• Journal of Mechanical Science and Technology
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• 제14권2호
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• pp.188-196
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• 2000

In this paper, our aim is to develop a model for two cooperating flexible manipulators handling a rigid object by using lumped parameters. This model is in turn analyzed on MATLAB. In order to validate the model, a precise simulation model is developed using $ADAMS^{TM}$ (Automatic Dynamic Analysis of Mechanical System). Moreover, to clarify the discussion, the motions of a dual-arm experimental flexible manipulator are considered. Using the developed model, we control a robotic system with a symmetric hybrid position/force control scheme. Finally, experiments and simulations are performed, and a comparison of simulation results with experimental results is given to a rerify the validity of our model.

• 대한환경공학회지
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• 제22권11호
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• pp.2017-2023
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• 2000

정유폐수의 성상에 적합한 동역학적 모델을 적용하여 활성슬러지법으로 처리할 때 모델의 적합성을 검토하기 위하여 실제 정유폐수 처리장 포기조내의 환경인자의 변화와 유출수 특성을 비교하였다 활성슬러지 포기조내 DO, pH, MLSS, COD의 실제 측정값과 비교하였다. Simulation한 결과, 유출수 평균 COD가 19.0~19.4mg/L로 측정 COD 23.1mg/L와 잘 일치하였고, 포기조내 평균 DO는 1.9~2.4mg/L로 예측되었는데 측정된 평균 DO가 2.2mg/L로 잘 일치하여 모델의 정유폐수 처리장의 적용 가능성이 검토되었다.

• 대한조선학회논문집
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• 제59권3호
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• pp.141-148
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• 2022

A hybrid turbulence model has developed by combining a sub-grid scale model using dynamic k equation in LES with k-𝜔 SST model of RANS equation. To ascertain potential applicability of the hybrid turbulence model, fully developed turbulent channel flows at Re_𝜏=180 have been simulated of which computational domain has a top wall with coarse cells and a bottom wall with fine cells. The streamwise mean velocity and turbulent intensity profiles showed a good agreement with DNS data when using the hybrid model rather than using a single model in k-𝜔 SST or dynamic k equation models. Computational simulations of turbulent flows around KVLCC2 with a pre-swirl duct have been mainly performed using the hybrid turbulence model. Compared to the results obtained from RANS simulation with k-𝜔 SST model as well as LES with dynamic k equation SGS model, turbulent wakes of the duct in the present simulation using the hybrid turbulence model were very similar to that of LES. Also, the resistances acting on hull, rudder and duct in hybrid turbulence model were similar to those in RANS simulation whereas the viscous forces acting on the hull in LES had a significant error due to coarse cells inappropriate to the sub-grid scale model.

• 한국지진공학회논문집
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• 제9권5호
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• pp.21-28
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• 2005

본 논문에서는 상부구조물과 진동대에서 측정된 가속도를 이용하여 구조물과 지반의 동적 상호작용을 고려한 진동대 시험을 수행하는 방법이 제안된다. 부분구조법을 기반으로 한 제안된 실험법은 상부구조물만을 실험체로 사용하고 지반모델에 대해서는 동적지반강성을 진동대 제어기에 반영하는 방법이다. 이 때, 실험부분인 상부구조물은 전체 구조물 지반계의 동적거동을 모사하기 위한 운동으로 진동대에 의해 가진된다. 먼저, 구조물 지반계의 운동방정식으로부터 유도된 수치 시뮬레이션 검증모델에 의해 제안된 방법의 타당성이 검증된다. 또한, 진동대의 전달함수를 고려한 시뮬레이션 모델로부터 진동대 시험에 의한 제안된 방법의 적용성이 수치 시뮬레이션에 의해 검증된다.

• 대한기계학회논문집B
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• 제27권7호
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• pp.853-858
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• 2003

The suitable estimation of the filter width in the dynamic eddy viscosity model were investigated in high Reynolds number channel flow. In this study, the improvement on matters by optimizing the test filter shape was attempted through the numerical experiment. The way that select optimum test filter width is recommended. Some test filters, one is based on a discrete representation of the top-hat filter and another are based on a high-order filtering operation, are evaluated in simulations of the turbulent channel flow at Reynolds number 1020, based on friction velocity and channel half width. It appears that the estimation of test filter width practically can decrease the dissipative nature of dynamic eddy viscosity model with explicit test filter. It shows that the value of the filter width ratio used in the dynamic procedure must match the properties of the test filter actually used in the calculation.

• 한국국방경영분석학회지
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• 제25권1호
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• pp.199-214
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• 1999

The Constructive Battle Simulation Model is very important to the recent military training for the substitution of the field training. However, real battlefield systems operate under real-time conditions, they are inherently distributed, concurrent and dynamic. In order to reflect these properties by the computer-based simulation systems which represent real world processes, we have been developing constructive simulation model for several years. Conventionally, scheduling and resource allocation activities which have timing constraints, we elaborated on these issues and developed the simulation system on commercially available hardware and operating system with lock-free resource allocation scheme and rate monotonic scheduling.

• International Journal of Computer Science & Network Security
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• 제22권1호
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• pp.175-182
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• 2022

This work presents a simulation model for a specific UV disinfection system (UVDS) powered by a Photovoltaic System. The global UVDS also includes the electronic converters, Electronic Ballast, UV Lamp and Motor Pump. The equations that model the physical components' behaviour are connected to obtain a dynamic global model. The latter is converted in a Simulink/Matlab model, which allows to carry out simulation series concerning the entire UVDS. The physical parameters: the irradiation G and the temperature T, are considered as inputs. series of measurements carried out in order to show how these parameters affect the current, the voltage of the PVs and especially the value of the current of the UV lamp, on the other hand a study on the behavior and the evolution of the parameters of the motor pump such as the armature current, motor torque, speed of rotation and the water flow. The purpose of all this is to realize how important are the two parameters concerning the lamp current and the water flow because they are two very important factors to keep an adequate water quality.

• Computers and Concrete
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• 제26권1호
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• pp.11-20
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• 2020

Concrete are the most widely used manmade materials for infrastructure construction across the world. These constructions gradually aged and damaged due to long-term use. However, there does not exist an efficient concrete recycling method with low energy consumption. In this study, concrete was regarded as a heterogeneous material composed of coarse aggregate and cement mortar. And the failure mode of concrete under ultrasonic dynamic loading was investigated by finite element (FE) analysis. Simultaneously, a 3D random aggregate concrete model was programmed by APDL and imported into ABAQUS software, and the damage plastic constitutive model was applied to each phase to study the damage law of concrete under dynamic loading. Meanwhile, the dynamic damage process of concrete was numerically simulated, which observed ultrasonic propagating and the concrete crushing behavior. Finally, the FE simulation considering the influence of different aggregate volume and aggregate size was carried out to illustrate the damage level of concrete.

• Earthquakes and Structures
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• 제2권2호
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• pp.189-206
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• 2011

In this study, the subspace stochastic realization theories (SSR model I and SSR model II) have been applied to a real bridge for estimating its dynamic characteristics (natural frequencies, damping constants, and vibration modes) under ambient vibration. A numerical simulation is carried out for an arch-type steel truss bridge using a white noise excitation. The estimates obtained from this simulation are compared with those obtained from the Finite Element (FE) analysis, demonstrating good agreement and clarifying the excellent performance of this method in estimating the structural dynamic characteristics. Subsequently, these methods are applied to the vibration induced by both strong and weak winds as obtained by remote monitoring of the Kabashima bridge (an arch-type steel truss bridge of length 136 m, and situated in Nagasaki city). The results obtained with this experimental data reveal that more accurate estimates are obtained when strong wind vibration data is used. In contrast, the vibration data obtained from weak wind provides accurate estimates at lower frequencies, and inaccurate accuracy for higher modes of vibration that do not get excited by the wind of lower intensity. On the basis of the identified results obtained using both simulated data and monitored data from a real bridge, it is determined that the SSR model II realizes more accurate results than the SSR model I. In general, the approach investigated in this study is found to provide acceptable estimates of the dynamic characteristics of highway bridges as well as for the vibration monitoring of bridges.

• 한국자동차공학회논문집
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• 제7권6호
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• pp.91-105
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• 1999

Dynamic simulation techniques are developed to analyze the shift characteristics of vehicle powertraisn with automatic transmission. In this study, the mathematical modeling of powertrain components such as engine , clutch system, planetary gear system and road load , is presented for the simulation. The clutch engagement condition, which determines the degree of freedom for the system, is also proposed .By using a detailed nonlinear model of torque converter, it is possibile to accurately analyze the extremely transient state such as the shift. Dynamo-based experiments are carried out to prove the validity of the proposed simulation techniques. Using the developed simulation program, the effects of the dynamic design variables and the control conditions , focused on the shift, are evaluated to improve the driving comforability.