• 대한전기학회논문지:전력기술부문A
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• 제52권6호
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• pp.307-315
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• 2003

This paper proposes a novel simulation method of WPGS (Wind Power Generation System). The rotation speed control method of turbine under variable wind speed using the pitch control is proposed. Moreover, when wind speed exceeds the cut-out wind speed, the turbine will be stopped by controlling pitch angle to 90$^{\circ}$, otherwise it will be controlled to steady-state operation. For the purpose of effective simulation, the SWRW (Simulation method for WPGS using Real Weather condition) is used for the utility interactive WPGS simulation in this paper, in which those of three topics for the WPGS simulation: user-friendly method, applicability to grid-connection and the utilization of the real weather conditions, are satisfied. It is impossible to consider the real weather conditions in the WPGS simulation using the EMTP type of simulators and PSPICE, etc. External parameter of the real weather conditions is necessary to ensure the simulation accuracy. The simulation of the WPGS using the real weather conditions including components modeling of wind turbine system is achieved by introducing the interface method of a non-linear external parameter and FORTRAN using PSCAD/EMTDC in this paper. The simulation of long-term, short-term, over cut-out and under cut-out wind speeds will be peformed by the proposed simulation method effectively. The efficiency of wind power generator, power converter and flow of energy are analyzed by wind speed of the long-term simulation. The generator output and current supplied into utility can be obtained by the short-term simulation. Finally, transient-state of the WPGS can be analyzed by the simulation results of over cut-out and under cut-out wind speeds, respectively.

• 한국식품과학회지
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• 제38권4호
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• pp.589-593
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• 2006

돈육 가공 공정에 대한 QRA에 Monte Carlo simulation이 적용된 바 있는데, 새로운 방법으로 fuzzy 연산을 적용하여 Monte Carlo simulation과 비교 분석하였다. Carcass단계에 대한 오염 예측치인 fuzzy 값과 Monte Carlo simulation 확률분포 값의 기술통계량인 평균값은 각각 -4.393 log $CFU/cm^2$, -4.589 log $CFU/cm^2$ 로 나타났으며, processing 단계에서는 -4.185 log $CFU/cm^2$, -4.466 log $CFU/cm^2$으로 두 가지 접근 방법들이 비슷한 경향을 보였다. Fuzzy 값은 Monte Carlo simulation 확률분포 값을 포함하는 것으로 나타났다. 한편 최근 국내에서는 위해 평가에 대한 연구가 많이 이루어지고 있는데 대부분 데이터 분석은 Monte Carlo simulation에만 의존하고 있고, 다른 접근 방법에 대한 연구는 미진한 실정이다. 따라서 본 연구는 위해 평가를 위한 방법적 도구들을 개발하는데 새로운 접근 방향을 제시하였다 또한 향후 fuzzy 연산법은 데이터가 불충분한 위해 평가의 초기 단계에서 유용하게 사용될 수 있는 방법이 될 것이다.

• 전기전자학회논문지
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• 제24권2호
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• pp.426-434
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• 2020

CPS의 대규모 시뮬레이션을 연동하기 위한 표준으로 FMI가 연구되고 있다. FMI를 이용한 대규모 시뮬레이션에서 결과의 신뢰성을 보장하기 위해 시간관리 기법을 통한 이벤트 처리가 필요하다. 본 논문은 CPS와 같은 대규모 Co-Simulation 환경에서 실시간성과 정확성을 보장하도록 한다. 실시간성을 보장하기 위해 Wallclock time과 Simulation time을 동기화한다. 또한 정확성을 보장하기 위해 시뮬레이션을 진행하기 전에 이벤트 여부를 확인한 후, 이벤트 발생시간까지 실시간성을 유지하면서 최대한 작은 step size로 시뮬레이션을 진행한다. 그 결과 Co-Simulation 환경에서 발생하는 이벤트를 순차적으로 즉시 처리하였으며, 실시간성을 보장함과 동시에 시뮬레이션 해상도를 최대로 하여 수치적분 에러를 최소화한다. 실험에서 제안하는 기법은 이벤트 처리가 즉시 이루어졌으며, 해상도를 보장하지 않는 기존의 시간관리 기법과 달리 수치적분 에러가 1/5가량 감소하는 것을 확인하였다.

• 정보과학회 논문지
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• 제42권2호
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• pp.213-219
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• 2015

현대 사회에서는 새로운 기술이나 가설을 증명하기 위해 시뮬레이션을 사용한다. 특히, 군사 훈련을 진행하거나 전쟁상황을 예측하기 위하여 국방 Modeling & Simulation(M&S)을 사용한다. 국방 M&S는 실제 환경에서 진행하는 Live Simulation, 가상환경에서 진행하는 Virtual Simulation, 그리고 워 게임과 같은 Constructive Simulation으로 이루어지며 각각을 L체계, V체계, C체계라고 한다. L체계는 실제 환경을 전제하기 때문에 현실성이 높지만 예산 효율성이 떨어진다. 이와 반대로 V와 C체계는 현실성이 떨어지지만 예산 효율성을 높인다. 이러한 각 체계의 장단점을 바탕으로 세 가지 체계를 모두 연동한 L-V-C 통합 환경을 구축한다면 시뮬레이션의 질을 향상시킬 수 있다. 본 논문에서는 L-V-C 통합 환경을 구축하기 위해 이기종 시뮬레이션 미들웨어 간 연동하는 방안을 제시하고 서로 다른 미들웨어간의 연동 테스트 결과를 보인다.

• 한국시뮬레이션학회:학술대회논문집
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• 한국시뮬레이션학회 1994년도 추계학술발표회 및 정기총회
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• pp.1-2
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• 1994

With the prevalence of computers in modern organizations, simulation is receiving more atention as an effectvie decision -making tool. Simualtion is a computer-based numerical technique which uses mathmatical and logical models to approximate the behaviror of a real-world system. However, iptimization of synamic stochastic systems often defy analytical and algorithmic soluions. Although a simulation approach is often free fo the liminting assumption s of mathematical modeling, cost and time consiceration s make simulation the henayst's last resort. Therefore, whenever possible, analytical and algorithmica solutions are favored over simulation. This paper discussed the issues and procedrues for using simulation as a tool for optimization of stochastic complex systems that are dmodeled by computer simulation . Its emphasis is mostly on issues that are speicific to simulation optimization instead of consentrating on the general optimizationand mathematical programming techniques . A simulation optimization problem is an optimization problem where the objective function. constraints, or both are response that can only be evauated by computer simulation. As such, these functions are only implicit functions of decision parameters of the system, and often stochastic in nature as well. Most of optimization techniqes can be classified as single or multiple-resoneses techniques . The optimization of single response functins has been researched extensively and consists of many techniques. In the single response category, these strategies are gradient based search techniques, stochastic approximate techniques, response surface techniques, and heuristic search techniques. In the multiple response categroy, there are basically five distinct strategies for treating the responses and finding the optimum solution. These strategies are graphica techniqes, direct search techniques, constrained optimization techniques, unconstrained optimization techniques, and goal programming techniques. The choice of theprocedreu to employ in simulation optimization depends on the analyst and the problem to be solved. For many practival and industrial optimization problems where some or all of the system components are stochastic, the objective functions cannot be represented analytically. Therefore, modeling by computersimulation is one of the most effective means of studying such complex systems. In this paper, after discussion of simulation optmization techniques, the applications of above techniques will be presented in the modeling process of many flexible manufacturing systems.

• 한국시뮬레이션학회:학술대회논문집
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• 한국시뮬레이션학회 1994년도 춘계초청 강연회 및 임시총회
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• pp.0.1-0
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• 1994

• 한국시뮬레이션학회:학술대회논문집
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• 한국시뮬레이션학회 1997년도 춘계 학술대회 발표집
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• pp.9-9
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• 1997

• 한국농공학회논문집
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• 제60권5호
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• pp.135-147
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• 2018

The objective of this study was to analyze the characteristics of combined 1D/2D inundation simulation of riverside farmland using the Hydrologic Engineering Center - River Analysis System (HEC-RAS). We compared and analyzed inundation simulation results between 1D and combined 1D/2D hydraulic simulation using HEC-RAS. Calibration and validation of stream stage were performed using three rainfall events. The coefficient of determination ($R^2$) and root mean square error (RMSE) between simulated and observed stream stage were 0.935 - 0.957 and 0.250 m - 0.283 m in calibration and validation, respectively. The inundation area showed no significant difference in 1D and combined 1D/2D simulation ($8.48km^2$ in 1D simulation, $8.75km^2$ in combined 1D/2D simulation). The average inundation depth by 1D simulation was 1.4 m deeper than combined 1D/2D simulation. In the lower inundation depth, the inundation area by combined 1D/2D simulation was larger than inundation area by 1D simulation. As the inundation depth increased, the inundation area by 1D simulation became wider. In the case of the 1D/2D combined simulation, low elevation areas along the river bank were inundated widely. Compared to 1D/2D combined simulation, the flood radius in some sections was longer in 1D simulation. In the 1D analysis, because the low altitude riverside farmlands are also assumed to stream, it is calculated that riverside farmlands have the same stage as the mainstream when the stream is overflowed. Therefore, the inundation area seems to be overestimated in those sections. In other regions, the inundation areas tend to be broken depending on overflow by each stream cross-section. In the case of river flooding, the overflow is expected to flow to the lower area depending on the terrain, such as the results of the combined 1D/2D simulation. It is concluded that the results of combined 1D/2D inundation simulation reflected the topographical characteristics of low-lying farmland.

• Journal of Korean Vacuum Science & Technology
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• 제6권1호
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• pp.22-29
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• 2002

The process of energetic deposition has been simulated by using molecular dynamics (W) simulation and kinetic Monte Carlo (KMC) simulation. The atomistic mechanisms of film growth in energetic deposition are discussed.

• 대한약리학회:학술대회논문집
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• 대한약리학회 2006년도 The 6th Congress of the Federation of Asian and Oceanian Physiological Societies
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• pp.80.1-80.1
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• 2006