• Composites Research
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• 제30권1호
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• pp.7-14
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• 2017

In this paper, the inter-lamina shear strength (ILSS) of multi-wall carbon nanotube (MWNT) reinforced carbon fiber reinforced plastics (CFRP) and thin-ply composites were verified under low earth orbit (LEO) space environment. CFRP, MWNT reinforced CFRP, thin-ply CFRP and MWNT reinforced thin-ply CFRP were tested after aging by using accelerated ground simulation equipment. The used ground simulation equipment can simulate high vacuum ($2.5{\times}10^{-6}torr$), atomic oxygen (AO, $9.15{\times}10^{14}atoms/cm^2{\cdot}s$), ultraviolet light (UV, 200 nm wave length) and thermal cycling ($-70{\sim}100^{\circ}C$) simultaneously. The duration of aging experiment was twenty hours, which is an equivalent duration to that of STS-4 space shuttle condition. After the aging experiment, ILSS were measured at room temperature ($27^{\circ}C$), high temperature ($100^{\circ}C$) and low temperature ($-100^{\circ}C$) to verify the effect of operation temperature. The MWNT and thin-ply shows good improvement of ILSS at ground condition especially with the thin-ply. And after LEO exposure large degradation of ILSS was observed at MWNT added composite due to the thermal cycle. And the degradation rate was much higher under the high temperature condition. But, at the low temperature condition, the ILSS was largely recovered due to the matrix toughening effect.

• 한국식품영양과학회지
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• 제41권5호
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• pp.591-597
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• 2012

숙성온도와 기간에 따른 대추의 성분변화 및 항산화활성 변화를 분석한 결과 갈변도는 무처리구에 비해 가온숙성처리구에서 전체적으로 증가하였으며, 숙성 30일차 및 50일차에서는 다소 감소하는 경향을 보였다. 환원당, fructose와 glucose함량은 가온숙성처리구에서 높았으며, 숙성온도 및 기간이 증가함에 따라 유의적으로 감소하였다. 5-HMF 함량은 숙성온도 및 기간이 증가함에 따라 증가하여 숙성 50일차 $80^{\circ}C$에서 최대값을 나타내었다. 총 폴리페놀 함량도 숙성 온도와 기간이 증가함에 따라 증가하였으며, DPPH 라디칼 소거능 및 ABTS 라디칼 소거능도 가온숙성처리구에서 높았으며, 환원력은 숙성온도가 증가함에 따라서 증가하였지만 숙성일수에 따른 변화는 작게 나타났다. 숙성 온도 및 기간이 증가함에 따라 페놀성 화합물의 증가로 인하여 항산화 활성도 증가하였으며, 대추의 항산화활성을 높일 수 있는 최적숙성조건은 $70^{\circ}C$에서 15~30일로 판단되었다. 이를 통하여 건대추의 항산화 활성을 향상시켜 새로운 건강기능성 식품소재로 이용가능하며, 이에 따라 대추의 활용도 제고 및 부가가치를 높일 수 있을 것으로 판단된다.

• Asian-Australasian Journal of Animal Sciences
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• 제23권12호
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• pp.1645-1656
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• 2010

This study was conducted to investigate the effects of strain on broiler performance, and age at slaughter and postchilling (PC) aging time on meat quality traits. A total of 500 one-day-old chicks (250 Hubbard classic and 250 Lohman) were reared under commercial conditions. Half of the broiler birds from each strain were slaughtered at 32 days and the other half at 42 days old. At each processing day, 168 carcasses were randomly selected (84 Hubbard and 84 Lohman) and divided into groups of 28 carcasses within each strain, and aged for 0, 4 and 24 h after chilling. Average weekly body weight was comparable between strains. Feed conversion ratio was higher (p<0.05) for the Hubbard strain during the second and third week of age. Initial carcass pH was significantly (p<0.05) affected by age where younger birds (32-d-old) had lower pH values than older (41-d-old) birds. Breast temperature was higher (p<0.001) for Lohman than Hubbard at 0, 2 and 4 h of PC. Younger birds had a lower breast temperature (p<0.001) at all measured times of PC. Thaw loss, cook loss and water holding capacity were not significantly affected by strain, age or aging time. Lohman strain had more tender meat (p<0.05) than Hubbard strain, and tenderness was improved with the increase of broiler age and aging time. Meats from Hubbard were lighter and less red than those from Lohman strain where younger birds had darker color. In conclusion, strain, age at slaughter and PC aging duration are critical to breast meat quality characteristics, and 4 h of aging are required before deboning in order to obtain more tender fillets.

• 한국도로학회논문집
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• 제18권3호
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• pp.1-9
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• 2016

PURPOSES : This study aims to show the difference of the binder aging level in the hot-mix asphalt (HMA) mixture after short-term aging (SA) under different aging conditions, such as mixture temperature and duration in hour. METHODS : Three SA times (i.e., 1 h, 2 h, and 4 h) at two temperatures (i.e., $160^{\circ}C$ and $180^{\circ}C$) were used for the normal mixtures prepared using a PG64-22 asphalt. The field long-term aging (LA) was simulated by applying the same LA procedure (65 h at $110^{\circ}C$) to all compacted specimens, prepared at the air void of 7% using each SA-treated mixture, in a convection oven. The binder aging level was measured in terms of large molecular size by gel-permeation chromatography (GPC) from the mixture and the absolute viscosity (AV) from the recovered binder. The aging levels were evaluated using those two properties after SA and LA, and then compared based on the normal SA (NSA) mixture (1 h at $160^{\circ}C$). The service life reduction caused by SA in various conditions was estimated based on the aging level of the field cores from different locations in various service lives. RESULTS : The results of the laboratory evaluation indicated that the binder of the mixture, which was treated at longer SA time and higher temperature, showed a significantly higher aging level than the NSA mixture. The binder aging level from a longer time, such as 2 h and 4 h SA, or at a higher temperature ($180^{\circ}C$), were estimated to be similar to that of the mixtures, which had already been in field service for several years. CONCLUSIONS : The HMA mixture should be produced at a moderate temperature, such as $160^{\circ}C$, and placed within a limited hauling and queuing time to avoid a significant short-term aging of the binder before placement in the field pavement. The SA for a longer time at a higher temperature than the NSA condition was found to be detrimental to the service life of the asphalt pavement.

• 한국지반공학회논문집
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• 제19권2호
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• pp.7-14
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• 2003

본 연구는 광양만 지역과 목포 남악지역의 점토를 이용하여 양생온도를 20$\times$, 50$\times$ , 80$\times$로 달리하고 각각의 온도에서 양생기간을 1일, 7일 14일, 40일로 하여 재성형.재압밀 시료를 제작하여 양생온도.양생기간이 연대효과 재현에 어떤 영향이 있는지를 밝히고, 불교란시료와 재압밀된 점토의 역학적 특성과 연대효과의 특성을 알아보기 위하여 1축압축시험, 3축압축시험 그리고 표준압밀시험을 실시하였다. 그 결과 압축지수비는 원지반점토의 연대효과를 나타내는데 유용한 지수임을 확인할 수 있었으며 또한 고온으로 양생한 점토가 연대효과를 잘 표현하고 연대효과의 재현에 필요한 최적의 양생온도는 80$\times$ 정도 부근이고 양생기간은 27일정도 임을 알 수 있었다.

• 한국작물학회지
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• 제46권4호
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• pp.325-327
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• 2001

Tobacco (Nicotiana tabacum L. cv KF109) seeds were artificially aged in a controlled environment of 45$^{\circ}C$ and 80% relative humidity condition for different duration up to 14 days before priming in polyethylene glycol 6000 solution of equivalent osmotic potential of -0.8 MPa for 8 days at $25^{\circ}C$. The seeds aged only and primed after aging were germinated at 15$^{\circ}C$ and $25^{\circ}C$ to observe the priming effects on the germination of aged seeds at different temperature. The germination percentage of the aged seeds was rapidly dropped starting from 8 days of aging and mean germination time (T$_{50}$) was greatly increased, particularly in germination at 15$^{\circ}C$. The germination capacity was greatly restored in the primed seeds after aging, particularly in the seeds of longer aging and germinating at 15$^{\circ}C$.>.

• Structural Engineering and Mechanics
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• 제91권2호
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• pp.135-147
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• 2024

The objective of this study is to analyze, using the finite element method, the durability of damaged and repaired structures under the effect of mechanical loading coupled with environmental conditions (water absorption and/or temperature). The study is based on the hybrid patch repair technique, considering several parameters based on the J integral to observe the behavior of the adhesive in transferring load from a damaged plate to the repair patch. The results clearly show that water absorption and increased temperature cause degradation of the mechanical properties of the adhesive, leading to an increase in its plasticization, which is beneficial for the assembly's strength. However, the degradation of the adhesive's properties due to aging in the repair results in poor load transfer from the damaged area to the patch. The findings of this study allowed the authors to conclude that the [0°]8 sequence consistently offers the best performance, with the lowest J integral values and superior crack resistance. The lowest the J integral for the [0°]8 stacking sequence is typically 3-7% lower than that of the [0/-45/45/90]S and [0/-45/90/45]S sequences at elevated temperatures. At 60℃, the J integral increases by approximately 3-6% compared to 40℃ and 20, depending on the aging duration and stacking sequences.

• 대한기계학회논문집A
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• 제20권5호
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• pp.1372-1381
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• 1996

As recieved boiler tuve steel was aged artificially at $650^{\circ}C$ and$690^{\circ}C$ for various time duration to simulate the material deterioration which could be occurred during the operation of fossiol power plants. And the tensile tests, the microhardness tests and the characterization of carbides formed in the aging process were performed to asses the relationship between the mechanical properties and the effect of thermal aging. Furthernore, the amout of Mo-rich carbide were investigated by ondestructive method by noticing the fact that formation of Mo-rich carbide were investigated by ondestructive melthod by noticing the fact that formation of Mo-rich carbides($Mo_6C$) which stabilizes lastly affects the mechanical properties. It was known that the microhardness results of service exposed materials were similar to the ones which are aged at $650^{\circ}C$. The room temperature measurement showed small variation in the yield points and ultimate strength in materials aged at $650^{\circ}C$. Those properties at $540^{\circ}C$ showed the abrupt decrease compared with as received material even if short aging time. And it was found that $650^{\circ}C$ $690^{\circ}C$ aging cause different effects on mechanical properties, although the temperature time parameters(LMP;Larson-Miller parameter) are same. And it was concluded that the aigng at $650^{\circ}C$ is more appropriate to simulate the service exposed condition. Finally, the relationship between high temperature tensile properties and Ip values were established, which offers a potential way of reliability tests onthe power plant components.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2001년도 춘계학술대회 논문집 유기절연재료 전자세라믹 방전플라즈마 연구회
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• pp.186-188
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• 2001

In this study, the correlation between leakage currents and temperature rise was investigated for the more accurate diagnosis of bad insulator by use of the infrared camera. For the purpose, leakage currents and thermal images were measured for the artificially aged insulators using salt fog. From the results, it is concluded as follows ; in case of artificially aged insulators, the leakage. current was decreased with the duration of voltage application and was largely affected by humidity, which seems due to ionic conduction. Also, the correlation between temperature rise and leakage current was appeared to be quite linear, although it showed below linearity at large leakage current.

• 대한임상검사과학회지
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• 제38권3호
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• pp.147-151
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• 2006

Although various automated CBC analyzers with different WBC analytical principles were consequently introduced to clinical laboratory, the specific information concerning the suitability or unsuitability of aging samples is scarce. For this reason, we studied the effect of storage duration and temperature on CBC parameter in SE-9000 (SYSMEX Medical Electronics Co., Ltd., Kobe, Japan), automated CBC analyzer. We tested 32 K3-EDTA specimens with SE-9000 during 72 hours. Specimens were kept at room temperature (RT) and refrigerated and were analyzed at 0 hr, 4 hr, 8 hr, 24 hr, 48 hr and 72 hr after the collection of the specimens. The percentage changes from initial value for each parameters were calculated. Among the CBC parameters, hemoglobin, red blood cell count, mean corpuscular hemoglobin and platelets were stable for the study period at both temperatures. The mean corpuscular volume (MCV), hematocrit (Hct) and red cell distribution (RDW) increased and the mean corpuscular hemoglobin concentration (MCHC) decreased over time at room temperature. These parameters were stable when refrigerated. The leukocyte count was stable during 72hr at RT and when refrigerated. At room temperature, the relative percentages of neutrophils tend to increase, whereas those of lymphocyte and monocytes tend to decrease after 48 hours. When refrigerated, those of neutrophils and monocytes tend to increase, whereas those of lymphocytes tend to decreased over time. CBC parameters of refrigerated specimen were reliable for 72 hr for the exception of differential count from 24 hr but many CBC parameters, such as MCV, Hct, MCHC, RDW and differential count of leukocyte of blood stored at room temperature for 24 hr were unreliable.