• KIPS Transactions on Computer and Communication Systems
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• v.4 no.3
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• pp.85-90
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• 2015

In this paper, anew parallel event-driven logic simulation is proposed. As the proposed prediction-based parallel event-driven simulation method uses both prediction data and actual data for the input and output values of local simulations executed in parallel, the synchronization overhead and the communication overhead, the major bottleneck of the performance improvement, are greatly reduced. Through the experimentation with multiple designs, we have observed the effectiveness of the proposed approach.

• KIPS Transactions on Computer and Communication Systems
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• v.8 no.3
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• pp.57-64
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• 2019

In this paper, an efficient prediction-based parallel simulation method using spatially partial simulation strategy is proposed for improving both the performance of the event-driven gate-level timing simulation and the debugging efficiency. The proposed method quickly generates the prediction data on-the-fly, but still accurately for the input values and output values of parallel event-driven local simulations by applying the strategy to the simulation at the higher abstraction level. For those six designs which had used for the performance evaluation of the proposed strategy, our method had shown about 3.7x improvement over the most general sequential event-driven gate-level timing simulation, 9.7x improvement over the commercial multi-core based parallel event-driven gate-level timing simulation, and 2.7x improvement over the best of previous prediction-based parallel simulation results, on average.

• KIPS Transactions on Computer and Communication Systems
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• v.4 no.5
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• pp.147-152
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• 2015

In general, there are two synchronization methods in parallel event-driven simulation, pessimistic approach and optimistic approach. In this paper, we propose a new approach, sporadic synchronization combining both for prediction-based parallel event-driven logic simulation. We claim this hybrid solution is pretty effective to minimize both checkpoint overhead and restart overhead, which are related problems with frequent false predictions for improving the performance of the prediction-based parallel event-driven logic simulation. The experiment has clearly shown the advantage of the proposed approach.

• KIPS Transactions on Computer and Communication Systems
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• v.5 no.12
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• pp.439-446
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• 2016

In this paper, an efficient prediction accuracy enhancement strategy is proposed for improving the performance of the prediction-based parallel event-driven gate-level timing simulation. The proposed new strategy adopts the static double prediction and the dynamic prediction for input and output values of local simulations. The double prediction utilizes another static prediction data for the secondary prediction once the first prediction fails, and the dynamic prediction tries to use the on-going simulation result accumulated dynamically during the actual parallel simulation execution as prediction data. Therefore, the communication overhead and synchronization overhead, which are the main bottleneck of parallel simulation, are maximally reduced. Throughout the proposed two prediction enhancement techniques, we have observed about 5x simulation performance improvement over the commercial parallel multi-core simulation for six test designs.

• KIPS Transactions on Computer and Communication Systems
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• v.3 no.3
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• pp.73-80
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• 2014

In this paper, we propose an incremental simulation method in event-driven HDL simulation to reduce the simulation execution time. In general, the simulation is repeated with a series of design changes. Incremental simulation is an efficient simulation method that shortens the simulation execution time for the following simulation by using the result of previous simulation. We have observed the effectiveness of the proposed approach through the experimentation with multiple real designs.

• Proceedings of the KIEE Conference
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• 2008.10b
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• pp.93-94
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• 2008

로봇을 개발함에 있어 많이 겪는 어려움 중 하나는 열악한 시뮬레이션 환경 및 소프트웨어 개발이다. Microsoft사(社)의 MSRDS(Microsoft Robotics Developer Studio)는 3D시뮬레이션 환경과 로봇 구동을 위한 각종 표준화된 서비스들을 지원함으로써 이러한 문제점들을 해결할 수 있다. 본 논문에서는 원자력 발전소의 중 저준위 폐기물 저장창고 검사 로봇을 대상으로 MSRDS를 이용하여 3D 시뮬레이션 및 온라인 피드백 제어를 수행하였다. 로봇은 사륜으로 이루어져 있으며, 주행 환경 확인을 위한 카메라, 장애물 감시용 LRF(Laser Range Finer)센서, 주변 환경 감지를 위한 온도센서, 습도센서 및 MSRDS가 장착된 산업용 3D가 탑재되어 있다. MSRDS의 제어신호는 이벤트로 생성되어 3D 시뮬레이션 렌더링 시간과 동기화되며, Brick 서비스를 통해 전송된다. 피드백은 10ms 주기로 LRF 센서, Motor 엔코더 값을 받아 3D 시뮬레이션에 반영된다. 본 논문에서는 MSRDS의 시뮬레이션 및 실제 로봇과의 동기화 방식을 제시하며 구동 실험으로 검증하였다.

• Journal of Advanced Navigation Technology
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• v.24 no.3
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• pp.184-191
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• 2020

Avionics System Integration Laboratory is the integrated test environment for integration and verification of avionics systems. When real equipment can not be used in the laboratory for various reasons, software models should be needed. Because there hasn't been any standardized method for the models so that it is difficult to reuse the developed models, the need for a framework to develop the avionics software models was emerged. We adopted DEVS(discrete event system specification) formalism as the standardized modeling method for the avionics software models. Due to DEVS formalism is based on event-driven algorithm, it doesn't accord a legacy system which has sequential and periodic algorithms. In this paper, we propose real-time event-driven modeling and simulation method for SIL to overcome these restrictions and to maximize reusability of avionics models through the analysis of the characteristics and the limitations of avionics models.

• Proceedings of the Korea Multimedia Society Conference
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• 2000.04a
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• pp.414-417
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• 2000

본 논문에서는 클라이언트/서버 형태로 긴급 이벤트 자동 호출 기능을 처리할 수 있는 원격제어 시스템을 설계하고 구현하였다. 웹 애플릿을 기반으로 구현된 클라이언트 시스템은 상황실에 위치하여 직접적으로 제어를 담당하는 서버에게 원격제어 명령을 내린다. 제어 명령은 서버시스템으로 전달되며, 서버시스템에 존재하는 구동기가 실질적으로 컨베이어 시스템을 제어하는 기능을 가진다. 여기서 컨베이어 시스템은 승용차 조립라인을 시뮬레이션 한 것이다. 이러한 원격제어 시스템에 이동 통신의 문자서비스를 이용하여 긴급한 상황을 자동으로 원격지에 있는 관리자에게 알려주는 기능까지 확대시켰다. 관리자는 원격 시스템을 항상 감시할 필요가 없이 어느 장소에서나 상황보고를 받을 수 있다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.37C no.11
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• pp.1170-1181
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• 2012

Wireless Sensor Networks(WSNs) are used in diverse applications. In general, sensor nodes that are easily deployed on specific areas have many resource constrains such as battery power, memory sizes, MCUs, RFs and so on. Hence, first of all, the efficient energy consumption is strongly required in WSNs. In terms of event states, event-driven deliverly model (i.e. surveillance and reconnaissance applications) has several characteristics. On the basis of such a model, clustering algorithms can be mostly used to manage sensor nodes' energy efficiently owing to the advantages of data aggregations. Since a specific node collects packets from its child nodes in a network topology and aggregates them into one packet to relay them once, amount of transmitted packets to a sink node can be reduced. However, most clustering algorithms have been designed without considering can be reduced. However, most clustering algorithms have been designed without considering characteristics of event-driven deliverly model, which results in some problems. In this paper, we propose enhanced clustering algorithms regarding with both targets' movement and energy efficiency in order for applications of surveillance and reconnaissance. These algorithms form some clusters to contend locally between nodes, which have already detected certain targets, by using a method which called CHEW (Cluster Head Election Window). Therefore, our proposed algorithms enable to reduce not only the cost of cluster maintenance, but also energy consumption. In conclusion, we analyze traces of the clusters' movements according to targets' locations, evaluate the traces' results and we compare our algorithms with others through simulations. Finally, we verify our algorithms use power energy efficiently.

• Proceedings of the Korea Information Processing Society Conference
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• 2000.04a
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• pp.704-710
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• 2000

본 논문에서는 클라이언트/서버 형태로 긴급 이벤트 자동 호출 기능을 처리할 수 있는 원격제어 시스템을 설계하고 구현하였다. 웹 애플릿을 기반으로 구현된 클라이언트 시스템은 상황실에 위치하여 직접적으로 제어를 담당하는 서버에게 원격 제어 명령을 내린다. 제어 명령은 서버시스템으로 전달되며, 서버시스템에 존재하는 구동기가 실질적으로 컨베이어 시스템을 제어하는 기능을 가진다. 여기서 컨베이어 시스템은 승용차 조립라인을 시뮬레이션 한 것이다. 이러한 원격제어 시스템에 이동 통신의 문자서비스를 이용하여 긴급한 상황을 자동으로 원격지에 있는 관리자에게 알려주는 기능까지 확대시켰다. 관리자는 원격 시스템을 항상 감시할 필요가 없이 어느 장소에서나 상황보고를 받을 수 있게 된다.