Markup Language (CSML) to easily specify the linking information between context and service.

• Proceedings of the Korea Database Society Conference
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• 2002.10a
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• pp.456-462
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• 2002

본 논문은 은행에서 사용하던 기존 Stream 기반 전문데이터 교환 방식에서 인터넷 뱅킹 시스템 환경의 XML 기반 전문데이터 교환 방식으로의 전환을 통해서 시스템의 성능을 개선하고 구조화된 데이터의 활용을 통해 재사용성과 관리 효율을 획기적으로 향상시킨 개선방안을 제시하고 있다. 기존 스트림 구조의 XML 프레임으로의 설계와 이의 실시간 활용으로 한층 더 지능화된 시스템으로 설계 및 구현하는 방식을 제시하고 있다.