• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2003.05a
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• pp.176-179
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• 2003

The mean temperature prediction of strip is very important in hot strip finishing mill because of affecting on product quality and shape. Also, temperature can be used by basic information in other on-line control models with affecting control accuracy in factory. So, FE based on-line temperature model was developed for predicting strip mean temperature accurately in various process conditions and factory environments. There are many variables in affecting strip mean temperature in on-line states of factory. But some problems are occurred in considering all variables for making temperature model because of the bad efficiency of regression or fitting analysis. In this report, we have adopted dimensional analysis for solving these problems. We have many variables with dimensions affecting strip temperature but we are able to make non-dimensional variables less than dimensional variables from the combination of dimensional variables caused by PI-Theorem in fluid mechanics. The developed models are divided by two parts. The one is interstand temperature prediction model. The other is roll gap temperature model.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.7A
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• pp.738-745
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• 2007

The non-linearity of HPA(high power amplifier) which is an important component in modern communications systems introduces AM/AM and AM/PM distortion so that the transmitted signal is deteriorated. And, the I/Q unbalances and phase error which are generated by non-ideal components are inevitable physical phenomena and lead to performance degradation when we implement a practical two-dimensional (2-D) modulation system. In this paper, we provide an exact and general expression involving the 2-D Gaussian Q-function for the error probabilities of arbitrary 2-D signaling with I/Q amplitude and phase unbalances in nonlinear additive white Gaussian noise (AWGN) channels by using the coordinate rotation and shifting technique.

• Journal of the Korean Society of Safety
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• v.14 no.2
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• pp.42-51
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• 1999

This research deals with the non-linearities associated with impact and sliding for the rocking behavior of rigid block subjected to two dimensional excitation of horizontal and vertical direction. The non-linearities examined of impact between block and base: The transition of two governing rocking equations, the abrupt reduction in kinetic energy associated with impact. In this study, the rocking vibration system of two types are considered for several friction condition. One is the undamped rocking vibration system, disregarding energy dissipation at impact and the other is the damped rocking system, including energy dissipation at impact. The response analysis by non-dimensional rocking equation is carried out for the change of excitation amplitude. The chaos responses were discovered in the wide response region, particularly, in the case of high vertical excitation and their chaos characteristics are examined by Poincare map, power spectra and Lyapunov Exponent. The complex behavior of chaos response, in the phase space, were illustrated by Poincare map. Therefore, Poincare map will be a significant material in order to understand chaos of rocking system.

• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
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• v.16 no.1
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• pp.9-18
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• 2010

For screening test of the non-volatile compounds which migrate from food packaging materials into foodstuffs, the traditional high performance liquid chromatography (HPLC) systems suffer from the lack of universal detector with high sensitivity and universality and high efficiency HPLC separation column which provides complete separation of complex mixtures into all individual substances. In this work, the use possibility of online two-dimensional liquid chromatography (2D-LC) system coupled with a charged aerosol detector (CAD), a universal detector, was reviewed. 2D-LC system permits to improve peak capacity and resolving power for complex mixtures. Charged aerosol detector (CAD) offers a new feasibility for detection of any non-volatile compounds with high sensitivity and constant response factor in a calibration range. The combination of size exclusion chromatography (SEC) and normal phase HPLC (NP-HPLC) is most frequently used for the separation of the natural and synthetic polymers which are mainly used as raw materials for the manufacture of food packaging materials. However, there is no commercial software available for data acquisition and handling and therefore the quantification in 2D-LC analysis is still rare.

• Geotechnical Engineering
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• v.13 no.3
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• pp.5-20
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• 1997

A governing equation of uncoupled three dimensional finite strain theory of consolidation is presented. This equation is suitable for relatively thick layers, possessing large strain, non-linear material property, and variable permeability. A special numerical solution procedure has to be adopted for the finite difference scheme because the solution is not stable in using Forward-Time Centered-Space (FTCS) method and the governing equation is highly non-linear. The solution is capable of predicting settlement with respect to time. The results predicted by the developed method of analysis have been compared with those of experimental tests on different types of highly compressible soils with vertical wick drain. The uncoupled three dimensional finite strain theory of consolidation appears to predict settlement behavior well. A detailed comparison shows good agreement in terms of total settlement, and reasonable agreement with respect to time.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.21 no.7
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• pp.394-401
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• 2009

A manipulator is operated for the motion of mechanical hands or arms. When a cup including liquid inside is shifted by a manipulator, it is important to know how a free surface of the liquid moves. In this study, non dimensional parameters have been found that affect the rise of the free surface in a cup moving with constant acceleration. The non-dimensional parameters are the dimensionless time, the ratio of inertia effect to viscous effect (the Reynolds number), the aspect ratio of the liquid inside the cup and the acceleration ratio (the Froude number). Through this study, the height of the free surface rise in a cup has been predicted and the detailed velocities in the liquid have been examined. Generally, the maximum rise of the free surface is dependent on the Reynolds number and Froude number strongly, but on the aspect ratio weakly. However, the influence of the aspect ratio on the maximum rise of the free surface is not negligible in the range of 10 < Re < 100.

• 한국데이터정보과학회:학술대회논문집
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• 2005.04a
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• pp.127-134
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• 2005

A suitable representation for the conceptual simplicity of the data in statistics and signal processing is essential for a subsequent analysis such as prediction, pattern recognition, and spatial analysis. Independent component analysis (ICA) is a statistical method for transforming an observed high-dimensional multivariate data into statistically independent components. ICA has been applied increasingly in wide fields of spectrum application since ICA is able to extract unknown components of a mixture from spectra. We focus on application of ICA for separating independent sources and predicting each composition using extracted components. The theory of ICA is introduced and an application to a metal surface spectra data will be described, where subsequent analysis using non-negative least square method is performed to predict composition ratio of each sample. Furthermore, some simulation experiments are performed to demonstrate the performance of the proposed approach.

• Computational Structural Engineering
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• v.7 no.2
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• pp.61-67
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• 1994

The objective of this numerical analysis is to trace the hysteretic behavior of steel angles under very-low-cycle loading test, especially the history and cumulative state of local stress-strain at their critical parts. The computer model is based on a three-dimensional, non-linear analysis by using the finite element program, MSC/NASTRAN, which includes the effects of the material and geometric non-linearities. The analysis was performed as two stage procedures, namely Analysis I and II. The overall behavior from this analysis showed good agreement with the experiment.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2002.10b
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• pp.81-82
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• 2002

A non-steady 3-dimensional elastohydrodynamic lubrication analysis was performed on the contacting teeth surfaces of involute spur gears. Kinematics of the gear and the pinion were taken into account to get accurate geometric clearance around the elastohydrodynamic lubrication region of the contacting teeth. Pressure and film thickness distribution for the whole contacting faces in lubricated condition at several time steps were obtained through the analysis. Besides the pressure spike at the outlet region, a representative phenomenon in elastohydrodynamic lubrication regime, the pressure at the inlet region was slight higher than that of the center region. The film thickness of non-steady condition was thicker than that of steady condition.

• Structural Engineering and Mechanics
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• v.10 no.2
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• pp.181-195
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• 2000

A two-step procedure for the application of non linear constrained programming to the limit analysis of rigid brick-block systems with no-tension and frictional interface is implemented and applied to various masonry structures. In the first step, a linear problem of programming, obtained by applying the upper bound theorem of limit analysis to systems of blocks interacting through no-tension and dilatant interfaces, is solved. The solution of this linear program is then employed as initial guess for a non linear and non convex problem of programming, obtained applying both the 'mechanism' and the 'equilibrium' approaches to the same block system with no-tension and frictional interfaces. The optimiser used is based on the sequential quadratic programming. The gradients of the constraints required are provided directly in symbolic form. In this way the program easily converges to the optimal solution even for systems with many degrees of freedom. Various numerical analyses showed that the procedure allows a reliable investigation of the ultimate behaviour of jointed structures, such as stone masonry structures, under statical load conditions.