• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.8 no.4
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• pp.123-129
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• 1999

Although type 316 stainless steel is widely used such as in reactors of petrochemical plants and pipes of steam power plants and s attracting attention as potential basic material for the fast breeder reactor structure alloys in nuclear power plants and is attracting attention as potential basic material for the fast breeder reactor structure alloys in nuclear power plants the effect of precipitates which form during the long term exposure at service temperature on creep properties is not known sufficiently. In this study to investigate the creep properties and the influence of prior aging on the microstructure to form precipitates specimens were first solutionized at 113$0^{\circ}C$ for 20 minutes and then aged for different times of 0 hr, 100 hrs, 1000 hrs and 2200 hrs at 75$0^{\circ}C$ After heat treatments tensile tests both at room temperature and $650^{\circ}C$ and constant load creep ruptuere tests were carried out.

• Transactions of the Korean Society of Pressure Vessels and Piping
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• v.11 no.2
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• pp.51-60
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• 2015

Local wall thinning and integrity degradation caused by several mechanisms, such as flow accelerated corrosion, cavitation, flashing and/or liquid droplet impingement, is a main concern in secondary steam cycle piping system of nuclear power plants in terms of safety and operability. Thinned pipe management program (TPMP) has being developed and optimized to reduce the possibility of unplanned shutdown and/or power reduction due to pipe failure caused by wall thinning. In this paper, newest technologies, standards and regulations related to the integrity assessment, repair and replacement of thinned pipe component are reviewed. And technical improvement items in TPMP to secure the reliability and effectiveness are also presented.

• Journal of the Korean institute of surface engineering
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• v.34 no.4
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• pp.289-296
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• 2001

Ni-P electroformed layers were investigated for developing a steam generator tube repair technology in PWRs. The effects of an additive, RPP (Reagent over Pitting Protection) and agitation on mechanical properties and microstructure of the layer were evaluated. The addition of the RPP showed to inhibit the formation of pores, to refine the grain size, and to increase the residual stress in the layer. However, the agitation of the solution during electroforming was observed to increase pores in local regions of the electroformed layer, resulting in decreasing its mechanical properties. The heat treatment of the layer at $343^{\circ}C$ for 1 hr. precipitated the very fine particles of Ni3P in the layer, which inhibited grain growth and increased microhardness.

• Journal of the Korean Society of Food Science and Nutrition
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• v.41 no.2
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• pp.278-282
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• 2012

The objectives of this study was to compare the physicochemical properties and antioxidant activities of raw, microwave-treated, steam-treated and high temperature and pressure-treated garlic. The hardness and strength of microwave-treated and steam-treated garlic decreased compared to raw garlic. The hardness and softness increased but strength decreased in dried garlic-treated at $60^{\circ}C$ for 48 hr. The reducing sugar content of raw garlic was 0.041 g/100 g, and reducing sugar content of high temperature and pressure-treated garlic increased temperature. Total polyphenol content of microwave-treated and steam-treated decreased compared to raw garlic, while that of high temperature and pressure-treated increased with increasing temperature. $IC_{50}$ value of the electron donating ability of raw garlic was 3.07 mg/mL, and the highest $IC_{50}$ value was 2.16 mg/mL for microwave-treated garlic at the 4 min. The ABTS radical scavenging activity of raw garlic was 40.94 mg AEAC/mL, and the highest AEAC value was 76.51 mg AEAC/mL with high temperature and pressure-treated garlic at $150^{\circ}C$ at the 2 hr.

• Journal of the Korean Ceramic Society
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• v.40 no.5
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• pp.468-474
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• 2003

Activated carbon fibers were prepared from stabilized PAN fibers by physical and chemical activation to compare their characteristics. In this study, stabilized PAN fibers were activated by physical activation with steam and CO$_2$, and by chemical activation with KOH. The fabricated activated carbon fibers were evaluated and compared such as specific surface area, pore size distribution, pore volume, and amount of iodine adsorption. In the steam activation, a specific surface area of 1635 m$^2$/g was obtained after heat treatment at 990$^{\circ}C$. Otherwise, in the CO$_2$ activation, produced activated carbon fibers had been a specific surface area of 671 m$^2$/g after heat treatment at 990$^{\circ}C$. In chemical activation using KOH, a specific surface area of 3179 m$^2$/g was obtained with a KOH/ stabilized PAN fiber ratio of 1.5 : 1 at 900$^{\circ}C$. Nitrogen adsorption isotherms for fabricated activated carbon fibers showed type I and transformation from type I and II in the Brunauer-Deming-Deming-Teller (B.D.D.T) classification. Increasing specific surface area Increased the amount of iodine adsorption in both activation methods. Because the ionic radius of iodine was smaller than the interior micropore size of activated carbon fibers.

• Journal of the Korean Professional Engineers Association
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• v.17 no.4
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• pp.28-39
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• 1984

Experiments were carried out for the development of a processing method of soybean into full-fat or defatted flour, using two varieties of soybean (kwangkyo produced in Korea and Bragg produced in India) Samples were subjected to dry dehulling, size reduction and wet heat treatment processes to make soybean flours. The quality of soybean flours were evaluated, and the results obtained were summarized as follows. 1. Crude fiber content of dehulled soybean was under 3.0% which indicated satisfactory dehulling, and there was no significant difference in crude fibre content between two varieties. 2. When dehulled soybean was cracked into soy grits by a hammer mill, 98.71∼98.86％ of the soy grit was in the range of 10∼18 mesh which was the optimum size of particle for quick and uniform penetration of heat into the intra-particle air spaces. 3. Moisture content of soy flour after steam treatment at 15 psig for 5 to 30 min was only 0.29∼1.68% which did not hinder the next milling operation. 4. From the color analysis of soy flours, it was observed that the dominant wavelength for all the samples are in a very narrow range from 575 to 581 nm and the color variation was from yellow to yellowish orange. Twenty to twenty five ％ higher reflectance was observed in the defatted flours than full fat flours. The ％ chroma of the defatted flour slightly increased as the duration of steaming of soy grits increased, whereas that of the full-fat flour did not. 5. The protein extractability in the defatted flour at pH 7.6 showed progressive decrease in solubility from 48.40％ (Bragg), 75.20％ (kwangkyo) for untreated flours to 9.75％ (Bragg), 26.27％ (kwangkyo) for 30 min steaming. But Kwangkyo variety showed twice higher protein extractability than Bragg variety.

• Journal of the Korean Society for Heat Treatment
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• v.35 no.3
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• pp.121-129
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• 2022

Recently the growth of the renewable energy production has caused the flexible operation in LNG combined cycle power plant. Due to the rapid start and stop operations, large CrMoV castings used for turbine casings and valve bodies could be distorted and lead to replacement or welding repair. This study was performed to find out the characteristics of the repair welding for a damaged CrMoV casting steel. A typical field repair method (arc & TIG welding) was applied to making specimens. The degraded N2 packing head sample from the steam turbine was used. The evaluations of weldments were carried out in terms of microstructural characterization, microhardness measurements, tensile, creep-rupture and fatigue tests. Color etching was also applied for better understanding of welding microstructures. As the boundary between HAZ and base material was deteriorated by welding, it caused microstructural changes formed during PWHT and the shortening of the remaining residual life. By comparing the properties according to repair welding method, it was possible to derive what important welding factors were. As a result, arc welding method is more suitable for repair welding on CrMoV castings.

• The Journal of Korean Academy of Prosthodontics
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• v.44 no.5
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• pp.617-627
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• 2006

Statement of problem: HA has been used as a coating material on Ti implants to improve osteoconductivity. However. it is difficult to form uniform HA coatings on implants with complex surface geometries using a plasma spraying technique. Purpose : To determine if Ti6Al4V sintered porous-surfaced implants coated with HA sol-gel coated and hydrothermal treated would accelerate osseointegration. Materials and Methods : Porous implants which were made by electric discharge were used in this study. Implants were anodized and hydrothermal treatment or HA sol-gel coating was performed. Hydrothermal treatment was conducted by high pressure steam at $300^{\circ}C$ for 2 hours using a autoclave. To make a HA sol, triethyl phosphite and calcium nitrate were diluted and dissolved in anhydrous ethanol and mixed. Then anodized implant were spin-coated with the prepared HA sols and heat treated. Samples were soaked in the Hanks solution with pH 7.4 at $37^{\circ}C$ for 6 weeks. The microstructure of the specimens was observed with a scanning electron microscope (SEM), and the composition of the surface layer was analyzed with an energy dispersive spectroscope (EDS). Results : The scanning electron micrographs of HA sol-gel coated and hydrothermal treated surface did not show any significant change in the size or shape of the pores. After immersion in Hanks' solution the precipitated HA crystals covered macro- and micro-pores The precipitated Ca and P increased in Hanks' solution that surface treatment caused increased activity. Conclusion : This study shows that sol-gel coated HA and hydrothermal treatment significantly enhance the rate of HA formation due to the altered surface chemistry.

• Carbon letters
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• v.3 no.1
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• pp.1-5
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• 2002

The regional bio-wastes available in abundance in India were converted into porous carbon by heat treatment at different temperatures from $650-950^{\circ}C$. The wood retain shapes after pyrolysis though shrinkage occured both in axial and radial directions. The shrinkage in radial direction was found to be more than in axial direction in all woods. The density of woods and chars from these at a given temperature has been found to follow linear relationship. Chars were steam activated at temperature $700-800^{\circ}C$ for different times between 45-240 min. Both the temperature and time of activation with steam has a profound effect on surface area. Chars from softwoods like bagasse and castor oil plant were activated at lower temperature, i.e. $700-750^{\circ}C$ whereas hard wood chars have to be activated at higher temperature around $800^{\circ}C$. The morphology of wood as well as of chars has been studied by SEM. The comparison of the two showed that the nature of porosity in chars depends on precursor morphology, nature and physical state of wood and presence of inorganic compounds in the wood. Hard wood results in cross inter connected pores while softwood leads to fibriller structure. The present studies show that activated carbon with reasonably good surface area (${\sim}1000m^2/gm$) can be prepared from soft wood bio-wastes like bagasse and castor oil plant, while surface area ${\sim}1370m^2/gm$ was achieved from hard wood bio waste of pine wood.

• Journal of Biomedical and Translational Research
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• v.19 no.4
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• pp.103-109
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• 2018

Aspergillus luchuensis 34-1 was inoculated into wheat pellets with different conditions of raw materials to produce nuruk. The degree of substrate reactivity improvement of steam treated raw materials compared with that of non-heat treated was analyzed. The water content of the pellet was adjusted to 25% and 35%, and steam treatment for 10 minutes improved the substrate reactivity at 2.1-fold and 3.1-fold, and sterilization was also possible. The characteristics of improvement pellet nuruk were investigated according to the degree of crushing and water content of raw materials according to the temperatures and humidities ($23^{\circ}C$, $30^{\circ}C$ and RH 60%, RH 80%). The pH of the pellet nuruk was higher depending on the temperature, humidity and moisture content of the koji were lower, and the pH of the flour-pellet nuruk was lower than that of 2 mm milling wheat-pellet nuruk according to milling degree. It can be seen that the milling degree affects the growth of mold. The acidity and amino acid were generally higher as fermentation time increased. Also, the higher the incubation temperature, humidity and moisture content, the higher the value. Glucoamylase activity was significantly the highest in moisture content 35% D2b nuruk, cultured at $30^{\circ}C$ and 80% RH for 38 hours. This is higher than the previous reports on glucoamylase of rice-koji or commercial nuruk using fungi isolated from traditional nuruk. From these study, it is expected that making of improvement pellet nuruk would save the fermentation time considerably compared with traditional nuruks.