• 한국전산유체공학회:학술대회논문집
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• 2000.05a
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• pp.153-158
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• 2000

For the analysis of compressible flow with real gas effect, characteristic form of Roe's Riemann solver was derived again using real gas equation of state and variable specific heal and it was extended to multi component reactive system. From this study, it is known that some correction should be made for the use of existing numerical algorithm. 1) Sonic speed and characteristic variable should be corrected with real gas effect. 2) Roe's average was applicable only with the assumption of constant properties. 3) Artificial damping term and characteristic variables should be corrected but their influence may not be significant.

• Proceedings of the KIEE Conference
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• 1995.07b
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• pp.886-888
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• 1995

Models of industrial robot manipulators are characterized by highly nonlinear equation with coupling between the variables of motion. In this paper, a case study that illustrates the use or nonlinear state feedback to decouple the control of a two axis SCARA type robot manipulator is presented. This method is based on a suitable partition about the dynamic equation of industrial robots. The performance of this method is showed by the computer simulation.

• Transactions of Materials Processing
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• v.30 no.4
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• pp.186-194
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• 2021

Finite element simulation is a widely applied method for practical purpose in various metal forming process. However, in the simulation of elasto-plastic behavior of porous material or in crystal plasticity coupled multi-scale simulation, it requires much calculation time, which is a limitation in its application in practical situations. A machine learning model that directly outputs the constitutive equation without iterative calculations would greatly reduce the calculation time of the simulation. In this study, we examined the possibility of artificial intelligence based constitutive equation with the input of existing state variables and current velocity filed. To introduce the methodology, we described the process of obtaining the training data, machine learning process and the coupling of machine learning model with commercial software DEFROM^TM, as a preliminary study, via rigid plastic finite element simulation.

• International conference on construction engineering and project management
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• 2005.10a
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• pp.662-666
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• 2005

Using data gathered from expert opinion of plant and equipment professionals; this paper presents the key variables that may constitute a maintenance proficient plant operator. The Multivariate Discriminant Analysis (MDA) was applied to generate data and was tested for sensitivity analysis. Results showed that the MDA model was able to classify plant operators' proficiency at 94.10 percent accuracy and determined nine (9) key variables of a maintenance proficient plant operator. The key variables included: i) number of years of experience as equipment operator (PQ1); ii) eye-hand coordination (PQ9); iii) eye-hand-foot coordination (PQ10); iv) planning skills (TE16); v) pay/wage (MQ1); vi) work satisfaction (MQ4); vii) operator responsibilities as defined by management (MF1); viii) clear management policies (MF4); and ix) management pay scheme (MF5). The classification procedure of nine variables formed the general model with the equation viz: OMP (general) = 0.516PQ1 + 0.309PQ9 + 0.557PQ10 + 0.831TE16 + 0.8MQ1 + 0.0216MQ4 + 0.136MF1 + 0.28MF4 + 0.332MF5 - 4.387

• 제어로봇시스템학회:학술대회논문집
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• 1997.10a
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• pp.1520-1523
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• 1997

A rigorous dynamic simulation was performed in binary gas mixture H$_{2}$/CO (70:30 vol.%) to determinate start-up operating conditions of PSA(Pressure Swing Adsorption) processes. The rigorous dynamic model for the PSA process contains an Ergun equation for expressing the pressure drop in a bed, and valve equations to compute the boundary pressure change of the bed. As the result of the continuous dynamic simulation of 100 operating cyles in various initial conditions, the unsteady-state appeared in the early period and the cyclic steady-state came out about 20th cycle in feed condition and vaccum condition, and 30th cycle in pure H$_{2}$ condition. As time goes by valve equations made change the pressure at each end of the bed in ressurization, countercurrunt-depressurization and pressure equalization steps. The H$_{2}$ purity and the recovery is 99.99% and 86.73% respectively, which is slightly higher than the experimental data. Main contributiion of this study includes supplying fundamental technologies of handling combined variables PSA processes by developing rigorous models.

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 2003.09a
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• pp.668-671
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• 2003

A concept of deadlock point of fuzzy sequential circuit is proposed. There are six cases of fuzzy sequential circuits of 1 state and 1 input variables with deadlock points. Examples of each case are shown both in a form of characteristic equation and in a graphical illustration. As fuzzy sequential circuit with 1 state and 1 input variables, D and T fuzzy flip-Hops are also characterized using the proposed concept. Thus one of the four types of D fuzzy Hip-Hops and T fuzzy Hip-flop have a deadlock point 1/2.

• Journal of Ocean Engineering and Technology
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• v.14 no.2
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• pp.70-75
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• 2000

In this paper a new constitutive model for ductile materials was proposed. This model can describe the material degradation due to the evolution of isotropic damage during elasto-platic deformation. The plastic flow rule was derived under the framework of thermodynamic approach of continuum damage mechanics(CDM) in which plastic strain hardening parameters and isotropic damage were taken as thermodynamic state variables. And the process to determine material constants for constitutive model using an experimental data was presented.

• Journal of Preventive Medicine and Public Health
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• v.15 no.1
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• pp.213-217
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• 1982

Self sensing symptoms were. surveyed by interview from the workers using lacquer-thinner(Male 35, Female 28). And the data was converted to point. Independent variables were state of the medication, education, alcohol drinking, smoking, living and past occupational history. Dependent variable was the point. The relationship between independent variables and the depenent variable was studied. The result of the study were briefly summarized as below. 1. The difference of point between sex and medication statement was significant by statistical test. 2. Age and past occupational history were not important variables. 3. The Multiple Stepwise Regression Equation obtained by this study was not useful.

• The Journal of Asian Finance, Economics and Business
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• v.8 no.1
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• pp.781-790
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• 2021

The purpose of this study is to test empirically the effect of Islamic business ethics and market conditions on organizational performance in state-owned construction companies in Indonesia. Data collection in this study was conducted online and the total number of data used was 81 respondents, both directors, heads of departments, and managers (general and project). This study uses a partial least squares structural equation model (PLS-SEM) with a quantitative approach that aims to test hypotheses and relationships between variables, such as Islamic business ethics, market conditions, project management, organizational culture, competitive strategy, and organizational performance. This study shows Islamic business ethics has a significant direct effect on organizational performance. Market conditions do not have a direct significant effect on organizational performance. Meanwhile, the mediating variables of project management and competitive strategy have a significant direct effect on organizational performance. Organizational culture does not have a significant influence on organizational performance. Conversely, market conditions have a significant influence through the mediating variables of project management and competitive strategy on organizational performance. Besides, this study is an attempt to determine the impact of the criteria factors affecting the measurement of the performance of construction organizations in Indonesia in terms of the external environment and organizational structure.

• Transactions of the Korean Society of Automotive Engineers
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• v.15 no.2
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• pp.165-174
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• 2007

Variable displacement type piston pump uses various controllers for controlling more than one state quantity like pressure, flow, power, and so on. These controllers need the mathematical model closely expressing dynamic behavior of pump for analyzing the stability of control systems which usually use various kinds of state variables. This paper derives the nonlinear mathematical model for variable displacement type piston pump. This model consists of two 1st oder differential equations by the continuity equations and one 2nd oder differential equation by the motion equation. To simplify the model we obtain the linear state variable model by differentiating the three nonlinear equations. And we verify this linearized model by comparison of simulation with experimentation and analyze the stability for the flow/pressure control. Finally this paper suggests the design compensation to ensure the stability of the systems.