• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 춘계학술대회논문집A
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• pp.553-560
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• 2001

Recently, ultrasonic testing simulation has becomes very important in the field of nondestructive evaluation due to its unique capability of providing testing signals without real inspection. The ultrasonic testing simulation requires three elementary models including the transducer beam radiation model, the flaw scattering model, and the reception model. In the present work, we briefly describe an approach to develop the ultrasonic testing model together with its elementary models with the multi-gaussian beam model. Based on this approach, we developed ultrasonic testing simulation program with MATLAB. The performance of the developed program is demonstrated by the predicting of ultrasonic signals from two types of flaws, circulars crack and spheres.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2002년도 ICCAS
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• pp.50.2-50
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• 2002

1. Introduction 2. Reduced-Order Model of Robot System 3. Model-Based Control 4. Simulation Results 5. Experimental Results and Considerations 6. Conclusions

• Journal of Advanced Marine Engineering and Technology
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• 제28권3호
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• pp.423-433
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• 2004

A large eddy simulation (LES) is performed for turbulent flow in a combustion device. The combustion device is simplified as a cylindrical chamber with sudden expansion. A flame holder is attached inside a cylindrical chamber in order to promote turbulent mixing and to accommodate flame stability. The turbulent sub-grid scale models are applied and validated. Emphasis is placed on the evaluation of turbulent model for the LES of complex geometry. The simulation code is constructed by using a general coordinate system based on the physical contravariant velocity components. The calculated Reynolds number is 5000 based on the bulk velocity and the diameter of inlet pipe. The predicted turbulent statistics are evaluated by comparing with the LDV measurement data. The Smagorinsky model coefficients are estimated and the utility of dynamic SGS models are confirmed in the LES of complex geometry.

• 한국생산제조학회지
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• 제21권3호
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• pp.368-375
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• 2012

Durability performance evaluation of automotive components is very important and time consuming task. In this paper, to reduce vehicle component development time and cost virtual testing simulation technology is used to evaluate durability performance of a passenger car front aluminum sub-frame. Multibody dynamics based vehicle model and virtual test simulation model of a half car road simulator are validated by comparisons between rig test results and simulation results. Durability life prediction of the sub-frame is carried out using the model with road load data of proving ground which can evaluate accelerated durability life. We found that the durability performance of the sub-frame is sufficient and it can be predicted within short time compared to rig test time.

• 한국가시화정보학회지
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• 제5권2호
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• pp.9-13
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• 2007

Typhoon simulation based on dynamical forecasting results is demonstrated by utilizing geodesic model GME (operational global numerical weather prediction model of German Weather Service). It is based on uniform icosahedral-hexagonal grid. The GME gridpoint approach avoids the disadvantages of spectral technique as well as the pole problem in latitude-longitude grids and provides a data structure extremely well suited to high efficiency on distributed memory parallel computers. In this study we made an attempt to simulate typhoon 'NARI' that passed over the Korean Peninsula in 2007. GME has attributes of numerical weather prediction model and its high resolution can provide details on fine scale. High resolution of GME can play key role in the study of severe weather phenomenon such as typhoons. Simulation of future typhoon that is assumed to occur under the global warming situation shows that the life time of that typhoon will last for a longer time and the intensity will be extremely stronger.

• 국제학술발표논문집
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• The 3th International Conference on Construction Engineering and Project Management
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• pp.400-408
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• 2009

Simulation applications for analyzing the productivity of construction operations at operation level and project schedules at project level are crucial methods in project management. The application at two different levels should be very tightly linked to each other in practice. However, appropriate integration at the levels is not achieved in that existing systems do not support to integrate operation models into a schedule model. This paper presents a new approach named to Discrete Event Simulation-Nesting modeling approach, which supports not only productivity analysis at operation level but also schedule management at a project level. The system developed by the authors allows creating operation models at the operation level, maintaining them in operation model library, executing sensitivity analysis to find the behaviors of the operation models when different combination of resources are used as existing DES systems do. On top of the conventional functions, the new system facilitates to find the optimum solution of resource combinations which satisfy the user's interest by computing the hourly productivity and the hourly cost of the operation. By drag-and-dropping an operation model kept in the operation model library, the operation models are integrated into an activity of the schedule model. When a complete schedule model is established by nesting operation models into the schedule model, stochastic simulation based scheduling is executed. A case study is presented to demonstrate the new simulation system and verify the validity of the system.

• 한국시뮬레이션학회논문지
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• 제2권1호
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• pp.46-54
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• 1993

Analytic and simulation models for prioritized token ring are presented in this paper. Its protocol is based on prioritized token ring with reservation (R-PTR). Since the protocol of the R-PTR is simple and the performance of the R-PTR is not inferior to that of the IEEE-PTR under almost all traffic load environments, we use the R-PTR as our token ring model. By using the properties of Markovian process, the expressions for average throughput and average packet transmission delay are derived. The results obtained from the analytic model are compared with that of the discrete event simulation model.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1987년도 정기총회 및 창립40주년기념 학술대회 학회본부
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• pp.193-196
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• 1987

We reported that hot electron phenomena in submicron nMOSFET by Monte Carlo method. In order to predict the influence of the hot electron effects on the device reliability, either simple analytical model or a complete two dimensional numerical simulation has been adopted. Results of numerical simulation, based on the static mobility model, may be inaccurate when gate length of MOSFET is scaled down to less than 1um. Most of device simulation packages utilize the static nobility model. Monte Carlo method based on stochastic analysis of carrier movement may be a powerful tool to characterize hot electrons. In this work, energy and velocity distribution of carriers were obtained to predict the relative degree of short channel effects for different device parameters. Our analysis shows a few interesting results when $V_{ds}$ is 5 volt, average electron energy does not increase with gate bias as evidenced by substrate current.

• Computers and Concrete
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• 제12권4호
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• pp.565-583
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• 2013

Existing numerical models for strain-hardening cement-based composites (SHCC) are short of providing sufficiently accurate solutions to the failure patterns of coupling beams of different designs. The objective of this study is to develop an effective model that is capable of simulating the nonlinear behavior of SHCC coupling beams subjected to cyclic loading. The beam model proposed in this study is a macro-scale plane stress model. The effects of cracks on the macro-scale behavior of SHCC coupling beams are smeared in an anisotropic model. In particular, the influence of the defined crack orientations on the simulation accuracy is explored. Extensive experimental data from coupling beams with different failure patterns are employed to evaluate the validity of the proposed SHCC coupling beam models. The results show that the use of the suggested shear stiffness retention factor for damaged SHCC coupling beams is able to effectively enhance the simulation accuracy, especially for shear-critical SHCC coupling beams. In addition, the definition of crack orientation for damaged coupling beams is found to be a critical factor influencing the simulation accuracy.

• 한국농공학회논문집
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• 제56권3호
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• pp.1-9
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• 2014

The aim of this study is to develop a simulation model for analyzing 2D truss structure using Generic Agricultural System Simulator (GASS). Although the truss is simple structure, numerical methods based on matrix analysis are cumbersome and complicated. This study suggests simple and convenient methods to remove calculating steps for whole stiffness matrices. The simulation environment based on independency of object-oriented components on GASS consists of component development and component deploy stages. A component for a truss structure is implemented based on equilibrium equations at nodes. The simulator can analyze truss structures through deploying components with attributes and links. The examples using GASS show intuitive graphical results of the movements of truss nodes.