• The Journal of Korean Institute of Communications and Information Sciences
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• v.16 no.1
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• pp.1-12
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• 1991

In this paper the design and construction of discrete model following servo dontroller on the position control system is proposed. The operational time delay of the plant in the controller which is proposed, is considered and the system which is added by the integral compensation in first order difference equation is constructed. By applying the optimal regulator method to the system, the method which find the optimal state feedback gain is developed theoretically. The output of a model which is correspond to a DC Servo motor follow quickly the speed response of a DC Servo motor and the velocity error in ansteady-state is reduced in zero and the position response is controlled correctly, the performance of the controller is contoller is confirmed by Computer Simulation.

• Journal of the Korea Society for Simulation
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• v.18 no.4
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• pp.219-225
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• 2009

The primary purpose of this study is to build computer models referring overall flow of complex and various semiconductor wafer manufacturing process and to implement a educational model which operates with a presentation tool showing device design. It is important that Korean semiconductor industries secure high competitive power on efficient manufacturing management and to develop technology continuously. Models representing the FAB processes and the functions of each process are developed for Seoul National University Semiconductor Research Center. However, it is expected that the models are effective as visually educational tools in Korean semiconductor industries. In addition, it is anticipated that these models are useful for semiconductor process courses in academia. Scalability and flexibility allow semiconductor manufacturers to customize the models and perform simulation education. Subsequently, manufacturers save budget.

• Journal of Information Processing Systems
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• v.12 no.2
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• pp.275-294
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• 2016

A primary task in wireless sensor networks (WSNs) is data collection. The main objective of this task is to collect sensor readings from sensor fields at predetermined sinks using routing protocols without conducting network processing at intermediate nodes, which have been proved as being inefficient in many research studies using a static sink. The major drawback is that sensor nodes near a data sink are prone to dissipate more energy power than those far away due to their role as relay nodes. Recently, novel WSN architectures based on mobile sinks and mobile relay nodes, which are able to move inside the region of a deployed WSN, which has been developed in most research works related to mobile WSN mainly exploit mobility to reduce and balance energy consumption to enhance communication reliability among sensor nodes. Our main purpose in this paper is to propose a solution to the problem of deploying mobile data collectors for alleviating the high traffic load and resulting bottleneck in a sink's vicinity, which are caused by static approaches. For this reason, several WSNs based on mobile elements have been proposed. We studied two key issues in WSN mobility: the impact of the mobile element (sink or relay nodes) and the impact of the mobility model on WSN based on its performance expressed in terms of energy efficiency and reliability. We conducted an extensive set of simulation experiments. The results obtained reveal that the collection approach based on relay nodes and the mobility model based on stochastic perform better.

• Journal of the Korea Society for Simulation
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• v.22 no.4
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• pp.49-55
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• 2013

Recently the CGF/SAF (Computer Generated Force / Semi-Automated Force) technology has been getting attention to deal with the increasing complexity in a DM&S(Defence Modeling and Simulation) environment. OneSAF is one of well-known CGF/SAF systems, however, it is not able to support the DEVS framework which is an advanced discrete event based modeling and simulation environment. Especially, most DM&S systems in Korea has been developed on the basis of the DEVS framework. In this paper, we have proposed the agent-based SAF design methodology and tool for supporting DEVS M&S environment. The proposed SAF modeling tool is divided into two parts; the agent modeling part and SAF modeling part. In the agent modeling environment, the modeler can simply create the agent model by writing down the necessary rules. It also provides the agent testing environment so that the modeler maybe conveniently verify the prescribed agent model. The SAF model is finally created by combing the individual agents based on the pre-defined structure. DM&S engineers will be able to employ our tools and modeling methodology to design the DEVS-based DM&S system to be developed.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 2000.04a
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• pp.253-256
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• 2000

In general, Automated Storage/Retrieval Systems (AS/RS ) have racks of equal sized cells to utilize the concept of unit-load. Most of the techniques for the performance estimation of a unit-load AS/RS are a static model or computer simulation. Especially, their models were developed under assumption that the Storage/Retrieval (S/R) machine performs only single command (SC) or dual command (DC). In reality, defending on the operating policy and the status of the system at a particular time, the S/B machine performs a SC or a DC, or becomes .: idle. In order to resolve these weak points, we propose a stochastic model for the performance estimation of unit-load AS/RS by using a single-server queueing model. Expected numbers of waiting storage and retrieval commands are found

• Proceedings of the KSME Conference
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• 2004.04a
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• pp.864-869
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• 2004

In this paper, a blackbox approach is carried out to model the nonlinear dynamic bushing model. One-axis durability test is performed to describe the mechanical behavior of typical vehicle elastomeric components. The results of the tests are used to develop an empirical bushing model with an artificial neural network. The back propagation algorithm is used to obtain the weighting factor of the neural network. Since the output for a dynamic system depends on the histories of inputs and outputs, Narendra's algorithm of 'NARMAX' form is employed in the neural network bushing module. A numerical example is carried out to verify the developed bushing model.

• Transactions of the Korean Society of Automotive Engineers
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• v.11 no.4
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• pp.151-157
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• 2003

In this paper, a blackbox approach is carried out to model the nonlinear dynamic bushing model. One-axis durability test is performed to describe the mechanical behavior of typical vehicle elastomeric components. The results of the tests are used to develop an empirical bushing model with an artificial neural network. The back propagation algorithm is used to obtain the weighting factor of the neural network. Since the output for a dynamic system depends on the histories of inputs and outputs, Narendra algorithm of 'NARMAX' form is employed to consider these effects. A numerical example is carried out to verify the developed bushing model.

• Journal of Korean Society on Water Environment
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• v.24 no.6
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• pp.784-792
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• 2008

Greater focus must be placed on ensuring that the water quality model (WQM) reflects the objective of its application and the characteristics of the water environment properly before it is selected. In the development or application of WQM, various factors influencing the model predictions should be reviewed so that it can perform more properly and reasonably based on scientific theory. This study reviewed the characteristic of existing WQM and the domestic river environment to find the requirements of the model application for TMDLs management in Korea. In this study, a water quality model, QUAL-NIER, was developed based on the USEPA's QUAL2E. The core structure and reaction scheme of the model was established followed by the formulation of equations according to the scheme with some supplements on the reaction mechanisms which are necessary for domestic rivers. Algorithms on the equations were set up and programmed to form a computer-based model. The developed model, QUAL-NIER was applied to the main stem of the Nakdong river. The model was calibrated and verified to data measured in 2004. The model results displayed good agrement with the field measurements for both calibration and verification. From this study, it was concluded that the developed QUAL-NIER model was very powerful with regard to the water quality simulation in domestic rivers.

• Journal of the Korea Society for Simulation
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• v.25 no.4
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• pp.53-63
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• 2016

This study aims to verify the feasibility of design by developing pressure flow-controlled swash plate type pump with the use of SimulationX, a computer analysis program. Developing analysis model based on design drawing data has a cost-saving effect because it is possible to figure out the effectiveness of design through the work and it never falls into repeated inaccuracies in the production process. Analysis model is developed in the following order. First, the structure of each part such as valve and rotating unit which have dynamic factor is analyzed and the modeling of single component is carried out, reflecting drawing data. Second, the modeling of pump assembly is carried out with the combination of each analysis model and a work is conducted to determine whether the modeling can perform pressure flow control function according to load condition smoothly based on design intent. At the end of the modeling process, the feasibility of design is verified by showing the parts which are moving as expected mechanism.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2001.05a
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• pp.136-142
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• 2001

Recently, a much amount of attention has been paid not only to produce products with precise dimensional accuracy, but also to predict and control the microstructural evolution and mechanical properties of parts. Especially, to do the latter through computer simulation, the history of states factors influencing on these evolution such as temperature, strain, strain rate etc., should be calculated and a appropriate mathematical models for the prediction of microstructural evolution must be developed. Thus, in this study thermo-viscoplastic finite element program including the model for predicting microstructural has been developed. Also for the verification of developed program warm forging process for the rotor pole was simulated and the comparison between the results calculated and ones in the literature was made.