• 한국전기전자재료학회논문지
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• 제17권2호
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• pp.138-143
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• 2004

CMP (Chemical Mechanical Polishing) technology for global planarization of multilevel interconnection structure has been widely studied for the next generation devices. Among the consumables for CMP process, especially, slurry and their chemical compositions play a very important role in the removal rates and within-wafer non-uniformity (WIWNU) for global planarization ability of CMP process. However, CMP slurries contain abrasive particles exceeding 1 ${\mu}{\textrm}{m}$ size, which can cause micro-scratch on the wafer surface after CMP process. Such a large size particle in these slurries may be caused by particle agglomeration in slurry supply-line. In this work, to investigate the effects of agglomeration on the performance of oxide CMP slurry, we have studied an aging effect of silica slurry as a function of particle size distribution and aging time during one month. We Prepared and compared the self-developed silica slurry by adding of alumina powders. Also, we have investigated the oxide CMP characteristics. As an experimental result, we could be obtained the relatively stable slurry characteristics comparable to aging effect of original silica slurry. Consequently, we can expect the saving of high-cost slurry.

• 한국세라믹학회지
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• 제43권9호
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• pp.575-581
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• 2006

To precipitate the complex gel of flux and aluminum hydroxides gel, aqueous solution of the mixture of $Na_2CO_3\;and\;Na_2PO_4{\cdot}12H_2O$ was added with stirring in aqueous solution of the mixture of $Al_2(SO_4)_3{\cdot}14{\sim}18H_2O,\;Na_2SO_4$, and then the complex gel was aged in $0{\sim}30h\;at\;90^{\circ}C$. As aging time passed, the aluminum hydroxides was grown into the acicular AlO(OH) gel. Also, aging time had an effect on physical properties of the AlO(OH) gel and on crystal growth of the flaky ${\alpha}-Al_2O_3$ prepared by molten-salt precipitation. In this study, the complex gel was crystallized in temperature range of $400{\sim}1,200^{\circ}C$ after drying at $110^{\circ}C$, and then it was investigated to effect of aging time on precipitation temperature, size, thickness, morphology and particle size distribution of the flaky ${\alpha}-Al_2O_3$ crystal. As aging time passed, the flaky a${\alpha}-Al_2O_3$ crystal showed a tendency toward an increase in size and thickness as result from an increase in BET surface area and pore volume of the acicular AlO(OH) gel.

• Elastomers and Composites
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• 제54권4호
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• pp.351-358
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• 2019

To evaluate the aging of a rubber pad in power window switch which is the part of a vehicle, the accelerated thermal aging test of rubber pad material is performed. Finite element analysis was performed using the nonlinear material constants of the rubber pad to calculate the operating force, and the Arrhenius relationship was derived from the aging temperature and time. The aging test was performed at 150, 180, 210, or 240 ℃ for 1 to 60 days. When the operating force of the rubber pad is changed by 10% from the initial value, the service life is expected to be 113 years, which is much longer than the life of the vehicle. This indicates that the aging life of the rubber pad is sufficiently safe and the operating force of the rubber pad during the life of the vehicle (20 years) was decreased by approximately 8.4%. By examining the correlation between the shear elastic modulus and operating force calculated from finite element analysis under each aging test condition, the changes in the operating force of the rubber pad and the shear elastic modulus showed good linear relationship. The aging life could be predicted by the change in shear elastic modulus and a process for predicting the aging life of automotive power window switch rubber pad parts is described herein.

• 한국노년학
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• 제38권3호
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• pp.521-536
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• 2018

본 연구는 노인의 노화에 대한 태도가 이들의 삶의 만족에 미치는 영향을 확인하고, 이를 매개하는 요인으로써 부모-자녀 간의 결속감의 역할을 확인하는 것을 목적으로 한다. 이를 위하여 전국의 노인 2,067명을 대상으로 설문조사를 진행하였고, SPSS macro PROCESS v.2.16을 활용하여 다중매개효과를 검증한 결과는 다음과 같다. 첫째, 노인의 노화에 대한 태도는 삶의 만족에 유의미한 영향을 미치고 있었다. 둘째, 노인의 노화태도는 부모-자녀 간의 결속감의 다섯가지 하위차원에 있어 모두 유의미한 영향을 미치고 있었다. 특히 노화에 대하여 부정적인 태도를 가질수록 부모-자녀 간의 결속이 더욱 높아지는 결과를 보이고 있었다. 셋째, 부모-자녀 간 결속의 하위차원들 중 애정적 일치적 기능적 결속이 노인의 노화태도와 삶의 만족간의 관계를 매개하는 것으로 나타났으며, 이 중 애정적 결속이 가장 큰 효과를 보이는 것으로 나타났다. 이상의 결과를 바탕으로 노인의 삶의 만족을 위한 실천적 개입방안을 제안하였다.

• 콘크리트학회논문집
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• 제14권2호
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• pp.148-155
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• 2002

본 연구는 폐지섬유보강 시멘트복합체의 수분 민감성 및 열화특성에 대하여 연구하였다. 폐지섬유는 건조공정에 의해 생산되었으며 슬러리-탈수 공법을 사용하여 폐지섬유보강 시멘트복합체를 제조하였다. 폐지섬유보강 시멘트복합체의 수분 민감성 덴 열화특성을 알아보기 위하여 수분민감성, 건조-습윤반복, 동결융해, 장기 오븐 건조의 영향을 실험실에서 촉진시험을 통하여 실시하였다. 폐지섬유보강 시멘트복합체에 대한 수분영향 및 열화에 대한 시험결과는 순수목질섬유보강 시멘트복합체와 통계적으로 비교 분석하였다 시험결과 폐지섬유보강 시멘트복합체는 수분노출 덴 장기 열화상태에서도 적절한 성능을 갖는 것으로 나타났다.

• 대한기계학회논문집A
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• 제30권10호
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• pp.1173-1178
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• 2006

In a primary reactor cooling system(RCS), a dissimilar weld zone exists between cast stainless steel(CF8M) in a pipe and low-alloy steel(SA508 cl.3) in a nozzle. Thermal aging is observed in CF8M as the RCS is exposed for a long period of time to a reactor operating temperature between 290 and $330^{\circ}C$, while no effect is observed in SA508 cl.3. The specimens are prepared by an artificially accelerated aging technique maintained for 300, 1800 and 3600 hrs at $430^{\circ}C$, respectively. The specimens for elastic-plastic fracture toughness tests are according to the process in the thermal notch is created in the heat affected zone(HAZ) of CF8M and deposited zone. From the experiments, the $J_{IC}$ value notched in HAZ of CF8M presented a rapid decrease up to 300 hours at $430^{\circ}C$ and slowly decreased according to the process in the thermal aging time. Also, the $J_{IC}$ value presented a lower value than that of the CF8M base metal. And, the $J_{IC}$ of the deposited zone presented the lowest value of all other cases.

• Journal of Microbiology and Biotechnology
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• 제27권2호
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• pp.365-371
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• 2017

Hydrogen has potential for preventive and therapeutic applications as an antioxidant. However, micro- and macroparticles of hydrogen in water disappear easily over time. In order to eliminate reactive oxygen species (ROS) related with the aging process, we used functional water containing nanoparticle hydrogen. Nanoparticle hydrogen does not disappear easily and collapse under water after long periods of time. We used murine embryonic fibroblasts that were isolated from 12.5-day embryos of C57BL/6 mice. We investigated the ability of nanoparticle hydrogen in water to suppress hydroxyurea-induced ROS production, cytotoxicity, and the accumulation of ${\beta}-galactosidase$ (an indicator of aging), and promote cell proliferation. The accumulation of ${\beta}-galactosidase$ in the cytoplasm and the appearance of abnormal nuclei were inhibited by daily treatment of cells with hydrogen water. When the aging process was accelerated by hydroxyurea-induced oxidative stress, the effect of hydrogen water was even more remarkable. Thus, this study showed the antioxidant and anti-senescence effects of hydrogen water. Nanoparticle hydrogen water is potentially a potent anti-aging agent.

• 한국기계기술학회지
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• 제20권6호
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• pp.818-823
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• 2018

In this study, the effect of pre-aging treatment for inhibition of natural aging of Al-4.8Zn-1.3Mg alloy by extrusion process was investigated. Firstly, the as-cast microstructure of Al-4.8Zn-1.3Mg alloy billet and its evolution during homogenization($460^{\circ}C$, $4h+510^{\circ}C$, 5h) were investigated by means of optical microscopy (OM), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), hardness analysis. The as-cast microstructures of Al-4.8Zn-1.3Mg alloy reveal $Mg_2Zn$, $Al_5Cu$, $Al_{13}Cu$ formed between dendrities. After homogenization, MgZn, $Al_4Cu$, $Al_{13}Cu$ phases precipitated into the matrix. In addition, standard deviation of homogenized billet was improved than as-cast billet from 2.62 to 0.99. According to pre-aging($100^{\circ}C$, 1h) Al-4.8Zn-1.3Mg alloy by extrusion process, yield strength and tensile strength deviation improved more than condition by natural aging.

• 대한금속재료학회지
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• 제49권1호
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• pp.9-16
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• 2011

To develop a 6061 aluminum alloy with low residual stress and high tensile strength, a cryogenic treatment process was investigated. Compared to the conventional heat treatment process for precipitation hardening with artificial aging, the cryogenic treatment process has two additional steps. The first step is cryogenic quenching of the sample into liquid nitrogen, the second step is up-hill quenching of the sample into boiling water. The residual stress for the sample was measured by the $sin^2{\psi}$ method with X-ray diffraction. The 6061 aluminum alloy sample showed 67% relief in stress at the cryogenic treatment process with artificial aging at $175^{\circ}C$. From this study, it was found that the optimum cryogenic treatment process for a sample with low residual stress and high tensile strength is relatively low cooling speed in the cryogenic quenching step and a very high heating speed in the up-hill quenching step.

• 한국콘텐츠학회논문지
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• 제18권7호
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• pp.194-206
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• 2018

본 연구는 장애인구의 고령화에 따라 장애노인의 성공적 노화에 영향을 미치는 요인을 분석하는 것을 목적으로 하였다. 이를 위해 장애노인의 성공적 노화 가능성을 심리사회적 측면에서 개념 정의하여 장애노인의 성공적 노화에 대한 정서 사회적 노후준비의 영향과 사회적 지지의 매개효과를 검증하였다. 본 연구의 대상은 국민노후보장패널(Korean Retirement and Income Study: KReIS) 4차 본조사와 3, 4차 부가조사 자료로부터 추출한 50세 이상의 장애노인 506명이다. 자료 분석을 위해서는 SPSS 23.0과 SPSS PROCESS macro v2.16을 활용하였다. 연구결과는 다음과 같다. 첫째, 정서 사회적 노후준비는 장애노인의 성공적 노화에 유의미하게 직접 영향을 미치는 것으로 나타났다. 둘째, 정서 사회적 노후준비는 사회적 지지를 통해 장애노인의 성공적 노화에 간접적으로 영향을 미친다고 할 수 있어 정서 사회적 노후준비와 성공적 노화 간 사회적 지지의 매개효과가 입증되었다. 이러한 연구결과를 바탕으로 정서 사회적 노후준비와 사회적 지지 제고를 위한 사회복지 정책 및 실천적 방안을 제언하였다.