• Title, Summary, Keyword: Humidity Aging

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Temperature and Humidity Aging Characteristics of Composite Solid Propellant (혼합형 고체 추진제 온$cdot$습도 노화 특성)

  • Lee Kyung-Joo
    • Journal of the Korean Society of Propulsion Engineers
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    • v.9 no.2
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    • pp.46-53
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    • 2005
  • We have analyzed the temperature and humidity aging test results of a composite solid propellant. The temperature aging test was performed to evaluate the storage life of a propellant, while the humidity aging test could provide the hygroscopicity of Ammonium Perchlorate(AP) exposed to .elative humidity (RH) 10, 30, $50\%$ environment. A specimen was used in the temperature test, and a block of propellant from the actual motor was used in the humidity test. We report that the 4-month storing at 60 degree is equivalent to the 10-year 60 degree condition. The composite solid propellant with HTPB binder showed signs of hardening with time lapse but the effect of humidity up to RH $50\%$ was not noticeable.

Effect of Humidity on Physico-chemical Properties of Hydrous Aluminum Oxide

  • Rhee, Gye-Ju;Han, Kwan-Sub
    • YAKHAK HOEJI
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    • v.21 no.2
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    • pp.101-109
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    • 1977
  • The effect of humidity on the aging process of hydrous aluminum oxide prepared by the reaction of aluminum chloride and sodium bicarbonate solution at pH 7.8, which was then kept in various atmosphere under relative humidity at 37.deg. was observed by the measurements of acid consuming capacity, X-ray diffraction and IR absorption. The humidity was one of the important factors influencing the aging process of hydrous aluminum oxide during storage. The higer the humidity, the more was accelerated age, crystalize and loss in acid reactivity. Depending on the humidity, the aging product was different, especially, in the case of up to the relative humidity of 72%, it forming bayerite. On the other hand, the hydrous aluminum oxide aged below the relative humidity of 50% was still amorphous even after 120 days storage. When hydrous aluminum oxide was aged under higher humidity, definite IR absorption bands develop as the hydroxys become part of an ordered structure, and it showed their characteristic absorption band around 1630 and 1060 cm$^{-1}$.

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Humidity Aging Effect on Adhesive Strength of Composite Single-lap Joint

  • Kim, Myungjun;Kim, Yongha;Kim, Pyunghwa;Roh, Jin-Ho;Park, Jungsun
    • International Journal of Aeronautical and Space Sciences
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    • v.18 no.1
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    • pp.56-62
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    • 2017
  • Because adhesively bonded joints are used in many structural systems, it is important to predict accurate adhesive strengths. Composite aircraft with many joints are easily exposed to low temperatures and high relative humidity. This paper presents a humidity aging effect on the adhesive strength of a composite single-lap joint (SLJ). The adhesive strength of the SLJ is predicted using a finite element analysis with a cohesive zone model (CZM) technique. The humidity aging effect is evaluated based on the adhesive strength and CZM parameters. A lap joint test is carried out on the composite SLJ specimens, which are exposed for four months of 100% R.H. at $25^{\circ}C$. The predicted strengths are in good agreement with experimental data, and the actual crack propagation is satisfactorily simulated using the local CZM technique.

Effect of Humidity on Polymorphic Transformation of Hydrous Aluminum Oxide (알루미나수화물(水和物)의 결정전이(結晶轉移)에 미치는 습도(濕度)의 영향(影響))

  • Rhee, Gye-Ju;Yoo, Byeong-Tae
    • Journal of Pharmaceutical Investigation
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    • v.13 no.1
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    • pp.1-9
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    • 1983
  • The effect of humidity on crystallization and polymorphic transformation of hydrous aluminum oxide under various humidity at $37^{\circ}$ was examined by means of X-ray diffraction, scanning electron micrograph, IR spectra and DTA. The humidity was an important factor influencing crystallization of hydrous aluminum oxide. The growth or crystal was strongly accelerated by humidity. The aging process is assumed that it is composed of two seperate steps, an increase of the diffraction around $36{\sim}42^{\circ}$, and an appearance and its development of the peak at $18{\sim}20^{\circ}$ of $2{\theta}$ value. The former is considered to be nucleation and the latter correspond to the growth period on crystallization. The crystalline form of aging products was various depending on the degree of humidity, directly it leads to the eventual formation of bayerite in more than 72%, $b{\"{o}}hmite$ in 50% and resembled to Nordstandite in 0% relative humidity, respectively but once formed, it was mostly stable in each surroundings and does not transform to the other more stable form in solid state even after aging for five years. The mechanism responsible for aging is further polymerization process of six-membered rings by deprotonation-dehydration reaction in which positively charged polynuclear hydroxy aluminum complexes formed in the presence of moisture are joined at their edges by double hydroxide bridges.

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Effects of aging on the phenolics content and antioxidant activities of rose flower (Rosa hybrida L.) extracts (숙성조건이 장미꽃 추출물의 페놀화합물(phenolics) 함량과 산화방지 활성에 미치는 영향)

  • Kim, Soyoung;Ko, Seung Hyun;Yoon, Hyungeun
    • Korean Journal of Food Science and Technology
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    • v.49 no.6
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    • pp.714-716
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    • 2017
  • Rose flower is widely used in the preparation of tea and contains a large variety of phytochemicals, including phenolics such as catechin, quercetin, and rutin. The effects of aging on rose (Rosa hybrida L.) flower extracts (RFE) were examined under conditions of varying temperature and relative humidity. The total phenolic content, antioxidative activity, and catechin levels were measured to evaluate the effects of temperature and relative humidity on the aging process. Performing the aging process at $30^{\circ}C$ under 60% or 90% relative humidity for 24 h significantly increased the total phenolic content and the antioxidant activities of RFE (p<0.05). Additionally, an aging process performed at $30^{\circ}C$ and 60% relative humidity for 24 h maximized the extraction rate of phenolics such as catechin and consequently led to increased antioxidative activity of RFE. In summary, this study indicates that the extraction rate of physiologically active phenolic compounds in rose flower can be increased by performing an aging process under optimized temperature and relative humidity conditions.

Accelerating aging test of distribution lightning arresters (배전용 피뢰기의 가속열화시험)

  • 김주용;송일근;김찬영;이병성;문재덕
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • pp.596-598
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    • 2000
  • This paper presents a new accelerating aging test facility for distribution lightning arresters. Aging parameters of lightning arrester are moisture ingress, electrical stress and surge absorption and so on. In this system, we applied 13.2kV to 6 samples and controled temperature and humidity of chamber and measured leakage currents of the all samples. Also we developed accelerating aging cycle which consists of -35$^{\circ}C$∼90$^{\circ}C$ temperature and 40%∼90% humidity. Through the aging test we found out the leakage current of aged sample increases rapidly according to the temperature rising. Hereafter we can determine the replacement guide of leakage current for field operating arresters and condition assessment of aged samples through this aging test.

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Electroluminescent and Accelerated Aging Properties of ZnS:Cu Phosphor (ZnS:Cu 형광체의 전계 발광 및 가속열화 특성)

  • 이종찬;황명근;박대희
    • Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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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.

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Evaluation Technology of Electrical and reliableility Characteristics for Outdoor Polymer Insulator Materials (폴리머 절연물 소재의 전기적 밀 복합열화 특성평가 기술)

  • Ahn, Myeong-Sang;Park, Hoy-Yul;Na, Moon-Kyeong
    • Proceedings of the KIEE Conference
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    • pp.1343-1344
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    • 2006
  • There have been numerous accelerated aging laboratory tests for evaluating suitability of polymeric materials and devices. Aging test for materials and its full scale device has been conducted. Service experience plays a key role in the utility section of composite insulators. A meaningful and reliable accelerated aging test is needed for evaluating composite insulator. During the service these insulators are subjected to aging stress such as humidity, pollution, and electrical field, and erosion and tracking of the weathershed occurs. This paper presents the criteria of reliability evaluation and evaluation facilities for 22.9 kV suspension composite insulator. We adopt the criteria of reliability evaluation consist of two test methods. One is CEA tracking wheel test for examining the tracking and erosion performance of composite insulator. The other is multi-stress aging test for examining effects of environmental factors such as UV, temperature, humidity, etc on composite insulator.

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Reliability Evaluation Criteria and Multi-Stress Aging Test for Polymer Insulator (폴리머 현수애자의 신뢰성 평가 및 복합가속열화 방법)

  • Park, Hoy-Yul;Kang, Dong-Pil;Ahn, Myeong-Sang
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • pp.469-472
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    • 2004
  • There have been numerous accelerated aging laboratory tests for evaluating suitability of polymeric materials and devices. Aging test for materials and its full scale device has been conducted, but poor correlation of aging test such as service experience were observed. Service experience plays a key role in the utility section of composite insulators. A meaningful and reliable accelerated aging test is needed for evaluating composite insulator. During the service these insulators are subjected to aging stress such as humidity, pollution, and electrical field, and erosion and tracking of the weathershed occurs. This paper presents the criteria of reliability evaluation and evaluation facilities for 22.9 kV suspension composite insulator. We adopt the criteria of reliability evaluation consist of two test methods. One is CEA tracking wheel test for examining the tracking and erosion performance of composite insulator. The other is multi-stress aging test for examining effects of environmental factors such as UV, temperature, humidity, etc on composite insulator.

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