• 인터넷정보학회논문지
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• 제2권5호
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• pp.59-70
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• 2001

최근 다양한 분야에서 XML이 인터넷상에서 정보교환의 표준으로 자리잡아 가고 있다. 따라서 그동안 XML 문서를 데이터베이스에 저장하고 검색하기 위한 데이터 모델링에 관한 연구가 활발히 진행되어 왔다. 그러나 기존의 연구들은 동적 환경에서 문서 변경 시 버전을 지원하면서 빠른 문서 검색을 효율적으로 지원하지 못하는 단점이 있다. 본 논문에서는 XML 저장 관리시스템에서 사용되고 있는 비분할 모델과 분할 모델의 장점들을 수용하여 동적 환경에 적합한 혼합 모델링 방법 4가지를 제안한다. 또한 시뮬레이션을 통하여 제안한 혼합형 모델링 기법의 우수성을 보인다. 이를 통해 다양한 동적 응용에 적합한 데이터 모델링을 제시하고자 한다.

• Journal of Astronomy and Space Sciences
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• 제27권4호
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• pp.377-382
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• 2010

In lunar explorer development program, computer simulator is necessary to provide virtual environments that vehicle confronts in lunar transfer, orbit, and landing missions, and to analyze dynamic behavior of the spacecraft under these environments. Objective of simulation differs depending on its application in spacecraft development cycle. Scope of use cases considered in this paper includes simulation of software based, processor and/or hardware in the loop, and support of ground-based flight test of developed vehicle. These use cases represent early phase in development cycle but reusability of modeling results in the next design phase is considered in defining requirements. A simulator architecture in which simulator platform is located in the middle and modules for modeling, analyzing, and three dimensional visualizing are connected to that platform is suggested. Baseline concepts and requirements for simulator development are described. Result of trade study for selecting simulation platform and approaches of defining other simulator components are summarized. Finally, characters of lunar elevation map data which is necessary for lunar terrain generation is described.

• Journal of Information Processing Systems
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• 제7권2호
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• pp.287-298
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• 2011

Efficient service description and modeling methodologies are essential for dynamic service composition to provide autonomous services for users in ubiquitous computing environments. In our previous research, we proposed a 'u-service' ontology which is an abstract and structured concept for device operations in ubiquitous environments. One of the problems that we faced during the design process was that there are not enough standards to analyze the effectiveness of a u-service ontology. In this paper, we propose a quality evaluation model to facilitate the design process of a uservice ontology. We extract modeling goals and evaluation indicators based on the uservice description specification. We also present quality metrics to quantify each of the design properties. The experiment result of the proposed quality model shows that we can use it to analyze the design of u-service ontology from various angles. Also, it shows that the model can provide a guideline, and offer appropriate recommendations for improvements.

• 한국문헌정보학회지
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• 제44권4호
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• pp.131-153
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• 2010

The fusion of learning, information, and technology presents dynamic challenges for all librarians, educators and students in 21st century libraries and schools. At the heart of this fusion is the growth of a pervasive, integrated information environment characterized by vast quantities of digital content, open choice, collaborative and participatory digital spaces, and the transition of the web environments from consumption of information to creation of information. This environment heralds important opportunities for librarians and teachers to rethink, re-imagine and recreate a dynamic approaches to information literacy instruction. Drawing on an extensive body of research undertaken through the Center for International Scholarship in School Libraries (CISSL), and published research on both information literacy and constructivist learning, this paper provides a critical examination of the current status of information literacy: its multiple conceptualizations, competing models, viewpoints, and its operationalizations in educational and library environments. The paper will challenge information literacy practices which center on simplistic, reductionist approaches to information literacy development, and the separation of information process and knowledge content. In particular it will address apparent contradictions in espoused conceptions of information literacy which revolve around "knowledge": knowledge construction, critical thinking, problem solving and the development of knowledgeable people; and information literacy practices which revolve around "information": a predominant focus on skills of access and evaluation of resources and with less attention given to engaging with found information to develop deep knowledge and understanding. The paper will present a series of challenges for moving forward with information literacy agendas in libraries and schools.

• Journal of Communications and Networks
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• 제13권6호
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• pp.583-590
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• 2011

Full-mesh IPSec tunnels pass through a black ("unsecure") network (B-NET) to any red ("secure") networks (RNETs). These are needed in military environments, because they enable dynamically changing R-NETs to be reached from a BNET. A dynamically reconfiguring security policy database (SPD) is very difficult to manage, since the R-NETs are mobile. This paper proposes advertisement process technologies in association with the tunnel gateway's protocol that sends 'hello' and 'prefix advertisement (ADV)' packets periodically to a multicast IP address to solve mobility and security issues. We focus on the tunnel gateway's security policy (SP) adaptation protocol that enables R-NETs to adapt to mobile environments and allows them to renew services rapidly soon after their redeployment. The prefix ADV process enables tunnel gateways to gather information associated with the dynamic changes of prefixes and the tunnel gateway's status (that is, 'down'/restart). Finally, we observe two different types of performance results. First, we explore the effects of different levels of R-NET movements on SP adaptation latency. Next, we derive the other SP adaptation latency. This can suffer from dynamic deployments of tunnel gateways, during which the protocol data traffic associated with the prefix ADV protocol data unit is expected to be severe, especially when a certain tunnel gateway restarts.

• 정보처리학회논문지A
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• 제12A권6호
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• pp.477-484
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• 2005

유비쿼터스 환경에서의 응용은 사용자의 요구사항 변경과 사용자의 서비스 환경 변화를 적응시킴으로써 사용자에게 최선의 서비스를 제공할 수 있어야 하며 상황 변화에 따른 하부 플랫폼의 동작에 서비스의 동작을 적응시킬 수 있어야 한다. 본 논문에서는 유비쿼터스 컴퓨팅 환경에서 사용자의 요구사항을 능동적으로 반영하고 사용자에게 유연한 서비스를 제공하기 위하여 상황 변화에 대한 동적인 응용 적응성을 지원하는 2-레벨 상황 적응 기법을 제안한다. 상황 적응성을 지원하기 위하여 상황의 범위를 사용자 요구사항으로 확대하여 응용 서비스 제공에 있어서 사용자의 선호도를 반영할 수 있도록 하였으며. 응용의 적응성은 적응 정책을 사용하여 발생할 수 있는 특정 상황에 대한 적응 방법을 명시적으로 요구함으로써 실제 상황이 발생했을 때 응용이 능동적으로 대처할 수 있도록 하였다.

• 전기학회논문지
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• 제64권10호
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• pp.1479-1485
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• 2015

Robot's technology was very simple and repetitive in the past. Nowadays, robots are required to perform intelligent operation. So, path planning has been studied extensively to create a path from start position to the goal position. In this paper, potential field algorithm was used for path planning in dynamic environments. It is used for a path plan of mobile robot because it is elegant mathematical analysis and simplicity. However, there are some problems. The problems are collision risk, avoidance path, time attrition. In order to resolve path problems, we amalgamated potential field algorithm with the artificial neural network system. The input of the neural network system is set using relative velocity and location between the robot and the obstacle. The output of the neural network system is used for the weighting factor of the repulsive potential function. The potential field algorithm problem of mobile robot's path planning can be improved by using artificial neural network system. The suggested algorithm was verified by simulations in various dynamic environments.

• 드라이브 ㆍ 컨트롤
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• 제20권2호
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• pp.24-30
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• 2023

This study aimed to analyze the fatigue of forklifts in industrial settings by assessing their stress levels during operation. Strain gauges were affixed to the dynamic components of the forklifts to gather real-time data and enhance the reliability of the analysis. Although monitoring structural loads in harsh testing environments can be challenging, the affixed strain gauges on the dynamic components can provide more precise results and improve the interpretation of data. By creating testing modes that simulate forklift usage environments and performing experiments with selected cargo and driving modes, a comparison of the damage severity of forklift parts under different driving conditions was done. These results can be utilized to forecast the lifespan of forklift parts under extreme driving conditions and assist in the design and optimization of new parts in the future.

• ETRI Journal
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• 제25권1호
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• pp.25-33
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• 2003

This paper describes interactive dynamic simulation schemes for articulated bodies in virtual environments, where user interaction is allowed through a haptic interface. We incorporated these schemes into our dynamic simulator I-GMS, which was developed in an object-oriented framework for simulating motions of free bodies and complex linkages, such as those needed for robotic systems or human body simulation. User interaction is achieved by performing push and pull operations with the PHANToM haptic device, which runs as an integrated part of I-GMS. We use both forward and inverse dynamics of articulated bodies for the haptic interaction by the push and pull operations, respectively. We demonstrate the user-interaction capability of I-GMS through on-line editing of trajectories for 6-dof (degrees of freedom) articulated bodies.

• 제어로봇시스템학회논문지
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• 제8권9호
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• pp.757-763
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• 2002

A newly designed haptic interface enables an operator to control a remote robot precisely. It transmits position information to the remote robot and feeds back the interaction force from it. A control algorithm of haptic interface has been studied to improve the robustness and stability to uncertain dynamic environments with a proposed contact dynamic model that incorporates human hand dynamics. A simplified hybrid parallel robot dynamic model fur a 6 DOF haptic device was proposed to from a real time control system, which does not include nonlinear components. LQC/LTR scheme was adopted in this paper for the compensation of un-modeled dynamics. The recovery of the farce from the remote robot at the haptic interface was demonstrated through the experiments.