• 대한의생명과학회지
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• 제3권2호
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• pp.161-168
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• 1997

나이가 들어가면서 나타나는 여러 가지 변화를 임상적으로 검사하고 측정하므로써 건강상태를 예측하는 것은 노화를 지연시키고 건강한 삶을 유지하는데 상당히 유용하고 기초적인지표가 될 것이다. 점차 증가일로에 있는 노인성 질환의 여러 문제점을 해결하기 위해 노령인구 집단을 정상군과 치매군으로 구분하여 13종의 임상화학 검사를 시행한 결과, 두 집단 사이에서, 임상 생화학적 검사의 양상이 다를 것이라는 예측대로의 결과를 얻을 수 있었다. 즉, serum albumin, APase, glucose, GOT, LDH 등의 수치는 정상군과 치매군 사이에서 현저한 차이를 보이는 반면, bilirubin, BUN, cholesterol, creatinine, total protein 등의 검사 수치에서는 별다른 차이를 볼 수 없었으며 , 그밖에 calcium, GPT, Pi 검사 등의 결과에서도 두 집단 사이에서 차이를 보였다. 이것은 치매가 체내에서 많은 생화학적 변화를 일으킴을 시사하고, 치매 발병에 여러 가지 환경 요인이 영향을 미치게 될 것이라는 결론을 유도할 수 있게 한다.

• Corrosion Science and Technology
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• 제5권6호
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• pp.189-195
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• 2006

Effects of tungsten (W) on the precipitation kinetics of secondary phases and the associated resistance to pitting corrosion of 25%Cr duplex stainless steels were investigated through microstructural and electrochemical noise analyses. With the partial substitution of W for Mo in duplex stainless steel, the potential and current noises of the alloy were significantly decreased in chloride solution due to retardation of the ${\sigma}$ phase precipitation. The preferential precipitation of the $\chi$ phase in the W-containing alloy during the early period of aging contributed to retarding the precipitation of the $\sigma$ phase by depleting W and Mo along grain boundaries. In addition, the retardation of the nucleation and growth of the $\sigma$ phase in the W-containing alloy appears to be attributed to the inherently low diffusivity of W compared with that of Mo.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2004년도 춘계 학술발표회 제16권1호
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• pp.466-471
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• 2004

Efficient numerical finite element analysis of creeping concrete structures requires the use Kelvin or Maxwell chain model, which is most conveniently identified from a continuous retardation or relaxation spectrum, the spectrum in turn being determined from the given compliance or relaxation function. The method of doing that within the context of solidification theory for creep with aging was previously worked out by Bazant and Xi, but only for the case of a continuous retardation spectrum based on Kelvin chain. The present paper is motivated by the need to incorporate concrete creep into the recently published microplane model M4 for nonlinear triaxial behavior of concrete, including tensile fracturing and behavior under compression. In that context. the Maxwell chain is more effective than Kelvin chain. because of the kinematic constraint of the microplanes used in M4. Determination of the continuous relaxation spectrum for Maxwell chain. based on the solidification theory, is outlined and numerical examples are presented.

• 소성∙가공
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• 제8권3호
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• pp.309-309
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• 1999

Effects of rare earth metals addition and aging treatment on corrosion resistance and mechanical properties of super duplex stainless steels were investigated using optical/SEM/TEM metallographic examination, an X-ray diffraction test, a potentiodynamic anodic polarization test and a tensile test. The performance of the experimental alloy with 0.32% REM addition was compared with commercial super duplex stainless steel such as SAF 2507 when they were exposed to solution annealing heat treatment and aging treatment. The corrosion resistance in CF environments and mechanical properties of the experimental alloy were found superior to those of the commercial duplex stainless steel. The REM with larger atomic radii than those of Cr, Mo and W may fill vacancies inside the matrix and around the grain boundaries, retarding formation of harmful intermetallic σ and χ phases. In addition, fine REM oxides/oxy-sulfides (1-3㎛) seemed to enhance the retardation effects. With REM additions, strength and ductility increased due to the phase and grain refinement caused by fine REM oxides and oxy-sulfides.

• 대한한방내과학회지
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• 제26권2호
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• pp.379-389
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• 2005

Objectives: It is well known that aging and aging-related diseases are linked to the increased level of oxidative stress caused by reactive oxygen species(ROS) and reactive nitrogen species(RNS). Nonprotein-SH decreases during aging, while substances such as ROS, nitric oxide(NO), peroxynitrite($ONOO^-$), myeloperoxidase(MPO), and dityrosine show a significant increase. This study investigated the effect of Ichungwhan on the aging process by examining its effect on the generation of the above-mentioned substances. Methods: Four comparison groups of SD rats were used. They were 6 month-old rats, 24 month-old rats, and 24 month-old rats fed with food containing 0.1% and 0.3% of Ichungwhan extract. The amount of NO, $ONOO^-$, and ROS in the rats' kidneys were examined using a fluorescence microplate reader. The reagents used for this purpose include: dihydrorhodamine 123 (DHR 123), 2',7' -dichlorodihydrofluorescein, diacetate(DCFDA), and 4,5-diaminofluorescein(DAF-2). A spectrophotometer was used to investigate the reactivity of nonprotein-SH and myeioperoxidase(MPO), using reagents such as trichloroacetic acid(TCA) and tetramethylbenzidine(TMB). The amounts of MPO protein and dityrosine were measued by western blot. Results: The observed effects of Ichungwhan on rats were as follows: increase of nonprotein-SH; effective decrease of RNS level by suppression of the generation system of $ONOO^-$ and NO; decrease of ROS level; decrease of the MPO reactivity and the subsequent reduction of amount of MPO protein; retardation of dityrosine formation. It can be hypothesized, therefore, that Ichungwhan affects both the earlier and later phases of the molecular inflammatory process, and retards the aging process. Conclusions: Empirical evidence in this study supports a role for Ichungwhan in generation mechanisms of aging process-linked substances ROS, NO, $ONOO^-$, nonprotein-SH, MPO and dityrosine. Affects contrary to the aging process observed in rats beg further empiricism to investigate potential application of Ichungwhan as a medication for age-related diseases in humans.

• 한국항공우주학회지
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• 제31권9호
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• pp.26-31
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• 2003

노후 항공기는 일반적으로 다중손상(MSD)이라고 하는 폭넓게 분포된 피로손상을 내포하고 있다. 2024-T3 알루미늄합금과 같은 연성재료에 있어서 다중손상은 전통적인 파괴역학에서 예측할 수 있는 것보다 낮은 운용수명을 예측하게 만드는 것으로 알려져 있다. 본 논문에서는 다중손상을 갖는 평판 구조물을 모델링한 Fastener Hole을 갖는 2024-T3 알루미늄합금 판재로 제작된 Hole/Slot type M(T) 시편에 예입압입을 적용한 후 피로시험을 수행하여 피로균열 성장지연에 의한 운용수명 증가에 대한 효과를 연구하였다. 예비압입을 적용한 시편은 파단에 이르는 사이클수가 최소 10배에서 최대 40배까지 증가하였으며, 일정진폭 하중의 최대값을 증가시킴에 따라서 그 효과가 감소함을 보여주었다. 또한, 압입에 의한 균열성장지연 메커니즘은 균열진전경로가 압입자국에 들어서면서 균열성장률이 감소하기 시작하며 압입자국의 중심을 지나면서 최소균열성장률 상태로 일정한 시간동안 균열성장이 정체됨으로써 피로수명이 연장됨을 밝혔다.

• 한국세라믹학회지
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• 제44권1호
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• pp.23-31
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• 2007

To examine the effects of chemical admixture on the fluidity and strength development of high chloride cement, experiments were conducted in which lignosulfonate (LS), naphthalenesulfonate (NS), and polycorboxylate (PC) were each added in standard and excessive amounts, and the results were as follows. 1. Because adding KCl to NS causes a decrease in flow, adding PC is better in maintaining high cement fluidity. 2. When cement contained much chloride comes in contact with water, hydration begins 4 h after contact and securing workability becomes difficult, but by adding PC, workability can be secured to 10 h. 3. The bound water ratio and compressive strength in aging 3 days occupy $70\sim80%$ of those in aging 28 days, and the early compressive strength increases not only by adding KCl, but also by chemical admixture. 4. Although compressive strength development is excellent in NS, PC, if NS is added excessively, hydration becomes slow and while the pore structures become slightly minute, the strength development decreases due to severe setting retardation.

• 한국식품영양과학회지
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• 제45권4호
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• pp.533-541
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• 2016

페놀화합물의 함량이 높다고 알려진 카카오(powder)로부터 카카오 추출물(CE)을 획득한 후, CE가 pancreatic lipase의 활성에 미치는 영향과 CE를 함유한 emulsion의 aging에 의한 가수분해율 변화를 살펴보기 위하여 두 가지 형태의 기질을 사용한 pH-stat digestion model을 이용하였다. Type I 의 경우 소화액에 CE와 콩기름을 첨가하여 emulsion을 제조하였으며 aging time(0, 5, 24시간)에 따른 가수분해 변화를 살펴보았다. CE를 첨가하였을 때의 가수분해율은 CE를 첨가하지 않았을 때와 큰 차이를 보이지 않아 CE가 pancreatic lipase 활성에 영향을 주지 않았다고 판단된다. 그러나 aging time이 지남에 따라 CE를 첨가하였을 때와 CE를 첨가하지 않았을 때의 가수분해율 모두 감소하였다. 이는 CE의 영향보다는 aging time이 길어짐에 따라 emulsion의 안정도가 낮아져 지방구 크기가 증가하여 가수분해율이 모두 감소한 것으로 생각되고, 따라서 이 모델에서는 CE에 의한 가수분해 저하가 크지 않았다. 한편 type II의 경우 먼저 콩기름과 CE, Tween 20를 혼합하고 고압균질기를 사용하여 micro-emulsion을 제조한 후, 이를 기질로 하여 aging time(0, 2, 4, 7, 18, 43일)에 따른 가수분해율 변화를 살펴보았다. 그 결과 aging time에 따라 CE를 첨가하지 않은 control과 CE를 첨가한 CE-emulsion의 가수분해율이 감소하였는데, 특히 control보다 CE-emulsion이 더 많이 감소하여 43일에는 control의 ${\Phi}$ max가 92.13%(0일, 96.53%)였으나 CE-emulsion은 77.69%(0일, 97.91%)를 보이면서 CE-emulsion의 가수분해 반응이 control에 비해 낮았다. 다른 kinetic parameter(k value, $t_{1/2}$ 등)에서도 이와 유사한 경향을 나타냈다.

• 대한한의학방제학회지
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• 제24권4호
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• pp.271-282
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• 2016

Objective : In this study, we compared the antioxidant and anticancer properties of four multi-herbal formulas which were recorded in 'Dongeuibogam': Gilgyung-tang (GGT), Mokdanpi-tang (MDPT), Samso-eum (SSE), Samchulbobi-tang (SCBBT). Methods : We checked antioxidant properties of four multi-herbal formula through total phenolic content, radical scavenging activities, protective effects on genomic DNA oxidation. To investigate anticancer effects, we conducted MTT assay and analyzed morphologic change in A549 non-small lung cancer cells. Results : Total phenolic contents of four multi-herbal formulas were in a rich order of MDPT > SSE > GGT > SCBBT. Especially, MDPT revealed the highest activity than others in all antioxidant experiments. Our results indicated that treatment of those multi-herbal formulas induced growth retardation in A549 cells and MDPT also showed the highest anticancer effect ($IC_{50}=1.374mg/ml$) among them. Conclusions : Our data suggested that MDPT would be a powerful ingredient for lung cancer treatment.

• BMB Reports
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• 제44권5호
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• pp.298-305
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• 2011

Most intracellular reactive oxygen species (ROS), especially superoxide anion ($O_2^{{\bullet}_-}$) that is converted from oxygen, are overproduced by excessive electron leakage from the mitochondrial respiratory chain. Intracellular oxidative stress that damages cellular components can contribute to lifestyle-related diseases such as diabetes and arteriosclerosis, and age-related diseases such as cancer and neuronal degenerative diseases. We have previously demonstrated that the excessive mitochondrial $O_2^{{\bullet}_-}$ production caused by SDHC mutations (G71E in C. elegans, I71E in Drosophila and V69E in mouse) results in premature death in C. elegans and Drosophila, cancer in mouse embryonic fibroblast cells and infertility in transgenic mice. SDHC is a subunit of mitochondrial complex II. In humans, it has been reported that mutations in SDHB, SDHC or SDHD often result in inherited head and neck paragangliomas (PGLs). Recently, we established Tet-mev-1 conditional transgenic mice using our uniquely developed Tet-On/Off system, which equilibrates transgene expression to endogenous levels. These mice experienced mitochondrial respiratory chain dysfunction that resulted in $O_2^{{\bullet}_-}$ overproduction. The mitochondrial oxidative stress caused excessive apoptosis leading to low birth weight and growth retardation in the neonatal developmental phase in Tet-mev-1 mice. Here, we briefly describe the relationships between mitochondrial $O_2^{{\bullet}_-}$ and aging phenomena in mev-1 animal models