• Restorative Dentistry and Endodontics
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• v.46 no.1
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• pp.6.1-6.10
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• 2021

Objectives: The aim of this study was to evaluate the corrosion resistance of heat-treated (Reciproc and WaveOne) and non-heat-treated (ProTaper and Mtwo) superelastic nickel-titanium endodontic files when immersed in a 5.25% sodium hypochlorite solution. Materials and Methods: Anodic polarization curves were obtained with potential sweeps that began at the open circuit potential or corrosion potential (E_corr). The pitting potential (E_pit) was identified on the anodic polarization curve as the potential at which a sudden increase in current was observed. The micromorphology of the 28 tested files was analyzed before and after the electrochemical assay using scanning electron microscope (SEM). The data were analyzed using 1-way analysis of variance with the post hoc Bonferroni test (for E_corr) and the Student t-test for independent samples (for E_pit). Results: The mean E_corr values were 0.506 V for ProTaper, 0.348 V for Mtwo, 0.542 V for Reciproc, and 0.321 V for WaveOne files. Only WaveOne and Protaper files exhibited pitting corrosion, with E_pit values of 0.879 V and 0.904 V, respectively. On the SEM images of the ProTaper and WaveOne files, cavities suggestive of pitting corrosion were detected. Conclusions: Signs of corrosion were observed in both heat-treated and non-heat-treated files. Of the evaluated files, WaveOne (a heat-treated file) and ProTaper (a non-heat-treated file) exhibited the lowest corrosion resistance.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.48 no.12
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• pp.1544-1553
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• 1999

Recently, ultrasonic testing techniques have been widely used in the evaluation of the quality of metal. In this experiment, six heat-treated temperature of specimen have been considered : 0, 1200, 1250, 1300, 1350 and 1387$^{\circ}C$. As heat-treated temperature increases, the grain size of stainless steel also increases and then, eventually make it destroy. In this paper, a pattern recognition method is proposed to identify the heat-treated temperature of metals by evidence accumulation based on artificial intelligence with multiple feature parameters; difference absolute mean value(DAMV), variance(VAR), mean frequency(MEANF), auto regressive model coefficient(ARC), linear cepstrum coefficient(LCC) and adaptive cepstrum vector(ACV). The grain signal pattern recognition is carried out through the evidence accumulation procedure using the distances measured with reference parameters. Especially ACV is superior to the other parameters. The results (96% successful pattern classification) are presented to support the feasibility of the suggested approach for ultrasonic grain signal pattern recognition.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2009.05a
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• pp.40-43
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• 2009

This study is for investigating the effect of induction heating with various alloy elements to manufacture the pre-heat treated steels of 100kgf/$mm^2$ for cold heading. For four kinds of steels, the condition of induction heating (especially, induction tempering) were observed, and their microstructure and tensile and compressive properties were investigated. The middle carbon steel and the low carbon Cr-Mo steel are needed the higher Grange-Baughman tempering parameter than that of the low carbon Cr steel to obtain 100kgf/$mm^2$ tensile strength. For accomplishing the pre-heat treated steel of 100kgf/$mm^2$ tensile strength having advanced cold heading. It is needed that the pre-heat treated steel is manufactured by induction quenching and tempering with the low carbon alloy steel to have the high ratio of ferrite and the fine globular cementite simultaneously.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2009.06a
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• pp.771-772
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• 2009

• Bulletin of the Society of Naval Architects of Korea
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• v.10 no.2
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• pp.9-18
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• 1973

The effects of carburization on the fatigue strength and cracks were studied. The fatigue phenomena of the carburized specimens were compared with noncarburized specimens those were either heat-treated or un-treated. The fatigue strength of these specimens were measured by rotating bending fatigue machine. The obtained results indicated that the fatigue strength of carburized specimens were increased ranging from 24-59 % than those of un-treated, and 22-38% than those of heat-treated. The Vickers hardness of carburized were also increased as much as 138-195% than those of un-treated, and 42-125% than those of heat-treated. The microscopic observation of the carburized specimens mostly composed of minute pearlitic structure at hard case exhibited to have more localized slip than those of non-carburized specimens.

• The Journal of Natural Sciences
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• v.11 no.1
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• pp.151-157
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• 1999

The study was investigated the improved printing effect of heat transfer ability for the cotton fabric treated with disperse dyes. Some important factors were studied to determine the most optimal conditions such as concentration of dye, treated time and temperature, after treatment and before treatment using swelling agent, and molecular weight of dye. The fastness to laundering and light for heat transfer printing was measured.The optimal conditions of heat transfer printing for cotton fabric treated with disperse dye were concentration of 5% owf, treated temperature of $200^{\circ}C$, treated time of 3 minute. The diffusion of disperse dyes inside cotton fabric was accelerated as a result of swelling agent such as glycerin, ethylene glycol, tetramethylene glycol, propylene glycol using in this study. The effects of heat transfer printing were increased that the increasement of before treatment time for swelling agent, decrease of molecular weight of dye.

• Journal of the Korean Wood Science and Technology
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• v.42 no.1
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• pp.13-19
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• 2014

Three heat-treatment schedules were applied to $90{\times}90mm$ dimension square lumber of Pinus koraiensis, one of major domestic species, and their colors and physical properties were investigated for obtaining an optimum schedule. Each square lumber was heat-treated three times. The temperatures of $170^{\circ}C$ and $190^{\circ}C$, and the time of 9 hours and 13 hours were used for the first heat-treatment. The schedule of $190^{\circ}C$ and 7 hours were used for the next two heat-treatments. The averages of brightness $L^*$ decreased linearly as the heat-treatment repeated and its standard deviations also decreased slightly. While the averages of color difference ${\Delta}E^*$ increased linearly as the heat-treatment repeated and its standard deviations also increased slightly. The average compressive strength of the heat-treated specimen was higher than that of the control by 9%, which deviates from previous reports. ASE and WPG of the heat-treated specimens were measured to confirm that heat-treatment improved dimensional stability significantly.

• Biotechnology and Bioprocess Engineering:BBE
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• v.11 no.1
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• pp.19-25
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• 2006

With particular regards to the hepatitis A virus (HAV), a terminal dry-heat treatment ($100^{\circ}C$ for 30 min) process, following lyophilization, was developed to improve the virus safety of a solvent/detergent-treated antihemophilic factor IX concentrate. The loss of factor IX activity during dry-heat treatment was of about 3%, as estimated by a clotting assay. No substantial changes were observed in the physical and biochemical characteristics of the dry-heat-treated factor IX compared with those of the factor IX before dry-heat treatment. The dry-heat-treated factor IX was stable for up to 24 months at $4^{\circ}C$, The dry-heat treatment after lyophilization was an effective process for inactivating viruses. The HAV and murine encephalomyocarditis virus (EMCV) were completely inactivated to below detectable levels within 10 min of the dry-heat treatment. Porcine parvovirus (PPV) and bovine herpes virus (BHV) were potentially sensitive to the treatment. The log reduction factors achieved during lyophilization and dry-heat treatment were ${\ge}5.60$ for HAV, ${\ge}6.08$ for EMCV, 2.64 for PPV, and 3.59 for BHV. These results indicate that dry-heat treatment improves the virus safety of factor IX concentrates, without destroying the activity. Moreover, the treatment represents an effective measure for the inactivation of non-lipid enveloped viruses, in particular HAV, which is resistant to solvent/detergent treatment.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2009.05a
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• pp.35-36
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• 2009

Development trend and current status were surveyed for pre-heat-treated high strength cold heading quality (CHQ) wire and it's forming technology. Spheroidizing, quenching, and tempering heat treatments are eliminated by adapting the pre-treated wire, which could reduce energy consumption rate and green house gas emission rate during produce parts requiring high strength. There are some challenging problems to expand application area such as enhancing forming tool life, and preventing delayed failure. Domestic research movement concerning the development and application of the new high strength wire was introduced.

• Journal of the Semiconductor & Display Technology
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• v.18 no.2
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• pp.29-31
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• 2019

The ZTO/p-Si thin film was produced and investigated for tunneling phenomena caused by the interface characteristics of the depletion layer. ZTO thin film was deposited and heat treated to produce barrier potentials by the depletion layer. The negative resistance characteristics were shown in the thin film of ZTO heat treated at $100^{\circ}C$, and the insulation properties were the best. Current decreased in the negative voltage direction by nonlinear show key characteristics, and current decreased in tunneling phenomenon by negative resistance in the positive voltage direction. Heat treated at $100^{\circ}C$, the ZTO thin film has increased barrier potential in the areas of the depletion layer and therefore the current has increased rapidly. The current has decreased again as we go beyond the depletion layer. Therefore, tunneling can be seen to make insulation better. In the ZTO thin film heat treated at $70^{\circ}C$ without tunneling, leakage current occurred as current increased at positive voltage. Therefore, tunneling effects by negative resistance were found to enhance insulation properties electrically.