• Metals and materials international
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• 제24권6호
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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.

• 열처리공학회지
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• 제7권4호
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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.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2005년도 춘계 학술발표회 논문집
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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.

• 한국세라믹학회지
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• 제46권2호
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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.

• 디지털융복합연구
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• 제17권11호
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• pp.339-347
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• 2019

이 연구는 중년여성의 노화불안에 사회적지지, 건강증진행위가 어떠한 영향을 미치는지 확인하기 위해 시도되었다. 연구대상자는 C시에 거주하는 40세에서 60세까지의 중년여성 160명이었다. 자료는 SPSS 23.0으로 기술통계, t-test, One-way ANOVA, 상관관계, 회귀분석을 하였다. 연구결과 (a) 노화불안은 사회적 지지(r=-.411, p<.001), 건강증진행위(r=-.614, p〈.001)와 음의 상관이 있었고, 사회적 지지(r=.429, p<.001)와 건강증진행위는 양의 상관이 있었다. (b) 중년여성의 노화불안에 영향을 미치는 변수는 건강증진행위의 하부요인인 영양(${\beta}=-0.329$, p<.001)과 스트레스 관리(${\beta}=-0.325$, p<.001), 폐경상태(${\beta}=0.214$, p<.001), 배우자지지(${\beta}=-0.160$, p=.011)였으며 이들의 설명력은 44.7% 이었다(F=33.12, p<.001). 이 연구에서 중년여성의 영양과 스트레스 관리, 배우자지지, 폐경 인식은 노화불안을 낮추는 것을 확인할 수 있었다. 추후 이들 변수를 포함하는 프로그램 개발과 그 효과를 확인할 연구가 필요하다.

• Transactions on Electrical and Electronic Materials
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• 제11권5호
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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.

• 펄프종이기술
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• 제43권3호
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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.

• 한국지반공학회논문집
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• 제20권6호
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• pp.137-150
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• 2004

모래의 aging 현상은 점성토에 비하여 무시할 정도로 매우 작아서 최근까지 연구되지 않았다. 그러나 퇴적이나 교란 후 시간경과에 따라 관입저항치의 증가가 관찰되면서 현장시험을 중심으로 모래의 aging 효과에 대하여 활발한 조사가 이루어졌고, 최근에는 현장시험뿐만 아니라 실내시험에서도 여러 연구자들에 의해 모래의 aging 효과가 규명 되어지고 있다. 본 연구에서는 모래의 비배수 정적전단거동에 대한 aging 효과를 살펴보기 위해 낙동강 모래를 이용하여 상대밀도 $(D_r)$, 압밀응력비$(K_c)$ 그리고 압밀시간을 달리하여 비배수 정적삼축압축시험을 실시하였다. 그 결과 응력-변형률의 탄성구간내 탄성계수가 압밀시간 경과에 따라 증가하는 것으로 나타났으며, 또한 상전이점 강도$(S_{PT})$와 한계응력비점 강도$(S_{CSR})$도 압밀시간 경과에 따라 증가하였다. 그러나 간극수압비$(u/{p_c}')$는 압밀시간에 비례하게 감소하는 등 모래의 정적전단에서 나타나는 aging 효과를 관찰할 수 있었다.

• 한국산업융합학회 논문집
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• 제24권1호
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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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• 제29권3호
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• pp.899-915
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• 2009

본 연구의 목적은 체력과 운동참여가 노인들의 건강한 노후에 미치는 영향에 대해 조사한 것으로 연구대상은 서울시 복지관에 다니고 운동에 참여하는 65세 이상의 노인 350명(남 96명, 여 223명)을 대상으로 하였고, 총 319부의 설문지와 체력측정을 실제 분석 자료로 사용하였다. 조사기간은 2006년 11월 1부터 11월 30일까지 설문조사와 체력측정을 실시하였으며, 자료처리는 Window용 SPSS 통계 Package 12.0 Version을 이용하여 빈도분석, 기술통계, 상관관계, 위계적 회귀분석 방법을 실시하였다. 위계적 회귀분석 결과는 다음과 같이 나타났다. 첫째, 월수입, 한달용돈, 주관적 건강상태, 하체근력, 운동행태, 참여기간이 건강한 노후에 영향을 주는 요인으로 나타났다. 둘째, 건강한 노후의 하위요인인 신체적 건강에서는 나이, 결혼유지 상태, 주관적 건강, 운동 행태, 운동참여기간이 영향을 미치는 요인으로 나타났다. 셋째, 건강한 노후의 하위요인인 인지·정신적 건강에서는 월수입, 한달용돈, 주관적 건강상태, 하체근력, 운동행태, 운동참여기간이 영향을 미치는 요인으로 나타났다. 넷째, 건강한 노후의 하위요인인 사회적·지지 건강에서는 월수입, 나이, 학력, 운동행태, 운동참여기간이 영향을 미치는 요인으로 나타났다. 따라서 이상과 같은 결과를 통해 얻어낸 결론은 다음과 같다. 첫째, 본 연구의 결과를 통해 한국 노인들의 건강한 노후를 반영했다는 점에서 의의가 크다. 둘째, 통계적용을 통해 얻어낸 결과 중에 운동행태에 대한 요인이 건강한 노후를 유지하는데 중요한 요소라는 점을 부각시켜야 할 것이다. 셋째, 노인들의 건강한 노후의 문항 점수에 관한 기준값 제시에 의의가 있다.