• Title, Summary, Keyword: Microscopic Simulation

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A Numerical Process for the Underhood Thermal Management with the Microscopic and Semi-microscopic Heat Transfer Method (미시적/준미시적 방법을 이용한 자동차용 열교환기 해석기법)

  • Lee, Sang-Hyuk;Kim, Joo-Han;Lee, Na-Ri;Hur, Nahm-Keon
    • 한국전산유체공학회:학술대회논문집
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    • pp.75-79
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    • 2008
  • In this study, the numerical process for analyzing the automotive louver fin heat exchanger was developed with a 3D microscopic and semi-microscopic analysis. In the microscopic analysis, the simulation with the detailed meshes was performed for obtaining the characteristics of the heat exchanger. From this simulation, the numerical correlations of the heat transfer and flow friction were obtained. In the semi-microscopic analysis, the Semi-microscopic Heat Exchanger (SHE) method, which is characterized by a conjugate heat transfer and porous media analysis was used with the numerical correlation from the microscopic analysis. This analysis predicted the flow and heat transfer characteristics of the louver fin heat exchanger in the wind tunnel and vehicle. In the design of the louver fin heat exchanger, this numerical process can predict the performance and characteristic of the louver fin heat exchanger.

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Modeling time-dependent behavior of hard sandstone using the DEM method

  • Guo, Wen-Bin;Hu, Bo;Cheng, Jian-Long;Wang, Bei-Fang
    • Geomechanics and Engineering
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    • v.20 no.6
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    • pp.517-525
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    • 2020
  • The long-term stability of rock engineering is significantly affected by the time-dependent deformation behavior of rock, which is an important mechanical property of rock for engineering design. Although the hard rocks show small creep deformation, it cannot be ignored under high-stress condition during deep excavation. The inner mechanism of creep is complicated, therefore, it is necessary to investigate the relationship between microscopic creep mechanism and the macro creep behavior of rock. Microscopic numerical modeling of sandstone creep was performed in the investigation. A numerical sandstone sample was generated and Parallel Bond contact and Burger's contact model were assigned to the contacts between particles in DEM simulation. Sensitivity analysis of the microscopic creep parameters was conducted to explore how microscopic parameters affect the macroscopic creep deformation. The results show that the microscopic creep parameters have linear correlations with the corresponding macroscopic creep parameters, whereas the friction coefficient shows power function with peak strength and Young's modulus, respectively. Moreover, the microscopic parameters were calibrated. The creep modeling curve is in good agreement with the verification test result. Finally, the creep curves under one-step loading and multi-step loading were compared. This investigation can act as a helpful reference for modeling rock creep behavior from a microscopic mechanism perspective.

A Study on Traffic Impact Assessment Method using Microscopic Simulation Model (미시적 교통류 시뮬레이션을 활용한 교통영향평가 분석기법 개선방안)

  • Shin, Dae-Sup;Lee, Seon-Ha
    • Journal of Korean Society of Hazard Mitigation
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    • v.8 no.1
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    • pp.31-37
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    • 2008
  • Traffic flow which is prescribed under previous traffic effect/access act is analyzed by traffic volume, V/C, mean speed on road and LOS on the intersection. These indexes based on analytical method can not consider stochastic characteristics of traffic flow. Moreover it is hard to analyze traffic flow visually in whole traffic effect area because only individual road and intersections are targeted. In this study, it is devised to show traffic flow analysis method within traffic effect area visually applying microscopic-simulation by car-following theory, and then based on this, effect analyze ways are studied according to space range plan, improvement measure establishment and etc. To execute this study, effect area is set up using V/C, and the change of traffic current around development area is analyzed using microscopic-simulation program.

Comparison Study of O/D Estimation Methods for Building a Large-Sized Microscopic Traffic Simulation Network: Cases of Gravity Model and QUEEENSOD Method (대규모 미시교통시뮬레이션모형 구축을 위한 O/D 추정 방법 성능 비교 - 중력모형과 QUEENSOD 방법을 중심으로 -)

  • Yoon, Jung Eun;Lee, Cheol Ki;Lee, Hwan Pil;Kim, Kyung Hyun;Park, Wonil;Yun, Ilsoo
    • International Journal of Highway Engineering
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    • v.18 no.2
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    • pp.91-101
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    • 2016
  • PURPOSES : The aim of this study was to compare the performance of the QUEENSOD method and the gravity model in estimating Origin-Destination (O/D) tables for a large-sized microscopic traffic simulation network. METHODS : In this study, an expressway network was simulated using the microscopic traffic simulation model, VISSIM. The gravity model and QUEENSOD method were used to estimate the O/D pairs between internal and between external zones. RESULTS: After obtaining estimations of the O/D table by using both the gravity model and the QUEENSOD method, the value of the root mean square error (RMSE) for O/D pairs between internal zones were compared. For the gravity model and the QUEENSOD method, the RMSE obtained were 386.0 and 241.2, respectively. The O/D tables estimated using both methods were then entered into the VISSIM networks and calibrated with measured travel time. The resulting estimated travel times were then compared. For the gravity model and the QUEENSOD method, the estimated travel times showed 1.16% and 0.45% deviation from the surveyed travel time, respectively. CONCLUSIONS : In building a large-sized microscopic traffic simulation network, an O/D matrix is essential in order to produce reliable analysis results. When link counts from diverse ITS facilities are available, the QUEENSOD method outperforms the gravity model.

Traffic Flow Analysis Using the Microscopic Traffic Simulation (미시적 교통류 시뮬레이션을 이용한 교통흐름분석)

  • 임예찬
    • Proceedings of the Korea Society for Simulation Conference
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    • pp.108-113
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    • 1999
  • 본 논문은 Zeigler가 제안한 이산 사건 시스템 형식론(DEVS : Discrete Event System Specification)을 기반으로 미시적 교통류 시뮬레이션 시스템의 교통 흐름 분석에 대한 연구를 주목적으로 한다. 도로교통망 모델링 방법은 미시적(microscopic)방법과 거시적(macroscopic)방법으로 분류하는데, 미시적 모형은 개별차량의 행태를 바탕을 둔 모형으로 거시적 모형에 비해 설명력이 뛰어나다는 장점을 가지고 있지만 실제 교통상황에서 관측하고 검증하기가 어렵다는 단점을 갖고 있다. 따라서 본 논문에서는 신뢰성 있는 미시적 교통류 모형의 설계를 위해 DEVS 형식론을 기반으로 개별 차량에 대한 차량 추종 및 차로 변경 모형을 모델링하고 이를 근거로 교통류 시뮬레이션 시스템의 교통흐름 분석을 한다.

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A Study of Microscopic Energy Simulation based on BIM - Illuminance & Energy Analysis of Illuminance Sensor Lighting (BIM 기반의 미시적 에너지 시뮬레이션에 관한 연구 -조도센서등의 조도 및 에너지 분석을 중심으로)

  • Baek, Ji-Woong
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.20 no.1
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    • pp.384-390
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    • 2019
  • The importance of architecture design focused on eco-friendly and low energy continues to grow. In addition, the energy conservation design is required from a micro-perspective. Energy simulations based on BIM have attracted recent attention because of the high efficiency. On the other hand, the parameters concerned with microscopic energy are not included in BIM data. This study examined the necessity of the sensor-light parameter using a simulation of illuminance sensor light. In this study, illuminance sensors were installed into the BIM data and the operating schedule data of sensor light were generated by an illuminance simulation. The schedule data was then inputted into the simulation application, and the reduction ratio of power consumption was verified by the simulation. According to research, the power consumption and thermal load decreased by more than 20 %. Therefore, it is necessary to supplement the sensor-light parameter into BIM data for microscopic energy conservation design. This study was not confined to checking whether sensor-light parameter is necessary or not, but to ascertaining the necessary of applying a microscopic factor to generate BIM data.

Development of a general purpose molecular simulation system from microscopic to mesoscopic scales (미시영역에서 중간역역까지 적용 가능한 범용 분자 시뮬레이션 시스템의 개발)

  • Oh, Kwang-Jin
    • The KIPS Transactions:PartD
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    • v.12D no.6
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    • pp.921-930
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    • 2005
  • In this paper, a general purpose molecular simulation system which has been developed by the author, are described. One of the most advantageous features is that the molecular simulation system can handle a coarse-grained model as well as an all-atom mode. Therefore, we can simulate mesoscopic phenomena as well as microscopic phenomena with the help of Langevin dynamics simulation and dissipative particle dynamics simulation techniques. Thus we could study anesthesia, protein folding, biopolymer flow in microchannel with single framework, which spans from microscopic to mesoscopic scales. We expect that we can also simulate many other bio/nano systems of technological importance which are not feasible by means of molecular dynamics simulation technique. Finally, performance data are shown and a bottleneck is identified for future optimization.

AN INTELLIGENT TRANSPORT MANAGEMENT SYSTEM FOCUSED ON MICROSCOPIC TRAFFIC SIGNAL CONTROL

  • Nazmi, Mohd;Takaba, Sadao
    • Proceedings of the Korea Society for Simulation Conference
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    • pp.77-82
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    • 2001
  • An intelligent road transport management system focused on microscopic, real-time traffic signal control is proposed. Referring to the development of those systems in Japan, extensive use of image traffic detectors observing the movement of vehicles inside intersections, and direct data exchange between the signal controllers of neighboring intersections are newly assumed. On site investigation of five intersections in Japan or in Malaysia shows the possibility of effective information provision and simple algorithm for solving heavy congestion, as well as easy installation.

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Macroscopic-Microscopic Sequential Traffic Simulation Analysis and Dynamic O/D Estimation for Sub-area (거시-미시 순차적 교통시뮬레이션 방법과 부분상세지구의 동적 O/D추정)

  • Lee, Jin Hak;Kim, Ikki;Kim, Dae Hyun
    • Journal of Korean Society of Transportation
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    • v.32 no.6
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    • pp.567-578
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    • 2014
  • The study suggested a method to improve analysis accuracy such that the interactive effects of transportation changes between outside and inside of sub-areas were sequentially considered in the analysis by linking a macroscopic network analysis and a microscopic traffic simulation. A dynamic O/D estimation method was developed for practical implement of sub-area microscopic simulation analysis by using the results of macroscopic network analysis, the results of selected link analysis at the cordon line of the sub-area, departure time data of household travel survey, timely observed traffic volume data at the cordon. This estimated dynamic O/D for the sub-area made it possible to analyze traffic phenomena in details. Various detailed phenomena such as traffic queues, delay at intersection, and conflicts between vehicles, which is impossible to be grasped through a macroscopic analysis, can be analyzed with the dynamic microscopic traffic analysis. Through implementing an empirical study and validation, the study provided a reference result about accuracy of a microscopic traffic simulation of a sub-area to help its application for real transportation policy analysis.

Optimum Speed Simulation for Electronic Toll Collection (Electronic Toll Collection 운영속도 시뮬레이션)

  • Sin, Heung-Gweon;Nam, Doohee
    • The Journal of The Institute of Internet, Broadcasting and Communication
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    • v.13 no.3
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    • pp.87-92
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    • 2013
  • This study is to analyze the impacts of different High-Pass lane speed limits. Paramics, microscopic simulation software, was used to perform microscopic simulations. For the simulations, Incheon toll gate traffic count data was used. The Paramics simulation results show that higher High-Pass speed limit (70Km/h) produced better traffic flow condition and less air pollution cost compared to existing High-Pass speed limit (30Km/h).