• 한국추진공학회지
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• 제9권2호
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• pp.46-53
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• 2005

혼합형 고체 추진제의 온도 및 습도 가속노화 시험을 수행하여, 그 결과를 분석하였다 수명 평가를 위해서 온도 가속 노화 시험을 수행하였고, 산화제인 AP의 흡습성에 의해 추진제가 연화되는 특성을 분석하기 위해 상대습도 10, 30, $50\%$에서 습도 노화 시험을 수행하였다 온도 가속 노화 시험은 시편을 제작하여 시험하였고, 습도 시험은 실제 모터와 유사한 추진제 블록을 만들어 시험하였다. 온도 가속 노화 결과 $60^{\circ}C$에서 4개월 저장 결과가 $20^{\circ}C$에서 10년 저장한 결과로 예측되었다 HTPB 바인더를 사용한 혼합형 고체 추진제는 시간에 따라 경화되는 경향을 나타내었으며, 상대 습도 $50\%$까지는 습기의 영향이 크게 나타나지 않았다.

• 한국조명전기설비학회:학술대회논문집
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• 한국조명전기설비학회 2001년도 학술대회논문집
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• pp.13-16
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• 2001

In this paper, the emission and aging properties of ZnS:Cu electroluminescent device were experiment respectively at room temperature and 7$0^{\circ}C$ relative humidity 100%. ZnS:Cu and BaTiO$_3$were respectively used for phosphor and dielectric. While AC 100V on 400Hz frequency were applied to the devices at room temperature and 70$_3$relative humidity 100%, the change of brightness were measured and compared. The surface of aged devices were investigated by scanning electron microscope. With the continuously operated environment of room temperature and 7$0^{\circ}C$ relative humidity 100%, the decay time were measured and the dark spot and aging status on the surface of the device were investigated. ZnS:Cu electroluminescent properties were deteriorated by the Increased temperature and humidity. Also the deteriorated properties were confirmed by the brightness and surface chanties of device, and the aging mechanism from the simulation on sulfur vacancy and deep tracts density.

• 한국재료학회:학술대회논문집
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• 한국재료학회 2008년도 춘계학술발표대회 및 제14회 신소재 심포지엄
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• pp.30.1-30.1
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• 2008

• 한국축산식품학회지
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• 제42권6호
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• pp.953-967
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• 2022

The objective of this study was to determine effects of aging methods (wet-aged, dry-aged, and packaged dry-aged) during 60 d on quality traits and microbial characteristics of beef. Wet-aged beef was packed by vacuum packaging and stored in a 4℃ refrigerator. Dry-aged beef was used without packaging. Packaged dry-aged beef was packaged in commercial bags. Dry-aged and packaged dry-aged samples were stored in a meat ager at 2℃-4℃ with 85%-90% relative humidity. Meat color, crust thickness, aging loss, cooking loss, Warner-Bratzler shear force (WBSF), texture profile analysis, Torrymeter, meat pH, water activity, volatile basic nitrogen (VBN), thiobarbituric acid reactant substances (TBARS), and microbial analysis were measured or performed every 15 d until 60 d of aging time. Meat color changed significantly with increasing aging time. Differences in meat color among aging methods were observed. Aging losses of dry-aged and packaged dry-aged samples were higher than those of wet-aged samples. Wet-aged beef showed higher cooking loss, but lower WBSF than dry-aged and packaged dry-aged beef. VBN and TBARS showed an increasing tendency with increasing aging time. Differences of VBN and TBARS among aging methods were found. Regarding microbial analysis, counts of yeasts and molds were different among aging methods at the initial aging time. Packaged dry-aged and dry-aged beef showed similar values or tendency. Significant changes occurred during aging in all aging methods. Packaged dry aging and dry aging could result in similar quality traits and microbial characteristics of beef.

• 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$^{\circ}C$.>.

• 한국축산식품학회지
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• 제39권4호
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• pp.655-667
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• 2019

The present study aimed at investigating the effects of dry- and wet-aging methods on flavor compounds and sensory properties of low fat Hanwoo beef muscles. All the beef samples were obtained from 2-grade carcasses of Hanwoo cows. The beef samples used in the dry- and wet-aging methods were prepared in the forms of quarter beef (bone-in) and cuts (boneless), respectively. The dry-aging was carried out at $2^{\circ}C-4^{\circ}C$ and humidity of 65%-85%, while the wet-aging was done at $1^{\circ}C$ for 0, 20, 40, and 60 d. At each aging time, three muscles: longissmus thoracis (LT), glutaeusmedus (GM) and semimembranosus (SM) were taken from the corresponding quarters and cuts, and used for the flavor compounds and sensory analyses. Results showed that both aging methods significantly increased the concentrations of flavor compounds and total amount of all classes of the flavor compounds as the aging time increased (p<0.05). In the dry-aging method, the GM and SM muscles presented significantly higher total amounts of pyrazines and sulfur-containing compounds compared to the LT muscle (p<0.05). Both the aging methods improved the eating quality attributes, indicating by increased scores of sensorial attributes with increased aging time for all the muscles studied (p<0.05). However, compared to the wet-aging, the dry-aging method resulted in significantly higher scores of tenderness and flavor for the GM and SM muscles after 40 to 60 d. Thus, postmortem aging, especially the dry-aging method could be used to improve eating quality attributes (tenderness and flavor) of low fat beef muscles such as GM and SM.

• 한국항공우주학회지
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• 제49권9호
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• pp.759-769
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• 2021

발사체 추진 시스템에서 Titanium Hydride Potassium Perchlorate (THPP)는 에너지를 인가받으면 gas를 발생시키는 pyrotechnic initiator로써 혹은 NASA Standard Initiator (NSI)의 supplement charge로써 흔히 사용되는 물질이다. 하지만 금속으로 이루어진 복합 화약이 오랫동안 보관이 되면 노화라는 문제에 직면하게 된다. 본 연구에서는 열분석 및 표면분석을 통하여 다양한 습도환경에서 노화된 THPP에 대하여 열역학적 특성의 변화를 확인하였고, 이를 바탕으로 THPP에 대한 전반적인 노화 메커니즘을 구축해내었다. 우선, THPP가 노화됨에 따라 산화제 표면의 균열빈도가 증가하고 길이가 길어졌는데, 이는 열·수분 노화가 공통적으로 산화제의 분해를 초래함을 보여준다. 이때 열 노화된 경우 Viton의 열화 현상이, 수분 노화된 경우 연료의 산화가 더욱 두드러졌다. 또한 실험을 통해 계산된 반응률에 대한 THPP의 화학반응인자의 경우 습도에 따라 크게 달라졌는데, 이는 수분이 THPP의 연소에 상당한 변화를 미쳐 결국에는 수명의 감소로 이어지게 될 것을 시사한다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2006년도 제37회 하계학술대회 논문집 B
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• pp.1151-1152
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• 2006

In this paper, we examined 10 domestic samples of three different model using thermal, humidity freeze, thermal-endurance and damp heat test under IEC61215 photovoltaic module environmental endurance test condition. Three was almost no changes on power generation. Insulation resistance capacity was much higher than judgement standard but, showed unstable results depending on environmental test items. On external appearance test, there were two models which showed bubble, humidity penetration, seal melted frame phenomenon. From this results, the degree of aging under the external environment is a main cause that shortens photovoltaic module life time. So it is considered that the efforts for finding optimum condition of manufacturing process should be needed.

• 한국구조물진단유지관리공학회 논문집
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• 제9권4호
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• pp.141-148
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• 2005

콘크리트가 외기에 노출되면 수분확산으로 인해 콘크리트 내에는 비선형 수분분포를 가진다. 이러한 비선형 수분분포는 부등건조수축을 야기시키고 콘크리트 표면에 수축균열을 일으키게 된다. 수축균열의 발생은 콘크리트 구조물의 내구성과 사용성에 영향을 미치게 되므로 근본적으로 수분확산에 대한 연구가 반드시 요구된다. 본 연구의 목적은 콘크리트 구조물의 수분확산을 지배하는 수분확산계수의 수정 모델식을 제안하는 것으로서 이를 위해 여러 가지 실험결과를 근거로 하여 수치해석을 수행하였다. 콘크리트의 수분확산계수는 재령에 따라 변화하며 특히, 초기재령에서 변화가 크게 나타난다. 본 연구에서 제안한 수분확산계수 모델식은 콘크리트의 습도뿐만 아니라 공극률의 함수로써 재령의 영향을 고려하였다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2003년도 하계학술대회 논문집 Vol.4 No.1
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• pp.481-484
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• 2003

Recently polymer insulators are being used for outdoor high voltage applications. Polymer insulators have significant advantages over porcelain and glass insulators. With the gradual improvement of their design and material, their reliability has also increased. It is however difficult to establish how they will perform after several years of service. Aging of the insulator weathershed may lead to damages such as excessive chalking and crazing, erosion and tracking which affect the insulator performance. In service insulator are subjected to aging stresses such as humidity, pollution and electrical field which act singly or in combination. There have been numerous accelerated laboratory tests developed with the intention of evaluating suitability of polymeric materials. Some of these are strictly material tests, where as, others evaluate full scale devices. Service experience plays a key role in the utility selection of polymer insulator, but is time consuming, and may not always be available. Hence there is a need for a meaningful and reliable accelerated aging test for polymer insulator. This paper describes multi-stress aging test for reliability of polymer insulator This paper presents the rule of multi-stress aging test and test chamber for polymer insulator in korea electrotechnology research institute.