• Journal of the Korean Society of Industry Convergence
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• v.24 no.3
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• pp.261-269
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• 2021

This study was evaluated the elastic wave properties according to tension of Incoloy 825 alloy with different solution treatment temperature and aging time. Solution treatment was carried out at 700, 800, 900, and 1000 ℃ for 1 hour, and aging was carried out at 700 ℃ for 1, 5, 10, and 30 hours. As the solution treatment temperature increased, the tensile strength decreased and the elongation increased. However, as the aging time increased, the tensile strength increased and the elongation decreased. The dominant frequency decreased as the solution treatment temperature increased, but increased as the aging time increased. The dominant frequency according to the solution treatment and aging time increased as the tensile strength increased, but increased despite the decrease in elongation.

• Journal of the Korean Society for Heat Treatment
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• v.15 no.1
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• pp.21-24
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• 2002

The electrode materials for welding machine in automobile industry such as Cu-Cr, Cu-Zr and Cu-$Al_2O_3$ require the high electrical conductivity and the proper hardness. Therefore the effects of solution heat treatment and aging treatment on the electrical conductivity and hardness of Cu-0.8wt%Cr and Cu-1.2wt%Cr alloys have been investigated. Cu-0.8wt%Cr alloy showed the higher electrical conductivity and hardness than Cu-1.2wt%Cr alloy and both alloys showed the better electrical conductivity at $930^{\circ}C$ among 930, 980 and $1030^{\circ}C$ solution heat treatment temperatures. The electrical conductivity and hardness in both alloys were not affected by aging treatment but remarkably affected by solution heat treatment temperature. The final drawing process reduced electrical conductivity and increased hardness more in Cu-1.2wt%Cr alloy.

• Journal of the Korean Ceramic Society
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• v.48 no.4
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• pp.263-268
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• 2011

ZnO hexagonal rods grown in aqueous solution can be changed into a tubular shape by two-step aging in the course of the growing process. In the first step, hexagonal ZnO rods is grown by aging at $90^{\circ}C$ under a highly supersaturated aqueous solution giving rise to a fast precipitation rate. Meanwhile, during the second step aging at $60^{\circ}C$ in the same aqueous solution, the hexagonal polar face (001) having higher surface energy than (010) side planes dissolves to minimize surface energy. Hence the flat (001) face changes to a craterlike face and the hexagonal rod length of ZnO decreases at an initial-stage of this step aging. The formation of the (101) wedge-type faces is ascribed to the resultant of competitive reactions between the dissolution of polar face minimizing the surface energy which is a dominant reaction at the initial stage and the precipitation reaction dissipating supersaturation. At a later stage of the second-step the reaction rates of these two processes in the aqueous solution become similar and the overall reaction is terminated.

• Journal of the Korean Society of Food Science and Nutrition
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• v.24 no.4
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• pp.606-612
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• 1995

Three different Oyijangachi(Kochujang, Doenjang and Ganjang) have been prepared by traditional method. Cucumbers have been dipped in six different solutions for 48 hrs. After dipping, the cucumbers have been aged in Kochujang, Doenjang and Ganjang for 30 days. The acidity, pH, salt content and sensory evaluation of the cucumbers which were treated by six different solutions has measured. Moisture content of fresh cucumber was 95%, and the moisture content of Kochujang, Doenjang and Ganjang of Oyijangachi was 66.78%, 76.94% and 81.33%, respectively, after 30 days of aging. Protein content fo Kochujang, Doenjang and Ganjang of Oyijangachi increased 57%, 258% and 197%, respectively, after 30 days of aging when they compared with fresh cucumber(control). Initial acidity of Oyijangachi of cucumbers which were treated with solution 1~5 at 0 day were between 0.49 and 0.56 and increased during aging. Initial acidity of Oyijangachi treated with solution 6 was 1.84 which was low because 1% of acetic acid was added and acidity increased during aging. The pH of Kochujang, Doenjang, and Ganjang of Oyijangachi decreased 4.37, 3.98 and 4.61, respectively, after 30 days aging. Salt content of Oyijangachi dipped in various salt solutions increased as the salt content of the solution increased. Salt content of three Oyijangachi increased drastically during 0~5 days of aging and slowly increase between 5~30 days of aging. The taste and smell of Kochujang Oyijangachi were highest as treated wih 12% NaCl solution(treatment 4) and the color was highest when the Oyijangachi was treated with solution 1. The taste, smell and color of Doenjang Oyijangachi were highest as treated with 12% NaCl solution plus CaCl2(treatment 5). It was observed that the firmness of Oyijangachi was generally higher as the cucumber treated.

• Journal of the Korean Society for Heat Treatment
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• v.30 no.3
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• pp.99-105
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• 2017

This study was carried out to investigate the effect of heat treatment on the microstructure and mechanical properties in 90% hot forged Incoloy 825 alloy. With increasing solution treatment temperature, the grain size increased and the volume fraction of total precipitates decreased, and the precipitates disappeared at $1,000^{\circ}C$. With increasing aging time at $700^{\circ}C$, the volume fraction of precipitate increased and the precipitates size increased. Most of the precipitates consist $Cr_{23}C_6$ carbide, and a small amount of TiC carbide was also observed. With decreasing solution treatment temperature and increasing aging time, tensile strength and hardness increased, and the elongation and impact value decreased. With increasing aging time, the impact value decreased sharply by the increased of the precipitate size.

• Journal of the Korean Society for Heat Treatment
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• v.15 no.2
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• pp.70-75
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• 2002

The depletion of solid solution elements from matrix and the change of carbides during artificial aging of 2.25CrMo steel at $630^{\circ}C$ were investigated. The Mo and Cr elements were found to be depleted drastically in the early stage of aging. The change of carbides was confirmed by analyzing the XRD patterns of electrolytically extracted carbides. Four type of carbides, $M_{23}C_6$, $M_3C$, $M_2C$ and $M_6C$, were found to exist in the specimen before aging. The amount of $M_6C$ carbides increased with aging time, while that of $M_3C$ carbides diminished after short aging time.

• Journal of Welding and Joining
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• v.11 no.2
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• pp.53-61
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• 1993

One of the most interesting and promising steel groups considered for the rocket motor case, aircraft and aerospace component is the maraging(martensitic plus aging) nickel steel, developed by International Nickel Company in 1960. This material attains a very high strength with good fracture toughness by simple heat treatments which do not involve a quenching. Full strength can be obtained by "maraging" at 480.deg. for 3 hours for the 18% Ni maraging steel. The effect of heat treatments was considered on the residual stress field of 18% Ni maraging steel weldments. In experiments, various heat treatments such as stress relieve heat treatment, aging and solution heat treatment were carried out of the GTA weldments and the residual stresses were measured by using the hole drilling method. Whereas the conventional pattern of residual stress shows the stresses to be maximum along the weld centerline with tensile stress extending into the heat affected zone, the pattern in maraging steels shows the centerline stress to be compressive. After welding, a series of aging, solution heat treatment and solution heat treatment plus aging treatment were carried out and the residual stresses were measured to reveal that these heat treatments almost completely remove the welding residual stresses.

• Journal of Acupuncture Research
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• v.18 no.1
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• pp.146-156
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• 2001

Objectrve : To research the trends of the study related to aging process, and to establish the direction of the study on aging process. Method : We reviewed the journal and essay about the aging process which are published as well in Korea as in foreign country. Results : 1. The study on the Oriental Medicine field can be classfied with the fourth. first, the study of single herb medication's effect on the aging process. second, the study of multiple herb medication's effect on the aging process. third, the study of herb-acupuncture solution's effect on the aging process. fourth, journal review. We find the fact that the study on the Oriental Medicine is concerned with pathology of deficiency syndrome of the kidneys, retention of phlegm and fluid, blood stasis. 2. On the Western Medicine field, mechanism and pathology of aging pracess primarily has been studied. The mechanism of aging process is classified with 'Wear and tear theory' and 'Genome-based theory'. Among the mechanism of aging process, 'Free radical theory' is the most important. Additionally 'Senescence-Accelerated Mouse' has been studied. 3. We review the journal published in foreign country and its subject was the following: first, moxibustion combined with acu-area skin allograft therapy for the aging was effective, second, the traditional chinese medicine bu-zhong-yi-qi-tang in mice have anti-aging effect. third, the overview Preventive geriatrics of Traditional chinese medicine. 4. We researched anti-aging effect study in the journal of the Korean Acupuncture and Moxibustion, and we found a few journal of Herb-acupuncture solution's anti-aging effect. Hereafter, it is necessory that we will study about relationship between acupuncture-moxibustion therpy and anti-aging effect using Senescence-Accelerated Mouse.

• The Journal of Korean Academy of Prosthodontics
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• v.40 no.3
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• pp.225-235
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• 2002

The color stability of current prosthetic composites is unknown, even though the quality of composite materials has been improving. This study examined the intrinsic color stability of various current prosthetic resins (ceramic-polymers) after an accelerated aging process and the extrinsic color stability after immersion in a coffee solution. By comparing the amount of discoloration after aging with that without aging, the effect of the accelerated aging process on external discoloration could be evaluated. Three current prosthetic composites (Artglass, Targis, Sculpture), one light polymerized direct composite (Z100) and one dental porcelain control (Ceramco) were assessed. The color changes (${\Delta}$E) of all the specimens were determined using the CIE $L^{*}a^{*}b^{*}$ color order system with a reflected spectrophotometer. The results were as follows: 1. The prosthetic composite materials subjected to the accelerated aging test showed no significant difference in color changes (p >.05). 2. In the coffee solution immersion test after the aging process, the color changes of the Targis and Artglass groups were not different from that of the Z100 group, which showed the highest color change. 3. In the immersion only test, a significantly high color change was observed in the sculpture glazing group. 4. The aging process influenced on the color changes more in the Targis, Artglass and Z100 groups than in the Sculpture and Ceramco groups.

• Journal of Electrochemical Science and Technology
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• v.7 no.1
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• pp.27-32
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• 2016

Although the time dependences of the electrocatalytic activities of Pt and Pd nanoparticles during electrochemical operations have been widely studied, the time dependences under nonpolarized conditions have never been investigated in depth. This study reports the changes in the electrocatalytic activities of Pt and Pd nanoparticles with aging in air and in solution. Pt (or Pd) nanoparticle-modified electrodes are obtained by adsorbing citrate-stabilized Pt (or Pd) nanoparticles on amine-modified indium-tin oxide (ITO) electrodes, or by electrodeposition of Pt (or Pd) nanoparticles on ITO electrodes. The electrocatalytic activities of freshly prepared Pt and Pd nanoparticles in the oxygen reduction reaction slowly decrease with aging. The electrocatalytic activities decrease more slowly in solution than in air. An increase in surface contamination may cause electrocatalytic deactivation during aging. The electrocatalytic activities of long-aged Pt (or Pd) nanoparticles are significantly enhanced and recovered by NaBH₄ treatment.