• 한국해양공학회지
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• 제22권3호
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• pp.47-57
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• 2008

Many accidents occur on the oceans. Accidents involving ships can cause enormous damage. When an accident occurs, the cost of environmental restoration can bankrupt even a top-ranked international company. The potential damages resulting from ship accidents have resulted in many international agreements such as MARPOL, SOLAS, ISM Code, etc. The viability of damaged ships has become more and more important. A damaged ship's viability and cargo safety can be improved by a safety assessment design procedure. We consider th￡ shipbuilding industry's distributed characteristics to define a safety assessment system with software engineering-based requirements analysis. We used a distributed network-based simulation method (HLA - High level architecture), because of ease of reuse and expansion of existing components to other situations, and because it is a military standard. HLA is the standard for distributed network-based simulation in many countries including the United States, Canada, Israel, and Korea. The paper describes research to develop a prototype of a network-based safety assessment simulation system by software engineering based analysis.

• 한국실천공학교육학회논문지
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• 제3권1호
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• pp.15-24
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• 2011

녹색에너지의 모델링과 시뮬레이션은 연구하고자 하는 시스템의 형태에 따라 크게 의존한다. 모델링과 시뮬레이션의 주요내용은 반도체 물리(태양전지), 전기모터/발전기(풍력터빈), 전형적인 제어전략에 의한 전력전자(계통연계)등 매우 다양하다. 이들 기술들을 정확하게 모델링하는 것은 다양한 시뮬레이션 기술과 많은 모델들을 필요로 한다. 시뮬레이션을 더욱 정확하게 혹은 상세하게 하기 위해서 모델링은 특정레벨 즉, 시스템, 회로, 요소 레벨 등으로 수행하여야 한다. 다양한 레벨의 조합은 모델 방정식과 이용 가능한 매개변수들에 대한 전체적인 모델의 유용성을 크게 개선할 수 있다.

• 국제학술발표논문집
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• The 3th International Conference on Construction Engineering and Project Management
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• pp.1053-1059
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• 2009

Construction system modeling can enhance work performance by following the behaviors of a system. System behaviors may originate from physical aspects of a system, namely operation level variables, or from non-physical aspects of a system known as context level variables. However, construction system modelers usually focus on only one type of system variable (i.e., operation level or context level) which can lead to less accurate results. Hybrid modeling with System Dynamics (SD) and Discrete Event Simulation (DES) is one of the approaches that has been utilized to address this issue. In this research, an SD-DES hybrid model of a steel fabrication shop is developed, and the benefits of capturing context level variables together with operation level variables in the model are discussed.

• 경영과학
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• 제24권2호
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• pp.81-93
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• 2007

Achieving a target operational availability is more economical and efficient than having many quantities of the weapon system, since the cost of weapon system becomes expensive. The intent of this study is twofold; first, we develop the simulation model to determine the optimal inventory level of the maintenance float while achieving a target operational availability of the Korean-made helicopter. The quantity decision model considers following factors such as a reliability. a turn around time(TAT). a protection level for inventory, and so on. Second, we analyze whether the existence of a lateral transshipment among bases and the reduction of TAT relate to an inventory level and the operational availability. The research result shows that both TAT and lateral transshipment have an effect on reducing the inventory level of the maintenance float and improving an operational availability.

• 한국시뮬레이션학회논문지
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• 제25권4호
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• pp.93-108
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• 2016

전기차 카셰어링은 친환경차량인 전기차를 여러 사용자들이 함께 이용함으로써 교통부문의 온실가스 발생량을 감소시키고, 동시에 자가용 증가로 인한 공간 및 환경문제를 해결할 수 있는 방안으로 주목받고 있다. 그러나 아직 도입단계에 불과하기 때문에 전기차 카셰어링 시스템의 효율성이나 사업가능성에 대한 연구나 분석이 필요한 실정이다. 이러한 배경하에 본 연구에서는 전기차 카셰어링 시스템의 운영상태와 결과를 분석이 가능한 모형을 개발하였으며, 현재 실시되고 있는 시범사업 내용을 반영하여 시뮬레이션을 실시하였다. 시뮬레이션 결과 전기차 카셰어링 시스템 운영과 관련된 변수들 사이의 관계와 운영효율을 최대화 할 수 있는 최적용량 등을 분석하였다. 시뮬레이션 분석에서는 차량대수와 충전기수가 증가할수록 서비스 제공율은 계속 증가하다가 일정수준에 도달하면 증가폭과 그 효율이 감소하는 것으로 나타났다. 또한 카셰어링 시스템 운영에 따른 수익과 비용을 분석하여 연간 운영 이익을 최대화 할 수 있는 최적 차량대수 및 최적 충전기 수를 도출하였다.

• 제어로봇시스템학회논문지
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• 제12권8호
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• pp.834-841
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• 2006

Recently, many enterprises are installing AMSs(Automated Manufacturing Systems) for their competitive advantages. As the level of automation increases, proper design and validation of control logic is a imperative task for the successful operation of AMSs. However, current discrete event simulation methods mainly focus on the performance evaluation. As a result, they lack the modeling capabilities for the detail logic of automated manufacturing system controller. Proposed in this paper is a method of validation of the controller logic for automated material handling system using an object-oriented design and simulation. Using this method, FA engineers can validate the controller logic easily in earlier stage of system design, so they can reduce the time for correcting the logic errors and enhance the productivity of control program development Generated simulation model can also be used as a communication tool among FA engineers who have different experiences and disciplines.

• Nuclear Engineering and Technology
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• 제50권8호
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• pp.1306-1313
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• 2018

The randomness and incipient nature of certain faults in reactor systems warrant a robust and dynamic detection mechanism. Existing models and methods for fault diagnosis using different mathematical/statistical inferences lack incipient and novel faults detection capability. To this end, we propose a fault diagnosis method that utilizes the flexibility of data-driven Support Vector Machine (SVM) for component-level fault diagnosis. The technique integrates separately-built, separately-trained, specialized SVM modules capable of component-level fault diagnosis into a coherent intelligent system, with each SVM module monitoring sub-units of the reactor coolant system. To evaluate the model, marginal faults selected from the failure mode and effect analysis (FMEA) are simulated in the steam generator and pressure boundary of the Chinese CNP300 PWR (Qinshan I NPP) reactor coolant system, using a best-estimate thermal-hydraulic code, RELAP5/SCDAP Mod4.0. Multiclass SVM model is trained with component level parameters that represent the steady state and selected faults in the components. For optimization purposes, we considered and compared the performances of different multiclass models in MATLAB, using different coding matrices, as well as different kernel functions on the representative data derived from the simulation of Qinshan I NPP. An optimum predictive model - the Error Correcting Output Code (ECOC) with TenaryComplete coding matrix - was obtained from experiments, and utilized to diagnose the incipient faults. Some of the important diagnostic results and heuristic model evaluation methods are presented in this paper.

• 정보처리학회논문지D
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• 제12D권5호
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• pp.709-718
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• 2005

예측 불가능한 미래 전략 환경에 부합하고, 보다 경제적이며 과학적인 수단으로 무기체계개발을 수행하기 위해 모델링 및 시뮬레이션 기술의 적용이 확대되고 있다. 본 연구는 모델링 및 시뮬레이션 표준연동구조인 HLA(High Level Architecture)및 TCP/IP를 지원하고, 실시간 분산 시뮬레이션을 지원하는 소프트웨어 프레임워크인 ADSF(Air Defense Simulation Framework)를 개발한 경험을 기술하고 있다. 개발된 ADSF는 대공유도무기 M-SAM(Medium Range Surface to Air Missile) 체계시뮬레이터에 적용하였으며, 위성항법장치(GPS : Global Positioning System) 시계를 사용하여 요구조건에 만족하는 시험결과를 산출하였다. 그 결과 ADSF는 HLA를 지원하고 실무기 체계의 통신 프로토콜인 TCP/IP를 지원하는 통신미들웨어가 만들어지고, 실시간 분산 시뮬레이션의 핵심 기술인 정밀모사를 지원하는 시뮬레이션 엔진도 갖추게 되었다. 대공유도무기 체계시뮬레이터는 다수의 구성요소로 이루어진 실시간 분산 시뮬레이션 시스템이므로 실시간 분산 시뮬레이션을 지원해 주는 시뮬레이션 엔진 개발이 요구되었다.

• 산업공학
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• 제17권1호
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• pp.1-12
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• 2004

In a modern semiconductor device manufacturing industry, statistical bin limits on wafer level test bin data are used for minimizing value added to defective product as well as protecting end customers from potential quality and reliability excursion. Most wafer level test bin data show skewed distributions. By Monte Carlo simulation, this paper evaluates methods and sample size effect regarding determination of statistical bin limits. In the simulation, it is assumed that wafer level test bin data follow the Poisson distribution. Hence, typical shapes of the data distribution can be specified in terms of the distribution's parameter. This study examines three different methods; 1) percentile based methodology; 2) data transformation; and 3) Poisson model fitting. The mean square error is adopted as a performance measure for each simulation scenario. Then, a case study is presented. Results show that the percentile and transformation based methods give more stable statistical bin limits associated with the real dataset. However, with highly skewed distributions, the transformation based method should be used with caution in determining statistical bin limits. When the data are well fitted to a certain probability distribution, the model fitting approach can be used in the determination. As for the sample size effect, the mean square error seems to reduce exponentially according to the sample size.

• 산업경영시스템학회지
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• 제39권1호
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• pp.31-36
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• 2016

Recently, Live-Virtual-Constructive (L-V-C) integrate training system has proposed as a solution for the problems such as limitation of training areas, increase of mission complexity, rise in oil prices. In order to integrate each training system into the one effectively, we should solve the issue about stress of pilots by the environmental differences between Live and Virtual simulation which could be occurred when each system is connected together. Although it was already examined in previous study that the psychological effects on pilots was occurred by the environmental differences between actual and simulated flights, the study did not include what the causal factors affecting psychological effects are. The aim of this study is to examine which environmental factors that cause pilots' psychological effects. This study analyzed the biochemical stress hormone, cortisol to measure the pilots' psychological effects and cortisol was measured using Enzyme-linked immunoassay (EIA). A total of 40 pilots participated in the experiment to compare the differences in pilots' cortisol response among live simulation, virtual simulation, and the virtual simulation applying three environmental factors (gravity force, noise, and equipment) respectively. As a result, there were significant differences in cortisol level when applied the gravity force and equipment factors to the virtual simulation, while there was no significant difference in the case of the noise factor. The results from this study can be used as a basis for the future research on how to make L-V system by providing minimum linkage errors and design the virtual simulator that can reduce the differences in the pilots' psychological effects.