• The Korean Journal of Physiology and Pharmacology
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• v.20 no.1
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• pp.111-117
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• 2016

Vagal nerve activity has been known to play a crucial role in the induction and maintenance of atrial fibrillation (AF). However, it is unclear how the distribution and concentration of local acetylcholine (ACh) promotes AF. In this study, we investigated the effect of the spatial distribution and concentration of ACh on fibrillation patterns in an in silico human atrial model. A human atrial action potential model with an ACh-dependent $K^+$ current ($I_{KAch}$) was used to examine the effect of vagal activation. A simulation of cardiac wave dynamics was performed in a realistic 3D model of the atrium. A model of the ganglionated plexus (GP) and nerve was developed based on the "octopus hypothesis". The pattern of cardiac wave dynamics was examined by applying vagal activation to the GP areas or randomly. AF inducibility in the octopus hypothesis-based GP and nerve model was tested. The effect of the ACh concentration level was also examined. In the single cell simulation, an increase in the ACh concentration shortened $APD_{90}$ and increased the maximal slope of the restitution curve. In the 3D simulation, a random distribution of vagal activation promoted wavebreaks while ACh secretion limited to the GP areas did not induce a noticeable change in wave dynamics. The octopus hypothesis-based model of the GP and nerve exhibited AF inducibility at higher ACh concentrations. In conclusion, a 3D in silico model of the GP and parasympathetic nerve based on the octopus model exhibited higher AF inducibility with higher ACh concentrations.

• Journal of ILASS-Korea
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• v.17 no.2
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• pp.77-85
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• 2012

The CFD simulation of diesel spray tip penetrations were compared with 0-D simulation for experimental data obtained with common rail injection system. The simulated four injection patterns include single, pilot and split injections. The CFD simulation of the spray penetration over these injection patterns was performed using the KIVA-3V code, which was implemented with both the standard KIVA spray and original gas jet sub-models. 0-D simulation of the spray tip penetration with time-varying injection profiles was formulated based on the effective injection velocity concept as an extension of steady gas jet theory. Both the CFD simulation of the spray tip penetration with the standard KIVA spray model and 0-D simulation matched better with the experimental data than the results of the gas jet model for the entire fuel injection patterns.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 1998.10a
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• pp.99-105
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• 1998

Simulation modeling has become an extremely important approach to analyzing complex system. In recent years the number of people using simulation as problem-solving aid has increased. In this Paper, we developed a simulation model for analyzing the physical distribution system in ports. we used Arena 2.2 which is a kind of simulation software based common simulation language, SIMAN V. And then, we applied this model to kwangyang port(partially) and analyzed the effect of it upon port system in according to change of the quantity of goods transported.

• Journal of Biosystems Engineering
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• v.16 no.2
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• pp.159-166
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• 1991

A simulation model was developed for analyzing a crop transport system using SLAMSYSTEM. The developed model could predict total delivered amount and delivery rate of a crop under various conditions of transport and analyze the effects of work factors on the efficiency of the crop transport system. A simulation model was also developed to analyze a rice transport system based on the generalized model of the crop transport system.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 1993.10a
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• pp.1127-1136
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• 1993

A mathematical model has been developed for the simulation of static stability of agricultural tractors. The model was based on Reichmann's model but modified to improve its shortcomings for practical applications. Two examples of model simulation were presented and showed its usefulness in evaluating the control and stability loss boundaries.

• 제어로봇시스템학회:학술대회논문집
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• 2005.06a
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• pp.1115-1117
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• 2005

This paper describes the three dimension model and simulation results of a thermal actuator based on polyMUMPs process, known as thermal multimorph actuator. The device has potential application in micro-transducers such as atomic force microscope (AFM) tip and scanning tunneling microscope (STM) tip. This device made of a multi-layer materials stack together with consisted of polysilicon, $SiO_2$ and gold. A mask layout design, three dimension model and simulation results are reported and discussed.

• Proceedings of the KIEE Conference
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• 2008.10c
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• pp.145-147
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• 2008

In this paper, the implementation of the Permanent Magnet Synchronous Machine (PMSM) model based on the Matlab/Simulink is described. Due to the analysis of the mathematical dq-modeling, a vector controlled PMSM drive simulation is approached. With the simulated system, unlike in black block models, all machine parameters are accessible for control and verification. Based on the Matlab/Simulink, the model of the PMSM with load torque is established, the simulation is studied and some conclusions are given.

• Proceedings of the Korea Society for Simulation Conference
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• 2001.10a
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• pp.103-109
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• 2001

Soft sensor is an effective method to deal with the estimation of variables, which are difficult to measure because of the reasons of economy or technology. Fuzzy logic system can be used to develop the soft sensor model by infinite rules, but the fuzzy dividing of variable sets is a key problem to achieve an accurate fuzzy logic model, In this paper, we proposed a new method to develop soft sensor model based on fuzzy neural network. First, using a novel method to divide the variable fuzzy sets by the process input and output data. Second, developing the fuzzy logic model based on that fuzzy set dividing. After that, expressing the fuzzy system with a fuzzy neural network and getting the initial soft sensor model based FNN. Last, adjusting the relative parameters of soft sensor model by the BP learning method. The effectiveness of the method proposed and the preferable generalization ability of soft sensor model built are demonstrated by the simulation.

• Journal of the Korean Institute of Intelligent Systems
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• v.21 no.1
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• pp.29-35
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• 2011

In this paper, an integrated simulation model for designing multi-agent system based DEMS (distributed energy management system) in stand-alone micro-grid system is proposed. In the design of the EMS(energy management system), the multi-agent based DEMS are more effective than conventional centralized EMS, but it is difficult to design the DEMS by general design tools for power system because of various states of a microgrid system during operation of stand-alone mode. Also, since performance test of the DEMS using a real system is inefficient, an integrated simulation model is required for designing an effective multi-agent system based DEMS. The proposed model consists of Matlab/SimPowerSystems based simulation model of the microgrid system and the Multi-agnet based DEMS designed by Matlab/StateFlow tool. In order to show the effect of the proposed model, the model outputs are analyzed for specified operation conditions.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.8 no.3
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• pp.131-138
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• 2009

The purpose of this paper is the development of an agent-based pedestrian simulation model. The simulation model is based on the Cellular Automata theory. The model consists of four components: initialization, pedestrian generation, lateral movement, and front movement components. We have applied this model for experiment about pedestrian facility. In particular, we have experimented how the installation of fence is effective to resolve conflict pedestrian movements in different directions. We have found that the installation of the fence as a pedestrian facility can divide conflict moving pedestrians effectively. We have also found that the effect of the fence is bigger in slightly congested pedestrian flows than in severely congested pedestrian flows.