• Journal of the Korean Society for Precision Engineering
• /
• v.22 no.7 s.172
• /
• pp.177-184
• /
• 2005

Recently, the engineering designer of injection mould has become more and more dependent on the CAE. In the design factors of injection mould, the shrinkage rate should be considered as one of the important performances to produce the reliable products. therefore the shrinkage rate can be mostly calculated by the MoldFlow and Pro-engineering. in the design process. However it is not easy to predict the shrinkage rate of a plastic injection mold in its design process because the analysis can take minutes to hours, the high computational costs of performing the analysis limit their use in design optimization. In this study, the surrogate models, DACE model, based on the Kriging in order to optimize the shrinkage rate of electric microwave oven window is used in lieu of the original models, facilitating design optimization.

• Journal of the Korean Vacuum Society
• /
• v.9 no.3
• /
• pp.290-295
• /
• 2000

In order to utilize as a pre-ionization means for reproducible ohmic plasma on KAIST-TOKAMAK, a simple, safe, economical and continuous microwave source has been developed using a home kitchen micro-wave oven. The magnetron used in the study can provide 500 W of power at 2.45 GHz. A conventional magnetron in a home kitchen microwave oven generates microwave for 8 ms at every 16 ms periodically due to the periodic (60 Hz) high voltage applied to the magnetron cathode. In order to generate continuous microwave which is suitable for tokamak pre-ionization, the magnetron operation circuit has been modified using a DC high voltage (5 kV, 1 A) power supply. It provides high-voltage with small ripple for magnetron cathode bias. Using the developed magnetron system, electron cyclotron resonace heated (ECH) plasmas were produced and the characteristics of the system were studied by diagnosing the ECH plasma using Langmuir probe and $H_{\alpha}$ emission diagnostics.

• Polymer(Korea)
• /
• v.25 no.5
• /
• pp.609-616
• /
• 2001

The application of microwave technology to synthesis of polymer in solvent media has been shown by the synthesis of copper phthalocyanine (CUPc). The increase of synthetic yield-was demonstrated successfully in this study. A power variable microwave synthetic system has been developed with modifying cavity of domestic microwave oven and attaching microwave power controller. The properties of the specimen synthesized at various condition under the conventional thermal processing and microwave processing has been characterized by the means of chemical analysis, X-ray diffractometry (XRD), scanning electron microscopy (SEM), and particle size analysis (PSA).

• Proceedings of the KSME Conference
• /
• 2004.11a
• /
• pp.864-869
• /
• 2004

It is net easy to predict the shrinkage rate of a plastic injection mold in its design process. The shrinkage rate should be considered as one of the important performances to produce the reliable products. The shrinkage rate can be determined by suing the CAE tools in the design produces. However, since the analysis can take minutes to hours, the high computational costs of performing the analysis limit their use in design optimization. In this study, the surrogate models based on the DACE is used in lien of the original models, facilitating design optimization.

• Journal of Electrochemical Science and Technology
• /
• v.12 no.3
• /
• pp.297-301
• /
• 2021

Microbial fuel cells (MFCs) convert chemical energy to electrical energy via electrochemically active microorganisms. The interactions between microbes and the surface of a carbon electrode play a vital role in capturing the respiratory electrons from bacteria. Therefore, improvements in the electrochemical and physicochemical properties of carbon materials are essential for increasing performance. In this study, a microwave and sulfuric acid treatment was used to modify the surface structure of graphite granules. The prepared expandable graphite granules (EGG) exhibited a 1.5 times higher power density than the unmodified graphite granules (1400 vs. 900 mW/m³). Scanning electron microscopy and Fourier transform infrared spectroscopy revealed improved physical and chemical characteristics of the EGG surface. These results suggest that physical and chemical surface modification using sulfuric acid and microwave heating improves the performance of electrode-based bioprocesses, such as MFCs.

• Journal of the Korean Crystal Growth and Crystal Technology
• /
• v.8 no.3
• /
• pp.513-517
• /
• 1998

Fly ashes mixed with clay as 70:30 weight percent were sintered by microwave energy and a 2.45 Ghz kitchen model microwave oven was used. Samples were sintered at $1,150^{\circ}C$ and kept at that temperature up to 50 minutes by 10 minutes intervals. Microstructures were taken by Scanning Electron Microscope (SEM) and Energy Dispersive Spectrometry (EDS) analysis of a raw fly ash was taken. X-ray diffraction analysis was done, and compressive strengths and apparent densities were measured. Pore sizes of the samples became smaller as time passed by, but compressive strengths and apparent densities did not change much. Numerical analysis on the microwave heated system was carried out in order to figure out heat transfer phenomena in the cavity.

• Journal of the Korean Chemical Society
• /
• v.47 no.6
• /
• pp.591-596
• /
• 2003

Aminothienopyridazines 1a, b and aminothienocoumarin 2 condensed with DMFDMA to yield amidines 3a, b and 4. These compounds reacted with N-phenylmaleimide to yield 9 and 10. On the other hand reacting 3a, b, 4, 18, 19 and 20 with maleic anhydride afforded only the formylated derivatives 5a, b, 6, 21, 22 and 23 respectively. The reaction of 3a, b with diethyl fumarate afforded 11, formed most likely via hydrolysis of the amidine 14 during working up the reaction mixture. Irradiation of N-phenylmaleimide in microwave oven afforded [2+2] and [2+2+2] cycloaddition product.

• The Journal of Advanced Prosthodontics
• /
• v.9 no.5
• /
• pp.394-401
• /
• 2017

PURPOSE. The purpose of this study was to compare the optical properties of pre-colored dental monolithic zirconia ceramics of various thicknesses sintered in a microwave and those in a conventional furnace. MATERIALS AND METHODS. A2-shade of pre-colored monolithic zirconia ceramic specimens ($22.0mm{\times}22.0mm$) in 3 thickness groups of 0.5, 1.0, and 1.5 mm were divided into 2 subgroups according to the sintering methods (n=9): microwave and conventional sintering. A spectrophotometer was used to obtain CIELab color coordinates, and translucency parameters and CIEDE2000 color differences (${\Delta}E_{00}$) were measured. The relative amount of monoclinic phase ($X_m$) was estimated with x-ray diffraction. The surface topography was analyzed by atomic force microscope and scanning electron microscope. Statistical analyses were conducted with two-way ANOVA (${\alpha}=.05$). RESULTS. There were small interaction effects on CIE $L^*$, $a^*$, and TP between sintering method and thickness (P<.001): $L^*$ (partial eta squared ${{\eta}_p}^2=0.115$), $a^*$ (${{\eta}_p}^2=0.136$), and TP (${{\eta}_p}^2=0.206$), although higher $b^*$ values were noted for microwave sintering regardless of thickness. Color differences between two sintering methods ranged from 0.52 to 0.96 ${\Delta}E_{00}$ units. The $X_m$ values ranged from 7.03% to 9.89% for conventional sintering, and from 7.31% to 9.17% for microwave sintering. The microwave-sintered specimen demonstrated a smoother surface and a more uniform grain structure compared to the conventionally-sintered specimen. CONCLUSION. With reduced processing time, microwave-sintered pre-colored dental monolithic zirconia ceramics can exhibit similar color perception and translucency to those by conventional sintering.

• Nuclear Engineering and Technology
• /
• v.48 no.5
• /
• pp.1219-1229
• /
• 2016

The present paper reports on a trial to shed further light on the characterization, applications, and operation of radar speed guns or Gunn diodes on different radiation environments of neutron or g fields. To this end, theoretical and experimental investigations of microwave oscillating system for outer-space applications were carried out. Radiation effects on the transient parameters and electrical properties of the proposed devices have been studied in detail with the application of computer programming. Also, the oscillation parameters, power characteristics, and bias current were plotted under the influence of different ${\gamma}$ and neutron irradiation levels. Finally, shelf or oven annealing processes were shown to be satisfactory techniques to recover the initial characteristics of the irradiated devices.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2004.10a
• /
• pp.223-226
• /
• 2004

It is net easy to predict the shrinkage rate of a plastic injection mold in its design process. The shrinkage rate should be considered as one of the important performances to produce the reliable products. The shrinkage rate can be determined by suing the CAE tools in the design produces. However, since the analysis can take minutes to hours, the high computational costs of performing the analysis limit their use in design optimization. In this study, the surrogate models based on the RSM is used in lien of the original models, facilitating design optimization.