• The KIPS Transactions:PartA
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• v.10A no.2
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• pp.141-148
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• 2003

Distributed applications based on standards such as CORBA, DCOM, and EJB have been widely used in distributed environments. Recently, another XML-based standard, SOAP, has been recommended for web applications. However, these standards have a shortcoming in inter-operation because they can be run on their own environments. In this paper, we design and implement a SOAP bridge for inter-operation of SOAP with other distributed object standards. Its function is to map formats between SOAP and CORBA/DCOM at run time. Through performance experiments, we show that the computing overhead is small compared to the whole transaction execution time. Therefore, distributed objects of other platforms can be reused instead of developing new objects based on SOAP. Also, using the SOAP bridge, we design and implement an XML-based bidding system on the web. Because it is based on the web standards, it has advantages such as extendibility and interoperability compared to previous proprietary electronic commerce systems.

• The KIPS Transactions:PartA
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• v.8A no.4
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• pp.375-384
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• 2001

The shared disk file systems use a technique known as file system journaling to support recovery of metadata on the SAN(Storage Area Network). In the existing journaling technique, the metadata that is dirtied by one host must be updated to disk space before some hosts access it. The system performance is decreased because the disk access number is increased. In this paper, we describe a new recovery technique using a global buffer to decrease disk I/O. It transmits the dirtied metadata into the other hosts through Fibre Channel network on the SAN instead of disk I/O and supports recovery of a critical data by journaling a data as well as metadata.

• Journal of Korea Society of Industrial Information Systems
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• v.7 no.5
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• pp.39-48
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• 2002

long with the rapid spread of the Internet, a new class of commercial applications which process transactions with respect to electronic dictionaries become popular Typical examples are Internet search engines. In this paper, we present a new approach to achieving high performance electronic dictionaries. Different from the conventional approach which use Trie data structures for the implementation of electronic dictionaries, our approach used multi-dimensional binary trees. In this paper, we present the implementation of our electronic dictionary ED-MBT(Electronic Dictionary based on Multidimensional Binary Tree). Exhaustive performance study is also presented to assess the performance impact of ED-MBT on the real world applications.

• Journal of KIISE:Computer Systems and Theory
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• v.28 no.3
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• pp.173-180
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• 2001

고가용도 클러스터 시스템에서 가동되는 인터넷 기반 소프트웨어의 복잡도가 증가됨에 따라 소프트웨어의 설계, 구현, 또는 그 밖의 여러 가지 원인과 관련된 결함으로 인하여 시스템 서비스의 오동작 또는 수행 중단으로 이어지는 사례가 늘어나고 있다. 특히 대량 트랜잭션을 처리하는 인터넷 기반 컴퓨팅 소프트웨어는 빈번한 통신 두절과 데이터 유실로 인하여, 이들이 탑재된 클러스터 시스템의 결함 발생이 더욱 심각할 가능성이 높다. 본 연구는 소프트웨어 재활 결함 허용 기법을 활용하여, 별도의 추가되는 하드웨어 없이도 가용도를 개선할 수 있다는 '소프트웨서 재활 기법을 적용한 다중계 시스템 가용도 분석'에 관한 논문에서 언급된 문제점들에 대한 해결 방안을 제시하였으며, 구체적으로는 1) 주서버의 고장 발생시 여분서버로의 작업전이(switchover) 상태를 클러스터 시스템 모델링에 포함시켰으며, 2) 작업전이 상태와 재활(rejuvenation) 상태에서 머무는 시간을 지수분포 대신에 k-stage Erlangian 분포를 사용하여 확정시간(deterministic time)을 표현할 수 있도록 하였다. 즉 본 논문에서는 고가용도 cold standby 클러스터 시스템의 운영 상태에 대한 상태전이도(state transition diagram)에서, 임의의 상태에서 머무는 시간분포가 memoryless 성질을 만족하지 않아도 되는 semi-Markov 프로세스 문제를 해결하였다.

• 한국공간정보시스템학회:학술대회논문집
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• 2003.11a
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• pp.84-90
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• 2003

최근 이동 컴퓨팅 기술이 급속도로 발전하면서 이동 객체의 위치정보를 활용한 위치 찾기 서비스, 교통 정보 서비스, 긴급 구조 서비스, 모바일 광고 서비스와 같은 위치 기반 서비스가 부각되고 있다. 이와 같은 다양한 서비스를 제공하기 위해서는 이동 객체의 위치정보를 신속하게 저장, 검색, 갱신할 수 있는 이동 객체 데이타베이스 시스템이 필수적으로 요구된다. 그러나, 기존의 데이타베이스 시스템을 사용할 경우에는 저장 공간을 많이 차지게 되고, 불필요한 트랜잭션 연산으로 인하여 대용량의 위치 데이타 관리에 큰 오버헤드가 발생한다는 문제가 있다. 그러므로, 이동 객체의 위치 데이타를 저장하고 관리하기 위하여 화일 기반의 저장 시스템을 사용하는 것이 보다 더 효율적이다. 이에 본 논문에서는 대용량의 위치 데이타를 효과적으로 저장 및 검색할 수 있는 화일 기반 이동 객체 저장 컴포넌트를 설계하고 구현하였다. 화일 기반 이동 객체 저장 컴포넌트는 다중 연결 관리자, 단순 질의 처리기, 메타데이타 관리자, 데이타 화일 관리자, 인덱스 화일 관리자, 로그 관리자, 관리툴로 구성된다.

• Journal of the Korean Society for Library and Information Science
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• v.32 no.1
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• pp.7-26
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• 1998

In this study, an ILL request system was implemented using Z39.50 item order extended service. ILL requests in this system are initiated by users through a gateway acting as a Z39.50 origin for searching remote catalog databases. When users initiate a request while searching OPACs of other libraries, an extended service request PDU for item order is first sent to the home library which subsequently generates an ILL protocol message to be sent to the target library. This approach enables users to request an item online while searching. and at the same time allows the home library to retain control over the ILL transaction.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.13 no.3
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• pp.235-242
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• 2020

This paper proposes a system that can manage and verify personal career information through a block chain to solve the problem of getting a job by forging an individual's career when hiring employees. Blockchain network uses private network, and inside the block, the user's academic and career information is kept. The functions of the block chain perform the functions of block creation, block internal data retrieval, career and academic verification, which works through chain code. As a result of the performance evaluation of the proposed system, the processing time per transaction was measured at approximately 110 ms and the search time was measured at 10 ms, and it was applied to the actual system to confirm that it was available.

• Journal of Korea Multimedia Society
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• v.5 no.4
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• pp.372-385
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• 2002

In this paper, we propose an efficient buffer replacement method for the real-time multimedia data. The proposed method has multi level priority to consider the real-time characteristics. Each priority level is divided into a cold data set that is likely to be referenced for the first time and a hot data set that is likely to be re-referenced. An operation to select the victim data is sequentially executed from the cold set with the minimum priority level to the hot set with the maximum Priority level. It is chosen only at the lower level than or equal to the priority of the transaction that requests a buffer allocation. In the cold set, our method selects a media that has the maximum size in the level for a target of victim first of all. And in the hot set, our method selects a medium that has the maximum interval of the reference first of all. Since it maintains many popular media in the limited buffer space, the buffer hit ratio is increased. It also manages many service requests. As a result, our method improves the overall performance of the system. We compare the proposed method with the Priority-Hints method in terms of the buffer hit ratio and the deadline missing ratio of transactions. It is shown through the performance evaluation that our method outperforms the existing methods.

• Journal of KIISE:Software and Applications
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• v.29 no.7
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• pp.436-449
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• 2002

This paper describes on our experience of developing the Database Connector as an interconnection method between multimedia database, and the streaming framework. It is possible to support diverse and mature multimedia database services such as retrieval and join operation during the streaming if an interconnection method is provided in between streaming system and multimedia databases. The currently available interconnection schemes, however have mainly used the file systems or the relational databases that are Implemented with separated form of meta data, which deafs with information of multimedia contents, and streaming data which deals with multimedia data itself. Consequently, existing interconnection mechanisms could not come up with many virtues of multimedia database services during the streaming operation. In order to resolve these drawbacks, we propose a novel scheme for an interconnection between streaming framework and multimedia database, called the Inter-Process Communication (IPC) based Database connector, under the assumption that two systems are located in a same host. We define four transaction primitives; Read, Write, Find, Play, as well as define the interface for transactions that are implemented based on the plug-in, which in consequence can extend to other multimedia databases that will come for some later years. Our simulation study show that performance of the proposed IPC based interconnection scheme is not much far behind compared with that of file systems.

• The Transactions of the Korea Information Processing Society
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• v.4 no.4
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• pp.895-907
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• 1997

The mining of assciation rules disovers the trndency of events ocuring simultaneously in large databases. Previous announced research on association rules deals with associations with associations with respect to the whole transaction. However, xome association rules could have very high confidence in a sub-range of the time domain, even though they do not have quite high confidence in the whole time domain. Such kind of association rules are ecpected to be very usdful in various decion making problems.In this paper, we define transient association rule, as an association with high cimfidence worthy of special attention in a partial time interval, and propose an dfficeint algorithm wich finds out the time intervals appropriate to transient association rules from large-databases.We propose the data-driven retrival method excluding unecessary interval search, and design an effective data structure manageable in main memory obtined by one scanning of database, which offers the necessary information to next retrieval phase. In addition, our simulation shows that the suggested algorithm has reliable performance at the time cost acceptable in application areas.