• Geosystem Engineering
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• v.21 no.6
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• pp.309-317
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• 2018

We employ a three-dimensional indirect boundary element method (BEM) to simulate temperature change around an underground liquefied natural gas storage cavern. The indirect BEM (IBEM) uses fictitious heat source strength on boundary elements as basic variables which are solved from equations of boundary conditions and then used to compute the temperature change at other points in the considered problem domain. The IBEM requires evaluation of singular integration for temperature change due to heat conduction from a constant heat source on a planar (triangular) region. The singularity can be eliminated by a semi-analytical integration scheme. However, it is found that the semi-analytical integration scheme yields sharp temperature gradient for points close to vertices of triangle. This affects the accuracy of heat flux, if they are evaluated by finite difference method at these points. This difficulty can be overcome by a combination of using a direct numerical integration for these points and the semi-analytical scheme for other points distance away from the vertices. The IBEM and the hybrid integration scheme have been verified with an analytic solution and then used to the application of the underground storage.

• Bulletin of the Korean Chemical Society
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• v.20 no.12
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• pp.1457-1463
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• 1999

Structure and their redox property of the vanadium oxides prepared by decomposing NH₄VO₃ at various temperatures were studied by XRD, SEM, XPS, and temperature programmed reduction/temperature programmed oxidation (TPR/TPO) experiment. All TPR profiles have two sharp peaks in the temperature range 650-750℃, and the area ratio of the two sharp peaks changed from sample to sample. There were three redox steps in TPR/TPO profiles. The oxidation proceeded in the reverse order of the reduction process, and both the reactions proceeded via quite a stable intermediates. The changes of the morphological factor $(I_{(101)}/I_{(010)})$, the ratio of $O_{1S}$ peak area (O$_{1S}$( α)/O$_{1S}$( β)) in the XPS results, and the ratio of hydrogen consumption in TPR profiles with various vanadium oxides showed the distinct relationship between the structural property and their redox property of vanadium oxides. The change of the specific yield of phthalic anhydride with various vanadium oxides showed a very similar trend to those of the peak area ratio in TPR profiles, which meant that the first reduction step related to the partial oxidation of o-xylene on the vanadium oxide catalyst.

• Journal of Aquaculture
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• v.12 no.3
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• pp.221-228
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• 1999

The effects of sparp changes of water temperature (WT) on the stree response and physiological change of the cultured olive flounder (Paralichthys olivaceus) were examined by manipulating WT (3 patterns) in a running seawater culture system. In the first group (Exp. I), the WT was decreased from 18$^{\circ}C$ to 11$^{\circ}C$ within 6 hours and increased back to the original WT quickly. WT was decreased from 2$0^{\circ}C$ to 11$^{\circ}C$ within 5 hours and main-tained at 11$^{\circ}C$ for 10 hours. and then increased to 2$0^{\circ}C$ in the second group (Exp. II). In the third group(Exp. III) WT was decreased to 11$^{\circ}C$ within 5 hours (type A) or 10 hrs. (type B). In Exp. I and III, the level of serum cortisol was increased from 2.5$\pm$0.3 ng/ml and 2.6$\pm$0.9 ng/ml to 13.6$\pm$3.0 ng/ml and 12.4$\pm$3.2ng/ml, respectively, with WT decrease. However, no consistent tendency in the change of serum glucose level was shown according to WT decrease. In Exp. III, the glucose level of fish in type A was decreased until 5 hours and increased at 7 hours, then decreased until 12 hours where as the glucose level in type B was decreased until 5 hours and stayed at the level of 15.7 mg/dl. The serum osmolality was reduced with WT decrease and the response of serum electrolytes in this experiment conflicted, and a tendency in total protein, AST and ALT was not found following WT decrease. In conclusion, olive flounder responded to the stress caused by WT decrease and acclimated to this condition when the lower temperature was maintained. But there was no stress response in the blood of olive flounder when WT was increased. On the other hand, the degree of stress response in olive flounder was various according to the range and gradient of WT change.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.36 no.1
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• pp.65-67
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• 2003

Flounder (Paralichthys olivaceus) fish goes through metamorphosis in the larvae phase. In this phase, it secretes much thyroid hormone to control metamorphosis. Sharp change in the environment and nutrition deficiency may cause stress in the metamorphosis phase. It leads to interfering with the development of thyroid hormone and finally inhibits the normal growth of larvae. In this study, the correlation between the change in thyroid hormones and the albinism appearance was examined by growing them with low temperature ($13^{\circ}C$) stress over the premetamorphosis stages (stage $D\~F$) of flounder metamorphosis. Albinism rate was $15\%$ in the low temperature group and $25\%$ in the control goup. $T_{4}\;and\;T_{3}$ of the control group tended to increase from stage F as larvae grew. $T_{4}$ increased 2 times compared to the control group as 72 ng/g at stage H, the increasing phae of water temperature, in the low temperature group. $T_{3}$ increased 8 times compared to the control group as 2.9 ng/g at stage E, the decreasing phase of water temperature. Therefore, it is judged that the albinism appearance of flouner is caused from the sharp increase in $T_{3}$ by the inappropriate secretion of thyroid hormone.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.56 no.8
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• pp.1430-1435
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• 2007

We developed a 440MHz surface acoustic wave (SAW) microsensor integrated with pressure-temperature sensors and ID tag. Two piezoelectric substrates were bonded, in which ${\sim}150\;{\mu}m$ cavity was structured. Four sides were completely sealed by JSR photoresist (PR). Pressure sensor was placed on the top substrate, whereas ill tag and temperature sensor were placed on the bottom substrate. Using network analyzer, the developed microsensor was wirelessly tested. Sharp reflection peaks with high S/N ratio, small signal attenuation, and small spurious peaks were observed. All the reflection peaks were well matched with the coupling of mode (COM) simulation results. With a 10mW RF power from the network analyzer, a ${\sim}1$ meter readout distance was observed. Eight sharp ON reflection peaks were observed for ID tag. Temperature sensor was characterized from $20^{\circ}C$ to $200^{\circ}C$. A large phase shift per unit temperature change was observed. The evaluated sensitivity was ${\sim}10^{\circ}/^{\circ}C$.

• Journal of Magnetics
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• v.2 no.1
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• pp.28-33
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• 1997

Very large in electrical resistivity by several orders of magnitude is obtained when an external magnetic field is applied to the colossal magnetoresistnace (CMR) materials such as La-Ca-Mn-O. The magnetoresistance is strongly temperature-dependent, and exhibits a sharp peak below room temperature, which can be shifted by adjusting the composition or processing parameters. The control of lattice geometry or strain, e.g., by chemical substitution, epitaxial growth or post-deposition anneal of thin films appears to be crucial in obtaining the CMR properties. The orders of magnitude change in electrical resistivity could be useful for various magnetic and electric device applications. .

• Journal of Environmental Science International
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• v.17 no.8
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• pp.907-918
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• 2008

In order to monitor the impact of high temperature which is seen frequently with climate change, we investigated the monthly change in globe temperature, air temperature, mean radiant temperature and effective radiant heat flow, because the four well reflect thermal radiation from bio-meteorological aspect. Both globe temperature and air temperature showed an increasing trend every month. Compared to air temperature, globe temperature had a wider range of temperature change and was more influenced by meteorological element such as precipitation. Diurnal trends of air temperature, globe temperature and the difference between their temperature had the lowest value before the sunrise and the highest around $1300{\sim}1500$ LST, showing the typical diurnal trends. Globe temperature and the difference between their temperature had a sharp increase around $1000{\sim}1100$ LST, maintained high value until 1700 LST and then reclined, though varied by month. The difference between globe temperature and air temperature was highly dependent on the amount of precipitation and clouds. The duration in which globe temperature was higher than air temperature was the lowest in July. Therefore the amount of precipitation was the most affecting, followed by the amount of clouds and wind. In order to find out the diurnal trends of temperature in city center and city outskirts, we assumed the roof of a concrete build ing as a city center, and the grass-covered observatory of the Gimhae International Airport as city outskirts. The diurnal trends of temperature in the two sites showed a strong correlation. The highest and lowest temperature also had the same trend.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.30 no.5
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• pp.284-287
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• 2017

The electrocaloric effect in $0.94(Bi_{0.5}Na_{0.5})TiO_3+0.06KNbO3+0.9wt%$ G.F.ferroelectricceramics was observed in terms of the temperature change (${\Delta}T$) of the fabricated ceramics, Curie temperature $T_c$, and applied electric field. The specimens were fabricated by a conventional solid-state reaction. $T_c$ appeared near $165{\sim}170^{\circ}C$. The P-E hysteresis showed a tendency to slim down with a temperature increase and finally was slimmest near $150^{\circ}C$. With the increase of temperature, the polarization revealed a gradual decrease, and a sharp decline near $T_c$. When an electric field of 45 kV/cm was applied, the largest polarization was shown. The maximum value of the temperature change (${\Delta}T=0.31^{\circ}C$) was obtained at $165^{\circ}C$ under an applied electric field of 45 kV/cm.

• Tribology and Lubricants
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• v.12 no.3
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• pp.33-38
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• 1996

High temperature wear behaviors of plasma-sprayed ZrO$_{2}$-$Y_{2}O_{3}$ composite coatings were investigated for high temperature wear resistance applications. The composite powders containing 20, 50, 80 vol% of alumina for plasma spray were made by spray drying method. Wear tests with composite coated specimens were performed at temperature ranges from room temperature to 800$^{\circ}$C. Wear tests were also carried out with heat treated specimens at room temperature. The microstructural change of coatings and the worn surface were examined by SEM and XRD. Sharp increase of wear loss at high temperature wear test was observed in specimens containing 50 and 80 vol% alumina. Similar trend was observed in the heat treated coatings. The measured residual stress was increased with increased alumina contents and heat treating temperatures. Residual stress induced during heat treatment appeared to be responsible to the observed harmful effect of alumina additions on the high temperature wear.

• Korean Journal of Acupuncture
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• v.38 no.4
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• pp.282-289
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• 2021

Objectives : The purpose of this study is to construct a model of the possible thermal runaway of electronic moxibustion and to implement an appropriate risk management method. Methods : To reproduce the system error situation of the electronic moxibustion circuit equipped with microcontroller unit, temperature sensor and heater, a code was set to disable the signal input to temperature sensor and maintain "high" heating signal to heater. The temperature change of electronic moxibustion was compared between 3 types of heater module; module 1 consisting of a combination of heater+0 ohm+0 ohm resistance, module 2 consisting of a combination of heater+Polymeric Positive Temperature Coefficient (PPTC)+0 ohm resistance, and module 3 consisting of a combination of heater+PPTC+10 ohm resistance. The temperature change was measured using a polydimethylsiloxane (PDMS) silicone phantom. After maintaining surface temperature of the phantom at 31~32℃ for 20 seconds, electronic moxibustion was applied. After operating electronic moxibustion, the temperature change was measured for 660 seconds on the surface and 900 seconds at 2 mm depth. Results : Regardless of the module type, the time-dependent change in temperature showed a rapid rise followed by a gentle curve, and a sharp drop in temperature after reaching the maximum temperature about 10 minutes after the switching the moxibustion on. Temperature measured at the depth of 2 mm below the surface increased slower and to a lesser extent. Module 1 reached highest peak temperature with largest change of temperature at both depths followed by module 2, and 3. Conclusions : Through the combination of PPTC+resistance with the heater of electronic moxibustion, it is possible to limit the rise in temperature even with the software error. Thus, this setting can be used as an independent safety measure for the electronic moxibustion control unit.