• 제목/요약/키워드: thermo stability

검색결과 154건 처리시간 0.024초

감포 지역의 제3기 층에서 산출되는 Ba-제올라이트인 웰자이트의 광물화학 및 열화학적 특성 (Mineral Chemistry and Thermo-chemical Characterization of Wellsite, a Barrian Zeolite, from the Tertiary Formation in Gampo Area)

  • 노진환;김기업
    • 한국광물학회지
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    • 제10권2호
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    • pp.105-113
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    • 1997
  • Mineral description and mineralogical characterization were made for the wellsite, a barrian zeolite, which found as diagenetic alterations in the Miocene pyroclastic rocks in Gampo area. The wellsite occurs together with clinoptilolite, smectite and apatite as euhedral crystallites (0.2~0.4mm) forming interpenetraion twinning in the vesicles of altered pmice fragments. Compared to other reported wellsites, the wellsite is rather silicic (Si/(Al+Fe): 3.12-3.16) and Ca-rich. Unit cell dimensions and chemical formular determined from XRD, EMPA and TGA data are as follows:a=9.883$\AA$, b=14.204$\AA$, c=8.677$\AA$, $\beta$-124.764$^{\circ}$, (Ba0.57K0.36)(Ca1.18Na0.04)Al3.9Si12.1O32.13.9H2O.The cation composition of the Gampo wellsite, which shows an exchange reaction in the form of Ba2++Ca2+=2(K++Na-), is deviated far from the compositional range of a phillipsite-harmotome series. Due to higher abundance of divalent cations (Ca, Ba) and si in the wellsite, cimpared to those of the phillipsite and harmotome reported in other areas, the zeolite seems to be characteristic of higher water content (18.7 wt%) and higher thermal stability. XRD, chemical and thermo-chemical results of the wellsite reflects that wellsite is rather a Ba- and Ca-rich end member of a phillipsite-harmotome-wellsite series than an intermediate phase of phillipsite-harmotome series or a barrian variety of phillipste.

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제동 패턴을 고려한 드럼 브레이크의 열적 거동 특성에 대한 연구 (A Study on the Thermal Behavior Characteristic of Drum Brake considering Braking Patterns)

  • 이계섭;손성수;양기현
    • 한국자동차공학회논문집
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    • 제14권5호
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    • pp.145-154
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    • 2006
  • Each part of drum brake system is loaded by continual mechanical force and thermal force every time of braking, so enough strength and stability are required. Thermal characteristic is one of the important factors in drum brake systems design. This paper presents the thermal performance such as temperature distribution and thermal contact stress of drum brake system considering several braking patterns; 80th heat braking test mode, heat fade braking test mode, general road mode, steep slope road mode and off road mode. Transient heat transfer analysis and Thermo elastic contact analysis is executed to obtain the temperature distribution, and to evaluate thermal stress of drum brake by using ABAQUS/Standard code. This procedure of analysis can effectively be used to improve the quality problem of brake system and to get design guideline of the new product.

Analysis of the thermal instability of laminated composite plates

  • H. Mataich;A. El Amrani;B. El Amrani
    • Coupled systems mechanics
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    • 제13권2호
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    • pp.95-113
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    • 2024
  • In this paper, we will analyse the thermo-elastic behavior of the plate element of a structure arranged in a climatically aggressive environment (extreme temperature), we use a refined four-variable thick plate theory to take the shear effect into consideration, the proposed theory less computationally expensive and more accurate so that it incorporates the shear effect into the formulation. The plate is assumed to be simply supported on its four edges, so exact (closed-form) solutions are found according to the Navier expansion, and the governing stability equations and associated boundary conditions of the problem are obtained via the virtual works principle. The plate studied ismade of laminated composite materials, so a parametric study is needed to see the effect of different types of parameters and coupling on the critical temperature value causing thermo-elastic instability of the plate and also on the natural frequency of free vibration, as well as for other parameters such as anisotropy, slenderness and aspect ratio of the plate and finally the lamination angle. Numerical results are obtained for specially orthotropic and antisymmetrical plates and are compared with those obtained by othertheoriesin the literature to validate the analysis approach used.

상온 및 고온 하 진삼축압축실험을 이용한 시추공의 파괴 거동 기초 연구 (A Basic Study on Borehole Breakout under Room Temperature and High Temperature True Triaxial Compression)

  • 윤정환;민기복;박의섭;정용복
    • 터널과지하공간
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    • 제30권6호
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    • pp.559-572
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    • 2020
  • 본 연구에서는 현지 암반의 진삼축 응력 조건과 온도 변화를 고려한 공벽 안정성 실험을 수행하고, 심부 지하의 응력 조건과 압력 조건에서 암석의 열역학적 거동을 관찰하였다. 중국 황색 사암과 국내 황등 화강암 시료를 이용하여 진삼축압축실험을 진행하였다. 역학 실험은 각각 9가지 구속압 조건에서 수행되었고 열역학 실험은 화강암 시료를 이용하여 6가지 구속압 조건에서 시료를 60℃~100℃로 가열하여 수행하였다. 역학 실험 결과 공벽 파괴가 발생하는 최대 주응력은 중간 주응력에 비례하는 것을 확인하였다. 열역학 실험에서는 온도 증가에 따라 공벽의 응력장에 열응력이 추가되어 공벽 파괴가 추가적으로 발생하는 것을 확인하였다. 실내 실험 결과를 분석하기 위해 모기쿨롱 파괴 기준식을 사용하여 분석하였다. 원통형 시료에 대한 전통적인 삼축압축시험 결과와 진삼축 조건 하의 공벽 파괴 실험 결과가 모두 진삼축 파괴 기준식인 모기쿨롱 파괴 기준식에 잘 부합됨을 확인하였다.

유기 솔더 보존제의 코팅 및 플럭싱에 대한 메탄올/이소프로필알콜 비율의 영향 (Effect of MeOH/IPA Ratio on Coating and Fluxing of Organic Solderability Preservatives)

  • 이재원;김창현;이효수;허강무;이창수;최호석
    • Korean Chemical Engineering Research
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    • 제46권2호
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    • pp.402-407
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    • 2008
  • 최근 모바일 전자 제품의 많은 사용으로 인하여 전자 기판의 기계적 충격에 대한 기준이 강화되고 있다. 따라서, 전자 기판의 패키징 공정에서 칩과 기판 간의 솔더 볼의 접합방법은 제품의 안정성과 신뢰성 확보를 위하여 기존의 금속간 화합물을 사용하는 방식에서 유기 솔더 보존제를 사용하는 방법으로 전환되고 있다. 그러나 기존의 유기 솔더 보존제들은 공정상에서의 열안정성 등의 여러 가지 단점이 발견되어 이를 보완하기 위한 새로운 유기 솔더 보존제의 개발이 요구되고 있다. 이전 연구에서 새로 개발된 유기 솔더 보존제를 기존 패키징 공정에 적용(플럭싱 공정에 적용)할 때, 사용되는 플럭스의 성분비(메탄올/이소프로필알콜)에 따른 플럭싱의 차이를 파악하고, 이를 통하여 새로운 유기 솔더 보존제에 적합한 플럭스를 포뮬레이션 하는 것을 목적으로 하고 있다. 연구 결과, 새로운 유기 솔더 보존제의 플럭싱에는 메탄올의 함량비가 높아질수록 플럭싱이 더 우수해지는 경향을 나타내었다.

Body Temperature Monitoring Using Subcutaneously Implanted Thermo-loggers from Holstein Steers

  • Lee, Y.;Bok, J.D.;Lee, H.J.;Lee, H.G.;Kim, D.;Lee, I.;Kang, S.K.;Choi, Y.J.
    • Asian-Australasian Journal of Animal Sciences
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    • 제29권2호
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    • pp.299-306
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    • 2016
  • Body temperature (BT) monitoring in cattle could be used to early detect fever from infectious disease or physiological events. Various ways to measure BT have been applied at different locations on cattle including rectum, reticulum, milk, subcutis and ear canal. In other to evaluate the temperature stability and reliability of subcutaneous temperature (ST) in highly fluctuating field conditions for continuous BT monitoring, long term ST profiles were collected and analyzed from cattle in autumn/winter and summer season by surgically implanted thermo-logger devices. Purposes of this study were to assess ST in the field condition as a reference BT and to determine any location effect of implantation on ST profile. In results, ST profile in cattle showed a clear circadian rhythm with daily lowest at 05:00 to 07:00 AM and highest around midnight and rather stable temperature readings (mean${\pm}$standard deviation [SD], $37.1^{\circ}C$ to $37.36^{\circ}C{\pm}0.91^{\circ}C$ to $1.02^{\circ}C$). STs are $1.39^{\circ}C$ to $1.65^{\circ}C$ lower than the rectal temperature and sometimes showed an irregular temperature drop below the normal physiologic one: 19.4% or 36.4% of 54,192 readings were below $36.5^{\circ}C$ or $37^{\circ}C$, respectively. Thus, for BT monitoring purposes in a fever-alarming-system, a correction algorithm is necessary to remove the influences of ambient temperature and animal resting behavior especially in winter time. One way to do this is simply discard outlier readings below $36.5^{\circ}C$ or $37^{\circ}C$ resulting in a much improved mean${\pm}$SD of $37.6^{\circ}C{\pm}0.64^{\circ}C$ or $37.8^{\circ}C{\pm}0.55^{\circ}C$, respectively. For location the upper scapula region seems the most reliable and convenient site for implantation of a thermo-sensor tag in terms of relatively low influence by ambient temperature and easy insertion compared to lower scapula or lateral neck.

콘 칼로리미터와 TGA를 이용한 할로겐 계통의 난연제를 첨가한 폴리프로필렌 수지의 난연성 및 열 안정성에 관한 연구 (Fire Resistance and Thermal Stability Study of Fire-Retarded Polypropylene Systems by Using Cone Calorimeter and Thermogravimetry)

  • 곽성복;정찬화;남재도;김준형;최미애
    • 폴리머
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    • 제24권6호
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    • pp.777-786
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    • 2000
  • 본 연구에서는 범용 열가소성 수지인 폴리프로필렌 (virgin polypropylene, VPP)과 폴리프로필렌을 주성분으로 하는 재생플라스틱의 난연성을 향상시키기 위하여, 난연제 decabromodiphenyl oxide (DBDPO)와 chlorinated paraffin wax (CPW)를 혼합하여 이것들의 난연 특성을 정량적으로 비교 분석 연구하였다. 난연성 평가 측정으로 콘 칼로리미터 (cone calorimeter, ASTM E1354, ISO 5660), 한계산소지수 측정 (LOI, ASTM D2863, ISO 4589) 등을 사용하였고, 콘 칼로리미터를 이용하여 DBDPO와 CPW의 난연효율을 정량적으로 측정하였다. 콘 칼로리미터의 결과로 난연제의 난연효율을 측정한 결과, DBDPO가 CPW보다는 약 2배의 난연효율을 가지고 있다는 것을 확인하였고, 한계산소지수 측정 결과와 유사한 난연효율을 보임을 확인하였다. 열중량 분석 (TGA) 측정결과 난연제 DBDPO를 첨가하였을 때 약 30~5$0^{\circ}C$의 열분해 온도의 상승을 확인할 수 있었다.

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A study on the dynamic instabilities of a smart embedded micro-shell induced by a pulsating flow: A nonlocal piezoelastic approach

  • Atabakhshian, Vahid;Shooshtaria, Alireza
    • Advances in nano research
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    • 제9권3호
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    • pp.133-145
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    • 2020
  • In this study, nonlinear vibrations and dynamic instabilities of a smart embedded micro shell conveying varied fluid flow and subjected to the combined electro-thermo-mechanical loadings are investigated. With the aim of designing new hydraulic sensors and actuators, the piezoelectric materials are employed for the body and the effects of applying electric field on the stability of the system as well as the induced voltage due to the dynamic behavior of the system are studied. The nonlocal piezoelasticity theory and the nonlinear cylindrical shell model in conjunction with the energy approach are utilized to mathematically modeling of the structure. The fluid flow is assumed to be isentropic, incompressible and fully develop, and for more generality of the problem both steady and time dependent flow regimes are considered. The mathematical modeling of fluid flow is also carried out based on a scalar potential function, time mean Navier-Stokes equations and the theory of slip boundary condition. Employing the modified Lagrange equations for open systems, the nonlinear coupled governing equations of motion are achieved and solved via the state space problem; forth order numerical integration and Bolotin's method. In the numerical results, a comprehensive discussion is made on the dynamical instabilities of the system (such as divergence, flutter and parametric resonance). We found that applying positive electric potential field will improve the stability of the system as an actuator or vibration amplitude controller in the micro electro mechanical systems.

Novel Imidazolium Ionic Liquids Containing Quaternary Ammonium Iodide or Secondary Amine for Dye-sensitized Solar Cell

  • Seo, Dong-Wan;Lim, Young-Don;Lee, Soon-Ho;Ur, Soon-Chul;Kim, Whan-Gi
    • Bulletin of the Korean Chemical Society
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    • 제32권8호
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    • pp.2633-2636
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    • 2011
  • A new type of ionic liquid based on N-(3-aminepropyl)imidazolium iodide, called IIQAI, which consists of imidazolium and quaternary ammonium salt, and APII-(hydroxyethyl, propyl, hexyl) were synthesized and used as ionic liquid in dye-sensitized solar cells. APII-hexyl is solid, whereas IIQAI, APII-(hydroxyethyl, propyl) are viscous liquids. The synthesized ionic liquid showed relative thermal stability compared to the commercial ionic liquid of DMII. Among them, IIQAI was more stable than the other ionic liquid because of the two salt groups. APII-hydroxyethyl, which contains two hydroxyl groups, showed low viscosity with good flow. New types of ionic liquids were examined by $^1H$-NMR spectroscopy, thermo gravimetric analysis (TGA). IIQAI enabled a solar energy conversion efficiency of 6.3%, which is slightly higher than that of the referenced (DMII, 6.2%).

Characteristic Studies of Plasma Treated unidirectional Hildegardia Populifolia Fabric

  • Prasad, C. Venkata;Lee, D.W.;Sudhakara, P.;Jagadeesh, D.;Kim, B.S.;Bae, S.I.;Song, J.I.
    • Composites Research
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    • 제26권1호
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    • pp.54-59
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    • 2013
  • This study deals with effect of plasma treatment on the properties of unidirectional ligno cellulosic fabric Hildegardia Populofolia (HDP) fabric. Thermal stability of the fabric was determined by differential scanning calorimetry (DSC) and Thermo gravimetric analysis (DSC). Morphological properties was analyzed by SEM analysis and found that the surface was rough upon plasma treatment which provides good interfacial adhesion with matrix during composite fabrication. Thermal stability and mechanical properties of the plasma treated fabric slightly increases compare to alkali and untreated fabric. It was observed that tensile properties of the fabric increases upon plasma treatment due to the formation of rough surface. SEM analysis indicates formation of rough surface on plasma treatment which helps in increasing the interfacial interaction between the matrix (hydrophobic) and fabric (hydrophilic).