• Proceedings of the KSME Conference
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• 2002.08a
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• pp.695-696
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• 2002

Three-dimensional blood flow in the sac of the KTAH(Korean total artificial heart) is simulated using fluid-structure interaction model. The aim of this study is to delineate the three-dimensional unsteady-blood flow in the sac of KTAH. Incompressible viscous flow is assumed for blood using the assumption of Newtonian fluid. The numerical method employed in this study is the finite element software called ADINA. Fluid-structure interaction model between blood and sac is utilized to represent the deformation of the sac by the rigid moving actuator. Three-dimensional geometry of cactus type KTAH is chosen for numerical model with prescribed pressure boundary condition on the sac surface. Blood flow is generated by the motion of moving actuator and strongly interacts with the solid material surrounding blood. High shear stress is observed mainly near the inlet and outlet of the sac.

• Proceedings of the KSME Conference
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• 2003.11a
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• pp.822-827
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• 2003

Experiments were done for the three dimensional unsteady flow in a counter rotating axial flow fan under stable operating condition. Flow fields in a counter rotating axial flow fan were measured at cross-sectional planes of the upstream and downstream of each rotor. Cross sectional flow patterns were investigated through the acquired data by the $45^{\circ}$ inclined hot-wire. Flow characteristics such as tip vortex, secondary flow and tip leakage flow were confirmed through axial, radial and tangential velocity vector plot. Swirl velocity, which was generated by the front rotor, was recovered in the form of static pressure rise by the rear rotor except for hub and tip regions.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.485.1-485.1
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• 2014

In this research, we report the synthesis of three-dimensional (3D) hierarchical porous graphene aerogels (hpGAs) for application to electrochemical energy storage. For electrochemical systems, the specific capacitance is a key parameter to evaluate the characteristics of electrode materials. By taking full advantage of large surface area, 3D hpGAs would achieve the larger specific capacitance over rGO film and GAs. Microscopic structures and topologies of hpGAs were investigated using field emission scanning electron microscopy and transmission electron microscopy. X-ray photoelectron spectroscopy was used to determine the chemical compositions of rGO film, GAs, and hpGAs. Raman spectra were recorded from 100 to 2500 cm-1 at room temperature using a Raman spectroscopy equipped with a ${\times}100$ objective was used. The specific area and pore distribution of GAs and hpGAs were obtained using a Brunauer-Emmett-Teller apparatus.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2006.05a
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• pp.355-356
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• 2006

This paper proposes an Molding error compensation method that improves accuracy with geometry information of injected parts using three-dimensional measuring instrument. a traditional mold design has been conducted by an experience-based trial and error, whereby generally the mold designer would decide the gate location and processing conditions. as a natural consequence, almost all creats inferior goods. It's just a process of trial and error and caught in a vicious circle. Due to this reason, this paper uses a three-dimensional measuring instrument, a commercial analysis package of injection molding(Moldflow, MPI) to analysis a state of flux. In addition to that axiomatic approach.

• Current Optics and Photonics
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• v.1 no.2
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• pp.95-100
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• 2017

The transmittance of the three dimensional (3D) transparent display is an important factor and can be enhanced by adding a see-through area to the displayed 3D image in order to transmit an ambient light with maximum transparency. However, there is a side effect that the perceived 3D resolution can be degraded due to the see-through area. In this paper, we propose an advanced method to resolve the above trade-off relation between the transparency and the 3D resolution by using an active parallax barrier (PB) with a see-through area. The experimental results are also presented to prove the proposed principle.

• 한국정보디스플레이학회:학술대회논문집
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• 2009.10a
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• pp.1341-1344
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• 2009

A novel method to control the viewing direction by moving aperture location in 4-f illumination optics to control light direction is proposed. Based on integral imaging principle, the relayed point light sources by 4-f optics are modulated by a spatial light modulator, displaying three-dimensional images. In the proposed method, we locate the aperture, which acts as a band pass filter, around an optic axis to control the light direction. Resultantly, assuming that we know the viewer position by a tracking system, we can display appropriate three-dimensional images over large viewing angle.

• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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• v.3B no.4
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• pp.159-164
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• 2003

In this paper, a three-dimensional finite element method and construction of equivalent-circuit for a linear ultrasonic motor are presented. The validity of three-dimensional finite element routine in this paper is experimentally confirmed by analyzing impedance of a piezoelectric transducer. Using this confirmed finite element routine, impedance and vibration mode of a linear ultrasonic motor are calculated. Elliptical motion of contact point between vibrator and rail of the linear ultrasonic motor is shown for determination of contact points. By using the finite element method and analytic equations, characteristics of the linear ultrasonic motor, such as thrust force, speed, losses, powers and efficiency, are calculated. The results are confirmed by experiment. Finally, equivalent circuit parameters of the linear ultrasonic motor are obtained using the three-dimensional finite element method and analytic equations.

• Journal of the Korean Society of Safety
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• v.19 no.1
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• pp.38-43
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• 2004

Many analysis methods, including finite element method, have been suggested and used for assessing the integrity of cracked structures. In the paper, in order to analyze arbitrary three dimensional cracks, the finite element alternating method is extended. The crack is modeled by the symmetric Galerkin boundary element method as a distribution of displacement discontinuities, which is formulated as singularity-reduced integral equations. And the finite element method is used to calculate the stress values for the uncracked body only. Applied the proposed method to several example problems for planner cracks in finite bodies, the accuracy and efficiency of the method were demonstrated.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2019.11a
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• pp.14-15
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• 2019

In this paper, it was tried to prove the possibility and effect of coordinate measurement by using MEP layout equipment at the construction stage, and to propose a method to improve measurement accuracy during construction. For this study, the passenger terminal site, which is a long span structure, was selected and compared with three dimensional CAD drawings and construction measurement results using MEP layout equipment for the precise construction of long-span irregular curved roof layers. As a result, it was found that it is possible to construct three-dimensional curved roof layers using MEP layout equipment through measurement and analysis.

• Current Optics and Photonics
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• v.2 no.5
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• pp.436-442
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• 2018

In a spatially interlaced stereoscopic (SIS) three-dimensional (3D) display to be realized by providing the observer a part of left-eye/right-eye images, a loss of information can be perceived due to the un-shown part of each image. In order to resolve that problem, an improved SIS 3D display is proposed to deliver the images without loss of information to the observer using a time-multiplexing scheme. However, that time-multiplexing SIS also has a problem of luminance distortion when the desired luminance is not shown due to an insufficient response of the liquid crystal cell. In this paper, we propose a new method by optimizing the image data to show correct luminance with minimum distortion.