• 한국윤활학회:학술대회논문집
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• 한국윤활학회 2003년도 학술대회지
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• pp.299-306
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• 2003

The SCM420 used mainly to automobile transmission gear has problems that it costs transmission gear maker much money in carburizing treatment. For this, it needs to alternate the existing material and heat treatment to new gear material and surface modification. For this, friction and wear experiment according to sliding speed and applied load was carried out to evaluate the wear resistance of two transmission gear materials with oxidation nitrocarburising and non-oxidation nitrocarburising NT100, The presumed wear volume was calculated with the image processing for evaluation of wear resistance of two transmission gear materials. The results show that the oxidation nitrocarburising has a distinguished wear resistance than non-oxidation nitrocarburising.

• 한국축산식품학회지
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• 제44권1호
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• pp.19-38
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• 2024

Meat contains high-value protein compounds that might degrade as a result of oxidation and microbial contamination. Additionally, various pathogenic and spoilage microorganisms can grow in meat. Moreover, contamination with pathogenic microorganisms above the infectious dose has caused foodborne illness outbreaks. To decrease the microbial population, traditional meat preservation methods such as thermal treatment and chemical disinfectants are used, but it may have limitations for the maintenance of meat quality or the consumers acceptance. Thus, non-thermal technologies (e.g., high-pressure processing, pulsed electric field, non-thermal plasma, pulsed light, supercritical carbon dioxide technology, ozone, irradiation, ultraviolet light, and ultrasound) have emerged to improve the shelf life and meat safety. Non-thermal technologies are becoming increasingly important because of their advantages in maintaining low temperature, meat nutrition, and short processing time. Especially, pulsed light and pulsed electric field treatment induce few sensory and physiological changes in high fat and protein meat products, making them suitable for the application. Many research results showed that these non-thermal technologies may keep meat fresh and maintain heat-sensitive elements in meat products.

• 소성∙가공
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• 제19권1호
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• pp.25-31
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• 2010

To achieve desired microstructure and mechanical property of a manufacturing product, heat treatment process is applied as a secondary process after forging. Especially, quenching process is used for improving strength, hardness, and wear resistance since phase transformation occurs owing to rapid heat transfer from the surface of the specimen. In the present paper, a study on surface temperature measurement for water quenching of eutectoid steel was investigated. In order to determine the temperature history in experiments, three different measuring schemes were used by varying installation techniques of K-type thermocouples. Depending on the measured temperature distribution at the surface of the specimen, convective heat transfer coefficients were numerically determined as a function of temperature by the inverse finite element analysis considering the latent heat generation due to phase transformation. Based on the inversely determined convective heat transfer coefficient, temperature, phase, and hardness distributions in the specimen after water quenching were numerically predicted. By comparing the experimental and computational hardness distribution at three different locations in the specimen, the best temperature measuring scheme was determined. This work clearly demonstrates the effect of temperature measurement on the final mechanical property in terms of hardness distribution.

• 한국레이저가공학회지
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• 제9권1호
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• pp.9-16
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• 2006

Glass is one of brittle materials. Generally, brittle material is weak for tensile stress but strong for compression stress. Laser breaking of glass used this brittle characteristics. Laser breaking of glass was simulated to optimize breaking condition by using commercial FEM code MARC which is applicable to thermo-mechanical coupling analysis. Various shapes of heat sources were applied to the analysis and the distance between heating and cooling source were varied for each simulation. The shapes of heat sources were circle, single and double ellipse and the distance was varied from 0mm to 30mm. Moving heat sources were designed on the basis of experimental condition. As a result, double elliptic shape of heat source was the most suitable among them in laser breaking of glass. And it should be useful to determine optimal condition of laser breaking for glass.

• 한국식품영양학회지
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• 제28권3호
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• pp.465-469
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• 2015

An analysis of changes in herbal tea composition according to the difference in processing conditions showed slightly reduced crude protein content and increased, moisture, crude fat and solid elution rate after treatment using the ash puffing process compared to roasting. Benzopyrene content was significantly reduced to 0.18 ppb from 0.51 ppb. This result indicated that, the $B({\alpha})P$ content differed depending on the processing condition and raw materials. Generation of food $B({\alpha})P$ is mainly include the thermal decomposition of food cooking, when the processing which is a main component of food carbohydrate, protein, fat reason despite severe heat treatment as a whole is to be detected even though the $B({\alpha})P$ in this way is considered to be. The taste, aroma and color did not show a large difference, but the strong bitters taste decreased.

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 2002년도 Proceedings of the International Welding/Joining Conference-Korea
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• pp.250-254
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• 2002

Intergranular corrosion of austenitic stainless steels is a conventional and momentous problem during welding and high temperature use. One of the major reasons for such intergranular corrosion is so-called sensitization, i.e., chromium depletion due to chromium carbide precipitation at grain boundaries. Conventional methods for preventing sensitization of austenitic stainless steels include reduction of carbon content in the material, stabilization of carbon atoms as non-chromium carbides by the addition of titanium, niobium or zirconium, local solution-heat-treatment by laser beam, etc. These methods, however, are not without drawbacks. Recent grain boundary structure studies have demonstrated that grain boundary phenomena strongly depend on the crystallographic nature and atomic structure of the grain boundary, and that grain boundaries with coincidence site lattices are immune to intergranular corrosion. The concept of "grain boundary design and control", which involves a desirable grain boundary character distribution, has been developed as grain boundary engineering. The feasibility of grain boundary engineering has been demonstrated mainly by thermomechanical treatments. In the present study, a thermomechanical treatment was tried to improve the resistance to the sensitization by grain boundary engineering. A type 304 austenitic stainless steel was pre-strained and heat-treated, and then sensitized, varying the parameters (pre-strain, temperature, time, etc.) during the thermomechanical treatment. The grain boundary character distribution was examined by orientation imaging microscopy. The intergranular corrosion resistance was evaluated by electrochemical potentiokinetic reactivation and ferric sulfate-sulfuric acid tests. The sensitivity to intergranular corrosion was reduced by the thermomechanical treatment and indicated a minimum at a small roll-reduction. The frequency of coincidence-site-lattice boundaries indicated a maximum at a small strain. The ferric sulfate-sulfuric acid test showed much smaller corrosion rate in the thermomechanically-treated specimen than in the base material. An excellent intergranular corrosion resistance was obtained by a small strain annealing at a relatively low temperature for long time. The optimum parameters created a uniform distribution of a high frequency of coincidence site lattice boundaries in the specimen where corrosive random boundaries were isolated. The results suggest that the thermomechanical treatment can introduce low energy segments in the grain boundary network by annealing twins and can arrest the percolation of intergranular corrosion from the surface.

• 산업식품공학
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• 제21권1호
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• pp.22-28
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• 2017

Ginger was steamed at $121^{\circ}C$ and $1.5lb/in^2$ for 30 min, dried at $60^{\circ}C$ for 12 h, and each step was repeated nine times. During processing, the lightness ($L^*$ value) and yellowness ($b^*$ value) decreased from $85.65{\pm}0.33$ and $26.99{\pm}0.20$ in the non-treated ginger to $56.91{\pm}0.25$ and $16.69{\pm}0.06$ in ginger treated for the ninth treatment. On the other hand, redness ($a^*$ value) increased from $-1.51{\pm}0.03$ to $7.34{\pm}0.08$ on the eight treatment and then decreased to $7.21{\pm}0.04$ on the ninth theatment. The contents of 6-gingerol decreased from $3.257{\pm}0.067mg/g$ in the non-treated ginger to $0.567{\pm}0.036mg/g$ on the theatment, whereas the contents of 6-shogaol increased from $1.299{\pm}0.050mg/g$ to $2.999{\pm}0.089mg/g$ on the sixth treatment and decreased to $2.099{\pm}0.039$ on the ninth treatment. The contents of 10-gingerol decreased slightly from $1.106{\pm}0.125mg/g$ to $0.806{\pm}0.026mg/g$. Unlike the 6- and 10-gingerol, the contents of 8-gingerol did not change greatly, with values between $0.916{\pm}0.005mg/g$ and $1.106{\pm}0.005mg/g$ being observed during processing. The tyrosinase inhibitory activities were increased from $43.42{\pm}11.45%$ in the non-treated ginger to 100% on the sixth treatment and then decreased to $51.98{\pm}7.36%$ on the theatment. The antioxidative activity was retained during processing.

• 한국축산식품학회지
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• 제39권2호
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• pp.296-308
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• 2019

Although the yellow mealworm (Tenebrio molitor L.) is a promising alternative protein source, the effects of processing conditions on functional properties are unclear. In this study, a protein extract of yellow mealworm larvae (PEYM) was subjected to different heat temperature ($55^{\circ}C$, $75^{\circ}C$, and $95^{\circ}C$) with different time (20, 40, and 60 min) to evaluate the functional properties and protein oxidation. Different heat temperature treatment significantly affected the exposure of surface hydrophobicity of the proteins and protein molecule aggregation, which reached maximum levels at $95^{\circ}C$ for 60 min. Protein oxidation was inversely proportional to the temperature. Both the highest carbonyl value (1.49 nmol/mg protein) and lowest thiol value (22.94 nmol/mg protein) were observed at $95^{\circ}C$ for 60 min. The heating time-temperature interaction affected several functional properties, including solubility, emulsifying potential, and gel strength (GS). Solubility decreased near the isoelectric point (pH 5 to 6). As the temperature and heating time increased, emulsifying properties decreased and GS increased. The oil absorption capacity and foaming properties decreased and the water absorption capacity increased. These results confirmed that PEYM is a suitable source of proteins for processing and applications in the food industry.

• Preventive Nutrition and Food Science
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• 제9권4호
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• pp.330-335
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• 2004

Changes in functional constituents of rice germ prepared using three different heat pretreatments: roasting, steaming and microwave heating, were determined and compared with those of non-treated rice germ. The yield of rice germ oil increased generally and then decreased with increasing time for all three heat pretreatments, although the yields of rice germ oil varied among the three heat pretreatments. There were no major differences in fatty acid compositions among the rice germ oils subjected to the three different heat pretreatments. Levels of $\alpha$-tocopherol in rice germ oil increased up to about 1.5 times at 3 min of roasting and microwave heating, compared to control, and then decreased with increasing treatment time, but $\alpha$­tocopherol concentrations in rice germ oil gradually decreased with increasing steaming time. The contents of three phytosterols ($\beta$-sitosterol, stigmasterol and ergosterol) decreased progressively with increases in roasting and steaming time, while concentrations of the three phytosterols increased up to - 15$\%$ with 3 min of microwave process as compared to control, and then decreased thereafter. Levels of $\gamma$-oryzanol in rice germ oil decreased gradually with increasing time during all three different heat pretreatments. However, levels of $\gamma$ -aminobutyric acid (GABA) in rice germ decreased gradually with increasing roasting time, while those of GABA increased greatly up to about 2 times after 10 min of steaming process, and then decreased slowly thereafter. During microwave heating, the contents of GABA increased at 3 min of treatment time and then decreased. These results suggest that microwave heating may be the most suitable processing method to preserve functional constituents in rice germ.

• 소성∙가공
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• 제30권1호
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• pp.43-48
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• 2021

The success of warm forming of Mg alloy sheet is greatly influenced by friction at elevated temperature, depending on the surface treatment of the tool. The tool coating affected the frictional characteristics of AZ31B Mg alloy sheet at elevated and room temperatures. The frictional behavior of the Mg alloy sheet at room temperature was not significantly affected by surface treatment conditions of the tool, but was significantly affected at elevated temperature. When the contact pressure is high, a few surface-treated tools exhibit a higher coefficient of friction than those without surface treatment. It is important to select the surface treatment conditions of the tool in order to ensure appropriate friction during warm forming of Mg alloy sheet.