• 한국CDE학회논문집
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• 제15권1호
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• pp.11-23
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• 2010

A flexible and correct model of the activity flows is required for workflows in product development environments. In particular, the design activity flows are not known until run-time, and conventional approaches have limit to handle this situation because they cannot predefine all the potentially reachable paths. Thus, the structure of the workflow model must be flexible enough to describe variety in workflow design and accommodate dynamic changes during workflow execution. In this paper, we provide the general primitive axioms and change patterns based on event calculus for dynamic workflow specification and execution mechanisms in product development environments. Also, we describe how to execute the workflow dynamically based on the workflow specification and workflow change patterns using abductive planning technique.

• Journal of Computing Science and Engineering
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• 제6권2호
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• pp.89-104
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• 2012

In dynamic Web service environments, the performance of the Internet is unpredictable; the reliability and effectiveness of remote Web services are also unclear. Therefore, it can hardly be guaranteed that the quality of Web service (QoWS) attributes of Web services do not fluctuate with the dynamic Web service environments. When a composite service is planned in the context of dynamic service environments, there is another aspect which has not been taken into account by existing works, namely, concurrency - the fact that multiple requests to a composite service may arrive at the same time. Considering the dynamics of Web service environments and concurrency of requests, we propose in this paper a service selection scheme which adopts top-k dominating queries to generate a composition solution rather than only select the best composition solution for a given request. The experimental results have investigated the efficiency and effectiveness of our approach and shown that it outperforms baseline and traditional methods for service selection.

• 전자공학회논문지SC
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• 제37권2호
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• pp.16-28
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• 2000

In this paper, we propose a navigation algorithm for a mobile robot, which is intelligently searching the goal location in unknown dynamic environments using an ultrasonic sensor. Instead of using "sensor fusion"method which generates the trajectory of a robot based upon the environment model and sensory data, "command fusion"method is used to govern the robot motions. The major factors for robot navigation are represented as a cost function. Using the data of the robot states and the environment, the weight value of each factor is determined for an optimal trajectory in dynamic environments. For the evaluation of the proposed algorithm, we peformed simulations in PC as well as real experiments with ZIRO. The results show that the proposed algorithm is apt to identify obstacles in unknown environments to guide the robot to the goal location safely.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2003년도 ICCAS
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• pp.1921-1926
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• 2003

We build a local minimum free motion planning for mobile robots considering dynamic environments by simple sensor fusion assuming that there are unknown obstacles which can be detected only partially at a time by proximity sensors and can be cleaned up or moved slowly (dynamic environments). Potential field is used as a basic platform for the motion planning. To clear local minimum problem, the partial information on the obstacles should be memorized and integrated effectively. Sets of linked line segments (SLLS) are proposed as the integration method. Then robot's target point is replaced by virtual target considering the integrated sensing information. As for the main proximity sensors, we use laser slit emission and simple web camera since the system gives more continuous data information. Also, we use ultrasonic sensors as the auxiliary sensors for simple sensor fusion considering the advantages in that they give exact information about the presence of any obstacle within certain range. By using this sensor fusion, the dynamic environments can be dealt easily. The performance of our algorithm is validated via simulations and experiments.

• 대한수학교육학회지:학교수학
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• 제15권2호
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• pp.481-501
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• 2013

본 연구는 역동기하 환경에서 "끌기"의 역할을 고찰하고자 한다. 끌기는 도형을 역동적으로 변화시키면서 기하 도형의 숨겨진 성질과 이들 사이의 관계를 나타내는 불변성을 탐색 가능하게 하는 중요한 역할을 한다. 따라서 본 연구는 선행 연구의 분석을 통해 역동기하 환경에서 끌기의 사용이 세 가지 관점으로, 즉 역동적 표상, 도구유발행위, 그리고 어포던스로 구분될 수 있다는 결론을 도출하였다. 본 연구에서는 끌기의 사용에 대한 이들 각각의 관점을 선행 연구를 중심으로 살펴보았다. 그리고 이로부터 (1) 연역적, 공리적, 형식적 지필기하를 실험수학으로 접근할 수 있게 하는 끌기의 가능성 탐구, (2) 추측과 증명 사이에서 끌기의 유형에 따른 작용 분석, (3) 학생과 DGS 사이의 도구발생 과정에 따른 기하 학습의 차이 분석, (4) 끌기에 의한 의사소통이나 담화 유형의 분석, (5) 어포던스로서 끌기에 의해 수반되는 측정 기능의 역할 분석, 그리고 (6) 끌기에 의한 기하 개념의 정의에 대한 학생들의 인식론적 변화를 기하의 교수-학습과 후속연구를 위한 제언으로 제시하고 있다.

• 대한기계학회논문집A
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• 제39권6호
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• pp.549-559
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• 2015

본 논문에서는 동적 움직임을 갖는 장애물이 위치한 주행환경에서 이동로봇의 충돌회피 기능을 포함하는 효율적인 반응경로계획 기법을 제안하고자 한다. 로봇의 동적 장애물과의 충돌회피 기능을 위해서 반응경로계획기법을 기반으로 키넥트센서를 이용한 센서융합기법의 보완을 통해서 자율주행의 강건성을 증대시키고자 하였다. 반응경로기법에서 사용된 접근방식은 동적장애물을 가상좌표평면에서 지역관측기개념을 이용하여 정적장애물로 좌표변환을 가능하게하며, 생성된 가상평면에서의 로봇과 장애물의 충돌 발생 가능한 속도와 경로의 운동학적 정보추출이 가능하게 된다. 또한 키넥트 센서 정보를 융합하여 장애물의 방향과 위치 정보를 추정하여 동적 환경에서의 주행성능의 정미도를 증대시키고자 하였다. 본 연구에서 제안 기술의 성능을 검증하기 위해서 임베디드 로봇플랫폼과 여러 개의 동적 장애물을 이용하여 시뮬레이션 해석 및 실험을 수행하였다.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1988년도 한국자동제어학술회의논문집(국내학술편); 한국전력공사연수원, 서울; 21-22 Oct. 1988
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• pp.658-662
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• 1988

The performance of a strapdown attitude reference system(SDARS) under dynamic environments was analyzed by means of computer simulation. The study is aimed toward the performance evaluation in the presence of translational or angular vibration during 20 sec of flight time. The simulation was based on the error model of rate gyro, and Euler angle algorithm was employed to compute the attitude.

• 한국IT서비스학회지
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• 제9권3호
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• pp.163-178
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• 2010

A service composition has received much interest to provide users with the ad-hoc, seamless, and context-sensitive services dynamically composed from various networked services in context-aware computing environments. In this paper, with the purpose of guiding trends in the researches for dynamic service composition technologies, we investigate and analyze the major related works. For this, we separate semantic based composition from syntax based composition and then establish the comparison criteria by dividing the service composition processes into 3 steps：definition, construction, and execution.

• ETRI Journal
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• 제37권2호
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• pp.369-379
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• 2015

Fault management of virtualized network environments using user-driven network provisioning systems (NPSs) is crucial for guaranteeing seamless virtual network services irrespective of physical infrastructure impairment. The network service interface (NSI) of the Open Grid Forum reflects the need for a common standard management API for the reservation and provisioning of user-driven virtual circuits (VCs) across global networks. NSI-based NPSs (that is, network service agents) can be used to compose user-driven VCs for mission-critical applications in a dynamic multi-domain. In this article, we first attempt to outline the design issues and challenges faced when attempting to provide mission-critical applications using dynamic VCs with a protection that is both user-driven and trustworthy in a dynamic multi-domain environment, to motivate work in this area of research. We also survey representative works that address inter-domain VC protection and qualitatively evaluate them and current NSI against the issues and challenges.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1997년도 한국자동제어학술회의논문집; 한국전력공사 서울연수원; 17-18 Oct. 1997
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• pp.1816-1819
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• 1997

Using the vision system, robotic tasks in unstructured environments can be accompished, which reduces greatly the cost and steup time for the robotic system to fit to he well-defined and structured working environments. This paper proposes a dynamic control scheme for robot manipulator with eye-in-hand camera configuration. To perfom the tasks defined in the image plane, the camera motion Jacobian (image Jacobian) matrix is used to transform the camera motion to the objection position change. In addition, the dynamic learning controller is designed to improve the tracking performance of robotic system. the proposed control scheme is implemented for tasks of tracking moving objects and shown to outperform the conventional visual servo system in convergence and robustness to parameter uncertainty, disturbances, low sampling rate, etc.