• Transactions of the Korean Society of Mechanical Engineers A
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• v.20 no.4
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• pp.1290-1300
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• 1996

The finite element method, based on rigid-plastic formulation, is widely used to simulate metal forming processes. In order to improve the computational efficiency of the rigid-plastic FEM, one-point integration is used to evaluate the stiffness matrix with four-node rectangular elements and eight-node brick elements. In order to control the hourglass modes, hourglass strain rate components were introduced and included in the effective strain rate definition, Numerical tests have shown that the proposed one-point integration scheme reduces the stiffness matrix evaluation time without deteriorating the convergence behavior of Newton-Raphson method. Simulations of a ring compression, a plane-strain closed-die forging and the three-dimensional spike forging processes were carried out by using the proposed integration method. The simulation results are compared to those obtained by applying the conventional integraiton method in terms of the solution accuracy and computational efficiency.

• Coupled systems mechanics
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• v.11 no.1
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• pp.79-91
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• 2022

Models for water treatment processes include simulation, i.e., modelling of water quality, flow hydraulics, process controls and design. Water treatment processes are inherently dynamic because of the large variations in the influent water flow rate, concentration and composition. Moreover, these variations are to a large extent not possible to control. Mathematical models and computer simulations are essential to describe, predict and control the complicated interactions of the water treatment processes. An accurate description of such systems can therefore result in highly complex models, which may not be very useful from a practical, operational point of view. The main objective is to combine knowledge of the process dynamics with mathematical methods for processes estimation and identification. Good modelling practice is way to obtain this objective and to improve water treatment processes(its understanding, design, control and performance- efficiency). By synthesize of existing knowledge and experience on good modelling practices and principles the aim is to help address the critical strategic gaps and weaknessesin water treatment models application.

• 제어로봇시스템학회:학술대회논문집
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• 1991.10a
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• pp.1028-1033
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• 1991

This paper describes the design of a neural network estimator to estimate weld pool sizes for on-line use of quality monitoring and control in GMA welding processes. The estimator utilizes surface temperatures measured at various points on the top surface of the weldment as its input. The main task of the neural net is to realize the mapping characteristics from the point temperatures to the weld pool sizes through training, A series of bead-on plate welding experiments were performed to assess the performance of the neural estimator.

• 제어로봇시스템학회:학술대회논문집
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• 1992.10a
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• pp.531-536
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• 1992

In GMA welding processes, monitoring and control of weld quality are extremely difficult problems. This paper describes a neural network-based method for monitoring and control of weld pool sizes. First, weld pool sizes are estimated via a neural estimator using multi-point surface temperatures, which are strongly related to the formation of weld pool, and then controlled using the estimated pool sizes. Two types of controllers using the pool size estimator are designed and tested. To evaluate the performance of the designed controllers, a series of simulation studies was performed.

• 한국연소학회:학술대회논문집
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• 2013.06a
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• pp.21-23
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• 2013

Various solid particle materials are treated in the industrial processes including fixed-beds or moving grate beds, and modeling approaches have been widely applied to the processes to predict and evaluate their performance. For this study, the modeling approach was applied to iron ore sintering process with various improvement measures. Based on the previous modeling approach, the changes and effects of the improvement measures were discussed at the point of controlling the combustion environment in the bed.

• Journal of the Korean Ceramic Society
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• v.47 no.1
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• pp.26-38
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• 2010

Degradation in Solid Oxide Fuel Cell performance can be ascribed to the following fundamental processes from the materials chemical point of view; that is, diffusion in solids and reaction with gaseous impurities. For SOFC materials, diffusion in solids is usually slow in operation temperatures $800\sim1000^{\circ}C$. Even at $800^{\circ}C$, however, a few processes are rapid enough to lead to some degradations; namely, Sr diffusion in doped ceria, cation diffusion in cathode materials, diffusion related with metal corrosion, and sintering of nickel anodes. For gaseous impurities, chromium containing vapors are important to know how the chemical stability of cathode materials is related with degradation of performance. For LSM as the most stable cathode among the perovskite-type cathodes, electrochemical reduction reaction of $CrO_3$(g) at the electrochemically active sites is crucial, whereas the rest of the cathodes have the $SrCrO_4$ formation at the point where cathodes meet with the gases, leading to rather complicated processes to the degradations, depending on the amount and distribution of reacted Cr component. These features can be easily generalized to other impurities in air or to the reaction of nickel anodes with gaseous impurities in anode atmosphere.

• Journal of the Korean Society for Precision Engineering
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• v.16 no.6
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• pp.190-196
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• 1999

In this study, a procedure for analyzing chip-tool friction and shear processes in 3-D cutting with a single point tool has been established. The edge of a single point tool including circular nose is modified to the equivalent straight edge, then 3-D cutting with a single point tool is reduced to equivalent oblique cutting. Transforming the conventional coordinate systems and using the measured three component of cutting forces, force components on the rake face and the shear plane of the equivalent oblique cutting system can be obtained. And it can be possible to assess the chip-tool friction and shear characteristics in 3-D cutting with a single point tool.

• 제어로봇시스템학회:학술대회논문집
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• 2000.10a
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• pp.395-395
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• 2000

Optimization of existing processes becomes more important than the past as environmental problems and concerns about energy savings stand out. When we can model a process mathematically, we can easily optimize it by using the model as constraints. However, modeling is very difficult for most chemical processes as they include numerous units together with their correlation and we can hardly obtain parameters. Therefore, optimization that is based on the process models is, in turn, hard to perform. Especially, f3r unknown processes, such as bioprocess or microelectronics materials process, optimization using mathematical model (first principle model) is nearly impossible, as we cannot understand the inside mechanism. Consequently, we propose a few optimization method using empirical model evolutionarily instead of mathematical model. In this method, firstly, designing experiments is executed fur removing unecessary experiments. D-optimal DOE is the most developed one among DOEs. It calculates design points so as to minimize the parameters variances of empirical model. Experiments must be performed in order to see the causation between input variables and output variables as only correlation structure can be detected in historical data. And then, using data generated by experiments, empirical model, i.e. response surface is built by PLS or MLR. Now, as process model is constructed, it is used as objective function for optimization. As the optimum point is a local one. above procedures are repeated while moving to a new experiment region fur finding the global optimum point. As a result of application to the pulp digester benchmark model, kappa number that is an indication fur impurity contents decreased to very low value, 3.0394 from 29.7091. From the result, we can see that the proposed methodology has sufficient good performance fur optimization, and is also applicable to real processes.

• Journal of the Korea Computer Industry Society
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• v.8 no.3
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• pp.173-180
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• 2007

This paper describes the point-detector arrays system to processes the fields of signal and noise of the turbulent atmosphere. By using aboves, the maxmum output of direct-detection shows a little differences between experimental datas and theoretical datas. As a whole the experimental datas are agreed with the joint Gaussian theoretical curves and K-distribution curves.

• Fashion & Textile Research Journal
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• v.19 no.5
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• pp.595-601
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• 2017

Advances in 3D garment simulation technology contribute greatly to consumers becoming more immersed in movies and games by realistically expressing the garments the characters in the movie or game are wearing. The fashion industry has reached a point where it needs to maximize efficiency in production and distribution to go beyond time and space in order to compete on the global market. The processes of design and product development in the fashion industry require countless hours of work and consume vast resources in terms of materials and energy to repeat sample production and assessment. Therefore, the design and product development tools and techniques must aim to reduce the sample making process. Therefore, this study aims to study a case for comparing the real garment sample making process to the virtual garment sample making process. In this study, we have analysed the differences between the real and virtual garment making processes by choosing designated patterns. As we can see from the study results, the real and virtual garments generally are made through similar processes in manufacturing, while the time consumed for each shows great variation. In real garment making, scissoring and sewing require the greatest number of work hours, whereas in virtual garment making, most of the time was spent in the simulation process.