• Title/Summary/Keyword: 노화

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Study on the Experimental Aging Estimation Technique for HTPB based Solid Propellant Considering Post Curing Effect (후경화를 고려한 HTPB 고체 추진제의 실험적 노화평가 기법 연구)

  • Jung, Gyoo Dong;Park, Jae Beom;Kim, Shinhoe
    • Journal of the Korean Society of Propulsion Engineers
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    • v.23 no.3
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    • pp.51-57
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    • 2019
  • Post curing effects are estimated by specimen tests. Propellant specimen accelerated aging tests are performed when post curing is estimated to be complete and the coefficients of Arrhenius aging equations are acquired. Simulated motors with cylindrical grain are designed and fabricated to confirm the application. Accelerated aging tests are conducted, and aged properties are measured and estimated for the inner bore, center and bond parts of the grain. The measured aging ratios of the modulus are compared with the ones predicted by the equations. As the results, the accelerated aging equations predict well the propellant aging trends; however, some differences are observed at the bond part. Therefore, the specimen extraction part must be carefully chosen to suit the test purpose when a rocket motor grain is used for the aging test.

An Evaluation of Moisture Sensitivity of Asphalt Concrete Pavement Due to Aging (노화에 따른 아스팔트 콘크리트 포장의 수분민감성 평가)

  • Kim, Kyungnam;Kim, Yooseok;Kim, Nakseok
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.39 no.4
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    • pp.523-530
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    • 2019
  • Pavement distress and traffic accidents are caused by pot-hole. In addition, direct and indirect damages of road users are increasing, such as loss of life due to personal injury and damage to vehicles. Generally, the asphalt concrete pavements are continuously aging from the production process to the terminal performance period. Aging causes stripping due to cracks and moisture penetration and weakening the pavement structure to induce pot-hole. In this study, adhesion performance and moisture sensitivity were evaluated according to aging degree in order to investigate the effect of aging on asphalt pavement. As a result of the study, the viscosity of the asphalt binder was increased with aging and the bond strength of the aged was increased 2~3 times than that of the unaged. The results of accelerated aging test showed an increases in indirect tensile strength and the increase in the TSR (Tensile Strength Ratio) by 4.2~8.9 %. As a result, it is noted that the anti-stripping and adhesion performances of the aged asphalt concrete are improved compared to the unaged one under the aging conditions of asphalt binder coated on aggregates.

Design and Implementation of a new aging sensing circuit based on Flip-Flops (플립플롭 기반의 새로운 노화 센싱 회로의 설계 및 구현)

  • Lee, Jin-Kyung;Kim, Kyung Ki
    • Journal of the Korea Industrial Information Systems Research
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    • v.19 no.4
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    • pp.33-39
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    • 2014
  • In this paper, a new on-chip aging sensing circuit based on flip-flops is proposed to detect a circuit failure of MOSFET digital circuits casued by aging phenomenon such as HCI and BTI. The proposed circuit uses timing windows to warn against a guardband violation of sequential circuits, and generates three warning bits right before circuit failures occur. The generated bits can apply to an adaptive self-tuning method for reliable system design as control signals. The aging sensor circuit has been implemented using 0.11um CMOS technology and evaluated by $4{\times}4$ multiplier with power gating structure.

Aging Behavior of Natural Rubber and EPDM (천연고무와 EPDM의 노화 거동)

  • Kim, Jin K.;Kim, In-Hwon;Shin, Jin-Soo
    • Elastomers and Composites
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    • v.33 no.3
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    • pp.159-167
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    • 1998
  • Rubber products are aged like human complexion by the attack of oxygen, ultra violet, ozone, etc.. Aging is very important and also very complicated phenomenon to understand. This may explain the rarity of papers on this subject. In this study, we tried to understand the aging behavior of EPDM compared to that of natural rubber. We also compared the sulfur vulcanized system to the peroxide vulcanized one. In our experiment, the peroxide vulcanizates were more advantageous in aging than the sulfur vulcanizates. The authors belived that this study about the high performance EPDM would be applicable to rubber industry.

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천연물로부터의 항노화소재 개발: Triterpenoid계 식물성분인 Oleanolic acid의 항노화 효과

  • 남개원;이소희;김승훈;김수현;성대석;김수남;이병곤
    • Journal of the Society of Cosmetic Scientists of Korea
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    • v.29 no.1
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    • pp.27-44
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    • 2003
  • 전반적인 피부세포의 생리적 지능 자하로 인한 자연노화와 더불어, 여러 피부 스트레스 요인들이 다양하게 작용하여 발생하는 외인성노화를 방지하거나, 개선할 수 있는 항노화소재로서의 개발 가능성을 알아보기 위해, 예로부터 항염활성이 있다고 알려진 oleanolic acid(OA)를 포함한 ursolic acid(UA), betulin, betulinic acid(BA) 등의 triterpenoids가 어떻게 피부에서의 항노화 활성을 나타내는지를 알아보았다. 시험 결과, OA는 자외선에 의한 각질형성세포에서의 PGE$_2$ 생성과 섬유아세포(NHF)에 의한 matrix metalloproteinase-1(MMP-1) 분비를 억제하였다. 그리고, NHF의 procollagen 생성을 촉진하였으며, 이런 procollagen 생성촉진활성이 in vivo에서도 발현되는 것을 무모생쥐의 실험을 통해서 확인하였다. 또한 OA는 각질세포의 증식과 분화를 촉진하여 표피세포로 하여금 세라마이므와 필라그린 생성을 증가시키도록 하는 작용도 있음을 보여주었다. 더불어 실험한 UA, betulin, BA 들은 비록, betulin, BA의 경우 세포 독성이 다른 물질 들에 비해 높았고, UA가 각질세포의 분화를 오히려 억제하는 양상을 보이기는 했지만, 대부분의 기능은 OA와 유사하였다. 피부세포보호작용과 진피 기질물질에 대한 작용, 그리고, 표피의 장벽기능과 보습기능에 대해 시험한 본 연구는, 식물성분인 triterpenoids가 피부를 위한 항노화소재로서의 개발 가능성이 있음을 확인하는 계기가 되었고, 그 중에서도 OA가 보다 우수한 항노화 소재가 될 수 있음을 시사하고 있다.

Influence of the Senior Simulation Program on Aging Anxiety in Nursing Students (간호대학생이 경험한 노인유사체험이 노화불안에 미치는 영향)

  • Jeong, Hye-Sun;Han, Jong-Sook;Kim, Jung-Hee
    • The Journal of the Korea Contents Association
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    • v.11 no.12
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    • pp.832-843
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    • 2011
  • This quasi-experimental study examined the effect of the a senior simulation program and following group discussion on the anxiety about aging. The senior simulation program did not raise the level of four factors of the anxiety about aging. The item of fear of losing friends when becoming old was the only significant one with increased level of anxiety. Discussion session for sharing the simulation experience revealed a positive effect of decreasing anxiety level in the factor score of fear of old people, the item of liking getting together with elders, and the item of liking to do something for elders. With the help of information technology.

Varietal Differences of Leaf Senescence and Photosynthate Translocation Rate During Grain Filling Period in Barley (대맥의 등숙기간중 엽신의 노화와 동화산물전류의 품종간 차이)

  • 남윤일;구본철;연규복
    • KOREAN JOURNAL OF CROP SCIENCE
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    • v.36 no.2
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    • pp.166-173
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    • 1991
  • In order to determine the relationships between the rates of leaf senescence and photosynthate translocation during the grain filling periods in barley, field experiments were conducted through 1989/1990 crop year. Thirty barley varieties and lines having different leaf senescence were used for the experiments. Varieties differed significantly in the rate of leaf senescence and rate of grain filling. The rate of leaf senescence at early (10-20days after heading) and late period (20-30days after heading) during of grain filling were positively correlated with the rate of grain filling in same period, respectively. But the rate of leaf senescence at 10-20 days after heading negatively correlated with the rate of grain filling during the whole grain filling period (10-35 days after heading). Whereas, the rate of leaf senescence at late period was positively associated with the rate of grain filling during the whole grain filling period. Rates of grain filling at the late and whole periods have positively influence on grain weight(r=0.62**~-0.93**), but rate of leaf senescence at early period and duration of grain filling negatively correlated with the grain weight (r=-0.33~ -0.15). The patterns of leaf senescence index for the varieties tested were grouped by four. Among these patterns, the most ideal pattern was IV type.

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Study on the Successful Aging of Baby-Boom Generation : Application of Rowe & Kahn's Theory (베이비붐 세대의 성공적 노화에 관한 연구 : Rowe & Kahn 이론을 적용하여)

  • Jeon, Byeong-Joo;Han, Hye-Sook
    • The Journal of the Korea Contents Association
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    • v.19 no.10
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    • pp.69-83
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    • 2019
  • Considering the reality that the baby boom generation which takes up 15% of the Korean population enters the old age, this study aimed to investigate level and factors affecting successful aging of the baby boom generation. The theory this study used is Rowe & Kahn, and the data it used are from 2,577 persons combining respondents of the fifth basic survey and the special survey of Korean Longitudinal Study of Ageing. This study utilized IBM SPSS Statistics ver. 20.0 for analysis, and the main results of this study were as follows. First, successful aging level of the baby boom generation was $6.36{\pm}1.39$(range: 0~9), proving that they consider their aging as successful. However, depending on sub-factors of successful aging, proportion that they viewed themselves as successfully aging were quite different. Second, examination of factors affecting successful aging of the generation found out that pocket money, educational level, and child-parents relationship satisfaction are important. By applying the theory of Rowe & Kahn which can be called the representative model of successful aging, this study examined successful aging and extracted some suggestions for future researches.

The SOC Strategy Intervention Program for Successful Aging of the Elderly: A Pilot Study (노인의 성공적 노화를 위한 SOC전략 중재프로그램의 효과: A Pilot Study)

  • Shin, Ga-In;Woo, Ye-Shin;Park, Dasol;Park, Hae Yean
    • Therapeutic Science for Rehabilitation
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    • v.8 no.4
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    • pp.33-39
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    • 2019
  • Objective : The purpose of this study is to examine the effect of successful intervention program on SOC strategy and successful aging of the elderly. Methods : Three elderly individuals aged ${\geq}65$ living in W-si, Gangwon-do, were included. A successful aging program using an SOC strategy was conducted twice a week for 6 sessions. To verify the effectiveness of the program, the Korean versions of the SOC scale and the successful aging scale were used. Descriptive statistics were used for general characteristics, and the Wilcoxon signed-rank test was used to compare successful aging and SOC strategies. Results : After 3 weeks for successful aging program, the SOC strategy levels of the subjects were constant or improved. In addition, the average score of successful aging level increased by 11.4 points. Conclusion : This study show that the successful aging program using the SOC strategy improved the level of SOC strategy and the level of successful aging. The results of this study can be used as basic data to develop programs that can promote SOC strategy and successful aging. Also, the result of this study can be used as a basic data for the development of guidelines for occupational therapists in the future.

고령사회 삶의 질 이끄는 '노화과학'

  • Park, Sang-Cheol
    • The Science & Technology
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    • no.2 s.453
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    • pp.82-85
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    • 2007
  • 65세 이상 총인구가 차지하는 비율이 14% 이상을 고령사회라고 한다. 우리나라는 지난해 이 비율이 8.7%에서 2019년에는 14.4%, 2026년에는 20%를 넘어 초고령사회로 진입할 것으로 예상되고 있다. 이러한 초고령 사회에서 노화와 이에 따른 질병은 개인에 있어서는 궁극적인 삶의 질 하락을, 국가에 있어서는 엄청난 재정 부담과 함께 국가 경제력 하락을 초래한다. 그러나 '99세까지 88하자(구구팔팔)'는 질병 없는 행복한 장수는 결코 꿈이 아니다. 지난 수십년간의 연구를 통해 노화의 원인들이 속속 밝혀지고 있기 때문이다. 월간 '과학과 기술'은 '노화'를 주제로 이번 2월호부터 10회에 걸쳐 연재한다.

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