• Journal of Communications and Networks
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• 제3권4호
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• pp.307-316
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• 2001

Two hard sub-problems have emerged relating to the use of mobile agents for service management tasks. First, what is their impact on security, and second, how can they receive a flexible capacity to adapt to an open range of different environments on demand, without introducing trio stringent prior assumptions. In this paper, we present work towards solving the second problem, which is of particular interest to management software, because it typically needs to excert fine-grained and therefore particular resource control. We suggest a mechanism that reassembles mobile agents from smaller sub-components during arrival at each hop. The process incorporates patterns of unmutable and mutable sub-components, and is informed by the conditions of each local environment. We discuss different kinds of software adaptation and draw a distinction between static and continuous forms. Our software prototype for dynamic adaptation provides a concept far exchanging environment-dependent implementations of mobile agents during runtime. Dynamic adaptation enhances efficiency of mobile code in terms of bandwidth usage and scalability.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제13권1호
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• pp.291-304
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• 2019

This paper proposes a dynamic-tiling-based bandwidth-efficient (DTBE) virtual reality (VR) streaming scheme. We consider 360-degree VR contents with multiple view points such as the front, back, upper, and bottom sides. At a given time, the focus of a client is always bound to a certain view among multiple view points. By utilizing this perspective, under our proposed scheme, tiles with high encoding rates are selectively assigned to the focused view where multiple view points consist of multiple tiles with different encoding rates. The other tiles with low encoding rates are assigned to the remaining view points. Furthermore, for reducing view adaptation delay, we design a novel rapid view adaptation mechanism that selectively delivers an I-frame during view point updates by using frame indexing. We implement the proposed scheme on a commercial VR test bed where we adopt the MPEG media transport (MMT) standard with high-efficiency video coding (HEVC) tile modes. The measurement-based experiments show that the proposed scheme achieves an average data usage reduction of almost 65.2% as well as average view adaptation delay reduction of almost 57.7%.

• 한국군사과학기술학회지
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• 제13권5호
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• pp.852-860
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• 2010

An environment in which the software is operated become more complex and changed dynamically. Such software requires the ability to adapt in accordance with operating environments, by monitoring the changes of user requirements and operating environments. Especially, the mobile device used in military operation requires more dynamical adaptation than the mobile device in normal environment. In this paper, we propose MOSAIC architecture based on Self-Adaptive Software suitable for military mobile device and verify the results. The proposed architecture consists of context manager, evaluation manager and adaptation manager. We simulate the MOSAIC architecture by modelling PRE(Position Reporting Equipment) used in the army and verify four types of operational mode and dynamical reconfiguration of user interface.

• 한국정보시스템학회지:정보시스템연구
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• 제14권3호
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• pp.48-52
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• 2005

The Mobile agent-based distributed systems become obtaining significant popularity as a potential vehicle to allow software components to be executed on heterogeneous environments despite mobility of users and computations. However, as these systems generally force mobile agents to use only common functionalities provided in every execution environment, the agents may not access environment-specific resources. In this paper, we propose a new framework using Aspect Oriented Programming technique to accommodate a variety of static resources as well as dynamic ones whose amount is continually changed at runtime even in the same execution environment. Unlike previous works, this framework divides roles of software developers into three groups to relieve application programmers from the complex and error prone parts of implementing dynamic adaptation and allowing each developer to only concentrate on his own part. Also, the framework enables policy decision makers to apply various adaptation policies to dynamically changing environments for adjusting mobile agents to the change of their resources.

• 한국정보과학회논문지:소프트웨어및응용
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• 제31권10호
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• pp.1320-1331
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• 2004

동영상 어댑테이션 시스템은 네트워크 제약, 클라이언트 제약 등을 만족하면서, 동영상의 품질이 최대가 되도록 동영상을 변환해 주는 시스템을 말한다. 본 논문에서는 정적으로 중간 동영상과 품질측정에 관한 정보를 생성해두는 준-동적 어댑테이션 시스템을 제안한다. 중간 동영상은 원본 동영상의 해상도를 반으로 줄여가며 생성되어, 서버에 저장된다. 품질 측정에 관한 정보는 프레임 율 별 부드러운 정도의 수치와, 픽셀 당 비트 량 별 선명한 정도의 수치에 대한 테이블을 정적으로 생성해 둔 것이다. 이런 중간 결과물들은 클라이언트에서의 서비스 품질을 고려하며 동적으로 동영상을 변환 할 때 가능한 빠르게 동영상 변환이 수행될 수 있도록 해준다. 실험 결과 제안된 어댑테이션 시스템은 기존의 동적 어댑테이션 시스템에 비해 약 30배정도 빠르게 어댑테이션을 수행하는 반면, 약 2%정도의 품질 저하가 있었고 중간동영상을 저장하기 위한 추가적인 서버공간이 필요하다는 것을 확인 할 수 있었다.

• 한국정보과학회:학술대회논문집
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• 한국정보과학회 2005년도 한국컴퓨터종합학술대회 논문집 Vol.32 No.1 (B)
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• pp.406-408
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• 2005

실행 환경 및 상황에 맞게 스스로 소프트웨어의 구성과 서비스를 변경시키기 위한 적응형 소프트웨어의 개발을 위해서는 변경 대상 및 변경 기법의 정의가 중요하다. 본 논문에서는 소프트웨어의 구성요소 및 기능을 실시간에 변경하기 위해 제품계열 방법에서 주로 사용되는 Information Hiding 기반의 가변성 관리 기법과 Parameterization 기반의 가변성 관리기법을 사용한다. 두 방법을 사용하면 실행 과정에 영향을 주지 않으면서 소프트웨어의 구성요소를 변경하거나 특성을 customizing할 수 있다.

• 산업공학
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• 제11권2호
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• pp.1-11
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• 1998

In this paper, a case study is introduced on the development on a production planning system for the efficient control of work-in-process material flows. A special attention has been given to the prevention of the shortage of the automobile-components at the auto-assembly lines and the dynamic adaptation of the production plan to the continuously changing environment. The expertise of the production planner is analyzed and transformed into the logic of the software developed.

• 정보처리학회논문지:소프트웨어 및 데이터공학
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• 제4권3호
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• pp.111-120
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• 2015

최근 동적인 환경에서 발생하는 다양한 문제를 스스로 해결할 수 있는 자가 적응 시스템에 대한 연구가 활발히 이루어지고 있다. 자가 적응 시스템에서 시스템이 문제를 스스로 인식하고 자가 적응할 수 있도록 요구사항을 설계하는 과정은 필수적이며, 만약 기존의 적응 전략들을 재사용하여 자가 적응 시스템을 설계한다면 소요되는 시간 및 비용을 절감할 수 있다. 따라서 이 논문은 새로운 자가 적응 시스템 개발 시 기존의 자가 적응 시스템으로부터 재사용 가능한 적응 전략을 추출하는 시스템을 제안한다. 이를 위하여 자가 적응 요소를 지식화하여 적응 전략 온톨로지 및 타깃 시스템 온톨로지를 정의하고, 이러한 온톨로지를 기반으로 재사용 가능한 적응 전략을 추출하는 기법을 기술한다. 또한, 이 논문은 제안 시스템을 구현하고 추출된 적응 전략에 대한 재사용률을 측정함으로써 제안 시스템을 비교 평가한다. 평가 결과, 제안 시스템은 추출된 적응 전략이 정확히 동작함을 보이며 제안 시스템의 추출 기법은 기존의 재사용 기법보다 높은 재사용률을 보인다.

• 한국시뮬레이션학회논문지
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• 제11권3호
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• pp.23-34
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• 2002

Dynamic storage allocation (DSA) is a field fairly well studied for a long time as a basic problem of system software area. Due to memory fragmentation problem of DSA and its unpredictable worst case execution time, real-time system designers have believed that DSA may not be promising for real-time application service. Recently, the need for an efficient DSA algorithm is widely discussed and the algorithm is considered to be very important in the real-time system. This paper proposes an efficient DSA algorithm called QSB (quick semi-buddy) which is designed to be suitable for real-time environment. QSB scheme effectively maintains free lists based on quick-fit approach to quickly accommodate small and frequent memory requests, and the other free lists devised with adaptation upon a typical binary buddy mechanism for bigger requests in harmony for the .improved performance. Comprehensive simulation results show that the proposed scheme outperforms QHF which is known to be effective in terms of memory fragmentation up to about 16%. Furthermore, the memory allocation failure ratio is significantly decreased and the worst case execution time is predictable.

• 경영과학
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• 제12권3호
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• pp.1-15
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• 1995

The Pusan Container Terminal faces a rapid increase in berthing time of container ships as well as in waiting time of external trucks, which is due to an absolute lack of yard space. This research is focused on the development of a decision support system for the planning of the container terminal yard assignment so that the yard space would be utilized most effectively. Efforts should be given to the reasonable assignment of the yard storage and the dynamic adaptation to the ever changing environment. The software introduced here is based on the know-how of the field exports and its framework takes the approach of the hierarchical decision making.