• Proceedings of the KIEE Conference
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• 1996.07a
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• pp.163-165
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• 1996

In the PIC simulation of plasma, the fields are commonly calculated on uniform spatial grids using FDM. But, FDM has a difficulty in modeling a complex shaped model. FEM has a good flexibiblity in treating a complex shape, so that we calculated the field by using FEM not FDM. In this paper, the plasma between plane-to-plane electrodes was simulated using FEM and FDM. Comparing the results of those two methods told us that FEM is also valid as a calculating method in PIC plasma simulation. In order to verify the use of FEM, the discharge of rod-to-plane was simulated. There was not a little distortion of the electric field between the electrodes due to the distribution of space charges.

• Journal of the Korean Institute of Telematics and Electronics
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• v.20 no.1
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• pp.27-36
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• 1983

The 12-Channe1 TDM/FDM translator is proposed which uses a periodically varying digital filter and the multiplexing weaver modulators. The general 12-Channel TDM/FDM translator using the Weaver modulators requires 24 interpolating FIR(finite impulse response) filters and 24 sinusoidal modulators, however the TDM/FDM translator proposed in this paper consists of one interpolating periodically varying digital filter and 12 sinusoidal modulators. The results obtained in this paper show that the system is simplified and the computation time is reduced. These facts are verified by the computer simulation.

• Journal of the Korean Institute of Telematics and Electronics
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• v.20 no.3
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• pp.21-28
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• 1983

Four new types of TDM/FDM translation system are proposed in this paper. In the proposed system, the periodically time varying filters (P.V.F) are used in order to modify the general TDM/FDM conversion systems. The new systems have the simple structure as compared with the existing systems and the multiplication rate is reduced to about 2.0${\times}$10 multiplications/s$.$channel. It is verified by the computer simulation that the proposed systems can be used as 12-channel TDM/FDM translation systems.

• 한국기계연구소 소보
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• s.17
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• pp.111-123
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• 1987

Two dimensional computer simulation of solidification behavior using FDM as simulation tool was applied to AI-bronze casting. By the comparison of computer simulation with the experimental results, it was showed that the final shrinkage position and solidification time are good accordance with results of computer simulation. It is expected that this software will be widely applied to casting design or rise ring for directional solidification.

• Journal of the Korean Society for Heat Treatment
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• v.14 no.4
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• pp.228-234
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• 2001

The present study was an attempt for systematic data conversion between FDM and FEM in order to evaluate the thermal stress distribution during quenching process. It has been generally recognized that FDM is efficient in flow and temperature analysis and FEM in that of stress. But it induced difficulty and tedious work in analysis that one uses both FDM and FEM to take their advantages because of the discrepancy of nodes between analysis tools. So we proposed field data conversion procedure from FDM to FEM in 3-dimensional space, then applied this procedure to analysis of quenching process. The simulation procedure calculates the distributions of temperature and microstructure using FDM and microstructure evolution equations of diffusion and diffusionless transformation. FEM was used for predicting the distributions of thermal stress. The present numerical code includes coupled temperaturephase transformation kinetics and temperature-microstructure dependent material properties. Calculated results were compared with previous experimental data to verify the method, which showed good agreements.

• Elastomers and Composites
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• v.51 no.4
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• pp.301-307
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• 2016

Additive manufacturing (AM), so called 3D Printing is a new manufacturing process and is getting attraction from many industries. There are several methods of 3D printing. Among them fused deposition modeling (FDM) type is most widely used by reason of cheap maintenance, easy operation and variety of polymeric materials. Articles manufactured by 3D printing have weak deposition strength compared with conventionally manufactured products. Deposition strength of FDM type 3D printed article is highly dependent of deposition temperature. Subsequently the nozzle temperature in the FDM type 3D printing is very important and it is controlled by heat source in the 3D printer. Nozzle is connected with heat block and barrel, and heat block contains heat source. Nozzle becomes hot through heat conduction from heat source. Nozzle temperature has been predicted for various thermal boundary conditions by computer simulation and compared with experimental measurement. Nozzle temperature highly depends upon thermal conductivities of heat block and nozzle. Simulation results are good agreement with experiment.

• Journal of Korea Foundry Society
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• v.14 no.5
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• pp.412-418
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• 1994

Efficient algorithm for the solidification simulation by FDM is described from the practical point of views. If a proper time step ${\Delta}t$ is selected, the calculation is accelerated by implicit algorithm with the temperature recovery method of latent heat method. The implicit routine in the calculation is processed by SOR method(relaxation factor＝1.5, truncation error＝$10^{-4}$). The calculation is more accelerated by linear-interpolated explicite algorithm with a time step larger than the minimum value of the time step. This explicit method, which is applicable to the practical casting simulation problems, produces almost same results with about 40% faster calculation speed compared with the conventional explicit method.

• Elastomers and Composites
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• v.52 no.3
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• pp.216-223
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• 2017

The additive manufacturing technology, also called 3D printing, is growing fast. There are several methods for 3D printing. Fused deposition modeling (FDM) type 3D printing is the most popular method because it is simple and inexpensive. Moreover, it can be used for printing various thermoplastic materials. However, it contains the cooling of layered road and causes thermal shrinkage. Thermal shrinkage should be controlled to obtain high-quality products. In this study, temperature distribution and cooling behavior of a layered road with cooling are studied through computer simulation. The thermal shrinkage of the layered road was simulated using the calculated temperature distribution with time. Shape variation of the layered road was predicted as cooling proceeded. Stress between the bed and the layered road was also predicted.This stress was considered as the detaching stress of the layered road from the bed. The simulations were performed for various thermal conductivities and temperatures of the layered road, bed temperature, and chamber temperature of a 3D printer. The simulation results provide detailed information about the layered road for FDM type 3D printing under operational conditions.

• The KSFM Journal of Fluid Machinery
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• v.15 no.1
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• pp.27-35
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• 2012

A numerical simulation for particle collection efficiency in a wire-plate electrostatic precipitator (ESP) has been performed. Method of characteristics and finite differencing method (MOC-FDM) were employed to obtain electric field and space charge density, and lattice boltzmann method (LBM) was used to predict the Electrohydrodynamic (EHD) flow according to the ion convection. Large eddy simulation (LES) was considered for turbulent flow and particle simulation was performed by discrete element method (DEM) which considered field charging, electric force, drag force and wall-collision. One way coupling from FDM to LBM was used with small and low density particle assumption. When the charged particle collided with the collecting plate, particle-wall collision was calculated for re-entertainment effect and the effect of gravity force was considered.

• Journal of the Korean Society of Safety
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• v.10 no.2
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• pp.56-63
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• 1995

A simulation of contaminant dispersion in a water reservoir has been done using 2-D finite difference method(FDM). The steady state velocity field of the reservoir was computed using stream function-vorticity formulation of Wavier-Stokes equation and continuity equation. Based on the computed steady state velocity field, the transient convective diffusion equation of the contaminant dispersion was computed. For the 1m$\times$1m reservoir model with inlet and outlet attached, it was shown that the center of circulation located toward right. For the numerical values of v =0.01($\textrm{cm}^2$/s) and D=0.6($\textrm{cm}^2$/s) and the flow of 50($\textrm{cm}^3$/s ), it was determined that the outflow had to be shut down in 18 seconds to prevent from severe pollution. Also the required time was computed to be 6 seconds for the inflow of 100 ($\textrm{cm}^3$/s). The result of this study is considered, hopefully, to be useful for the design of the water reservoir systems that are the subjects to various contamination.