• Title/Summary/Keyword: Temperature Sensitivity

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Sensitivity of Electroplating Conditions on Young's Modulus of Thin Film (니켈박막의 공정조건에 따른 탄성계수 변화)

  • Kim, Sang-Hyun
    • Journal of the Korean Society for Precision Engineering
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    • v.25 no.8
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    • pp.88-95
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    • 2008
  • Young's modulus of electroplated nickel thin film is systematically investigated using the resonance method of atomic force microscope. Thin layers of nickel to be measured are electroplated onto the surface of an AFM silicon cantilever and Young's modulus of plated nickel film is investigated as a function of process conditions such as the plating temperature and applied current density. It is found that Young's modulus of plated nickel thin film is as high as that of bulk nickel at low plating temperature or low current density, but decreases with increasing plating temperature or current density. The results imply that the plating rate increases as increasing the plating temperature or current density, therefore, slow plating rate produces a dense plating material due to the sufficient time fur nickel ions to form a dense coating.

THERMAL EFFECTS OF EYELID IN HUMAN EYE TEMPERATURE MODEL

  • Gokul, K.C.;Gurung, D.B.;Adhikary, P.R.
    • Journal of applied mathematics & informatics
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    • v.32 no.5_6
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    • pp.649-663
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    • 2014
  • Presence of eyelid on anterior ocular surface and its thermal effects play significant role in maintaining eye temperature. In most of the literatures of thermal modeling in human eye, the eyelid is not considered as an eye component. In this paper, finite element model is developed to investigate the thermal effects of eyelid closure and opening in human eye. Based on different properties and parameter values reported in literatures, the bio-heat transfer process is simulated and compared with experimental results in steady and transient state cases. The sensitivity analysis using various ambient temperatures, evaporation rates, blood temperatures and lens thermal conductivities is carried out. The temperature values so obtained in open eye show a good agreement with past results. The closure of eyelid is found to increase/decrease the eye temperature significantly than its opening, when the parameter values are considered to be at extreme.

Mechanical Properties of Aluminium Alloy with Cellular Structure. (미세기공 알루미늄 소재의 기계적 성질)

  • 윤성원;이승후;강충길
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2002.05a
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    • pp.695-698
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    • 2002
  • Induction heating process is one of the most efficient heating process in terms of temperature control accuracy and heating time saving. In the past study, fabrication process of cellular 6061 alloys by powder metallurgical route and induction heating process was studied. To supplement the framing conditions that studied in past study, effect of induction heating capacity and holding time at foaming temperature were investigated. Under the achieved framing conditions, teamed 6061 alloys were fabricated for variation of foaming temperature, and porosities(%)-foaming temperature curves were obtained by try-error experimental method. Uniaxial compression tests were performed to investigate the relationship between porosities(%) and stress-strain curves of framed 6061 alloy. Also, energy absorption capacity and efficiency were calculated from stress-strain curves to investigated. Moreover, dependence of plateau stress on strain rate was investigated in case of cellular 6061 alloy with low porosities(%)

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A Stochastic Pplanning Method for Semand-side Management Program based on Load Forecasting with the Volatility of Temperature (온도변동성을 고려한 전력수요예측 기반의 확률론적 수요관리량 추정 방법)

  • Wi, Young-Min
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.64 no.6
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    • pp.852-856
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    • 2015
  • Demand side management (DSM) program has been frequently used for reducing the system peak load because it gives utilities and independent system operator (ISO) a convenient way to control and change amount of electric usage of end-use customer. Planning and operating methods are needed to efficiently manage a DSM program. This paper presents a planning method for DSM program. A planning method for DSM program should include an electric load forecasting, because this is the most important factor in determining how much to reduce electric load. In this paper, load forecasting with the temperature stochastic modeling and the sensitivity to temperature of the electric load is used for improving load forecasting accuracy. The proposed planning method can also estimate the required day, hour and total capacity of DSM program using Monte-Carlo simulation. The results of case studies are presented to show the effectiveness of the proposed planning method.

Dynamic Strain Aging on the Leak-Before-Break Analysis in SA106 Gr.C Piping Steel

  • Kim, Jin-Weon;Kim, In-Sup
    • Proceedings of the Korean Nuclear Society Conference
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    • 1996.05c
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    • pp.193-198
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    • 1996
  • The effect of dynamic strain aging (DSA) on the leak-before-break (LBB) analysis was estimated through the evaluation of leakage-size-crack and flaw stability in SA106 Gr.C piping steel. Also. the results were represented as a form of "LBB allowable load window". In the DSA temperature region. the leakage-size-crack length was smaller than that at other temperatures and it increased with increasing tensile strain rate. In the results of flaw stability analysis. the lowest instability load appeared at the temperature corresponding to minimum J- R curve which was caused by DSA. The instability load near the plant operating temperature depended on the loading rate of J-R data. and decreased with increasing tensile strain rate. These are due to the strain hardening characteristic and strain rate sensitivity of DSA. In the "LBB allowable load window". LBB allowable region was the narrowest at the temperature and loading conditions where DSA occurs.

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Evaluation of Mechanical Properties for Magnesium Sheet Forming by Tension and Compression Tests (마그네슘 판재성형을 위한 인장 및 압축실험을 통한 기계적 물성 평가)

  • Oh, S. W.;Choo, D. K.;Lee, J. H.;Kang, C. G.
    • Transactions of Materials Processing
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    • v.14 no.7 s.79
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    • pp.635-641
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    • 2005
  • The crystal structure of magnesium was hexagonal close-packed (HCP), so its formability was poor at room temperature. But formability was improved in high temperature with increasing of the slip planes. Purpose of this paper was to know about the mechanical properties of magnesium alloy (AZ31B), before warm and hot forming process. The mechanical properties were defined by the tension and compression tests in various temperature and strain-rate. As the temperature was increased, yield·ultimate strength, K-value, work hardening exponent (n) and anisotropy factor (R) were decreased. But strain rate sensitivity (m) was increased. As strain-rate increased, yield·ultimate strength, K-value, and work hardening exponent (n) were increased. Also, microstructures of grains fined away at high strain-rate. These results would be used in simulations and manufacturing factor fer warm and hot forming process.

An Effect on the Process Parameter of Mg Alloy at Warm Sheet Forming (Mg 합금 온간 판재 성형시 공정 변수의 영향에 관한 연구)

  • Lee, Y.S.;Kwon, Y.N.;Kim, M.C.;Choi, S.W.;Lee, J.H.
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • 2006.05a
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    • pp.43-47
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    • 2006
  • Since the sheet metal forming of Mg alloy is performing at elevated temperature, the effect of process conditions related with the forming temperature is very important factor. Therefore, the investigation for process variables is necessary to design the tools and process conditions. In this study, the effects of process variables were studied by the experimental and FE analysis using the square cup deep drawing. The temperature, forming speed, and lubricant condition were investigated. When forming temperature was $250^{\circ}C$, speed forming was low, and teflon sheet was used as lubricant, the formed parts were good without defects.

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Effect of MgO Contents on Electrical Properties and Oxygen Sensing Characteristics in Co1-xMgxO Ceramics (Co1-xMgxO세라믹스의 MgO함량에 따른 전기적 성질 및 산소가스 감지특성)

  • 최현국;이덕동;조상희
    • Journal of the Korean Ceramic Society
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    • v.26 no.1
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    • pp.7-12
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    • 1989
  • The effects of composition ratios and sintering conditions in Co1-xMgxO ceramics on the sintering characteristics, electrical properties and oxygen sensing characteristics were investigated. In the same sintering conditions, porosity decreased with increase of MgO contents. The relationshiop of temperature and resistance in Co1-xMgxO ceramics showed NTC(negative temperature coefficient) characteristics at the temperature range from $700^{\circ}C$ to 1,10$0^{\circ}C$. In the case of pure CoO, however, the PTC(positive temperature coefficient) characteristics were shown over about 90$0^{\circ}C$. The electrical conductivity of Co1-xMgxO ceramics decreased proportionally with decrease of oxygen partial pressure at the range from 1 to 10-4(atm). Particularly, Co0.5Mg0.5O ceramics showed the highest sensitivity to oxygen gas.

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Characteristics of Surface Micromachined Capacitive Pressure Sensors for High Temperature Applications (표면 MEMS 기술을 이용한 고온 용량형 압력센서의 특성)

  • Seo, Jeong-Hwan;Noh, Sang-Soo;Kim, Kwang-Ho
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.23 no.4
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    • pp.317-322
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    • 2010
  • This paper reports the fabrication and characterization of surface micromachined poly 3C-SiC capacitive pressure sensors on silicon wafer operable in touch mode and normal mode for high temperature applications. FEM(finite elements method) simulation has been performed to verify the analytical mode. The sensing capacitor of the capacitive pressure sensor is composed of the upper metal and the poly 3C-SiC layer. Measurements have been performed in a temperature range from $25^{\circ}C$ to $500^{\circ}C$. Fabrication process of designed poly 3C-SiC touch mode capacitive pressure sensor was optimized and would be applicable to capacitive pressure sensors that are required high precision and sensitivity at high pressure and temperature.

Optimization of Thermo-Optic Parameters for Temperature-Insensitive LPWG Refractometers

  • Lee, Dong-Seok;Kim, Kyong-Hon;Hwang, Seok-Hyun;Lee, Min-Hee;Lee, El-Hang
    • ETRI Journal
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    • v.28 no.6
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    • pp.739-744
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    • 2006
  • In this paper, we report numerically calculated results of testing a temperature-insensitive refractive sensor based on a planar-type long-period waveguide grating (LPWG). The LPWG consists of properly chosen polymer materials with an optimized thermo-optic coefficient for the core layer in a four-layer waveguide structure. The resonant wavelength shift below the spectral resolution of the conventional optical spectrum analyzer is obtained accurately over a temperature change of ${\pm}7.5^{\circ}C$ even without any temperature control. The refractive index sensitivity of the proposed grating scheme is about 0.004 per resonant wavelength shift of 0.1 nm for an optimized thermo-optic coefficient.

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