• 제목/요약/키워드: AGING

검색결과 10,227건 처리시간 0.035초

Translucency changes of direct esthetic restorative materials after curing, aging and treatment

  • Lee, Yong-Keun
    • Restorative Dentistry and Endodontics
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    • 제41권4호
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    • pp.239-245
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    • 2016
  • The purpose of this article was to review the changes in translucency of direct esthetic restorative materials after curing, aging and treatment. As a criterion for the evaluation of clinical translucency changes, visual perceptibility threshold in translucency parameter difference (${\Delta}TP$) of 2 was used. Translucency changes after curing were perceivable depending on experimental methods and products (largest ${\Delta}TP$ in resin composites = 15.9). Translucency changes after aging were reported as either relatively stable or showed perceivable changes by aging protocols (largest ${\Delta}TP$ in resin composites = -3.8). Translucency changes after curing, aging and treatment were perceivable in several products and experimental methods. Therefore, shade matching of direct esthetic materials should be performed considering these instabilities of translucency in direct esthetic materials.

고령화가 노동 생산성에 미치는 영향 (Aging Influence on Labor Productivity)

  • 이근부;오세호;양희중
    • 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.

베이비부머세대의 성공적 노화 : 중산층을 중심으로 (Successful Aging of the Middle-class Baby Boomer Generation)

  • 홍성희;곽인숙
    • 가족자원경영과 정책
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    • 제16권4호
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    • pp.69-92
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    • 2012
  • The purpose of this study is to describe and analyze the baby boomers' perception of and preparation for their successful aging. Seven women and three men were interviewed with the use of an unstructured questionnaire. Their perceptions of their likelihood of future successful aging were not negative, and were influenced by a range of considerations that included health, leisure, finance, volunteer services, family relationships, and elderly life without children's supports. They tried to prepare several kinds of sports, leisure activities, and volunteer services for their elderly life. However, their reasons for preparing these activities varied, and the background of their differences consisted of the family background, personal values, and experiences. Moreover, men and women responded differently to their personal experiences as they related to their elderly life. Women were likely to match their family relationship with their perception and preparation for successful aging, and men were not.

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축하중을 받는 철근콘크리트 부재의 재령계수식 제안 (Aging Coefficient Formula of Reinforced Concrete Members under Axial Compression)

  • 유재욱;유은종
    • 한국공간구조학회논문집
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    • 제13권4호
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    • pp.67-74
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    • 2013
  • The Age-adjusted effective Modulus Method(AEMM) is one of the methods adopted for the construction stage analysis of concrete structures. The AEMM uses the aging factor to consider the effects of the varying concrete stress. In the aspects of computation time and the accuracy of the results, the AEMM is considered as one of most appropriate methods for construction stage analysis of tall building structures. Previous researches proposed appropriate values of the aging factor in the forms of graphs or using very simple equations. In this paper, an equation for estimating the aging factor as a function of rebar ratio in the section, compressive strength of concrete, notional member dimension, and age of concrete at the load application. The validity of aging factor proposed in this paper were examined by the comparison with the results of step-by step method.

발전기 고정자 권선의 가속열화 특성 (Characteristics of Accelerated Aging in Generator Stator Windings)

  • 김희동;공태식;주영호
    • 한국전기전자재료학회:학술대회논문집
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    • 한국전기전자재료학회 2008년도 하계학술대회 논문집 Vol.9
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    • pp.279-280
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    • 2008
  • Accelerated aging tests were conducted under laboratory conditions on two generator stator bars. Electrical stress is applied in No. 1 model stator bar. Electrical and thermal stresses are applied in No. 2 model stator bar. As aging times increased from 0 to 4780h, diagnostic tests were performed on No. 1 and No. 2 model stator bars. Diagnostic tests included AC current, dissipation factor(tan$\delta$) and partial discharge magnitude. The ${\Delta}tan{\delta}$ and $\Deta$I of No. 1 and No. 2 model stator bars increased with increased in aging time.

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Effects of Channel Aging in Massive MIMO Systems

  • Truong, Kien T.;Heath, Robert W. Jr.
    • Journal of Communications and Networks
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    • 제15권4호
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    • pp.338-351
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    • 2013
  • Multiple-input multiple-output (MIMO) communication may provide high spectral efficiency through the deployment of a very large number of antenna elements at the base stations. The gains from massive MIMO communication come from the use of multi-user MIMO on the uplink and downlink, but with a large excess of antennas at the base station compared to the number of served users. Initial work on massive MIMO did not fully address several practical issues associated with its deployment. This paper considers the impact of channel aging on the performance of massive MIMO systems. The effects of channel variation are characterized as a function of different system parameters assuming a simple model for the channel time variations at the transmitter. Channel prediction is proposed to overcome channel aging effects. The analytical results on aging show how capacity is lost due to time variation in the channel. Numerical results in a multicell network show that massive MIMO works even with some channel variation and that channel prediction could partially overcome channel aging effects.

배전용 폴리머애자의 현장열화 특성평가 (Characterization of Field-Aged Polymer Insulators for Distribution Power Systems)

  • 이병성;김찬영;한재홍
    • 한국전기전자재료학회논문지
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    • 제13권10호
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    • pp.847-858
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    • 2000
  • The aging characteristics of 2 kinds of 3 years field-aged distribution polymer insulators which were dismounted from 5 regions have been investigated by electrical test and material characterization. Although the tan $\delta$of specimens prepared from weathershed was increased with surface aging, the tan $\delta$and leakage current of real products had no difference between virgin and dismounted ones. Due to the aging, all dismounted polymer insulators had micro-cracks on the surface of weathershed and only the products of manufacturer B showed the reduction of OIT(oxidation induction time). But, there were no differences between virgin and dismounted products in contact angle and chemical structure. Therefore, it can be considered that the aging is only limited on the surface of dismounted polymer insulators and that NMR technique are very useful to evaluate the aging of polymer materials.

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배전용 폴리머애자 열화특성 평가를 위한 복합열화 시험장치 구축 (A Combined Aging Test Facility for Evaluating an Aging Characteristics of Distribution Polymer Insulators)

  • 이병성;한재홍;김찬영;윤태상
    • 대한전기학회:학술대회논문집
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    • 대한전기학회 2000년도 하계학술대회 논문집 C
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    • pp.1948-1950
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    • 2000
  • Polymeric composite insulators have been in use for outdoor insulation. However, our knowledge about their long-term performance in an outdoor environment is still very limited. Especially, these insulators are subjected to the environmental stress such as ultraviolet radiation, electrical stress, mechanical load, etc.. Hence, in this paper, we simulated the factors having influence on aging of polymer insulators using the combined aging test chamber. In order to evaluate an aging characteristics with time, we measured leakage current on these insulators to make out the degree of aging.

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Particle Growth in Oxalate Process II; Control of Barium Titanyl Oxalate Particle Size

  • Hyo-Soon Shin;Zee Hoon Park;Chang Hyun Kim;Byung Kyo Lee
    • The Korean Journal of Ceramics
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    • 제2권2호
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    • pp.70-75
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    • 1996
  • On the basis of growth mechanism proposed by recent work, partile of barium titanyl oxalate was controlled by aging in water. From aging at $25^{\circ}C$ for 3 hours, uniform particles of 0.3 ${\mu}$m were obtained. During aging, abnormal particle growth was observed, which were thought to be caused by impurities in water. With increase of aging time and temperature, particle grows more, and differential growth was promoted. In aging for long time, grown particles were cracked.

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기공여방지쇠노적작용(氣功與防止衰老的作用) (Qigong and Anti-aging)

  • ;이경섭;남상수
    • 대한예방한의학회지
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    • 제8권1호
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    • pp.155-161
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    • 2004
  • The average life span is expanded due to the development of modem society, material and cultural life and increasing level of public health. This means that the aging society is rapidly progressing. Geniatric diseases also have increased due to increasing of the aged population. Along with an increase of the aged patient, the anti-aging, prevention of geniatric disease and quality of life is tending high on social concern and medical issues. Many reports showed the evidence to the positive anti-aging effect of Oriental medicine. Qigong therapy, a kind of Oriental medicine, has been used to prevent aging and life prolongation with positive effect for many thousand years. Therefore, qigong practice is popular and common to middle age and old age in China.

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