• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2008년도 추계학술대회 논문집
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• pp.203-206
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• 2008

Transformation of austenite to martensite during cold rolling has been widely used to strengthen metastable austenitic stainless steel grades. Aging treatment of cold worked metastable austenitic stainless steels, including ${\alpha}'$-martensite phase, results in the further increase of strength, when aging is performed in $200^{\circ}C$ to $450^{\circ}C$ temperature range. The purpose of the present study was to evaluate the effect of time and temperature on the stress-strain behavior of cold worked austenitic stainless steels. The amount of ${\alpha}'$-martensite during cold working and aging was examined by ferrite scope and X-ray diffraction (XRD). During aging at $450^{\circ}C$ for 1hr, tensile strength dramatically increased by 150MPa. Deformed metastable austenitic steels containing the "body-centered" ${\alpha}'$-martensite are strengthened by the diffusion of interstitial solute atoms during aging at low temperature.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2002년도 하계학술대회 논문집
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• pp.406-409
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• 2002

The primary insulation system used in an oil-filled transformer is Kraft paper, wood, porcelain and, of course, oil. Modern transformers use paper that is chemically treated to improve its tensile strength properties and resistance to aging caused by immersion in oil. These insulation papers are mainly aged to thermal stress. Over the course of the insulation paper and oil's life it is exposed to high temperatures, oxygen and water. Its interaction with the steel of the tank and core plus the copper and aluminium of the windings will eventually cause the chemical properties of the oil to decay. High temperature have an effect on mechanical strength of cellulous paper using the layer insulation. We made two aging cell in which thermal aging tests of insulation papers and mineral oil are conducted. It is measured dielectric strength, number of acid, moisture, etc. of insulation paper and oil aged in the aging cells.

• 대한안전경영과학회지
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• 제8권2호
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• pp.81-90
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• 2006

As aging society makes rapid progress, various social problems arise. The drop of productive labor and the increase of welfare cost can be taken as examples. From this point of view, a use of aged labor is a matter of great Important to national productivity improvement. But, the participation rate of the aged in economical activity amounts to 49.8 percent and their unemployment rate does 2.1 percent. The purpose of this paper is to analyze the deterioration of skill and the lowering of adaption to new working environments due to aging. Since the aging effect is closely related to worker's productivity, it should be properly measured and analyzed. The coordination tester is used to find out activity limitations. Experimental results show that the expert skill of the workers can be improved through the effective of their experience. Therefore we can say that some operation is not influenced by aging.

• 한국표면공학회지
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• 제50권5호
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• pp.380-385
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• 2017

Mechanical characteristics of the STS 304 which is heat resistance steel were investigated after artificial aging at $650^{\circ}C$ with 1,000 hours. Tensile test specimens and small test pieces were done artificial aging up to 1,000 hours in the high temperature atmospheric environment. The results present that as the aging time increased, tensile properties were deteriorated. In the case of failure mechanism, the configuration of the fractography presented drastic change from ductile to brittle with aging time. $M_{23}C_6$ carbide leading to the change of the mechanical properties and fracture mode of the aged STS 304 steel continuously precipitated along the grain boundaries of austenite microstructure.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2005년도 하계학술대회 논문집 Vol.6
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• pp.99-100
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• 2005

Reliability of the thyristor has a major effects on the high power systems such as HVDC, SVC and FACTs, etc. Therefore, analyzing method for thyristor aging is important to improve the stability of thyristor and high power systems. In this paper, we explain the analyzing method for examine the thyristor aging effect. And also, the thyristor aging experiments were performed to investigate the characteristic degradation due to the aging.

• Biomolecules & Therapeutics
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• 제19권2호
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• pp.224-230
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• 2011

In order to develop silk peptide (SP) preparations possessing cognition-enhancing effect, several candidates were screened through in vitro assays, and their effectiveness was investigated in facilitated brain aging model rats. Incubation of brain acetyl-cholinesterase with SP-PN (1-1,000 ${\mu}g/ml$) led to inhibition of the enzyme activity up to 35%, in contrast to a negligible effect of SP-NN. The expression of choline acetyltransferase (ChAT) mRNA of neural stem cells expressing ChAT gene (F3.ChAT) was increased by 24-hour treatment with 10 and 100 ${\mu}g/ml$ SP-NN (1.35 and 2.20 folds) and SP-PN (2.40 and 1.34 folds). Four-week subcutaneous injections with D-galactose (150 mg/kg) increased activated hippocampal astrocytes to 1.7 folds (a marker of brain injury and aging), decreased acetylcholine concentration in cerebrospinal fluid by 45-50%, and thereby impaired learning and memory function in passive avoidance and water-maze performances. Oral treatment with SP preparations (50 or 300 mg/kg) for 5 weeks from 1 week prior to D-galactose injection exerted recovering activities on acetylcholine depletion and brain injury/aging as well as cognitive deficit induced by D-galactose. The results indicate that SP preparations restore cognitive functions of facilitated brain aging model rats by increasing the release of acetylcholine, in addition to neuroprotective activity.

• 디지털융복합연구
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• 제16권1호
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• pp.93-101
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• 2018

본 연구에서는 한국 베이비붐 세대의 은퇴 후 준비 상태에 대해 이해하고 이들의 사회참여 태도가 성공적 노후에 미치는 영향에 대해 노후준비의 매개효과를 확인하여 이에 따른 대안을 제시하고자 하였다. 연구방법은 설문조사를 실시하였으며, 수집된 자료의 분석은 SPSS Win 23.0 프로그램을 이용하여 빈도분석, 기술통계분석, 상관분석, 위계적 다중회귀분석을 시행하였다. 연구 결과 첫째, 사회참여 태도는 성공적 노후에 영향을 미치는 것으로 나타났다. 둘째, 사회참여 태도는 노후준비에 영향을 미치는 것으로 나타났다. 셋째, 노후준비가 성공적 노후에 영향을 미치는 것으로 나타났다. 넷째, 사회참여 태도와 성공적 노후간의 관계에서 노후준비가 매개효과가 있는 것으로 나타났다. 마지막으로 본 연구의 의의와 제한점 및 추후 연구과제에 대해 논의하였다.

• 한국응용과학기술학회지
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• 제38권6호
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• pp.1616-1626
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• 2021

본 연구는 액티브 시니어 골프참여자를 대상으로 지각된 환경적요인과 주관적 건강 및 활동적 노화에는 어떠한 관계가 있는지 규명하는데 목적이 있다. 본 연구의 목적을 달성하기 위하여 SPSS(Statistical Package for the Social Sciences) 18.0과 AMOS(Analysis of Moment Structures) 18.0을 이용하여 빈도분석, 확인적 요인분석, 신뢰도분석과 상관관계분석을 실시하였고 모형을 설정한 뒤 구조방적식모형(Structural Equation Modeling)을 통하여 변인 간의 인과적 관계를 규명하였다. 이상과 같은 연구방법과 연구모형 검증을 기초로 하여 본 연구에서 도출된 결과는 다음과 같다. 첫째, 지각된 환경적요인은 활동적 노화에 정적인 영향을 미치는 것으로 나타났다. 둘째, 활동적 노화는 주관적 건강에 정적인 영향을 미치는 것으로 나타났다. 셋째, 지각된 환경적요인은 주관적 건강에 정적인 영향을 미치는 것으로 나타났다. 넷째, 지각된 환경적요인과 주관적 건강의 관계에서 활동적 노화는 매개하는 것으로 나타났다.

• 대한기계학회논문집A
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• 제32권5호
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• pp.444-450
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• 2008

The conventional studies of the aging effect on cardio-vascular system are mostly obtained from human experiences and can only provide local information. In this study, the effect of fatigue fracture of arterial wall on the blood pressure was investigated by hemodynamic analysis. The aging process was simulated with three stages. The pulse wave velocity increased with age. The systolic blood pressure increases consistently but diastolic blood pressure decreases with age. The simulated results show in good accordance with the clinical ones.

• 동력기계공학회지
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• 제18권3호
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• pp.14-19
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• 2014

The purpose of the study is to investigate the effect of additive catalyst according to the thermal aging of vanadia SCR catalysts. At a fresh condition, the $3V_2O_5-5WO_5-92TiO_2$ SCR showed the highest NOx conversion rate of about 30%, the performance of 5 kinds of SCR to which additive catalysts were added was not improved due to the insignificant effect of acid site control. For catalysts aged for 12h at $700^{\circ}C$, the SCR to which 3wt% Zeolite was added decreased in NOx conversion rate by 2.5% on average compared to the fresh SCR, it showed higher thermal durability than other additive catalyst. For 3Zeolite with high performance of NOx conversion rate during thermal aging, the Zeolite with stronger durability at a high temperature than other 5 kinds of SCR catalysts decreased the sintering of catalysts.