• Journal of KIISE
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• v.45 no.2
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• pp.187-194
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• 2018

Recently, Hypertext Transfer Protocol (HTTP) adaptive streaming service is attracting attention. The existing quality adaptive scheme of HTTP adaptive streaming service adjusts the video quality according to the network bandwidth or the client buffer size. However, the problem with the existing quality adaptive scheme is the QoE (Quality of Experience) degradation caused by the unnecessary quality change that occurs due to frequent bandwidth change or fixed buffer threshold. We propose a video quality maintenance scheme that improves average video quality and minimizes unnecessary quality change in order to improve the QoE of HTTP adaptive streaming service in the changing network environment. The proposed scheme maintains high quality for a long time by setting the quality maintenance duration to be long when buffer occupancy and video quality are high. The experimental results show that the proposed scheme improves QoE by improving the average video quality and minimizing the quality change.

• Journal of the Korea Society of Computer and Information
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• v.29 no.8
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• pp.67-75
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• 2024

Frequently changeable functional requirements in System Management CSCI Software make it difficult to reuse an overall application, but only the partial class codes repeatedly as a new version of Naval Combat Management System is developed. This structural environment leads to increasing development time and expenses. This is why modularization for System Management CSCI Software is proposed as a solution, leveraging the advantages of proper standardization and functional expandability offered by Standard Interface Architecture. This paper outlines the comparisons of modified class ratios as well as software reliability test runtime results between before and after implementing the modularization for System Management CSCI Software. The findings demonstrate there is sufficient improvement in areas, such as higher maintenance and reusability, supporting the application of modularization for System Management CSCI Software with the implementation of Standard Interface Architecture.

• The Journal of the Convergence on Culture Technology
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• v.7 no.4
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• pp.879-892
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• 2021

In a make-to-order manufacturing environment, the manufacturer's quotation information is important information used as basic information for bidding, receiving orders, and producing products in response to various customer demands. This quotation information is changed according to various factors such as customer demands, changes in product production environment, changes in drawing information of technical partners, and technological improvement of products. Due to this change, various changes occur in the quotation information that the manufacturer is preparing to reflect the customer's requirements. The change of quotation information according to these various change factors puts a lot of burden on the quotation management work from the standpoint of a make-to-order manufacturing company. In particular, the change of quotation information due to the change factors of quotation is inevitable and frequently occurs due to the requirements of the customer in the customer-oriented make-to-order production environment. In this paper, we propose a quotation change process based on the quotation creation process and propose a consistent and efficient quotation change processing method. To this end, the factors causing the change of quotation were defined, and the types of changes for each factor were defined. And it shows the procedure of applying the quotation change process to the quotation management system through the cases of each cause of the quotation change. In addition, in order to show the usefulness of the quotation change factors, the type of quotation change, the quotation change process, and the quotation system management, the proposed quotation change process and function was applied in the integrated quotation management system for the ship engine division of a typical make-to-order manufacturing company 'H'. As a result, it was confirmed that the proposed quotation change process and management system according to the quotation change factors were efficiently performed.

• Journal of KIISE:Databases
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• v.32 no.2
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• pp.151-160
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• 2005

As web pages are created, destroyed, and updated frequently, web databases should be updated to keep up-to-date web pages. In order to keep web databases fresh effectively, we need to understand the change of real web pages. Previous researches on the change of the web pages have directed their efforts on the contents modification of web pages only, and have not taken into account the factors of creation and destruction of web pages In their research. This paper investigates the web page changes, which include contents modification, page creation, and page destruction. We introduce three metrics, namely DR (Download Rate), MR (Modification Rate), and CAV (Coefficient of Age Variation) to represent the change of the web pages. We have monitored three million web pages collected from the famous and random sites every other day for one hundred days. With the Download Rate and the Modification Rate, we learned that the download success and the modification depends on the past change of them, and proposes two estimation formulae that predict the download success and modification. With the Coefficient of Age Variation, we show how web pages do not change periodically.

• The Journal of Society for e-Business Studies
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• v.9 no.1
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• pp.139-154
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• 2004

Recent business environments require a company to communicate frequently with other companies. This makes it essential to use XML (eXtensible Markup Language) documents for integration of information systems. Especially in e-Business environments, change management of documents is important to record and trace the history of the documents. In this paper, we propose a new method of storing a document by detecting changes automatically and reconstructing the document version when a user requests. In addition, based on the method, we also propose a model to recover a document into previous state even when system errors occur. A prototype system is implemented on top of a workflow system and an experiment is carried out to present efficiency of our method. Our approach provides efficiency of storage space and convenient management of documents.

• The Journal of Korean Association of Computer Education
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• v.7 no.1
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• pp.27-35
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• 2004

Software documents consist of a number of objects and relationships between them, and structure of documents can be changed frequently. In the existing software version management models, changes in one object may be propagated to other objects unnecessarily. In this paper, we propose an efficient version management model for software objects based on history of operations applied to software objects. Operations applied to objects are recorded in the operation history, and those are used to retrieve versions of a document. Because versions of objects are stored and retrieved using the operation delta, it is not required to compare versions of a document to extract delta during check-in process. In addition, it can manage changes of structure of objects efficiently because it supports not only object creation, deletion, and update operation but also object move operation.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.17 no.4
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• pp.885-892
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• 2013

In the model Utilizing the TCP / IP socket communication to transmit and receive data, if the size of data is small and if data-transmission aren't frequently requested, the importance of communication speed between a server and a client isn't emphasized. But nowadays, it has emerged for large amounts of data transfer requests and frequent data transfer request. This paper propose the TCP/IP communication model that can be improved the data transfer rate in multi-core environment by changing the receiving structure of the client to receive large amounts of data and the transmission structure of the server to send large amounts of data.

• Proceedings of the Korean Information Science Society Conference
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• 2004.10b
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• pp.202-204
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• 2004

최근 이동컴퓨팅(Mobile Computing) 환경에서의 잦은 접속 단절로 인한 클라이언트 캐시 일관성(consistency) 문제를 해결하기 위한 방법과 함께 통신 대역과 에너지의 제약을 고려한 연구가 진행되고 있다. 이러한 캐시 유지 방법의 한 분야로서 방송(Broadcasting)에 대한 연구가 진행 중이다. 그러나 기존의 무효화 보고에 대한 연구는 서버에서의 갱신 정도와 상관없이 전송되기 이전 일정 시간동안의 서버갱신에 대한 정보만을 포함한다. 이러한 전송기법은 다수의 클라이언트가 필요로 하면서 갱신정도가 빈번한 데이터에는 적합한 방송 방법이 아니다. 본 논문은 이 같은 단정을 보안하기 위해 자주 갱신되는 데이터의 빈도 수에 따라 데이터를 방송하고 클라이언트의 요청에 의해서 데이터 방송빈도 수를 변경하여 클라이언트가 특정 데이터의 응답시간을 최소화 할 수 있도록 하는 방안을 제시하였다.

• Annual Conference of KIPS
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• 2002.11c
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• pp.2297-2300
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• 2002

본 논문의 수신자들간의 일관성과 원자성을 보장하는 Concurrent Notification Service는 일반적인 Publish-and-Subscribe 모델의 Notification 서비스에서는 처리할 수 없었던 수신자를 예측하는 기능, 다른 수신자들이 허락하지 않은 송신자로부터의 메시지를 여과하는 기능, 원자성(Atomicity)을 지원하기 위하여 그룹 통신 시스템의 멤버쉽 관리 기법을 도입한다. 또한, 이동 인터넷 환경이나 원거리 통신에서와 같이 불안정한 네트워크 환경에서 자주 발생하는 서버와 수신자들간의 통신 단절로 인하여 발생할 빈번한 멤버쉽 변경과정의 부하를 줄일 수 있는 융통성 있는 멤버쉽 관리 알고리즘을 설계한다. 그리고, 서버 측 메시지 버퍼에서 서로 관계가 없는 메시지들의 병행 처리할 수 있도록 설계하여 처리 속도를 향상시킬 수 있다. 이를 통하여 응용 개발자는 수신자들의 일관성과 원자성을 보장하는 응용의 개발을 단순화할 수 있으며 동시에 고성능을 기대할 수 있다.

• Proceedings of the Korean Association of Geographic Inforamtion Studies Conference
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• 2006.05a
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• pp.78-83
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• 2006

선택율 추정은 질의 최적화를 위한 기법중의 하나이다. 이동객체에 대한 기존 선택율 추정 기법은 시간에 따른 빈번한 이동객체의 위치 변화를 요약 정보에 반영하지 못함으로써 선택 율 추정시 많은 에러를 발생시키고 있다. 따라서 이 논문에서는 이동객체의 질의에 대한 선택율 추정을 위한 색인 기반의 히스토그램 기법을 제안하였다. 또한 제안된 기법의 구현과 평가를 통 해 제안된 기법의 성능을 분석하였다. 이 논문에서 제안된 기법은 차량 추적 시스템, 위치 기반 서비스, 응급 구조 서비스, 그리고 텔레매틱스 서비스 통과 같은 연속적으로 위치를 변경하는 이동객체의 정보를 실시간으로 관리하고 검색하는 응용분야에 활용 가능할 것이다.