• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.37 no.3
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• pp.280-285
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• 2024

In this paper, the electrical properties of liquid insulating oil were analyzed by changing the ambient temperature change at 10℃ in-tervals from 0℃ to 30℃ through an insulation breakdown experiment in order to analyze the insulation performance of liquid in-sulating oil that varies according to temperature changes. As a result, it was confirmed through experiments that the lower the am-bient temperature, the higher the insulation breakdown voltage, depending on both the electrode shape and the electrode interval, and it was determined that the lower the ambient temperature, the higher the insulation performance of the liquid insulating oil.

• 한국정보디스플레이학회:학술대회논문집
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• 2007.08b
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• pp.1600-1602
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• 2007

TPS (Temperature Programmed Sublimation) technology is known to research for the plane evaporation of the organic film.[5] Using TPS technology, the plane source evaporation of NPB organic film has been studied for the first time. The NPB organic film consists of nano scale film phase and bulk phase on a substrate. The 400 ${\AA}$ in film phase thickness of NPB sublimates at the $175^{\circ}$ of the Ta made metal plate. It was proved that the sublimation temperature of the organic film has much lower than that of the organic powder. ($130^{\circ}$ is lower for Alq3 and $90^{\circ}$ is lower for NPB.)

• Journal of the Korean Society of Combustion
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• v.8 no.4
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• pp.9-14
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• 2003

High temperature air combustion technology has been utilized by using preheated air over 1100 K and excessive exhaust gas recirculation. Numerical analysis was performed to investigate the combustion characteristics with high temperature deficient oxygen air combustion by adopting a counterflow as a model problem accounting for detailed chemical kinetics. Methane($CH_4$) was used as a test fuel and calculated oxidizer conditions were low temperature high oxygen (300K, $X_{O2}=0.21$) and high temperature low oxygen (1300K, $X_{O2}=0.04$) conditions. The latter case showed that the flame temperature is lower than the former case and its profile showed monotonic decrease from oxidizer to fuel side, without having local maximum flame temperature at high stretch rate. Also, heat release rate was one order lower and it has one peak profile because of low oxygen concentration and heat release rate integral is almost same for stretch rate. High temperature low oxygen air combustion shows low NO emission characteristics.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.8
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• pp.492-501
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• 2016

This study was conducted to investigate the physiochemical characteristics of Cheongju prepared using different types of rice (rice and glutinous rice) according to addition rate of Nuruk during low temperature fermentation. The characteristics of Cheongju prepared using three different temperatures ($10^{\circ}C$, $18^{\circ}C$, $25^{\circ}C$) were compared. After fermentation for 30-50 days, the pH of mash prepared at lower temperature was lower, as was that of mash made from rice relative to that prepared using glutinous rice. The total acidity was formed at lower temperature and generated in mashing prepared by glutinous rice. The organic acid content of mash made from rice at $18^{\circ}C$ was lowest, while that of mash prepared from glutinous rice was lowest at $10^{\circ}C$. The fermentation speed was lowest at $10^{\circ}C$; however, low temperature fermentation resulted in the highest alcohol content. The mash prepared from glutinous rice showed faster fermentation than that made from rice. In addition, the pH was lower when lower levels of Nuruk were added and higher in mash made from glutinous rice than that prepared from rice. The lower addition rate of Nuruk also showed a lower sugar content and final alcohol content. The levels of citric acid and lactic acid were higher, while those of succinic acid, acetic acid, and ethyl acetate were lower when lower levels of Nuruk were added. The mash prepared from glutinous rice showed a higher alcohol content than that made from rice.

• Journal of Bio-Environment Control
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• v.25 no.4
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• pp.262-269
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• 2016

The objective of this study was to evaluate the effect of storage temperature on fruit quality attributes and physiological disorders including peel blackening in 'Sangjudungsi' persimmon (Diospyros kaki Thunb.) fruit stored in air at -1, 0.5 or $3^{\circ}C$ for up to 3 months. Higher storage temperature reduced ethylene production but not respiration rate, compared with lower storage temperature. Flesh firmness decreased continuously as storage time passed but firmness was reduced rapidly in the fruits stored at higher storage temperature. Fresh weight loss increased at higher storage temperatures. Soluble solids content was higher at lower storage temperature than at higher storage temperature. All color variables ($L^*$, $a^*$, $b^*$) were reduced by lower storage temperature, compared with higher storage temperature, regardless of tissue regions. Fruit softening increased as storage duration advanced and with the increase in storage temperature. Results indicated that the 'Sangjudungsi' persimmon fruits stored at higher storage temperature ($3^{\circ}C$) could not retain fruit quality properly on account of lower flesh firmness and higher incidence of peel blackening and fruit decay, compared with lower storage temperature.

• 한국방재학회:학술대회논문집
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• 2007.02a
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• pp.357-360
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• 2007

Water retaining pavement is a pavement to lower the surface temperature by using evaporation of the water that the pavement contains when the pavement is heated by the sun in the daytime. The objective of this study is to develop water retaining materials. In this study we evaluated the practical application of a sepiolite and a charcoal as a water retaining material. We produced dense grade asphalt pavement, porous asphalt pavement, semi-rigid Pavement, semi-rigid pavement included a charcoal and semi-rigid pavement included a sepiolite, and then tested surface temperature characteristics. The test result says that water retaining pavements using a sepiolite and a charcoal lower surface temperature more than $10^{\circ}C$ compared to dense grade asphalt pavement. We confirm the practical application of a sepiolite and a charcoal as a water retaining material according to the test results.

• Journal of the Korean Ceramic Society
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• v.13 no.1
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• pp.20-24
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• 1976

These are many kinds of self-hardening methods for sand mold using sodium silicate. When sodium silicate solution is mixed with calcium-orthosilicate powder hardening reaction occurs, which is based for self-hardening method at high temperature. The high temperature strength and resicual strength of mold are related to the mole ratio of sodium silicate and the contents of calcium-orthosilicate powder. The results obtained in this study were as follows: 1) The high temperature strength of mold was maximum at about $600^{\circ}C$, and at higher temperature showed lower value on the contrary. 2) The high temperature strength of mold was increased by increasing the amount of sodium silicate having lower mole ratio and high concentration. 3) The residual strength of mold was reduced by increasing the mole ratio of sodium silicate and increasing the concentration of calcium-orthosilicate.

• Journal of Sensor Science and Technology
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• v.28 no.3
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• pp.177-181
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• 2019

Pressure sensors are used in various industries such as automobiles, airplanes, medical equipment, and coolers. Even if the ambient temperature changes, the measurement is reliable and stable. In this study a diaphragm-type pressure sensor was used to derive a temperature-compensated pressure estimation equation for accurate pressure measurement at $100^{\circ}C$ and $-40^{\circ}C$. To understand the characteristics of the pressure sensor diaphragm with respect to temperature and pressure, experiments were conducted in temperature-variable chamber using FEM analysis to confirm that the influence of temperature effect was nonlinear. Based on the experimental results, a nonlinear method for calculating the pressure by compensating for the error due to temperature was derived. The calculated pressure value is lower than 0.5 % at low and high temperatures, and lower than 0.4 % at $22^{\circ}C$, thereby eliminating the effect of temperature.

• Journal of Astronomy and Space Sciences
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• v.37 no.1
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• pp.69-75
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• 2020

We analyze the observations of temperature and ozone measured by the Microwave Limb Sounder (MLS) during the period of 2005-2016, to investigate the vertical structures of temperature and ozone in the stratosphere and mesosphere during stratospheric sudden warming (SSW). We compute the height profiles of the correlation coefficients between 55 height levels of MLS temperature anomalies and compare them with the results of Whole Atmosphere Community Climate Model simulations for three major SSWs. We also construct the temperature and ozone anomalies for the events to investigate the changes in the temperature and ozone distributions with height. There seems to always be a relatively weak but broad negative correlation between the temperature anomaly at 10 hPa and temperature anomalies over the entire mesosphere during the period before SSW events. However, this pattern gets stronger in the lower mesosphere but becomes a positive correlation in the upper mesosphere and lower thermosphere after the onset of SSW. We also found that the temperatures from the simulations show a similar trend to the observational results but with smaller variations and the transition height from negative to positive correlation in the mesosphere is much lower in the simulation than in the actual observations.

• Corrosion Science and Technology
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• v.22 no.3
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• pp.175-186
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• 2023

Effects of high-temperature environment and low-temperature environment on corrosion behaviours of 18Cr stainless steels (type 304L, type 441) in simulated selective catalytic reduction (SCR) environments were studied using weight loss test in each environment and rust analysis. With time to exposure to the high-temperature environment, type 441 was more resistant to corrosion than type 304L due to both higher diffusivity of Cr and lower thermal expansion coefficient in α-iron. The former provides a stable protective Cr₂O₃ layer. The latter leaded to low residual stress between scale and steel, reducing the spallation of the scale. With time to exposure to the low-temperature environment, on the other hand, type 304L was more resistant to corrosion than type 441. The lower resistance of type 441 was caused by Cr-depleted zone with less than 11% formed during the pre-exposure to a high-temperature environment, unlike type 304L. It was confirmed by results from the crevice corrosion test of sensitised 11Cr steel. Hence, to achieve higher corrosion resistance in simulated SCR environments, ferritic stainless steels having lower thermal expansion coefficient and higher diffusivity of Cr but containing more than 18% Cr are recommended.