• The Transactions of the Korea Information Processing Society
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• v.3 no.1
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• pp.87-94
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• 1996

In order to design an extended relational database management system supporting multilevel security, the standard relational data model is extended and new relational integrity constrains are proposed for the model. The extended relational model and proposed multilevel integrity constraniants maintain database in consistent state and produce a basis that can eliminat eambiguity of entity and relation ship representations bypoly instantiation. The proposed up dates emantics canincreases the efficiency of up date operations by supporting multilevel entry and up dates. The semantics also provides a basis for the implementation of decomposition of extended relations.

• The KIPS Transactions:PartA
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• v.10A no.4
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• pp.313-320
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• 2003

This paper design and implements a synchronized agent mechanism that be able to synchronize SFT (Slow Frequency Transaction) data among e-business processes in distributed environment. This synchronized agent system is adopted to use mobile agent to guarantee the interoperability of the distributed processes and to solve some problems at the client/server architecture and proposes a policy to synchronize data of e-business processes on the any platforms of distributed heterogeneous systems. The proposed synchronization policy is based on the time-stamp transaction with the system priority on the unicasting transportation.

• Journal of Scientific & Technological Knowledge Infrastructure
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• s.7
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• pp.32-43
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• 2001

정보화사회에 있어서 인간의 지적 활동에 필수적인 요소는 과학기술에 의존한 정보의 수집과 축적 및 검색과 이용이라고 할 수 있다. 이러한 요구에 따른 다양한 형태의 정보나 데이터를 효율적으로 구축, 유지, 운영할 수 있는 정보 검색시스템 개발의 중요성이 점차 증가하고있다. 특히, 웹과 컴퓨터의 보급이 확산됨에 따라 수많은 전자문서들이 생산되면서 기존의 검색시스템의 기능, 즉 정형적인 텍스트문서에 대한 단순한 불리언질의만으로는 사용자의 요구를 충족시킬 수 없게되었다. 따라서, 본 논문에서는 이러한 사용자 요구를 빠르고 정확하게 처리하기 위해 기존의 정보 검색시스템인 "KRISTAL-2001"의 특징은 저장엔진, 시스템제어기, 검색기, 색인기, 분산엔진 모듈이 각각 서버 역활을하며 통신을 통하여 상호간의 정보를 전달한다. 따라서 분산검색을 통한 빠른 질의처리가 가능하다는 장점을 가지고 있다. 그리고 문서 또는 문서그룹단위의 트랜잭션처리를 지원하기 때문에 데이터의 안정적인 저장 및 수정을 보장한다. 또한 구조문서, 멀티미디어 데이터등 다양한 형태의 데이터를 관리할 수 있기 특징을 가지고 있다. KRISTAL-2001은 순수 국내기술로 개발된 대용량 데이터를 위한 차세대 정보검색시스템으로서 국제 경쟁력 향상에 중요한 역할을 수행할 것으로 기대된다.

• Proceedings of the Korea Information Processing Society Conference
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• 2022.05a
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• pp.252-255
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• 2022

기존 블록체인 기술을 활용해 새로운 비즈니스 모델을 개발 및 투자하려는 기업들의 관심이 높아지고 있으나, 낮은 확장성으로 인해 기존 블록체인 기술만으로는 시장에서 활용되기 어렵다. 블록체인의 낮은 확장성을 해결하기 위해 검증된 참여자만 참여하는 프라이빗 블록체인과 프라이빗 블록체인 고속화를 위한 관련 연구가 같이 진행되고 있다. 삼성의 넥스레저는 하이퍼레저 패브릭의 다중 버전 동시성 제어(MVCC) 충돌로 인한 낮은 TPS 문제를 해결하기 위해 Accelerator를 추가하여 고속화를 진행하였다. 하지만 모든 트랜잭션을 수집하여 처리하는 방식인 Accelerator는 중앙화로 인해 악의적인 공격 타깃이 되어 단일 장애 지점 문제가 발생할 수 있으며, 공격으로 인해 위조되거나 분실된 데이터는 검증 없이 블록체인 블록에 반영되고, 한번 반영된 데이터는 수정이 어렵다. 본 논문에서는 이와 같이 프라이빗 블록체인 고속화 상황에서 발생할 수 있는 단일 장애 지점 문제를 해결하기 위해 CMT와 사기증명 기반의 고속화 하이퍼레저 패브릭 시스템을 제안했으며, 제안한 시스템을 구축하고 성능 테스트를 통해 CMT 하이퍼레저 패브릭 시스템 성능이 99.58% 유지됨과 사기증명이 가능함을 확인하였다.

• Journal of KIISE:Software and Applications
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• v.30 no.5_6
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• pp.529-539
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• 2003

Due to the emersion of J2EE (Java 2, Enterprise Edition), many enterprises inside and outside of the country have been developing the enterprise applications appropriate to the J2EE model. With the help of the component model of Enterprise JavaBeans (EJB) which is the J2EE core technology, we can develop the distributed object applications quite simple. EJB application can be implemented by using the component-oriented object transaction middleware and the most applications utilize the distributed transaction. Due to these characteristics, EJB technology became popular and then the study for EJB based application has been done quite actively. However, the research of techniques for the performance monitoring during run-time of the EJB applications has not been done enough. In this paper, we propose the techniques for monitoring the performance of EJB Application on the run time. First, we explore the workflow for the EJB application service and classily the internal operation into several elements. The proposed techniques provide monitoring the performance elements between the classified elements. We can also monitor by extracting the performance information like state transition and process time of the bean which is related to the lifetime occurred during one workflow, and the resource utilization rate.

• Journal of the Korea Convergence Society
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• v.8 no.8
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• pp.59-69
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• 2017

Humanities and social sciences researchers and database experts have teamed up to build a database of IPR materials prepared by the Institute of Pacific Relations (IPR). This paper presents the issues and solutions inherent in the database construction for ensuring the quality of IPR materials. For the accessibility of the database, we maintain the database on the Web so that researchers can access it via web browsers; for the convenience of the database construction, we provide an integrated interface that allows researchers to perform all tasks in it; for the completeness of IPR materials constructed, we support the responsible input and the responsible approval that identify responsibilities of each IPR material entered; and for the immediacy of the approval, we support an interactive approval process facilitating the input of researchers. We also use database design, query processing, transaction management, and search and sorting techniques to ensure the correctness of IPR materials entered. In particular, through concurrency control using existence dependency relationships between records, we ensure the correctness between the operating system files and their paths. Our future studies include content search, database download and upload, and copyright related work on IPR materials.

• The Journal of the Korea Contents Association
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• v.18 no.7
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• pp.620-627
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• 2018

With the widespread adoption of blockchain in the field of business, the importance of confidentiality of critical information has been emerging. Although blockchain models solve the security problem regarding integrity threat by sharing transactions and making them public, it is vulnerable in terms of confidentiality. Therefore, a security mechanism to provide confidentiality of critical information and private information of a firm is necessary to utilize block chain in the process of work. In order to solve the problem, we suggest Private blockchain based cryptographic protocol application model using Smart contract commitment scheme of the Ethereum. It can contribute to activation of blockchain services by enabling non-trusted participants to perform businesses through application of smart contract enhanced in terms of confidentiality and integrity to private blockchain.

• The Journal of Korean Association of Computer Education
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• v.11 no.4
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• pp.71-83
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• 2008

The recent advances of the information technology have motivated lots of research efforts to develop new computer-aided teaching and learning methodologies on various computer science topics, such as data structures, operating system, computer networks, and computer architecture. However, there have been only few studies to educate the database subject although it is one of the most important topics in the computer science. Specifically, among the various issues in the database subject, a learner often suffers to understand the mechanism of the concurrency control and recovery of database transaction in the database because it highly interacts with other functions in the database. Obviously, an intelligent visualization tool can help a learner to understand the process of the concurrency control and the recovery of database transaction. The purpose of this study is to develop an efficient visualization tool which can help users understand the two phase locking protocol (2PLP)-based concurrency control. Specifically, this visualization tool is designed to encourage a users' participation and raise their interest by visualizing the process of transactions and allowing users to specify and manipulate their own transactions.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.4B
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• pp.411-423
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• 2004

This paper defines test methodologies and performance indices for SIP server system, and describes elements that can have influence on the test of SIP network equipments. Moreover, we implement a tester to evaluate the performance of SIP Servers such as Registrar and Proxy server. The performance indices for testing SIP servers are message processing rate, transaction delay, and call success probability. The parameters that can have an effect on the performance of SIP servers are user population, transport protocol, method of database access, method of DNS, call creation pattern, definition of transactions, and size of packets. We tested several SIP servers that act as Registrar, Proxy, and Redirect server using the implemented SIP tester, and, as a result, verified functions of the tester and performance indices and input parameters defined in this paper. Performance indices and methodologies presented in this paper can be used to evaluate SIP servers in NGN

• Journal of Internet Computing and Services
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• v.5 no.3
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• pp.25-33
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• 2004

Mobile IP Low Latency Handoffs(l) allow greater support for real-time services on a Mobile IP network by minimizing the period of time when a mobile node is unable to send or receive IP packets due to the delay in the Mobile IP Registration process. However, on Mobile IP network with AAA servers that are capable of performing Authentication, Authorization, and Accounting(AAA) services, every Registration has to be traversed to the home network to achieve new session keys, that are distributed by home AAA server, for a new Mobile IP session. This communication delay is the time taken to re-authentication the mobile node and to traverse between foreign and home network even if the mobile node has been previously authorized to old foreign agent. In order to reduce these extra time overheads, we present a method that performs Low Latency Handoffs without requiring further involvement by home AAA server. The method re-uses the previously assigned session keys. To provide confidentiality and integrity of session keys in the phase of key exchange between agents, it uses a key sharing method by gateway foreign agent that performs a trusted thirty party. The proposed method allows the mobile node to perform Low Latency Handoffs with fast as well as secure operation.