• Proceedings of the Korean Society For Composite Materials Conference
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• 2000.04a
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• pp.43-48
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• 2000

Composite materials have been increasingly used in automotive and aircraft industries, naturally leading to active researches on the materials. The carbon-epoxy composite is selected to study its thermal characteristics. During multiple thermal cycles composed of repeated cooling and heating variations of elastic constants are investigated to understand thermal effects on the carbon-epoxy composite. In this investigation longitudinal resonance method and flexural resonance method was used to characterize. The values of $E_1$ show small amount of increases depending on number of cycles of the thermal fatigue processes whereas values of $G_13$ do not indicate noticeable changes. Also, in cases of $E_2$ and $G_23$ their values decrease to a certain extend in initial stages after applications of thermal fatigue processes. However, the number of cycles of the applied thermal fatigue processes does not seem to affect their values.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.11 no.4
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• pp.12-18
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• 2002

Silicon on insulator(SOI) wafer is used in a variety of microsensor applications in which thermal deformations and other mechanical effects may dominate device Performance. One of major Problems associated with the manufacturing Processes of the microaccelerometer based on the tunneling current concept is thermal deformations and thermal stresses. This paper deals with finite element analysis(FEA) of residual thermal deformations causing popping up, which are induced in micrormaching processes of a microaccelerometer. The reason for this Popping up phenomenon in manufacturing processes of microaccelerometer may be the bending of the whole wafer or it may come from the way the underetching occurs. We want to seek after the real cause of this popping up phenomenon and diminish this by changing manufacturing processes of mic개accelerometer. In microaccelerometer manufacturing process, this paper intend to find thermal deformation change of the temperature distribution by tunnel gap and additional beams. The thermal behaviors analysis intend to use ANSYS V5.5.3.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.07a
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• pp.657-658
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• 2005

Flame retard of polymers was studied for prevention from burning by various additives stimulated the char formation during heating and thermal degradation of polymer materials. Forming char have high porosity, low thermal conductivity and act as thermal shield for heat transmission from the flame to the polymer and. oxygen towards the polymer. The results showed that various additives may regulate the processes of intumecsence. The efficient fire protective intumescent char was result of processes of melting, gas evolution, cross-linking, carbonization etc.

• The Journal of Advanced Prosthodontics
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• v.12 no.1
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• pp.9-14
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• 2020

PURPOSE. The aim of this study was to investigate the effect of different numbers of heat treatments applied to superstructure porcelain on optical, thermal, and phase formation properties of zirconia. MATERIALS AND METHODS. Forty zirconia specimens were prepared in the form of rectangular prism. Specimens were divided into four groups (n = 10) according to the number of firing at heating values of porcelain. Color differences and translucency parameter were measured, and X-ray diffraction (XRD) analysis and differential scanning calorimetry (DSC) were performed. Data were analyzed with analysis of variance (ANOVA). RESULTS. There were no statistically significant differences in ∆E, TP, L, a, and b value changes of the zirconia specimens as a result of repetitive firing processes (P>.05). CONCLUSION. Although additional firing processes up to 4 increase peak density in thermal analysis, additional firing processes up to 4 times can be applied safely as they do not result in a change in color and phase character of zircon frameworks.

• Nuclear Engineering and Technology
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• v.55 no.10
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• pp.3808-3814
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• 2023

The thermal stability of nitric acid solutions after contact with non-irradiated and irradiated tributyl phosphate (TBP) and its solution in Isopar-M has been studied. It has been established that exothermic processes occur during heating due to the interaction of soluble radiolysis products and the decomposition of the extractant with nitric acid. Such processes can occur at temperatures below 100 ℃, but unlike a thermal explosion that occurs in seconds, they are longer in time and are accompanied by weak heat evolution. Their intensity depends on the composition of the extractant, the concentration of HNO₃, and the volume ratio of the organic and aqueous phases. The presence of extractant degradation products in raffinates does not pose a risk of a rapid evolution of gaseous products during evaporation, however, the presence of reducing agents can significantly increase the intensity of the exothermic decomposition of raffinates.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2021.11a
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• pp.17-18
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• 2021

In the present study, Al-Zn coating was deposited by Arc thermal (AT) and plasma arc thermal (PAT) spray processes, and their corrosion characteristics were studied in 3.5% NaCl through electrochemical impedance spectroscopy (EIS), scanning electron microscope (SEM) and mechanical tests. The bond adhesion result showed that plasma arc sprayed coating had a higher value attributed to compact, dense, and less porous coating compared to arc thermal spray coating which contains defects/pores and uneven morphology as revealed by scanning electron microscope analysis. Electrochemical results revealed that the plasma arc sprayed coating had a high polarization resistance at early stage of immersion, suggesting its excellent corrosion protection performance.

• Journal of the Korea Institute of Military Science and Technology
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• v.15 no.2
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• pp.224-230
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• 2012

Thermal batteries have excellent mechanical robustness, reliability, and long shelf life. Due to these characteristics as well as their unique activation mechanism, thermal batteries are widely adopted as military power sources. Li(Si)/$FeS_2$ thermal batteries, which are used mostly in these days, use LiCl-KCl and LiBr-LiCl-LiF as molten salt electrolyte. However, it is known that Li(Si)/$FeS_2$ thermal batteries have high internal resistance. Especially, $FeS_2$ cathode accounts for the greater part of internal resistance in unit cell. Many efforts have been put into to decrease the internal resistance of thermal batteries, which result in the development of new electrode material and new electrode manufacturing processes. But the applications of these new materials and processes are in some cases very expensive and need complicated additional processes. In this study, internal resistance study was conducted by adding carbon black and carbon nano-tube, which has high electron conductivity, into the $FeS_2$ cathode. As a results, it was found that the decrease of internal resistance of $FeS_2$ cathode by the addition of carbon black and carbon nano-tube.

• Bulletin of the Korean Chemical Society
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• v.17 no.8
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• pp.682-685
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• 1996

Photothermal properties depend on the characteristics of energy transfer processes in solution. In this study, a time-resolved single beam thermal lens experiment in various solvents is employed to investigate the energy coupling effects which govern the energy transfer processes. Interestingly, it is observed that the behaviour of the photothermal propagation in solution depends on the property of solution and the concentration of solute in a single beam thermal lens configuration. These characteristics lead us to consider the solute-solvent coupling effects as well as the solvent-solvent interactions.

• The Magazine of the Society of Air-Conditioning and Refrigerating Engineers of Korea
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• v.17 no.4
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• pp.377-381
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• 1988

Effects of thermal resistance of mold during freezing processes have been investigated. Saturated liquid is chosen to present one-dimensional quasi-steady solution and this solution is compared with numerical solutions. Front tracking finite element method has been applied for the numerical solutions. Results show that mold should be considered as well as phase change material except the cases when the very thin mold with relatively high thermal conductivity is used.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.27 no.9
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• pp.1499-1507
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• 2003

Physical importance of cutting temperatures has long been recognized. Cutting temperatures have strongly influenced both the tool life and the metallurgical state of machined surfaces. Temperatures in drilling processes are particularly important, because chips remain in contact with the tool for a relatively long time in a hole. Tool temperatures tend to be higher in drilling processes than in other in machining processes. This paper concerns with modeling of thermal behaviors in drilling processes as well as estimation of the cutting temperature distribution based on remote temperature measurements. One- and two-dimensional estimation problems are proposed to analyze drilling temperatures. The proposed thermal models are compared with solutions of finite element methods. Observer algorithms are developed to solve inverse heat conduction problems. In order to apply the estimation of cutting temperatures, approximation methods are proposed by using the solution of the finite element method. In two-dimensional analysis, a moving heat source according to feedrate of the drilling process is regarded as a fixed heat source with respect to the drilling location. Simulation results confirm the application of the proposed methods.