• Journal of Korea Foundry Society
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• v.34 no.5
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• pp.162-169
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• 2014

The effect of the mold preheat temperature on the solidification crack strength was investigated in AC2B aluminum alloy. A tension type apparatus as part of a solidification crack test which could measure the stress-strain relationship quantitatively was utilized. The evaluation of the solidification crack strength with varying mold preheat temperatures was performed by the test procedure established in this research. When the mold preheat temperatures were $250^{\circ}C$, $150^{\circ}C$ and $50^{\circ}C$, the solidification crack strengths were found to be $7.8Kgf/cm^2$, $12.9Kgf/cm^2$ and $28.6Kgf/cm^2$, respectively. In the same way, when the mold preheat temperatures were $250^{\circ}C$, $150^{\circ}C$ and $50^{\circ}C$, the corresponding temperatures of the failure sites were $610^{\circ}C$, $600^{\circ}C$ and $571^{\circ}C$, and the calculated solid fractions were 14.0%, 29.3% and 50.8% when the specimens failed, respectively. The solidification crack strength increased in proportion to the solid fraction of the failure site. The solidification crack strength obtained in this test is assumed to reflect the effects of metallurgical factors on the thermo-plastic characteristics of a solidifying alloy such as the grain size of the solid, the grain morphology, and the distribution of solid grain.

• Plant Resources
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• v.8 no.2
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• pp.130-134
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• 2005

This study was conducted to evaluate the control effect of fungicides on control of Gray mold, growth characteristics, and root yield in the cultivation of Scutellaria baicalensis after barley cropping. All fungicides treated had no effect on the growth and flowering rate of Scutellaria baicalensis. All seed disinfectants had no effect on the growth and flowering date of Scutellaria baicalensis Georg. The major seed disinfectants were Benomyl Wp, $20\%$, Captan Wp, $50\%$, Hymexazol Ec, $30\%$, Carboxin D, $37.5\%$. Dry root yield were increased largely with Benomyl Wp, $20\%$, seed disinfectant than the other seed disinfectants had no injury with standard dosage. On the other hand, all seed disinfectants had slight injury in the double dosage level for the Scutellaria baicalensis Georg.

• Elastomers and Composites
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• v.49 no.3
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• pp.220-224
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• 2014

The tire tread is contacted with road surface directly. It gives significant effect on the breaking conditions, traction, noise and so on. The tread having grooves with complex geometry is molded by shaping process. The flow behavior of tread rubber in a mold affects the quality of the tread and it leads to the running performance of automobile. In this study, the flow behavior of rubber in shaping process has been investigated by computer simulation. The objective of flow simulation is the design of tread shape based on the contact of rubber on the mold surface and flow behavior of rubber. Different sequences of contact of rubber on the mold surface and flow behavior of rubber are observed according to the shape of tread on the mold surface. It was verified that the shape of tread gives significant effect on the flow behavior of rubber. Different flow behaviors of rubber and sequential contact of rubber to the mold surface were observed according to the shape of tread on the mold surface. Therefore, we have identified that the shape of tread give a change in the flow behavior of rubber.

• Design & Manufacturing
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• v.15 no.2
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• pp.42-48
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• 2021

In this paper, when manufacturing large/multi-mold parts (more than 30 core parts),A mold manufacturing (tolerance) management system was established through design-processing linkage.The mold manufacturing (tolerance) management system is a design-based measurement shape/measurement position determination system, M/C processing-linked measurement drive system,It is composed of four parts: CAD-linked measurement result analysis system and manager mold part quality management system.In addition, the constructed system was applied to the field and the effect of system construction was evaluated by comparing it with the existing process.As a result of the evaluation, the measurement precision is within 0.02mm, and the time it takes to measure after the end of processing is shorter than that of the existing process.(12 hours → 2 hours) It was shortened to 16.7%.In addition, it was confirmed that the time required for reprocessing after measurement was reduced by 25% (4 hours → 1 hour) compared to the existing process.

• Journal of the Korean Society for Precision Engineering
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• v.13 no.5
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• pp.84-94
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• 1996

In order to prevent shell sticking by providing sufficient lubrication between the strand and the mold, the mold oscillation has been used. Now it is well known that the shape of the oscillation curve has a decisive effect on the surface quality of the cast product. Besides, oscillation parameters such as stroke and frequency are also very important. In order to guarantee that parameters which have been found to be optimal for a certain grade of steel do not change with time, periodical checks of the physical condition of the whole equipment are necessary. The portable mold oscillation analyzer with integrated computer, developed by POSCO, records the movement of the mold in every spatial direction. The system uses the gap sensors to measure the mold movement (displacement ) in the two horizontal directions according to the mold narrow and broad faces and the vertical strokes in the four corners of mold. The gap sensor is a non-contacting minute displacement measuring device using the principle of high frequency eddy current loss. The mold oscillation diagnosis system integrates the gap sensors, their converters and the industrial portable computer with plug-in data acquisition boards. The all programs, such as the fast Fourier transformation module (amplitude and phase spectrums) and harmonic analysis module, was coded by LabVIEW$^{TM}$ software as the graphical language. In an own 'expert module' which is included in the diagnosis program, one can obtain much information about the mold oscillation equipment.

• KSBB Journal
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• v.28 no.6
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• pp.400-407
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• 2013

The growth characteristics and production of color pigments by Monascus strains were investigated during liquid culture, and production of monacolin K in red mold rice was carried out by solid state fermentation. Four different Monascus ruber strains were cultured in potato dextrose yeast extract broth (PDYB) media at $25^{\circ}C$ for 15 days. The high producing strain for red pigment was not corresponded to the strain for yellow pigment. Production of red pigment was high in the strain causing the fast pH change in culture broth. Production of monacolin K in red mold rice by solid state fermentation was influenced by a combination of wet cell weight and spore density in inoculum by liquid culture. Most strains showed the high production of monacolin K in red mold rice, when submerged fermentation was carried out for 5 days as inoculum for solid state fermentation. These results suggest that submerged fermentation period of inoculum have an effect on the production of monacolin K in red mold rice by solid state fermentation, and monacolin K in red mold rice could be increased by controlling the condition of submerged fermentation for inoculum.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2006.05a
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• pp.199-200
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• 2006

It will not be an exaggeration to say that one of the most important features of RT (Rapid Tooling) technology is to easy manufacturing complex shape of cooling channel in injection mold. That is, RT technology is hardly influenced complex shape of tool, Therefore, mold designer can optimize the position and shape of cooling channel whatever they want. In this study, we optimized cooling channel through CAE analysis to solve the problem; prototype-connector-mold applied conventional cooling channel, locally warped by internal stress: The effect of three-dimensional cooling channel was supported by simulation result. But it is impossible to produce injection mold applied three-dimensional cooling channel through machining operation. Therefore, we produced the prototype-connector-mold with three-dimensional cooling channel using Direct Metal Laser Sintering (DMLS) process, and get good-quality prototype-connector without warpage.

• Journal of Korea Foundry Society
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• v.17 no.3
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• pp.237-244
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• 1997

This study has been carried out to investigate into the influence of solidification conditions mold on the structure and mechanical properties of Al-5wt%Mg alloy by metallic mold casting. The percentage of equiaxed grain of Al-5wt%Mg alloy castings increased both when pouring temperature decreased and when the low part or bottom of metallic mold was cooled. The hardness was checked and showed that hardness of outside in the castings was higher than that inside, and that it is the highest at the pouring temperature of $680^{\circ}C$. The castings had the highest U.T.S. and elongation when the bottom of metallic mold was cooled. At the same pouring temperature, the structure of castings was changed as the position of cooling parts of metallic mold was varied. When the castings were solidified through cooling of the bottom of the metallic mold, the morphology of Fe intermetallic compound has tendency to change to a Chinese script and the U.T.S. and elongation of Al-5wt.%Mg alloy castings was increased.

• Journal of Korea Foundry Society
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• v.13 no.2
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• pp.155-162
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• 1993

This study has been focused on the influence of the metallic mold cooling effects on the solidification structures and the mechanical properties for Al-10%Si alloy castings by the variation of pouring temperatures, metallic mold temperatures and Cooling part of metallic mold. The dendrite arm spacing of Al-10%Si alloy was decreased with increasing cooling rate. In case of bottom cooling of metallic mold, DAS was appeared to be $20-22{\mu}m$ and in the middle cooling, it was increased to $36-40{\mu}m$. The DAS decreased proportionally $with(cooling\;rate)^{-3/2}$ at pouring temperatures $680^{\circ}C$ and $(cooling\;rate)^{-1/2}$ at pouring temperature $760^{\circ}C$, but it was proportionally increased to $(local\;solidification\;time)^{1/2-1/3}$ at pouring temperature $680^{\circ}C$ and $760^{\circ}C$. The maximum tensile strength of Al-10%Si alloy casting was obtained in case of bottom cooling of mold at pouring temperature $680^{\circ}C$ and metallic mold temperature $320^{\circ}C$.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2009.10a
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• pp.437-440
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• 2009

High-frequency induction is an efficient way to heat mold surface by electromagnetic induction in a non-contact manner. Thanks to its capability of rapid heating and cooling of mold surface, it has been recently applied to the injection molding. The present study applies the high-frequency induction heating for elimination of weldlines in an injection-molded plastic part. To eliminate weldlines, the mold temperature of the corresponding weld locations should be maintained higher than the glass transition temperature of the resin material. Through experiments, the maximum temperature of $143^{\circ}C$ is obtained on the mold surface around the elliptic coil, while the temperature of the mold plate is lower than $60^{\circ}C$. An injection molding experiment is then performed with the aid of induction heating, and the effect of induction heating conditions on the surface appearance of the weldline is investigated.