• Corrosion Science and Technology
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• v.11 no.6
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• pp.280-285
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• 2012

Aluminum is on active metal, but it is well known that its oxide film plays a role as protective barrier which is comparatively stable in air and neutral aqueous solution. Thus, aluminum alloys have been widely applied in architectural trim, cold & hot-water storage vessels and piping etc., furthermore, the aluminum alloy of AC8A have been widely used in mold casting material of engine piston because of its properties of temperature and wear resistance. In recent years, the oil price is getting higher and higher, thus the using of low quality oil has been significantly increased in engines of ship and vehicle. Therefore it is considered that evaluation of corrosion resistance as well as wear resistance of AC8A material is also important to improve its property and prolong its lifetime. In this study, the effect of solution and tempering heat treatment to corrosion and wear resistance is investigated with electrochemical method and measurement of hardness. The hardness decreased with solution heat treatment compared to mold casting condition, but its value increased with tempering heat treatment and exhibited the highest value of hardness with tempering heat treatment temperature at $190^{\circ}C$ for 24hrs. Furthermore, corrosion resistance increased with decreasing of the hardness, and decreased with increasing of the hardness reversely. As a result, it is suggested that the optimum heat treatment to improve both corrosion and wear resistance is tempering heat treatment temperature at $190^{\circ}C$ for 16hrs.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2000.05a
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• pp.109-114
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• 2000

In this paper, we studied the relation between heat-treatment temperature of ferrite and electromagnetic wave absorbing properties of ferrite-rubber composite. The heat-treatment temperatures of ferrite are 1200 and 1300 $^{\circ}C$, 2 hr. As s result, it has been shown that the optimum heat-treatment temperature of ferrite for electromagnetic wave absorber are related to the chemical composition. And, we can control electromagnetic wave absorbing properties of ferrite-rubber composite by the control of heat-treatment temperature of ferrite.

• Journal of Power System Engineering
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• v.17 no.4
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• pp.72-78
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• 2013

Compacted graphite iron 340 was carried out the heat treatment from 873 to 1,273 K. Compacted graphite iron 340 was evaluated relationship between the sound velocity, the attenuation coefficient and the tensile strength. The obtained results are as following. The signal strength of C scan images were weak according to increasing of heat treatment temperature and time. The amplitude of A scan and B scan was also low. This can be cause that the graphite was grown into the type of vermicular, and the many of grain boundary with ultrasound scattering were increase. The sound velocity was depend upon the heat treatment temperature and time, the attenuation coefficient had nothing to do with the temperature and time. The higher the heat treatment temperature, the tensile strength and the sound velocity were decreased. However, the tensile strength was proportional to the sound velocity. The higher tensile strength, the faster the sound velocity.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.3
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• pp.1795-1800
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• 2014

The temperature change in the biologically activated sludge wastewater treatment process was predicted using the heat transfer model. All incoming and outgoing heats in wastewater treatment processes were considered. Incoming heats included the solar radiation heat, the heat from impeller mechanical energy, and the biochemical heat in the aeration process. Outgoing heats comprised the radiation heat from the waste itself, the heat of vaporization and surface aeration, the wind convection heat and the conduction heat between the surface and aerator. All heats were used as an input to the existing empirical heat transfer model. The heat transfer model of wastewater treatment processes is presented also. To test the validity of the heat transfer model, the operating conditions of the actual wastewater treatment plant were used. The temperatures were compared with the model temperatures. Model predictions were consistent within the $1.0^{\circ}C$.

• Journal of the Korean Wood Science and Technology
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• v.38 no.2
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• pp.101-107
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• 2010

Heat treatment was performed to improve sound absorption properties for four tree species; Tulip tree, Korean Paulownia, Red pine and Costata birch, at temperature of $175^{\circ}C$ and $200^{\circ}C$under vacuum condition. Sound absorption properties of two kinds of boards, which were in radial and tangential sections, were measured under a frequency range of 100 to 3200 Hz by the two microphone transfer function method. It was found that sound absorption properties were increased by heat treatment and the efficiency was higher at $200^{\circ}C$ than that at $175^{\circ}C$. Even Costata birch had a little effect on low temperature of $175^{\circ}C$, $200^{\circ}C$ heat treatment for sound absorption property, the efficiencies of sound absorption were 14, 19%, respectively. The efficiencies of sound absorption ranged 22 to 120% for heat-treated Tulip tree, Korean Paulownia.

• Proceedings of the KSME Conference
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• 2000.04b
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• pp.258-263
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• 2000

River water is higher in temperature than the surrounding environment during the winter. It is highly suitable a heat source for heat pump system. Despite its suitability, however, it is not widely used, due to its fouling and corrosive nature in heat exchanger tubes of evaporator. It is designed prior-treatment system which come into direct contact with the river water, such as auto-seamer, ozone generator for bactericidal test and auto-cleaning system. And it is analyzed treatment effects for its operation. It is designed two-stage compression heat pump system using R-134a with heating load 35.16kW, ad analyzed its performance. As a result it is obtained 3.08 COP when mid-point pressure is 1,200kPa, and bypass ratio of flowing refreigerant to high-stage compressor is 25.1%

• Journal of the Semiconductor & Display Technology
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• v.12 no.4
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• pp.39-44
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• 2013

In the semiconductor heat-treatment process, the temperature uniformity determines the film quality of a wafer. This film quality effects on the overall yield rate. The heat transfer of the wafer surface in the heat-treatment process equipment is occurred by convection and radiation complexly. Because of this, there is the nonlinearity between the wafer temperature and reactor. Therefore, the accurate prediction of temperature on the wafer surface is difficult without the direct measurement. The thermal camera and the T/C wafer are general ways to confirm the temperature uniformity on the heat-treatment process. As above ways have limit to measure the temperature in the precise domain under the micro-scale. In this study, we developed the thin film type temperature sensor using the MEMS technology to establish the system which can measure the temperature under the micro-scale. We combined the experiment and numerical analysis to verify and calibrate the system. Finally, we measured the temperature on the wafer surface on the semiconductor process using the developed system, and confirmed the temperature variation by comparison with the commercial T/C wafer.

• Clean Technology
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• v.28 no.2
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• pp.110-116
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• 2022

In this study, iron oxide (FeO_x) nanoparticles were synthesized using iron (Fe) by-products recovered from NdFeB permanent magnet scraps, and the effect of heat-treatment temperature on the physical properties of the FeO_x nanoparticles was investigated. In order to prepare the FeO_x nanoparticles, 2.0 M ammonia (NH₄OH) solution was added to an iron by-product solution diluted to c.a. 10 wt% in D.I. water, which led to the precipitation of the iron oxide precursor. Then, the FeO_x nanoparticles were synthesized by heat-treatment at 300 ℃, 400 ℃, 500 ℃ and 600 ℃. After that, the physical properties of the FeO_x nanoparticles were investigated in order to understand the effect of the heat-treatment temperature. The results of the X-ray diffraction (XRD) analysis showed that the diffraction peak in accordance with the <104> direction increased as the heat-treatment increased, and a diffraction peak indicating the α-Fe₂O₃ crystal structure was detected at heat-treatment temperatures above 500 ℃. The BET specific surface area analysis revealed that the specific surface area decreased as the heat-treatment temperature increased to above 400 ℃. Observation with a high resolution transmission electron microscope (HRTEM) showed that rod-shaped nanoparticles were formed, and the size of the nanoparticles showed a tendency to increase as the heat-treatment temperature increased.

• Textile Coloration and Finishing
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• v.25 no.3
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• pp.206-214
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• 2013

There has been an increasing demand for high performance and energy-saving of blind. In order to develop the eco-friendly blind textiles, heat treatment process has been utilized for LM(Low Melting) polyester fabrics and the changes of the physical properties of the treated fabrics were examined according to temperature of heat treatment. Morphology, surface reflectance, contact angle, luster, thermal property and mechanical property of heat treated LM polyester fabrics were investigated. As results, morphology analysis of thermal treated fabrics confirmed that degree of fusion of LM polyester yarns improved with increase of temperature. Surface reflectance of thermal treated fabrics decreased with increase of temperature. Luster and contact angle of a water droplet on thermal treated fabrics increased slightly with increase of temperature. The mechanical properties of the fabrics by KES-FB system were found to be temperature-dependent and especially, bending and shear properties among them were highly related to temperature.

• Journal of the Korean Society for Heat Treatment
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• v.6 no.4
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• pp.223-229
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• 1993

Extensive reseach has been performed on the process condition-micro structure-stress relations of TiN film. The various proposed models are mainly base on physical vapor deposition processes. Especially the study on the micro-structure and deposition condition has not been sufficient in TiN deposited by PECVD. In this study, therefore, we discussed the morphological changes of TiN films by PECVD with different temperature and pressure, and compared it with the structure zone model. We could find out that the oxygen and chlorine contents and the texture coefficient increased with deposition temperature, and the morphology of TiN transformed from Zone 1 to Zone T, but deposition pressure didn't remarkly affected.