• 한국시뮬레이션학회논문지
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• 제8권1호
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• pp.113-138
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• 1999

Driven by the explosive expansion and acceptance of the Internet and its multimedia front-end, the Web, a new generation of the modeling and simulation tools have come up with the name of Web-Based Simulation (WBS). Most of WBS libraries inherit its powerful advantages from Java. However, there are cases where explicit specification of models or interface objects is more desirable than the black-box programs. This paper presents an XML-based DEVS (Discrete Event System Specification) markup language for sharing simulation models on the Web. DEVS provides a system-theoretic formalism for the language while XML supports platform-independent data access. This paper focuses on the design of such a language.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제6권10호
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• pp.2473-2492
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• 2012

Energy conservation is a vital issue in wireless sensor networks. Recently, employing mobile sinks for data gathering become a pervasive trend to deal with this problem. The sink can follow stochastic or pre-defined paths; however the controlled mobility pattern nowadays is taken more into consideration. In this method, the sink moves across the network autonomously and changes its position based on the energy factors. Although the sink mobility would reduce nodes' energy consumption and enhance the network lifetime, the overhead caused by topological changes could waste unnecessary power through the sensor field. In this paper, we proposed EEDARS, an energy-efficient dual-sink algorithm with role switching mechanism which utilizes both static and mobile sinks. The static sink is engaged to avoid any periodic flooding for sink localization, while the mobile sink adaptively moves towards the event region for data collection. Furthermore, a role switching mechanism is applied to the protocol in order to send the nearest sink to the recent event area, hence shorten the path. This algorithm could be employed in event-driven and multi-hop scenarios. Analytical model and extensive simulation results for EEDARS demonstrate a significant improvement on the network metrics especially the lifetime, the load and the end-to-end delay.

• 한국통신학회논문지
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• 제38B권10호
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• pp.824-831
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• 2013

델타 구동 GMSK는 바이폴라 델타 신호로 가우시안 펄스를 생성하고 $+T_b/2$와 $-T_b/2$ 사이의 차분 신호로 위상변조하는 방식이다. 이러한 방식에 대한 복조는 기존의 GMSK와는 다르게 설계해야 한다. 본 논문에서는 인접한 비트 간의 위상 변화를 검출하고 위상 영역을 경판정한 다음에 상태 전이로 이진 데이터를 복원하는 방식을 설계하였다. AWGN 채널에 대한 전산모의실험 결과, 이진 데이터의 런 랭스에 의한 비트 오율의 영향이 확인되었으며, 이론적인 코히어런트 복조의 BER과 비교해서 $BT_b$=0.3에 대하여 2[dB] 정도의 성능 저하가 있는 것으로 분석되었다.

• 한국방사성폐기물학회:학술대회논문집
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• 한국방사성폐기물학회 2005년도 Proceedings of The 6th korea-china joint workshop on nuclear waste management
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• pp.76-85
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• 2005

The conceptual study of Accelerator Driven System (ADS) had lasted for about five years and ended in 1999 in China. As one project of 'the major state basic research program (973)' in energy domain, which is sponsored by the China Ministry of Science and Technology (MOST), a five years program of basic research for ADS physics and related technology has been launched since 2000 and passed national review last month. CIAE (China Institute of Atomic Energy), IHEP (Institute of High Energy Physics), PKU-IHIP (Institute of Heavy Ion Physics in Peking University) and other institutions are jointly carrying on the research. The research activities are focused on HPPA physics and technology, reactor physics of external source driven sub-critical assembly, nuclear data base and material study. For HPPA, a high current injector consisting of an ECR ion source, LEBT and a RFQ accelerating structure of 3.5MeV has been built. In reactor physics study, a series of neutron multiplication experimental study has been carried out and is being carrying on. The VENUS facility has been constructed as the basic experimental platform for the neutronics study in ADS blanket. It's a zero power sub-critical neutron multiplying assembly driven by external neutron produced by a pulsed neutron generator. The theoretical, experimental and simulation study on nuclear data, material properties and nuclear fuel circulation related to ADS is carrying on to provide the database for ADS system analysis. The main results on ADS related researches will be reported.

• 한국전산유체공학회지
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• 제14권3호
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• pp.115-122
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• 2009

Numerical methods are applied to simulate the smoke behavior in a ventilated tunnel using large eddy simulation (LES) which is incorporated in FDS (Fire Dynamics Simulator) with proper combustion and radiation model. In this study, present numerical results are compared with data obtained from experiments on pool fires in a ventilated tunnel. The model tunnel is $182m(L){\times}5.4m(W){\times}2.4m(H)$. Two fire scenarios with different ventilation rates are considered with two different fire strengths. The present results are analyzed with those from LES without combustion and radiation model and from RANS ($\kappa-\epsilon$) model as well. Temperature distributions caused by fire in tunnel are compared with each other. It is found that thermal stratification and smoke back-layer can be predicted by FDS and the temperature predictions by FDS show better results than LES without combustion and radiation model. The FDS solver, however, failed to predict correct flow pattern when the high ventilation rate is considered in tunnel because of the defects in the tunnel-inlet turbulence and the near-wall turbulence.

• 한국게임학회 논문지
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• 제6권4호
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• pp.63-70
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• 2006

본 논문에서는 모바일 3D 그래픽 가속기의 텍스쳐 데이터 메모리 지연시간을 감소하기 위해 사용하는 텍스쳐 캐쉬의 다양한 저전력 구조를 고찰하였다. 또한 텍스쳐 필터링 알고리즘에 따라서 가변적 전력 모드 전환 기준을 갖는 텍스쳐 캐쉬를 설계하였다. 각 텍스쳐 캐쉬 구조의 성능 비교 분석을 위하여 Quake 게임 엔진을 벤치마크로 사용한 트레이스 기반의 시뮬레이션을 수행하였다. 또한 저전력 텍스쳐 캐쉬 구조에 적합한 텍스쳐 필터링 알고리즘에 따라서 가변적 전력 모드 전환 기준을 갖는 알고리즘을 제안하고 시뮬레이션을 통하여 검증하였다.

• 한국시뮬레이션학회논문지
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• 제20권3호
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• pp.89-100
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• 2011

새로운 교통수단으로서 실용화가 진행 중인 자기부상열차 시스템은 무인자동운전으로 운영되며, 사전에 면밀한 열차운행 계획의 수립과 검증이 요구된다. 일반적으로 열차운행 계획을 수립할 때는, 노선계획에 따른 통계화된 수송수요 예측자료를 활용하지만, 실제 열차 운행 시에는 수송 파동이 생길 수 있으며, 이를 고려하여 열차 운행 계획과 서비스 품질을 사전에 검토할 수 있는 수요기반 시뮬레이션 기술이 요구된다. 본 연구에서는 연속적인 수요파동을 반영할 수 있는 자기부상열차 운행 시뮬레이션 방법 및 모델을 제시하였다. 이를 위해, 열차 운행에 따른 승객 수송과정을 가장 효과적으로 모사할 수 있는 이산사건 모델을 적용하였으며, DEVS 형식론을 이용하여 시스템을 체계적으로 모델링 하였다. 또한, DEVSim++시뮬레이션 환경을 이용한 구현과 실험을 통해, 제안한 모델에 대한 구현 가능성을 검증하였고, 이러한 수요기반 시뮬레이션을 이용하면 운행계획과 전략에 대한 효과적인 사전 검토가 가능함을 확인하였다.

• Nuclear Engineering and Technology
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• 제48권2호
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• pp.304-317
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• 2016

An accelerator-driven system consists of a subcritical reactor and a controllable external neutron source. The reactor in an accelerator-driven system can sustain fission reactions in a subcritical state using an external neutron source, which is an intrinsic safety feature of the system. The system can provide efficient transmutations of nuclear wastes such as minor actinides and long-lived fission products and generate electricity. Recently at Kyoto University Research Reactor Institute (KURRI; Kyoto, Japan), a series of reactor physics experiments was conducted with the Kyoto University Critical Assembly and a Cockcrofte-Walton type accelerator, which generates the external neutron source by deuteriu-metritium reactions. In this paper, neutronic analyses of a series of experiments have been re-estimated by using the latest Monte Carlo code and nuclear data libraries. This feasibility study is presented through the comparison of Monte Carlo simulation results with measurements.

• 한국환경과학회지
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• 제11권1호
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• pp.41-56
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• 2002

In order to estimate the quantitative roles of the tide induced residual currents, density currents and wind driven currents on the residual currents in Kwangynag Bay Korea, numerical experiments with a diagnostic multi-level model were carried out. Density currents were calculated from the temperature and salinity data observed in January, May, August and November 1998. Anti-clockwise circulations are formed at the western inner part of the bay, the location from the east of Myodo Is. to the south of POSCO Co. and the place between Yeosu peninsula and Namhae Is. from the calculation results of the tide induced residual currents. Velocities of the density currents are less than 3cm/s at the western inner part of the bay and about 5cm/s at the southern entrance of the bay. Density currents get strong in summer and weak in autumn. Wind driven currents at the surface layer flow in the directions of the given winds which are the daily mean winds when the temperature and salinity observations are carried out. In the middle and lower layers, however the wind driven currents flow in the opposite direction to the surface currents as supplementary currents. The surface wind driven currents are greater than the tide induced residual currents or the density currents. The calculated residual currents including the tide induced residual currents, density currents and wind driven currents agree with the results of the current observations approximately. In the Bay, the wind driven currents affect on the residual currents greatestly and tide induced residual currents and density currents do in the second place and the third place.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1987년도 전기.전자공학 학술대회 논문집(II)
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• pp.1577-1580
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• 1987

This paper proposes a gate and functional level logic simulator which can be run on XENIX O.S. The simulator has hierarchical structure including Hardware Description Language compiler, Waveform Description Language compiler, and Simulation Command Language compiler. The Hardware Description Language compiler generates data structure composed of gate structure, wire structure, condition structure, and event structure. Simulation algorithm is composed of selective trace and event-driven methods. To improve simulation speed, Cross Referenced Linked List Structure ia defined in building the data structure of circuits.