• 한국시뮬레이션학회논문지
• /
• 제6권2호
• /
• pp.45-57
• /
• 1997

MAC (media access control) bridge is used to interconnect separate LANs and to relay frames between the BLANs (bridged LANs). Bridge architecture consists of MAC entity, MAC relay entity and bridge protocol entity protocol entity and performs learning, filtering and forwarding functions using filtering database. In this paper, we simulate these functions of bridge and the STP (spanning tree protocol). The STP derives an active topology from an arbitrarily connected BLAN. Our simulation model assumes a BLAN consisted of three bridge forming a closed loop. In order to remove the loop, each bridge process exchanges configruation BPDU (bridge protocol data unit0 with other bridge processes connected to the bridge itself. To simulate the communication between bridges, we implement the IPC (inter-process communication) server using message queues. Our simulation results show that the assumed BLAN contains no closed loop and then there is no alternative route and no unnecessary traffic.

• Wind and Structures
• /
• 제24권3호
• /
• pp.287-306
• /
• 2017

In the present study, a new assessment simulation of ride safety based on a new wind-traffic-pavement-bridge coupled vibration system is developed considering stochastic characteristics of traffic flow and bridge surface. Compared to existing simulation models, the new assessment simulation focuses on introducing the more realistic three-dimensional vehicle model, stochastic characteristics of traffic, vehicle accident criteria, and bridge surface conditions. A three-dimensional vehicle model with 24 degrees-of-freedoms (DOFs) is presented. A cellular automaton (CA) model and the surface roughness are introduced. The bridge deck pavement is modeled as a boundless Euler-Bernoulli beam supported on the Kelvin model. The wind-traffic-pavement-bridge coupled equations are established by combining the equations of both the vehicles in traffic, pavement, and bridge using the displacement and interaction force relationship at the patch contact. The numerical simulation shows that the proposed method can simulate rationally useful assessment and prevention information for traffic, and define appropriate safe driving speed limits for vulnerable vehicles under normal traffic and bridge surface conditions.

• 한국항해항만학회지
• /
• 제28권8호
• /
• pp.735-743
• /
• 2004

현재 목포 북항과 고하도를 연결하는 목포 연육교의 건설이 추진 중에 있으며, 이 교량은 2009년 말에 완공될 예정이다. 항행수역에 건설되는 교량에 대해서는 선박 운항 측면에서의 안전성 평가가 필수적이지만, 아직 이에 대한 구체적인 지침이 마련되어 있지 않은 실정이다. 본 연구에서는, 목포 연육교 평면 배치 계획에 대한 선박 운항 측면에서의 평가 절차를 소개하고, 교량의 계획 단계에서부터 고려되어야 하는 사항들에 대해 검토하였다. 교량의 주경간 등 전반적인 배치 계획에 대한 평가를 위해, 대상 해역에 교량이 건설된 상황을 설정하여 실시간 시뮬레이션(real time simulation) 및 배속 시뮬레이션(fast time simulation) 등의 운항 시뮬레이션을 실시하였다. 이로부터, 선박과 교각과의 충돌위험도를 추정하기 위해, 항로상에서의 선박의 항행 궤적 분포는 정규분포를 따른다는 가정 하에 통계적 분석을 수행하였다.

• Coupled systems mechanics
• /
• 제1권2호
• /
• pp.133-154
• /
• 2012

In this paper a bridge flutter prediction is performed by using advanced numerical simulation. Two novel approaches were developed simultaneously by utilizing the ANSYS v12.1 commercial software package. The first one is a fluid-structure interaction simulation involving the three-dimensional elastic motion of a bridge deck and the fluid flow around it. The second one is an updated forced oscillation technique based on the dynamic mode shapes of the bridge. An aeroelastic wind tunnel model was constructed in order to validate the numerical results. Good agreement between the numerical results and the measurements proves the applicability of the novel methods in bridge flutter assessment.

• 한국전산구조공학회논문집
• /
• 제23권2호
• /
• pp.175-182
• /
• 2010

본 연구에서는 복합소재 교량용 방호울타리를 개발하여 컴퓨터 시뮬레이션을 통해 강재 교량용 방호울타리와 복합소재교량용 방호울타리의 성능을 비교하였다. 구조적 강도 성능 측면에서, 복합소재 교량용 방호울타리의 경우 교량용 방호울타리의 변형이 17%로 감소하여 강재 교량용 방호울타리 보다 강도 성능이 우수하였다. 탑승자 보호 성능 측면에서, 복합소재 교량용 방호울타리는 THIV 47.1%, PHD 49.0%로 감소하여 강재 교량용 방호울타리 보다 탑승자 보호성능이 우수하였다. 충돌 후 차량의 거동 측면에서, 복합소재 교량용 방호울타리는 이탈속도가 증가하고 이탈각도가 감소하여 강재 교량용방호울타리 보다 충돌 후 차량의 거동이 우수하였다. 교량용 방호울타리의 비산 측면에서, 강재 및 복합소재 교량용 방호울타리는 비산이 발생하지 않았다.

• 한국철도학회:학술대회논문집
• /
• 한국철도학회 2007년도 추계학술대회 논문집
• /
• pp.395-400
• /
• 2007

LRT(Light Railway Train), which is a intermediate system of train and bus, is arose for the solution of subway construction cost and the transportation capacity of bus. LRT was introduced in 1980's. About 30 local governments are plan to introduce LRT or constructing LRT, at present. AGT(Automated Guide-way Transit) system, which is a kind of LRT, is operated without driver. Rubber wheeled AGT system can reduce the noise and vibration compare to steel wheeled AGT, so it is estimated as ideal transportation system for urban area. And live loads at bridge are classified as the static load of vehicle and the dynamic wheel contact load which is occurred from the interaction of bridge and vehicle vibration, and the surface roughness. In the case of AGT system, the dynamic increment factor of bridge is greater than the normal train bridge and roadway bridge, because, the weight of AGT vehicle is more light that the train of truck. The exact method for dynamic increment factor is experiment. But this method is needed much money and time, moreover, this method cannot be adopted in design. Therefore, a simulation program for the interaction of AGT bridge, vehicle and surface roughness was developed, in this study. And the program was verified by experiment. As a result, the accuracy of the simulation program can be verified.

• 산업기술연구
• /
• 제20권A호
• /
• pp.149-158
• /
• 2000

After measuring actual stress by two measurements(Dynamic Strain Meter, Histogram Recorder) on truss rail road bridge, we could perform time history analysis by 3-D beam element method on modelling bridge. And then, after analyzing bridge structure in static by 3-D modelling, we estimated degree of fatigue damage in main member, secondary member of tie zone, cutting area of base metal cross section for confirming the result. In case that the simulated stress is carried out on modeling bridge, most of those simulation mainly is performed by main members. But in real bridge fatigue damage problems generally caused by junctions, connections, joints in which especially local stress is activated. Therefore, in this paper actual stress on critical area was estimated through the analysis result by simulation. With this study, we can estimate the degree of fatigue damage from a safety point of view and comparative accuracy.

• Wind and Structures
• /
• 제31권3호
• /
• pp.209-216
• /
• 2020

Aiming at the wind-resistant design of a sea-crossing arch bridge, the static aerodynamic coefficients of its girder (composed of stretches of π-shaped cross-section and box cross-section) were studied by using computational fluid dynamics (CFD) numerical simulation and wind tunnel test. Based on the comparison between numerical simulation, wind tunnel test and specification recommendation, a combined calculation method for the horizontal force coefficient of intermediate and small span bridges is proposed. The results show that the two-dimensional CFD numerical simulations of the individual cross sections are sufficient to meet the accuracy requirements of engineering practice.

• Structural Engineering and Mechanics
• /
• 제17권2호
• /
• pp.267-279
• /
• 2004

This paper presents an improved Monte Carlo simulation for the probabilistic determination of initial cable forces of cable-stayed bridges under dead loads using the response surfaces method. A response surface (i.e. a quadratic response surface without cross-terms) is used to approximate structural response. The use of the response surface eliminates the need to perform a deterministic analysis in each simulation loop. In addition, use of the response surface requires fewer simulation loops than conventional Monte Carlo simulation. Thereby, the computation time is saved significantly. The statistics (e.g. mean value, standard deviation) of the structural response are calculated through conventional Monte Carlo simulation method. By using Monte Carlo simulation, it is possible to use the existing deterministic finite element code without modifying it. Probabilistic analysis of a truss demonstrates the proposed method' efficiency and accuracy; probabilistic determination of initial cable forces of a cable-stayed bridge under dead loads verifies the method's applicability.

• Wind and Structures
• /
• 제13권4호
• /
• pp.347-362
• /
• 2010

Researches on the Reynolds number effect on bridge decks have made slow progress due to the complicated nature of the subject. Heretofore, few studies on this topic have been made. In this paper, aerostatic coefficients, Strouhal number ($S_t$), pressure distribution and Reynolds number ($R_e$) of Great Belt East Bridge and Sutong Bridge were investigated based on deterministic vortex method (DVM). In this method, Particle Strength Exchange (PSE) was chosen to implement the simulation of the flow around bluff body and to analyze the micro-mechanism of the aerostatic loading and Reynolds number effect. Compared with the results obtained from wind tunnel tests, reliability of numerical simulation can be proved. Numerical results also showed that the Reynolds number effect on aerostatic coefficients and Strouhal number of the two bridges can not be neglected. In the range of the Reynolds number from $10^5$ to $10^6$, it has great effect on the Strouhal number of Sutong Bridge, while the St is difficult to obtain from wind tunnel tests in this range.