• 제어로봇시스템학회:학술대회논문집
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• 1997.10a
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• pp.1754-1757
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• 1997

Three-dimensional optimum design of coat-hanger die is performed using power-law and Carreau models. It is found that the three-dimensional optimum design algorithm shows good convergence with the non-Newtonian fludis. the nore realistic optimum design is accomplished by employing Carreau model with the three-dimensional design method. The effect of vixcosity modles is investigated by comparing the optimum manifold profiles and flow rate distributions of power-law and Carreau modles. Through the accurated viscosity representation of Carreau model, the effect of total flow rate on the optimum manifold profile is investigated.

• Journal of information and communication convergence engineering
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• v.7 no.3
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• pp.361-365
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• 2009

This paper has been presented the transport characteristics of FinFET using the analytical potential model based on the Poisson's equation in subthreshold and threshold region. The threshold voltage is the most important factor of device design since threshold voltage decides ON/OFF of transistor. We have investigated the variations of threshold voltage and drain induced barrier lowing according to the variation of geometry such as the length, width and thickness of channel. The analytical potential model derived from the three dimensional Poisson's equation has been used since the channel electrostatics under threshold and subthreshold region is governed by the Poisson's equation. The appropriate boundary conditions for source/drain and gates has been also used to solve analytically the three dimensional Poisson's equation. Since the model is validated by comparing with the three dimensional numerical simulation, the subthreshold current is derived from this potential model. The threshold voltage is obtained from calculating the front gate bias when the drain current is $10^{-6}A$.

• Journal of the Korea Institute of Military Science and Technology
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• v.22 no.4
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• pp.460-466
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• 2019

It takes a lot of time and human resources to build a detailed three-dimensional finite element analysis model that is almost similar to the actual structure for sophisticated analysis, and a lot of experience and know-how is required to form a reliable analytical model. In this paper, the one-dimensional beam model connected by stiffness matrix through blade analysis library was compared with the results of three-dimensional analysis with the stress calculated through the process of dimensional restoration analysis based on the principle of virtual work. By comparing the stress calculated through dimensional restoration analysis with the three-dimensional analytical model, We will introduce the development status and application case of the blade analysis library by comparing efficiency and accuracy.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.21 no.7
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• pp.911-918
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• 1997

The turbulent viscous wake flows behind a single airfoil, two-dimensional stationary blade row and three-dimensional rotating blade row were calculated, and the numerical results were compared with experimental ones. The numerical technique was based on the SIMPLE algorithm using three turbulent closure models, standard k-.epsilon. model(WFM), low Reynolds number k-.epsilon. model(LRN) and Reynolds stress model (RSM). In the case of a single airfoil, WFM, LRN and RSM presented fairly good velocity distributions in the wake compared with experimental data. In the case of the stationary blade row, LRN and RSM presented better results than WFM for wake velocity distribution, and especially LRN showed best results among these three turbulent models. In the case of the rotating blade row, WFM and LRN showed fairly good agreement with experimental data of the three-dimensional velocity component distributions in the range from hub to mid span region. LRN was also superior to WFM in accuracy of prediction for the wake velocity distribution as same with the cases of a airfoil and the stationary blade row.

• Proceedings of the KSME Conference
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• 2007.05b
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• pp.3039-3044
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• 2007

A few fluid structure interaction analyses have been developed for turbomachinery blades in comparison with aircraft wings. Also, the existing aeroelastic analyses for turbomachinery blades have been mostly limited to cases with a steady freestream. In reality, however, the inflowing freestream is often pulsating. Therefore, this paper presents stability and forced response analyses of an isolated three-dimensional blade under pulsating freestream conditions. A new three-dimensional unsteady vortex lattice model under a pulsating freestream has been developed in discrete time domain to examine unsteady aerodynamic forces acting on a vibrating blade. The blade's structural behaviors have been analyzed by using a three-dimensional plate model. In the aeroelastic analysis, the flutter onset of a blade under pulsating freestream is predicted by the Floquet analysis. The new time domain method can predict aeroelastic stability as well as time history.

• Transactions of the Korean Society of Mechanical Engineers
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• v.14 no.2
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• pp.376-381
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• 1990

An interactive computer program to design a mold cavity with the proper rigging system has been developed. In addition to the pattern and the risers generated in part 1 of this work, the various components of the gating system are generated in complete three dimensional models by a rational approach. Then they are laid interactively by the user, and united together with the pattern and the risers to result in the three dimensional model of the mold assembly. Finally, the vents and the mold box are constructed following the user's interactive specification and then the mold cavity is completed in a three dimensional geometric model by subtraction the mold assembly and the vents from the mold box. The three dimensional model of a mold cavity is useful for many related applications such as the solidification simulation for mold evaluation and the NC tool path generation for mold production.

• Proceedings of the KIEE Conference
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• 1991.11a
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• pp.67-70
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• 1991

When analyzing field or optimizing the shape of electrode in three dimensional space by using the surface charge method, we need to divide finely the surface of electrode into surface element like triangle or rectangle. In this case, there exist any variables in field analysis or field optimization. In particular, smoothness on the surface of optimized shape is not good. Recently, A paper is published where introducing NURB curve to field analysis and field optimization about two dimensional space model and axial symmetric three dimensional space model results in reduced variables, enhenced accuracy and improved smoothness. NURB curve has some useful properties like continuity, controllability and locality. Therefore in this paper, in order to improve the demerits of the established optimization method for three dimensional space models, the NURB surface that has same properties in common with NURB curve is used to analyze and optimize simple model.

• Journal of the Korean Society of Propulsion Engineers
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• v.24 no.5
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• pp.65-76
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• 2020

On the initial design process of a scramjet vehicle such as the trajectory prediction, it is inevitable to estimate the aerodynamic performance of a three-dimensional effect. Despite the necessity of intensive computing for the three-dimensional model, it is inefficient in predicting a wide range of aerodynamic performance. In this study, an engineering model for aerodynamic performance was developed based on two-dimensional computational fluid analysis and linearized supersonic inviscid flow theory. Correspondingly, the three-dimension aerodynamic performance relations are presented based on the two-dimensional results. And the additional three-dimensional computation was performed to evaluate the adequacy for the extended relations.

• Computers and Concrete
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• v.2 no.4
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• pp.249-266
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• 2005

In the present paper a transient three-dimensional thermo-mechanical model for concrete is presented. For given boundary conditions, temperature distribution is calculated by employing a three-dimensional transient thermal finite element analysis. Thermal properties of concrete are assumed to be constant and independent of the stress-strain distribution. In the thermo-mechanical model for concrete the total strain tensor is decomposed into pure mechanical strain, free thermal strain and load induced thermal strain. The mechanical strain is calculated by using temperature dependent microplane model for concrete (O$\check{z}$bolt, et al. 2001). The dependency of the macroscopic concrete properties (Young's modulus, tensile and compressive strengths and fracture energy) on temperature is based on the available experimental database. The stress independent free thermal strain is calculated according to the proposal of Nielsen, et al. (2001). The load induced thermal strain is obtained by employing the biparabolic model, which was recently proposed by Nielsen, et al. (2004). It is assumed that the total load induced thermal strain is irrecoverable, i.e., creep component is neglected. The model is implemented into a three-dimensional FE code. The performance of headed stud anchors exposed to fire was studied. Three-dimensional transient thermal FE analysis was carried out for three embedment depths and for four thermal loading histories. The results of the analysis show that the resistance of anchors can be significantly reduced if they are exposed to fire. The largest reduction of the load capacity was obtained for anchors with relatively small embedment depths. The numerical results agree well with the available experimental evidence.

• Proceedings of the Korean Geotechical Society Conference
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• 1999.10a
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• pp.489-496
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• 1999

The safety of a structure can be improved by applying the three dimensional passive earth pressure. Because the three dimensional passive earth pressure is much larger than the two dimensional passive earth pressure and it is determined by the size(width B and height H) and the wall frictional angle of the resistant wall. Therefore, the three dimensional passive resistance behavior was studied through the model tests in sandy ground, where the size of the resistant wall and the wall frictional angle were varied. The results show that three dimensional passive earth pressure is 1.1∼3.4 times larger than that of the two dimensional value depending on the wall size and the wall friction.