• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.6
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• pp.2596-2603
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• 2013

The precision and endurance of tire mold are very important factors to decide the quality of tire. However, the investigation on the thermal deformation of tire mold has a lot of trouble because the tire mold is produced in airtight permanent casting material. In this study, the thermal deformations such as temperature, displacement and stress distributions inside the AC7A tire mold casting material were analyzed by numerical analysis according to the preheating temperature of permanent casting device. In order to verify the results of numerical analysis, the experiments for temperature measurement of the AC7A casting material were carried out under the same condition with numerical analysis. For the numerical analysis, "COMSOL Multiphysics" was used. The preheating temperatures were set up $150^{\circ}C$, $200^{\circ}C$, $250^{\circ}C$ and $300^{\circ}C$, respectively. The thermal deformations were calculated in each case. When the preheating temperature is $300^{\circ}C$, displacement and stress are the lowest with 0.25mm and 0.351GPa, but the temperature is the highest with $374.27^{\circ}C$. When the experimental results were compared with the numerical results, there were some temperature differences because of the latent heat by phase change heat transfer. However, the cooling patterns were almost similar except for the latent heat section.

• Korean Journal of Food Science and Technology
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• v.21 no.1
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• pp.149-153
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• 1989

Polygalacturonase(PG) and pectinesterase(PE) were extracted from Chinese cabbage and physicochemical properties of the enzymes were characterized. The preheating conditions for maximum retention of Kimchi texture were also studied. The activity of PE was highest at $50^{\circ}C$ and at 0.02M $CaCl_2$ but decreased in 0.2M $CaCl_2$, PG exhibited maximum activity at $65^{\circ}C$ with 0.3mM $CaCl_2$ but was inhibited by $CaCl_2$ at 0.5mM. Both of the enzymes, however, exhibited the maximum activity with 0.25M NaCl. Optimum preheating treatment was determined for minimum PG activity and maximum PE activity. Thus a maximum crispness and firmness was obtained with preheating in 0.05M $CaCl_2$ solution at $50^{\circ}C$ for 1.5hr results indicated that PE activity and calcium ion were very effective in preserving firmness.

• Journal of the Ergonomics Society of Korea
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• v.10 no.2
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• pp.43-50
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• 1991

This paper reports the results of four related studies concerning the combined effects of impermeable clothing and alternating levels of workload. The negative consequences of impaired evporation due to impermeable clothing are compared for different schedules, workloads, preheating, and high heat conditions.

• Journal of the Korean Society for Precision Engineering
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• v.34 no.3
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• pp.227-227
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• 2017

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2012.10a
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• pp.681-682
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• 2012

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2012.10a
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• pp.95-96
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• 2012

• Proceedings of the KWS Conference
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• 2006.10a
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• pp.144-146
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• 2006

• Proceedings of the KWS Conference
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• 1996.05a
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• pp.176-178
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• 1996

• Journal of Korea Foundry Society
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• v.17 no.6
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• pp.608-614
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• 1997

The effect of mold preheating temperature on the microstructure such as grain size, eutectic silicon morphology was investigated for the Al-7wt%Si-0.3wt%Mg alloy. Microstructural variations have been characterized as a function of Sr addition and cooling rate during solidification. Microstructures were correlated with cooling rate, local solidification time and eutectic nucleation temperature, etc. In this study, Sr addition caused increase of local solidification time, undercooling and reduction of eutectic plateau temperature. In logarithmic scale, local solidification time was in inverse proportion to cooling rate. Eutectic nucleation temperature was in inverse proportion to cooling rate of logarithmic scale. Increasing the cooling rate refined dendrite arm spacing and eutectic silicon. Dendrite arm spacing was logarithmically in inverse proportion to cooling rate. Without modifier addition, eutectic silicon was modified at cooling rate of $7^{\circ}C/s$ or higher.

• New & Renewable Energy
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• v.5 no.3
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• pp.40-48
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• 2009

Recovered heat has been considered as a renewable energy in Europe since 2008 because its great effect on energy saving and carbon decreasing in plant process. Energy saving and decreasing green gas are critical issue today, so various technologies to save energy and decrease carbon dioxide in plant process have been applied to many industrial area. In this paper, the feasibility of condenser heat recovery by heat pump in power plant for district heating and fuel line preheating were reviewed by verifying energy (heat) balance and mass balance of power plant model. Some ways to compose proper system to recover heat of condenser are suggested and their possibilities are also reviewed. Limitations on heat recovery in power plant are also reviewed. The results are verified by calculating input/output energy based on actual performance test data of Taean Thermal Power Plant in Korea. There is noticeable improvement of plant performance in some cases which demand low temperature (<100 C) heat like distrcit heating, fuel line heating, and so forth.