• 산업경영시스템학회지
• /
• 제22권49호
• /
• pp.125-133
• /
• 1999

Nonrecurring congestions are generally caused by random or less predictable events, such as accidents, spilled loads stalled or broken-down vehicles that, temporarily reduce the capacity of the freeway. The purpose of this paper is to present the effect of incidents on the traffic congestion on the urban freeway by simulation method. The simulation scenario is composed of two level traffic conditions, two level incident severities, and eight level incident durations. After incident, the recovering duration to the normal traffic flow, increased by linear of incident duration. Total vehicles travel time increased and average travel speed decreased by squares curve of incident duration. Considering incident impacts, incident management system is evaluated the major function of the urban freeway traffic management system. Also, necessary the related research to detect, verify, and develop effective response strategies for traffic incidents.

• 한국원자력학회:학술대회논문집
• /
• 한국원자력학회 1996년도 춘계학술발표회논문집(1)
• /
• pp.484-490
• /
• 1996

The Pressurizer Level Control System (PLCS) logic for YGN 5&6 was developed to incorporate the design changes on the Chemical and Volume Control System (CVCS). The YGN 5&6 CVCS uses the centrifugal charging pumps and letdown orifices replacing the positive displacement pumps and letdown control valves in the YGN 3&4 and UCN 3&4. The purpose of this study is to develop new PLCS as well as validate newly developed control logic and its implementation method in the simulation computer code. The analysis results show that the new PLCS has adequate ability to control the pressurizer level in response to the design bases events, and the simulation computer code is useful for YGN 5&6 NSSS design code.

• Journal of Power Electronics
• /
• 제16권4호
• /
• pp.1598-1611
• /
• 2016

In some special occasions with strict size requirements, such as mine hoists, improving the design accuracy of the forced-air cooling systems of NPC three-level inverters is a key technology for improving the power density and decreasing the volume. First, a fast power-loss calculation method was brought. Its calculation principle introduced in detail, and the computation formulas were deduced. Secondly, the average and dynamic power losses of a 1MW mine hoist acting as the research target were analyzed, and a forced-air cooling system model based on a series of theoretical analyses was designed with the average power loss as a heat source. The simulation analyses proves the accuracy and effectiveness of this cooling system during the unit lifting period. Finally, according to an analysis of the periodic working condition, the maximum power-loss range of a NPC three-level inverter under multi cycle operation was obtained and its dynamic power loss was taken into the optimized cooling system model as a heat source to solve the power device damage caused by instantaneous heat accumulation. The effectiveness and feasibility of the optimization design based on the dynamic power loss calculation of the maximum power-loss range was proved by simulation and experimental results.

• 한국시뮬레이션학회논문지
• /
• 제9권4호
• /
• pp.41-50
• /
• 2000

We have many simulation constraints to meet as a modeled system becomes large and complex. Real-time simulations are the examples in that they are constrained by certain non-function constraints (e.g., timing constraints). In this paper, an enhanced hierarchical modeling methodology is proposed to efficiently deal with constraint-simulations. The proposed modeling method enhances hierarchical modeling methods to provide multi-resolution model. A simulation model is composed by determining the optimal level of abstraction that is guaranteed to meet the given simulation constraints. Four modeling activities are defined in the proposed method: 1) Perform the logical architectural design activity to produce a multi-resolution model, 2) Organize abstraction information of the multi-resolution model with AT (Abstraction Tree) structure, 3) Formulate the given constraints based on U (Integer Programming) approach and embrace the constraints to AT, and 4) Compose a model based on the determined level of abstraction with which the multi-resolution model can satisfy all given simulation constraints. By systematically handling simulation constraints while minimizing the modeler's interventions, we provide an efficient modeling environment for constraint-simulations.

• 한국시뮬레이션학회논문지
• /
• 제16권3호
• /
• pp.19-28
• /
• 2007

무기체계의 개념설계 단계에서부터 체계 사양 도출 및 관 요구분석의 효과적인 수행을 위한 교전수준(Engagement Level)의 M&S(Modeling & Simulation) 적용을 위해 수중무기체계인 어뢰체계의 표준모델을 구성하였다. 추후 수중 교전 시뮬레이션에 공통적으로 사용될 수 있도록 재사용성(Reusability)과 상호운용성(Interoperability) 및 공학 모델로의 확장성을 고려하였다. 어뢰체계의 표준에 대하여 모델의 WBS(Work Breakdown Structure)를 정의하고 각 하부 모델들 사이의 정보 흐름을 구체화하여 모델간의 입력 및 출력 파라미터를 정의하였다. 어뢰 모델링은 WBS의 하부 모델 중에서 초기입력 장치, 수중운동, 전투탄두, 음향탐지, 유도제어, 추진동력에 대해서 모델링 하였으며, 중어뢰와 경어뢰의 운용상의 차이점을 구분하여 모델링하였다. 표준모델은 가능한 공학 수준 M&S와 동일한 구조를 갖도록 하였으며 앞으로 정립될 V&V(Verification & Validation) 절차에 따라 교전 시뮬레이션에 사용될 다른 체계들과 검증될 것이다.

• 한국시뮬레이션학회논문지
• /
• 제30권1호
• /
• pp.21-29
• /
• 2021

본 연구에서는 하드-킬 방식 어뢰 방어체계의 운동 및 센서 분야 주요 파라미터가 방어 성능에 미치는 영향을 분석하기 위한 실험 설계 및 구성요소 모델에 대해서 소개하였다. 시뮬레이션은 적-아 플랫폼이 상호작용하는 교전수준에서 구현되었으며, 방어체계의 핵심 성능을 측정할 수 있는 종말 단계로 범위를 한정하였다. 한편 공학수준 시뮬레이션의 주요 관심사항인 기동(Kinematics), 센서 성능, 음향탐지 이론에 대해 세부적으로 모사하여 현실 충실도를 높였다. 본 연구는 새로운 운용 개념을 가진 무기체계 개발 시 선행되어야 하는 성능 영향 요인 분석을 위한 방법론을 제시하고 있으며 실험을 통하여 주요 파라미터 변화에 따른 방어 성능 변화를 확인 할 수 있었다.

• 한국시뮬레이션학회논문지
• /
• 제11권2호
• /
• pp.1-16
• /
• 2002

The need for network security is being increasing due to the development of information communication and internet technology. In this paper, firewall models, operating system models and other network component models are constructed. Each model is defined by basic or compound model, referencing DEVS formalism. These models and the simulation environment are implemented with MODSIM III, a general purpose, modular, block-structured high-level programming language which provides direct support for object-oriented programming and discrete-event simulation. In this simulation environment with representative attacks, the following three attacks are generated, SYN flooding and Smurf attack as an attack type of denial of service, Mail bomb attack as an attack type of e-mail. The simulation is performed with the models that exploited various security policies against these attacks. The results of this study show that the modeling method of packet filtering system, proxy system, unix and windows NT operating system. In addition, the results of the simulation show that the analysis of security performance according to various security policies, and the analysis of correlation between availability and confidentiality according to security empowerment.

• 한국정보과학회논문지:소프트웨어및응용
• /
• 제26권1호
• /
• pp.80-80
• /
• 1999

As Temporal DataBase Systems(TDBSs) manages both the historical versions and the current version of each data item, a temporal transaction may access more data records than atransaction in traditional database systems. Hence, the concurrency control subsystem of temporaldatabase management system should be able to correctly and efficiently detect actual conflicts amongconcurrent temporal transactions while the cost of detecting conflicts is maintained in low levelwithout detecting false conflicts which cause severe degradation of system throughput.In this paper, Two-Level Conflict Detection(TLCD) scheme is proposed for efficient conflictdetection between concurrent temporal transactions in TDBs. In the proposed TLCD scheme, sincechecking conflict between concurrent temporal transactions is performed at two levels, i, e., logicallevel and physical level, conflicts between concurrent temporal transactions are efficiently and correctlydetected,Furthermore, we also evaluate the performance of the proposed TLCD scheme with those oftraditional conflict detection schemes, logical-level conflict detection scheme and physical-level conflictdetection scheme by simulation approach, The result of the simulation study shows that the proposedTLCD scheme outperforms the previous conflict detection schemes with respect to the averageresponse time.

• 한국시뮬레이션학회논문지
• /
• 제22권4호
• /
• pp.67-82
• /
• 2013

본 논문은 공학급 국방 모델의 시뮬레이션 성능 향상을 위해 다중 충실도(Multi-fidelity) 모델링 시뮬레이션(M&S: Modeling and Simulation) 기법을 제안한다. 제안하는 기법은 다양한 충실도를 지닌 모델을 활용하여 고 충실도 모델의 시뮬레이션과 비교하여 유사한 수준의 시스템 분석 결과를 얻음과 동시에 시뮬레이션 성능 측면에서 이득을 가져오는 방안이다. 다중 충실도 원리를 적용하기 위해 본 논문은 충실도를 모델 동작과 실행 측면으로 세분화하고, 충실도 변환 지점을 FCP (Fidelity Change Point)로 정의한다. 이러한 원리를 바탕으로 본 논문은 다음의 세 가지 쟁점을 다룬다. 먼저, 모델 동작과 실행 측면의 충실도 변환을 위한 모델 구조와 제안하는 모델에 대한 수학적 형식론, 마지막으로 모델 실행을 위한 시뮬레이션 알고리즘을 제안한다. 사례 연구로 어뢰의 표적 추적 시나리오에 대한 기초 실험을 수행하였고, 실험 결과 제안하는 기법을 사용한 경우 기존의 시뮬레이션과 비교하여 최대 4.24배의 시뮬레이션 성능 향상을 보임을 확인하였다. 본 논문에서 제안하는 기법은 M&S 기반의 시스템 분석을 하는 다양한 분야에서 활용될 수 있음을 기대한다.

• 한국CDE학회논문집
• /
• 제16권4호
• /
• pp.305-313
• /
• 2011

This paper proposes a method for reusing kinematic design data for virtual facilities, Making a virtual model of a facility involves two major activities: geometric design (virtual model visualization) and kinematic design that should be remodeled frequently whenever design changes occur, Conventionally, a virtual model of an automated facility focuses on the design level, which mainly deals with design verification, alternative comparison, and geometric model diagnosis, Although a design level model can be designed with the information of past models from PLM system, a simulation level model is not sufficient utilized to be reused for kinematic design purpose, We propose a method for reusing kinematic information of a past simulation model to cope with this problem, We use the concept or the 'center of mass', which is a point representing the mean position of the matter in a body or system. And we also use comparison method of a boundary box to identity which 3D objects have to be involved from the design model to a link structure that is contained in the simulation model. Because a proposed method only use not a historical approach but a geometrical approach, it is more effective to apply to the field.