• 제목, 요약, 키워드: Aging

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Influence of the Cure Systems on Long Time Thermal Aging Behaviors of NR Composites

  • Choi, Sung-Seen;Kim, Jong-Chul;Lee, Seung-Goo;Joo, Yong-L.
    • Macromolecular Research
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    • v.16 no.6
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    • pp.561-566
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    • 2008
  • NR composites with different curing systems were aged thermally at 60, 70, 80, and $90^{\circ}C$ for 2-185 days in a convection oven, and the changes in the crosslink density were investigated as a function of the accelerated thermal aging. The overall crosslink densities increased with increasing aging time irrespective of the aging temperatures and curing systems. The changes in crosslink density were enhanced by increasing the aging temperature. The degree of the increased crosslink density was in the following order: "the conventional cure system > the semi-EV system > the EV system". For short term thermal aging, the change in crosslink density with the aging time was complicated, particularly for low temperature aging. The activation energies of the change in crosslink density with thermal aging using the conventional and semi-EV cure systems increased and then remained relatively constant with increasing aging time, whereas that of the specimen with an EV cure system tended to increase linearly. The experimental results were explained by the dissociation of the existing polysulfidic linkages and the formation of new cross links through the crosslinking-related chemicals remaining in the sample.

『동의보감(東醫寶鑑)』에서 발굴한 항노화 효능을 가진 주방(酒方) 후보군에 대한 연구 (Anti-aging Joobang(酒方)s in Dongeuibogam : Identification of candidates by text mining)

  • 류정아;백진웅
    • 대한한의학원전학회지
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    • v.28 no.2
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    • pp.47-60
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    • 2015
  • Objectives : To investigate the anti-aging effects of Joobang(酒方) on Dongeuibogam Methods : We analyzed the effect of 27 Joobang(酒方)s on Dongeuibogam and finally extracted 11 Joobang(酒方)s, which have anti-aging effects. Results & Conclusions : 1. We finally selected 12 terms of Joobang(酒方)'s anti-aging effect on Dongeuibogam. 2. We finally selected 11 Joobang(酒方)s as anti-aging candidates. 3. Twelve terms of Joobang(酒方)'s anti-aging effect and 11 candidates with anti-aging effects were classified into five categories. 4. We finally selected 17 medicinal herbs from the 11 candidates. 5. Eleven candidate anti-aging Joobang(酒方)s and 17 medicinal herbs proposed in this study have the potential to reduce the time required for experimental and clinical research for developing novel compounds with anti-aging effects.

발전기 고정자 권선의 절연열화 메카니즘 분석 (Analysis of Insulation Aging Mechanism in Generator Stator Windings)

  • 김희동
    • 한국전기전자재료학회논문지
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    • v.15 no.2
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    • pp.119-126
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    • 2002
  • The mica/epoxy composite used in generator(rated 22 kV and 500 MW) stator windings was aged at 180$\^{C}$ for up to 1000 hours in air and hydrogen. The degradation mechanism was investigated through the defect of evolution and microstructural analysis by performing SEM(Scanning Electron Microscope). As the thermal aging time increases, the number of voids per unit volume increases at the mica/epoxy interface of generator stator windings. The aged specimens in hydrogen showed retarded generation and growth of voids. Accelerated aging tests were conducted using the combination of thermal and electrical aging in air and hydrogen. The aging was carried out at a combined stress such as thermal aging at 110$\^{C}$, electrical aging at 5.5 kV/mm and frequencies 420 Hz in air, and electrical aging at 5.5 kV/mm and frequencies 420 Hz in hydrogen (pressure 4 kg/㎠). Thermal and electrical aging generates large voids at the mica/epoxy interface in air. Electrical aging in hydrogen also generates small voids, delaminations and cracks in mica tapes.

PZT 세라믹스에 있어서 길이진동모드의 경시변화 (Aging of Length-Extensional Vibration Modes in PZT Ceramics)

  • 이개명;김병효;황충구;강찬호;현덕수
    • 한국전기전자재료학회논문지
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    • v.15 no.10
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    • pp.858-864
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    • 2002
  • Aging stabilities of the operating frequency of piezoelectric devices such as filter, oscillator and discriminator are very important. In this study it was studied aging stabilities of the length-extensional vibration mode of Pb(Zr$\^$y/O$_3$+ x[wt%]Cr$_2$Co$_3$ ceramics. PZT ceramics in morphotropic phase boundary have higher aging rates of k$\_$31/ and resonance frequency than those in tetragonal phase or rhombohedral phase. Thermal aging moves the composition with maximum aging rate to Zr-rich side in Cr$_2$O$_3$ not added PZT system. In the PZT system, aging rates of k$\_$31/ and resonance frequency for first 30 days are bigger than those for the following 90 days. Thermal aging decrease those for first 30 days. Aging rate of resonance frequency of the ceramics with x=0.1, y=0.53 and x=0.3, y=0.53 increased by thermal aging.

댄스중심의 신체활동에 참여하는 노인들의 성숙한 노화태도와 우울 및 성공적 노화의 관계: 라인댄스와 리듬체조 참여자를 중심으로 (Relationship among Matured Aging Attitude, Depression, and Successful Aging of Elderly Participating in Dance-Oriented Physical Activity: Focused on Line Dance and Rhythmic Gymnastics)

  • 신석환
    • 디지털융복합연구
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    • v.18 no.10
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    • pp.469-477
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    • 2020
  • 본 연구는 주요 목적 달성을 위해 라인댄스와 리듬체조 중심의 신체활동에 참여하고 있는 65세 이상 노인 202명을 대상으로 성숙한 노화태도, 우울 그리고 성공적 노화 설문지를 이용하여 연구를 진행하였다. 연구결과를 제시하면, 첫째, 신체활동 참여 노인들의 성숙한 노화태도가 높을수록 우울은 감소하였다. 둘째, 신체활동 참여 노인들이 성숙한 노화태도를 높게 인식할수록 성공적 노화도 높았다. 셋째, 신체활동 참여 노인들이 우울을 높게 지각할수록 성공적 노화는 낮아지는 것으로 나타났다. 이상의 결과에 근거하면, 노인들이 신체활동에 규칙적으로 참여할 수 있도록 독려하고, 우울에 대한 적극적인 중재를 통해 신체활동 참여노인들이 성공적 노화를 이룰 수 있도록 해야 할 것이다.

저온 플라즈마 침질탄화처리된 마르텐사이트계 석출경화형 스테인리스강의 내식성에 미치는 시효 전처리의 영향 (Effects of Pre-Aging Treatment on the Corrosion Resistance of Low Temperature Plasma Nitrocarburized AISI 630 Martensitic Precipitation Hardening Stainless Steel)

  • 이인섭;이천호
    • 한국표면공학회지
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    • v.53 no.2
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    • pp.43-52
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    • 2020
  • Various aging treatments were conducted on AISI 630 martensitic precipitation hardening stainless steel in order to optimize aging condition. Aging treatment was carried out in the vacuum chamber of Ar gas with changing aging temperature from 380℃ to 430℃ and aging time from 2h to 8h at 400℃. After obtaining the optimized aging condition, several nitrocarburizing treatments were done without and with the aging treatment. Nitrocarburizing was performed on the samples with a gas mixture of H2, N2 and CH4 for 15 h at vacuum pressure of 4.0 Torr and discharge voltage of 400V. The corrosion resistance was improved noticeably by combined process of aging and nitrocarburizing treatment, which is attributed to higher chromium and nitrogen content in the passive layer, as confirmed by XPS analysis. The optimized condition is finalized as, 4h aging at 400℃ and then subsequent nitrocarburizing at 400℃ with 25% nitrogen and 4% methane gas for 15h at vacuum pressure of 4.0 Torr and discharge voltage of 400V, resulting in the surface hardness of around 1300 HV0.05 and α'N layer thickness of around 11 ㎛ respectively.

항노화산업 활성화 방안에 관한 연구 (A Study on Strategies to Galvanize the Anti-aging Industry)

  • 정태영;고영곤;정혜주
    • 보건의료산업학회지
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    • v.10 no.2
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    • pp.145-154
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    • 2016
  • Objectives : Because people have increasingly more interest in their quality of life, the anti-aging industry has grown worldwide. The purpose of this study is to suggest strategies for galvanizing the anti-aging industry in Korea. Methods : To accomplish this aim, we explored the definition, classification, problem and activating strategies of the anti-aging industry through a systematic review. Results : From the results, the following suggestions are given: planning a national strategy to galvanize the anti-aging industry, establishing an anti-aging research institute, developing a business model, developing an anti-aging cluster, statistics development and an information system related to anti-aging, training personnel, and legislation. Conclusions : The anti-aging industry has the potential to reduce health expenses through early intervention of diseases due to aging and through activation of the national economy by win-win growth of the industry related to aging. Therefore, understanding the anti-aging industry as well as political support is critical.

The effect of aging on the quality of Semimembranosus muscle from Hanwoo

  • Kim, Sun Hyo;Kim, Hyun Joo;Lee, Hyun Jung;Yong, Hae In;Jo, Cheorun;Nam, Ki Chang;Jung, Samooel
    • 농업과학연구
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    • v.43 no.1
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    • pp.61-71
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    • 2016
  • The effect of postmortem aging on the quality of Semimembranosus muscle (SM) from Hanwoo was investigated. The quality of SM was compared with that of Longissimus dorsi muscle (LD). SM contained higher moisture, protein, and ash, and lower fat than LD (p<0.05). The $a^*$ and $b^*$ values of SM were significantly decreased after 21 days of aging. SM showed higher $a^*$ values than LD at 1 and 7 day of aging (p<0.05). The cooking loss of SM was not affect by aging. SM had higher cooking loss than that of LD throughout the aging period. Although the shear force of SM was significantly decreased by aging, SM showed high shear force compared to LD during aging period (p<0.05). Aging increased lipid oxidation in both muscles (p<0.05). However, TBARS value of SM was significantly lower than that of LD throughout the aging period (p<0.05). There was no effect of aging on the betaine and L-carnitine contents of SM. SM contained higher betaine and L-carnitine than LD in all aging days (p<0.05). Therefore, we concluded that consumer acceptability of SM could be increased by aging based on the increase of tenderness in addition to its high nutritional properties.

PZT 압전세라믹스 공진자의 공진주파수의 경시변화 (Aging of Resonant Frequency of PZT Piezoelectric Ceramic Resonantors)

  • 이개명;강찬호;김병효;황충구;고승우
    • 한국전기전자재료학회:학술대회논문집
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    • pp.109-114
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    • 2002
  • Aging stabilities of the operating frequency of piezoelectric devices such as filter, oscillator and discriminator are very important. In this study it was studied aging stabilities of the length-extensional vibration mode of Pb(Zr$\_$y/Ti$\_$1-y/)O$_3$+x[wt%]Cr$_2$O$_3$ ceramics. PZT ceramics in Morphotropic phase boundary have higher aging rates of k$\_$31/ and resonant frequency than those in tetragonal phase or rhombohedral phase. Thermal aging moves the composition with maximum aging rate to Zr-rich side in Cr not added PZT system. Aging rate of resonant frequency of the ceramics with x=0.1, y=0.53 and x=0.3, y=0.53 increased by thermal aging.

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22.9 kV CV 전력케이블의 14주기 고온 열화에 대한 Lightning-Impulse 특성 (Lightning Impulse Characteristics for 22.9 kV CV Power Cable Before and After Cyclic Aging for 14days)

  • 김위영;윤대혁;박태곤
    • 대한전기학회:학술대회논문집
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    • pp.1549-1551
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    • 2001
  • Cyclic aging for 14 days is performed to remove a large amount of the volatiles found in freshly manufactured cable. In this paper, we examined lightning impulse characteristics of 22.9 kV CV power cable before and after cyclic aging for 14days. As the result, the breakdown voltage after aging under normal temperature was lower than that before aging, and the breakdown voltage after aging under hot temperature was lower than that before aging. We found that the dispersion of lightning impulse breakdown voltage before 14 cyclic aging test were reduced rather than those after 14 cyclic aging test.

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