• Title, Summary, Keyword: Temperature rise

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Prediction of Adiabatic Temperature in Concrete as Semiadiabatic Temperature (간이단열온도로서 콘크리트의 단열온도 추정을 위한 연구)

  • Moon, Han-Young;Moon, Dae-Joong
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.5 no.4
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    • pp.121-129
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    • 2001
  • The semi-adiabatic temperature rise and the losses of temperature of cement paste, mortar and concrete were measured by an apparatus of semi-adiabatic temperature. Heat of hydration was measured by a conduction calorimeter and adiabatic temperature rise of concrete was measured by an adiabatic calorimeter. The derived equation which can assume the adiabatic temperature was proposed by measuring the semi-adiabatic temperature of concrete. The maximum adiabatic temperature rise of concrete obtained by the derived equation of adiabatic temperature, $T_{ad}(t)=T_{sad}(t)+T_{dis}(t)$, showed $55^{\circ}C$ approximately and it had good relation with the other one obtained by the heat of hydration of cement paste and with maximum value which was measured by the adiabatic calorimeter. The adiabatic temperature rise obtained by derived equation was a different information in comparison with the value obtained by adiabatic temperature rise equations by Hell and et. al. in early age, but it showed similar tendencies with the other one according to elapsed time. Adiabatic temperature rise of lich mix concrete with highly cement content was predicted. The adiabatic temperature rise of cement paste and mortar obtained by derived equation from us showed comparatively matching results to compared with that of obtained by adiabatic temperature equation from concrete standard specification.

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Analysis about CO Diffusion Change Caused by Climate Change Using CALPUFF (CALPUFF 모델을 이용한 기후변화에 따른 일산화탄소의 대기오염 영향 분석)

  • Ha, Minjin;Lee, Taekyeong;Lee, Im Hack;Jeon, Eui Chan
    • Journal of Climate Change Research
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    • v.8 no.2
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    • pp.81-89
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    • 2017
  • In this study CALPUFF was used to estimate the influence of temperature rise, according to the observation value of temperature rise based RCP scenario, on meteorological elements (wind direction, wind speed, mixing height) and the change of pollutant diffusion. According to the result. applying estimated value of year 2050 temperature rise, the mixing height is increased as per the temperature rise, so the range of atmospheric diffusion is widened. In summer case, by applying temperature rise of $4^{\circ}C$ and comparing with before applying temperature rise, there was change of diffusion range as per the change of temperature between 10 AM to 11 PM. And the range of diffusion was wider than that of before temperature rise. In winter case, by applying estimated value of temperature rise, $2.3^{\circ}C$, diffusion range has been changed between 8 AM to 4 PM, showing different diffusion aspect from summer. Also, according to the result of air pollution level assessment with temperature rise, it was proved that the ratio of area with increasing air pollution level has been getting higher by increase of temperature.

Estimation of Adiabatic Temperature Rise of Concrete (콘크리트 단열온도 상승 예측에 관한 연구)

  • 방기성;정원섭;송영철;조철희
    • Proceedings of the Korea Concrete Institute Conference
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    • pp.934-939
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    • 1998
  • This study discusses the results of adiabatic temperature rise tests which were performed considering various parameters, such as cement type, water-cement ratio, unit cement weigh, admixtures and placing temperature, which influence the temperature rise(K) and reaction velocity ($\alpha$). Theadiabatic temperature rise models obtained from this study are similar to those of Japan Concrete Institute. The models to calculate temperature rise and reaction velocity could be used the analysis f concrete thermal stress.

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Prediction of A Rise in Temperature Distribution of Mold Transformer for Power Distribution System (배전용 몰드변압기에 대한 상승 온도 분포 예측)

  • Lee, Jeong-Keun;Kim, Ji-Ho;Lee, Hyang-Beom
    • 한국정보통신설비학회:학술대회논문집
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    • pp.391-394
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    • 2009
  • In this paper, achieved rise temperature distribution about degradation phenomenon of 2 MVA distribution mold transformer using finite element method (FEM). Usually, life of transformer is depended on temperature distribution of specification region than thermal special quality of transformer interior. Specially, life of transformer by decline of dielectric strength decreases rapidly in case rise by strangeness transformer interior hot spot temperature value permits. Because calculating high-voltage winding and low-voltage winding of mold transformer and Joule's loss of core for improvement these life, forecasted heat source, and high-voltage winding and low-voltage winding of mold transformer and rise temperature distribution of core for supply of electric power and temperature distribution of highest point on the basis of the result Also, calculated temperature rise limit of mold transformer and permission maximum temperature using analysis by electron miracle heat source alculate and forecasted rise temperature distribution by heat source of thermal analysis with calculated result.

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A Study on the Temperature-rise at the Stator end portion of Turbine Generator (터빈 발전기 고정자단부의 온도상승에 관한 연구)

  • 임한석
    • Journal of the Korean Professional Engineers Association
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    • v.10 no.1
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    • pp.10-14
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    • 1977
  • In accordance with introducing extra high voltage system, system power plants have to be operated in underexcited condition, which causes temperature rise at the stator end portion of turbine generator. This Paper deals with (1) various elements affecting temperature rise and (2) methods of pre-estimating temperature rise.

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A Study on the Absorption Phenomena of Ultrasonic Exergy in the Mortar with different Mixing Ratio of Sand to Cement (배합률의 변화에 의한 MORTAR의 초음파 흡수현상)

  • 전춘생;홍봉식
    • 전기의세계
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    • v.25 no.6
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    • pp.74-80
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    • 1976
  • The temperature rise of the mortars while are being irradiated by ultrasonic waves and immersed in a liquid medium, are measured. The mixing ratios of sand to cement are varied for the different mortars. The results of the experiment are as follows, 1. The temperature rise of the mortar is decreased as themixing ration (S/C) is increased. 2. Thd temperature rise of the specimen is increased as its length is increased. 3. The surface conditions, either smooth or rough, may not have much influence on the temperature rise of the mortar. 4. The initial slope of temperature rise may not have much effect of the viscosity of liquid. The results, describes above, appear well coincide with the theory that the temperature rise is attributed mainly to the absorption heating. Since the absorption heating of the mortars varies with the mixing ratios of sand to cement, the strength of them would be estimated by means of irradiation of ultrasonic waves on the specimen.

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Dynamic Analysis of a Large Tilting Pad Journal Bearing Including the Effects of Temperature Rise and Turbulence (온도상승 및 난류효과를 고려한 대형 틸팅패드 저널베어링의 동특성 해석)

  • 하현천;김경웅
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.19 no.2
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    • pp.313-321
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    • 1995
  • The effects of the temperature rise and the turbulence are very important factors to predict the accurate performance of a large tilting pad journal bearing. In this study, the dynamic characteristics of a large tilting pad journal bearing are analyzed, taking into account the three dimensional variation of lubricant viscosity and turbulence. The effects of the temperature rise and the turbulence on the stiffness and damping coefficients are investigated in comparison with the results from the laminar or isothermal theory. The stiffness and damping coefficients increase due to the turbulence but decrease due to the temperature rise. The results show that the effects of both the temperature rise and turbulence must be considered simultaneously in order to predict the dynamic characteristics of a large tilting pad journal bearing more accurately.

Lifetime-Temperature Rise Model for the Evaluation of Degradation in Electric Connections/Contacts (전기적 접속/접촉부 열화 평가를 위한 수명 온도상승 모델)

  • Kim, Jeong-Tae;Kim, Nam-Jun
    • The Transactions of the Korean Institute of Electrical Engineers C
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    • v.51 no.2
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    • pp.55-61
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    • 2002
  • In this paper, 'lifetime-temperature rise model' based on the 'lifetime-resistance model' is theoretically Proposed, in order to find out the evaluation method of degradation and the residual lifetime by use of infrared image camera for electric connections/contacts. Two assumptions have been builded up for the 'lifetime-temperature rise model': one is associated with the linear relationship between the temperature ism ΔK and contact resistance, and the other the functional relationship between the temperature of electric connections/contacts and the operating time presenting in the 'lifetime-resistance model'. To prove the proposed model, experiments have been performed for various electric connections/contacts. From the experimental results, measured values were quite similar to the calculated values, which proved the above-mentioned two assumptions. Therefore, by use of 'lifetime-temperature rise model', it is possible to estimate the trend of degradation and the residual lifetime for electric connections/contacts through the temperature measurements .

Analysis and Measurement of Rough Surface Temperature Rise in Lubricated Condition (거친 표면의 마찰온도 해석 및 온도측정 실험에 관한 연구)

  • Lee, Sang-Don;Cho, Yong-Joo
    • Tribology and Lubricants
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    • v.23 no.2
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    • pp.56-60
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    • 2007
  • The main object of this study is to compare the results that have been concluded by the experiment and to estimate the temperature rise that can cause the contacting surface to be damaged. The former studies are based on the Blok and Jaeger formula. By these formulas we assume that two of the contacted objects are a kind of semi-infinite solid and with this assumption we can make a temperature analysis. But this method doesn't consider lubrication conditions and the calculation time requires a lot of time in that we have to face many difficulties in measuring the actual temperature rise. In this study we combines the semi-infinite solid method and the finite volume method to analyze the temperature of the contacting surface. And we measure temperature rise of the contact surface by dynamic thermocouple.

Cooling Geometry Dependent Operation Properties in a Diode End-Pumped Monolithic Yb:YAG Laser

  • Moon, Hee-Jong;Lim, Changhwan
    • Journal of the Optical Society of Korea
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    • v.20 no.5
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    • pp.593-600
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    • 2016
  • Operation properties, such as output power, beam radius, and crystal temperature rise were investigated in a diode-pumped edge-cooled monolithic Yb:YAG laser with ~ 4 W pumping level. The output power showed saturation behavior because of severe temperature rise and poor spatial overlapping between pump beam and lasing mode. Face cooling geometry by using a sapphire plate was also investigated. No apparent saturation behavior in output power was observed due to the reduced temperature rise, which could be attributed to efficient heat removal through the crystal-sapphire interface.