• Title/Summary/Keyword: Thermal effect

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Effects of Accelerated Iso-Thermal Aging on Elastic-Plastic Fracture Toughness and Fracture Resistance Curve by Unloading Compliance Method in SA533B Low Alloy Steel (제하 컴플라이언스법에 의한 SA533B강의 $J_1C$ 및 J-R 곡선에 미치는 열시효 영향)

  • 윤한기;차귀준
    • Journal of Ocean Engineering and Technology
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    • v.8 no.2
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    • pp.157-165
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    • 1994
  • Effect of an accelerated iso-thermal aging (375 degree C x 66days, 375 degree C x 200days) on elastic-plastic fracture resistance curve were examined in SA533B low alloy steel. Fracture toughness test are conducted by unloading compliance method at room temperature. But the apparent negative crack growth phenomenon, usually arise in partial unloading compliance test. The phenomenon of negative crack growth may be eliminated by the offset technique. There is no effect of aging on J sub(IC) and dJ/da in iso-thermal aged (375 degree C x 66 days) specimen, but there is very little effect in iso-thermal aged (375 degree C x 200 days) specimen.

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Rock mechanics and wellbore stability in Dongfang 1-1 Gas Field in South China Sea

  • Yan, Chuanliang;Deng, Jingen;Cheng, Yuanfang;Yan, Xinjiang;Yuan, Junliang;Deng, Fucheng
    • Geomechanics and Engineering
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    • v.12 no.3
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    • pp.465-481
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    • 2017
  • Thermal effect has great influence on wellbore stability in Dongfang 1-1 (DF 1-1) gas field, a reservoir with high-temperature and high-pressure. In order to analyze the wellbore stability in DF1-1 gas field, the variation of temperature field after drilling was analyzed. In addition, the effect of temperature changing on formation strength and the thermal expansion coefficients of formation were tested. On this basis, a wellbore stability model considering thermal effect was developed and the thermal effect on fracture pressure and collapse pressure was analyzed. One of the main challenges in this gas field is the decreasing temperature of the wellbore will reduce fracture pressure substantially, resulting in the drilling fluid leakage. If the drilling fluid density was reduced, kick or blowout may happen. Therefore, the key of safe drilling in DF1-1 gas field is to predict the fracture pressure accurately.

Experimental Study on the Thermal Effect of BIPV Modules Depending on the Ventilation Type of PV Module Backside (후면 환기조건에 따른 건물외피용 태양광발전(BIPV) 모듈의 열적 영향에 관한 실험연구)

  • Yoon, Jong-Ho;Kim, Jae-Ung
    • Journal of the Korean Solar Energy Society
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    • v.26 no.1
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    • pp.81-89
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    • 2006
  • Building integrated photovoltaic (BIPV) system operates as a multi-functional building construction material. They not only produce electricity, but also are building integral components such as facade, roof, window and shading device. On the other hands lots of architectural considerations should be reflected such as Installation position, shading, temperature effect and so on. As PV modules function like building envelope in BIPV, combined thermal and PV performance should be simultaneously evaluated This study is on the combined thermal and PV performance evaluation of BIPV modules. The purpose of this study is to investigate a temperature effect of PV module depending on the ventilation type of PV module backside. Test cell experiment was performed to identify the thermal and power effect of PV modules. Measurement results on the correlation of temperature and power generation were obtained. Those results can be utilized for the development of optimal BIPV installation details in the very early design stage.

Design of Microstructure by Evaluating the Effect of Thermal Barrier Coating's Microstructure on TGO Interface Stress (열차폐코팅의 미세구조가 TGO 계면 응력에 미치는 영향 평가를 통한 미세구조 형상 설계)

  • Kim, Damhyun;Park, Kibum;Wee, SungUk;Kim, Keekeun;Park, Soo;Seok, Chang-Sung
    • Journal of the Korea Institute of Military Science and Technology
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    • v.23 no.5
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    • pp.435-443
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    • 2020
  • Thermal barrier coating(TBC) applied to fighter and turbine engines is a technology that improves the durability of core parts by lowering the surface temperature of base material. The thermal stress caused by mis-match of the coefficient of thermal expansion between the top coating and the TGO interface is the main cause of TBC breakage. Since the thermal stress is dependent on the microstructure of the TBC, designing microstructure of TBC can improve the durability as well as lower the thermal stress. In this study, the effect of coating thickness, volume of porosity and vertical cracking on the thermal stress was analyzed through finite element analysis. Through the analysis results, a design range of a microstructure that can improve the durability of thermal barrier coating by lowering thermal stress is proposed.

The effect of air velocity on the thermal resistance of wool ensembles (풍속변화에 따른 순모의류의 온열특성)

  • 송민규;전병익
    • Journal of the Korean Society of Clothing and Textiles
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    • v.22 no.5
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    • pp.565-574
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    • 1998
  • The purpose of the study was to determine the effect of air velocity on the thermal resistance of wool ensembles. Three suits for men with different weaving structure and density were made with the same design and size for the study. In addition, Y-shirt, underwear, and socks were prepared for constructing the ensembles. Thermal insulation of air layer and 3 ensembles were measured by using thermal manikin in environmental chamber controlled at 2$0^{\circ}C$ and 65% RH with various air velocity. The results were as follows: 1. Thermal resistance of air layer was 0.079 m2.$^{\circ}C$/W with no air velocity(less than 0.2m/sec). 2. Thermal resistance of air layer decreased with increasing the air velocity rapidly. When the air velocity was 0.25 and 2.89 m/sec, the decreasing rate was 15% and 61%, respectively compared with no air velocity. 3. While there was little difference among the effective thermal insulation of 3 ensembles having different weaving structure and density with no air velocity, there was sharp difference among them when the air velocity increased. That is, the decreasing rate of effective thermal insulation of the ensemble which has higher air permeability was higher. 4. The decreasing rates of the effective thermal resistances of plain, twill and satin ensemble were 61, 54, and 49%, respectively when the air velocity was 2.89 m/sec which was a maximum air velocity in this study.

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The Effect of Shrink fit on the Thermal Crown Analysis in Twin Roll Strip Casting Process (쌍롤형 박판주조공정에서 열박음을 고려한 열적 크라운해석)

  • 박철민;박경진
    • Journal of the Korean Society for Precision Engineering
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    • v.19 no.11
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    • pp.200-210
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    • 2002
  • In twin roll strip casting process, coupled analyses of heat transfer and deformation for the cast roll are carried out by using the finite element program MARC to examine the thermal crown. Shrink fit effect and plastic deformation are considered. The results shows that the thermal crown is greatly influenced by shrink ft and that the thermal crown for POSCO Pilot Caster 2 Copper Roll has “M” shape. The effects of several factors on thermal crown are also investigated. The amount of thermal crown increases as heat flux, casting speed, steeve thickness and casting roll width increase and decreases as the casting roll diameter increases.

Synthesis of Epoxy Functional Siloxane and its Effect on Thermal Stress

  • Hyun, Dae-Sup;Jeong, Noh-Hee
    • Journal of the Korean Applied Science and Technology
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    • v.26 no.4
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    • pp.379-384
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    • 2009
  • Epoxy resin based encapsulants are widely used in semiconductor packaging applications. Epoxy resin based encapsulants are often subject to crack or delamination during the reliability test due to the thermal stress caused by high modulus nature of epoxy resins. Epoxy functional siloxanes are often added into epoxy resin to reduce the modulus so that the thermal stress can be reduced. Epoxy functional siloxanes, additives for reduced modulus, were synthesized and added into the curable epoxy resins. The modulus and the coefficient of thermal expansion (CTE) were also measured to investigate the thermal stress and to see whether the epoxy functional siloxane adversely affects the CTE or not. As a result, around 26% to 72% of thermal stress reduction was observed with no adverse effect on CTE.

Effect of the size of active device and heatsink of power MOSFETs on its the junction to ambient transient thermal behavior

  • Koh, Jeong-Wook;An, Chul
    • Proceedings of the IEEK Conference
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    • 2000.11b
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    • pp.241-244
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    • 2000
  • To investigate the compact effect of the different area of an active layer and the different type of heatsink on the junction to ambient transient thermal impedance, we have characterized the thermal behavior of power MOSFETs that have three different areas of an active layer and two types of heatsink. To do so, the "cooling curve method" has been used in order to measure the junction-to-ambient transient thermal impedance Zthja that represents the thermal behavior of the devices. The measured data depiets that the larger area of an active layer gives the better-in other words. smaller-thermal impedance, and that the larger size of a heatsink improves the thermal impedance.

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Analysis of Nocturnal Thermal Insulation Effect of Thermal Curtain in Plastic Greenhouse (야간(夜間)의 온실내(溫室內) 보온(保溫)커텐의 보온효과분석(保溫效果分析))

  • Cho, Yong-Baeg;Koh, Hak-Kyun;Kim, Moon-Ki;Kim, Yong-Hyeon
    • Solar Energy
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    • v.9 no.1
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    • pp.22-29
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    • 1989
  • A simulation model of plastic greenhouse was developed to evaluate the insulation effect of thermal curtain. Change in thermal environment with and without thermal curtain was verified through experiments, which agreed with the predicted values satisfactorily. About 18 to 20% of energy was saved in the plastic greenhouse by employing the P.E. film thermal curtain. Employing P.E. film thermal curtain also raised the temperature of the covering film and inner air by $1^{\circ}C$ and $1.5{\sim}1.8^{\circ}C$, respectively.

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A Study of the Effect of Borehole Thermal Resistance on the Borehole Length (보어홀 전열저항이 보어홀 길이에 미치는 영향에 관한 연구)

  • Lee, Se-Kyoun;Woo, Joung-Son
    • Journal of the Korean Solar Energy Society
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    • v.29 no.5
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    • pp.20-27
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    • 2009
  • The effect of borehole thermal resistance on the borehole length is studied. In performing this work a new concept BLRR(borehole length reduction rate) is developed based on the line source model. The solution of line source model is shown to be valid through the comparison with the data of thermal response test. It is shown that BLRR is a function of soil thermal conductivity(k) and borehole thermal resistance($R_b$). The value of BLRR increases with increasing k, which means reducing $R_b$ is more effective when k is high. The reduction of borehole length with change of $R_b$ is easily estimated with BLRR. The validity of BLRR is also examined with EED analysis.