• Metals and materials international
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• v.24 no.6
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• pp.1221-1231
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• 2018

The effect of strain aging on tensile behavior and properties of API X60, X70, and X80 pipeline steels was investigated in this study. The API X60, X70, and X80 pipeline steels were fabricated by varying alloying elements and thermomechanical processing conditions. Although all the steels exhibited complex microstructure consisting of polygonal ferrite (PF), acicular ferrite, granular bainite (GB), bainitic ferrite (BF), and secondary phases, they had different fractions of microstructures depending on the alloying elements and thermomechanical processing conditions. The tensile test results revealed that yielding behavior steadily changed from continuous-type to discontinuous-type as aging temperature increases after 1% pre-strain. After pre-strain and thermal aging treatment in all the steels, the yield and tensile strengths, and yield ratio were increased, while the uniform elongation and work hardening exponent were decreased. In the case of the X80 steel, particularly, the decrease in uniform elongation was relatively small due to many mobile dislocations in PF, and the increase in yield ratio was the lowest because a large amount of harder microstructures such as GB, BF, and coarse secondary phases effectively enhanced work hardening.

• Journal of the Korean Society for Heat Treatment
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• v.7 no.4
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• pp.270-276
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• 1994

The effects of thermomechanical and duplex aging treatment on precipitation behavior were investigated for the 8090 aluminium alloy by tensile test, hardness test, plane-strain fracture toughness test and electron microscope. Both pre-aging stretch and duplex aging with pre-aging stretch were effective to homogenize the distribution of S' phase in this alloys. The latter makes more homogeneous distribution of S' phase than that of the former, but the sizes of S' phase in both specimens are almost same. The size and distribution of 0' phase were not changed by thermomechanical or duplex aging treatment. The strength was increased by thermomechanical treatment, but the elongation was decreased. Duplex aging treatment couldn't change the strength and elongation. Pre-aging stretch and duplex aging with pre-aging stretch have same effect on the strength and elongation. The increase of strength by thermomechanical treatment in 8090 alumunium alloy was caused by homogeneously precipitated S' phase.

• Proceedings of the Korean Geotechical Society Conference
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• 2005.03a
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• pp.916-923
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• 2005

In this study, to observe aging effect of undrained shear behavior for Nak-Dong River sand, undrained static and cyclic triaxial tests were performed with changing relative density ($D_r$), consolidation stress ratio($K_c$) and consolidation time. As a result of the test, the modulus of elasticity to all samples estimated within elastic zone by the micro strain of about 0.05% in case of static shear behavior increased with the lapse of consolidation time significantly, so aging effect was shown largely. Also strength of phase transformation point(S_{PT}$) and strength of critical stress ratio point($S_{CSR}$) increased with the lapse of consolidation time. Undrained cyclic shear strength($R_f$) obtained from the failure strain 5% increased in proportion to relative density($D_r$) and initial static shear stress($q_{st}$), $R_f$ of consolidated sample for 1,000 minutes increased about 10.6% compared to that for 10 minutes at the loose sand, and $R_f$ increased about 7.0% at the medium sand. In situ application range of $R_f$ to the magnitude of earthquake for Nak-Dong River sand was proposed by using a increasing rate of $R_f$ as being aging effect shown from this test result.

• Journal of the Korean Ceramic Society
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• v.46 no.2
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• pp.219-223
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• 2009

Effects of MgO or $R_2O_3$(R:Dy, Ho, Yb) on the capacitance aging behavior of multilayer ceramic capacitors (MLCCs) based on $BaTiO_3$ dielectrics under DC electrical fields has been studied. At a DC field of 1 $V{/\mu}m$, the capacitance of MLCC specimens dropped immediately in a very short period (<10 s, the first stage) and then decreased continuously with time (the second stage). Mn doping significantly increased the aging rate in the second stage. The addition of MgO or $R_2O_3$ notably decreased the second stage aging rate of Mn-doped specimens. Yb doping gives rise to the lowest aging rate in the second stage, which is due to the larger population of defect dipoles associated with oxygen vacancies.

• Journal of Digital Convergence
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• v.17 no.11
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• pp.339-347
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• 2019

The purpose of this study was to identify the influence of social support and health promotion behavior on aging anxiety among middle aged women. The sample for this study consisted of 160 women aged 40 to 60 living in C city in Korea. Data were analyzed by descriptive statistics, t-test, One-way ANOVA, Pearson correlation and stepwise multiple regression with SPSS/WIN 23.0. It was found that: (a) aging anxiety had a negative correlation with health promoting behavior(r=-.614, <.001), spousal support(r=-.411, <.001), whereas health promotion behavior had a positive correlation with spousal support(r=.429, <.001) (b) Factors influencing aging anxiety were identified as following; nutrition, stress management, menopause, spousal support with 44.7% explanatory power. In this study, it was found that nutrition, stress management, spouse support, and menopause awareness among middle-aged women lowered aging anxiety. Further research is needed to develop programs that include these variables and to verify their effects.

• Transactions on Electrical and Electronic Materials
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• v.11 no.5
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• pp.216-221
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• 2010

The microstructure, electrical properties, and DC-accelerated aging behavior of the Zn-Pr-Co-Cr-Y-Er (ZPCC-YE) varistors were investigated for different amounts of erbium oxide ($Er_2O_3$). The microstructure consisted of zinc oxide grain and an intergranular layer ($Pr_6O_{11}$, $Y_2O_3$, and $Er_2O_3$-rich phase) as a secondary phase. The increase of $Er_2O_3$ amount decreased the average grain size and increased the sintered density. As the $Er_2O_3$ amount increased, the breakdown field increased from 5094 V/cm to 6966 V/cm and the nonlinear coefficient increased from 27.8 to 45.1. The ZPCC-YE varistors added with 0.5 to 1.0 mol% $Er_2O_3$ are appropriate for high voltage, with high nonlinearity and stability against DC-accelerated aging stress.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.43 no.3
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• pp.73-79
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• 2011

The annals of Joseon Dynasty is one of the UNESCO's Memory of the World Register. For the safety preservation of wax applied volumes of the annals of Joseon Dynasty, the aging behavior of beeswax and beeswaxed Hanji with $CO_2$, $O_3$, $SO_2$ and $NO_2$ gas has been evaluated. The weight loss of beeswaxed Hanji after aging under ozone gas were increased because of strong acidity of ozone. The acid value and relative intensity of carbonyl groups in beeswax were stabilized with aging time. The physical strength of dewaxed Hanji after ozone aging were rapidly decreased by aging time. The crystallinity of dewaxed Hanji were stabilized at all aging times.

• Journal of the Korean Geotechnical Society
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• v.20 no.6
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• pp.137-150
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• 2004

Aging effect of sands showed insignificant result in comparison with that of clay, so that it has not been studied so far. But, as penetration resistance increase has been observed with the lapse of time after deposition and disturbance, aging effect of sands has been actively investigated by field tests, and recently many researchers are performing not oかy field tests but also laboratory tests on sands, so aging effects of sands have been also examined by laboratory tests. In this study, to observe the aging effect of undrained static shear behavior for Nak-Dong River sand, undrained static triaxial tests were performed with changing relative density$(D_r)$, consolidation stress ratio$(K_c)$, and consolidation time. These tests showed that modulus within elastic section increased as consolidation time increased, and in addition, phase transformation point strength$(S_{PT})$ and critical stress ratio point strength $(S_{CSR})$ also increased. But pore water pressure ratio$(u/{p_c}')$ decreased as consolidation time increased, so with this various result, aging effect of static shear for sands can be observed as well.

• Journal of the Korean Society of Industry Convergence
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• v.24 no.1
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• pp.9-17
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• 2021

This aim of this study examined the relationship among the interest in anti-aging, health promotion behaviors and the need for anti-aging services by their 20s. Survey was conducted among adults from their 20s in the Changwon City. 228 responses were used for analysis. The overall average score of the interest and effort of anti-aging were 2.97 point and 2.62 point (out of 5), respectively. And those were both higher in female than men (p<0.01~p<0.001). The overall average score of need for anti-aging service was 3.50 point(total score is 5). In The demand for each area of anti-aging service were ≥3.5 point in all 5 areas, and stress management (4.00 point) was the highest, while the beauty management (3.60 point) was the lowest. There were significant differences in all five areas by sex (p<0.01~p<0.001). The overall score of the performance of health promotion behaviors was 2.44 point(total score is 4), and the interpersonal relationship score (2.85 point) was the highest, while the health responsibility score (2.08 point) was the lowest. The interest in anti-aging and performance of health promotion behaviors showed positive relationship to anti-aging services, and their explanation powers were 34.6% (p<0.001). The results of this study suggest be used as data to establish strategies revitalizing various anti-aging service in the twenties.

• 한국노년학
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• v.29 no.3
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• pp.899-915
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• 2009

The purpose of this study was examined effect of physical fitness and exercise participation on healthy aging of the elderly. The subjecrts were a total 319 people that they were participate in the regular exercise, and go to welfare center in Seoul. Data were collected during the period from November 1 to November 30, 2006. The collected data were analyzed frequency, descriptive statistics, correlation and hierarchical regression analysis using the SPSS-Win 12.0 program. The results of hierarchical regression analysis were appeared as follows. According to the results of hierarchical regression analysis, significant factors influencing healthy aging were monthly income, monthly pocket money, self-perceived health status, leg muscle strength, exercise behavior and period of exercise. 2. According to the results, significant factors influencing physiological health were age, marital status, self-perceived health status, exercise behavior and period of exercise. 3. According to the results, significant factors influencing cognitive-mental health were monthly income, monthly pocket money, self-perceived health status, leg muscle strength, exercise behavior and period of exercise. 4. According to the results, significant factors influencing social-support health were monthly income, age, education, self-perceived health status, leg muscle strength, exercise behavior and period of exercise. In conclusion, First, this questionnaire demonstrates good reliability and validity and therefore it is an appropriate measurement of healthy aging for the elderly in Korea. Second, it is important that exercise behavior is main factor to healthy aging life on the elderly. Third, There is important mean values of the items for healthy aging.