• Design & Manufacturing
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• v.8 no.1
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• pp.1-4
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• 2014

Large injection molds commonly have molding defects such as flashes and variation of product thickness. In this study, we conducted injection molding CAE analysis to find out the cavity pressure and structural analysis to find out mold deflection as input load conditions injection pressure obtained from injection molding analysis. As the results from CAE analysis, we found which element is the most effective on the mold deflection and we suggested a mold design to minimize the mold deflection.

• Transactions of Materials Processing
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• v.18 no.7
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• pp.519-530
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• 2009

The study is concerned with shape correction of stamped product using the laser irradiation. As a fundamental study, laser irradiation process has been analyzed through the thermo-mechanical FE analysis. For the purpose of validation, laser scanning experiment has been carried out also. Since the deformation mechanism involved in the laser scanning is extremely complicated due to the highly temperature dependent material properties, the determination of laser scanning pattern is not easy for the application of real stamped parts. A simplified method for the application of springback correction has been suggested with the thermo-mechanical FE analysis.

• The Journal of the Korean bone and joint tumor society
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• v.2 no.1
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• pp.101-105
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• 1996

Prosthetic reconstruction of musculoskeletal defects about the knee for tumor has many advantages, particularly the maintenance of motion and immediate functional restoration. But, prosthetic reconstruction has inherent limitations in terms of long-term durability. The authors have reported here a patient who had mechanical failure at 61 months later following use of a modular resection system to reconstruct the segmental defect of proximal tibia in osteosarcoma. In this case, another technique of extensor mechanism reconstruction using Achilles tendon allograft was attempted. Because of the concerns involving durability of tumor prosthesis, increased emphasis has to be placed on innovation in prosthetic design.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2002.05a
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• pp.220-224
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• 2002

In this paper, flow in the wake region of a butterfly valve is studied numerically and experimentally. The disk angle of the valve is fixed as $30^{\circ}$ and the free stream velocity as 0.13m/s in the experiment. Numerical analysis is performed in similitude of the experiment. The standard LES model is used to represent the turbulence effect in the commercial code Fluent 5.5. It is shown that the numerical result is similar to the experimental result for the wake flow of a butterfly-type valve.

• Journal of computational fluids engineering
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• v.21 no.4
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• pp.46-53
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• 2016

Direct numerical simulation is conducted to observe the behavior of microbubbles in isotropic turbulence. Navier-Stokes equation and the motion of equation for microbubbles are solved with periodic boundary condition in a cube domain. Vorticity contour, enstrophy ratio, relative reduction of bubble rise velocity, and the closest distance of particles are investigated for various Stokes numbers and gravity factors to understand clustering of microbubbles. Also, clustering due to the effect of the lift force is investigated.

• Journal of Mechanical Science and Technology
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• v.16 no.9
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• pp.1033-1039
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• 2002

Partial penetration welding joint refers to the groove weld that applies to the one side welding which does not use steel backing and to both side welding without back gouging, that is, the partial penetration welding joint leaves an unwelded portion at the root of the welding area. In this study, we analyzed the residual stress and fracture on the thick metal plates that introduced the partial penetration welding method. According to the above-mentioned welding method, we could draw a conclusion that longitudinal stress and traverse stress occurred around the welding area are so minimal and do not affect any influence. We also performed the fracture behavior evaluation on the partial penetration multi pass welding with 25.4 mm thick plate by using the J-integral, which finally led us the conclusion that the partial penetration multi-pass welding method is more applicable and effective in handling the root face with less than 6.35 mm.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.27 no.3
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• pp.387-392
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• 2003

The mechanical behavior of two rectangular spot-welded plates under bending is investigated in detail. The equivalent thickness of spot-welded plates is introduced in this study and used in explaining the results. The focus of the analysis is to evaluate the effect of spot-welding from the view point of equivalent thickness. The investigation of deflection has been performed as comparing the result from finite element analysis with the measured data of the spot-welded plates for various parameters, such as aspect ratio, area ratio, and distance ratio of spot-welding points. The effect of spot-welding is as large as 62%(at r=1.0) when the area ratio of spot-welding point is just 4.52%.

• International Journal of Precision Engineering and Manufacturing
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• v.9 no.3
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• pp.82-84
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• 2008

A surface encoder based on the Half-shaded square pattern (HSSP) is presented. The HSSP working as reference grid is composed of the straight lines which are easy to be fabricated and make measuring time short. Since the periodic cell is separated in ON/OFF by the $45^{\circ}$ straight line, the duration from the starting point of scanning to the first rising edge and the duty cycle of the pulse train vary with respect to the position of the starting point. And the relationship between X and Y position and the duration, and duty cycle is described in the simple linear equation. Therefore, it is possible to measure X and Y position with the measured duration and duty cycle without calculating load. Through the test set-up, the feasibility of the proposed surface encoder was verified. Also the future works for improvement of performance were suggested.

• 제어로봇시스템학회:학술대회논문집
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• 1992.10b
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• pp.344-348
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• 1992

This paper describes a procedure to design a hovering flight controller for a model helicopter using LQG theory. Parameters of the model helicopter in hover are obtained using direct measurements and calculations proposed by other research. A feedback co is by using digital LQG theory. First, a full state feedback controller is designed to the discretized system taking desirable transient response and other assumptions into account. Then a full-state estimator is designed and revised until desirable response is obtained while global stability is maintained. Performance of the controller is tested by computer simulations. Experiments have been performed using a 3-degree-of-freedom gimbal that holds the model helicopter, and the controller exhibited stable hover capability.

• Proceedings of the KSME Conference
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• 2008.11a
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• pp.1655-1659
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• 2008

Using numerical models, we investigated the efficiency of toxin removal using pulsatile flow in blood purification systems that use semipermeable membranes. The model consisted of a three-compartmental mass transfer model for the inside body and a solute kinetics model for the dialyzer. The model predicted the toxin concentration inside the body during blood purification therapy, and the toxin removal efficiencies at different flow configurations were compared quantitatively. According to the simulation results, the clearances of urea and ${\beta}_2$ microglobulin (B2M) using a pulsatile pump were improved by up to 30.9% for hemofiltration, with a 2.0% higher urea clearance and 4.6% higher B2M clearance for high flux dialysis, and a 3.9% higher urea clearance and 8.2% higher B2M clearance for hemodiafiltration. These results suggest that using a pulsatile blood pump in blood purification systems with a semipermeable membrane improves the efficacy of toxin removal, especially for large molecules and hemofiltration treatment.