• 한국마이크로전자및패키징학회:학술대회논문집
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• 한국마이크로전자및패키징학회 2002년도 추계기술심포지움논문집
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• pp.39-47
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• 2002

Heat is always the root of stress acting upon the electronic package, regardless of the heat due to the device itself during operation or working under the adverse environment. Due to the significant mismatch in coefficient of thermal expansion (CTE) and the thermal conductivity (K) of the packaging components, on one hand intensive research has been conducted in order to enhance the device reliability by minimizing the mechanical stressing and deformation within the package. On the other hand the effectiveness of different thermal enhancements are pursued to dissipate the heat to avoid the overheating of the device. However, the interactions between the thermal-mechanical loading has not yet been address fully. in articular when the temperature gradient is considered within the package. To address the interactions between the thermal loading upon the mechanical stressing condition. coupled-field analysis is performed to account the interaction between the thermal and mechanical stress distribution. Furthermore, process induced defects are also incorporated into the analysis to determine the effects on thermal conducting path as well as the mechanical stress distribution. It is concluded that it feasible to consider the thermal gradient within the package accompanied with the mechanical analysis, and the subsequent effects of the inherent defects on the overall structural integrity of the package are discussed.

• 한국정밀공학회지
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• 제19권1호
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• pp.56-64
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• 2002

Machine tools are engineered to give high dimensional accuracy in machining operation. However, errors due to thermal effects degrade dimensional accuracy of machine tools considerably, and many machine tools are equipped with thermal error compensation function. In general, thermal errors can be generated in the angular directions as well as linear directions. Among them, thermal errors in the angular directions contribute a large amount of error components in the presence of offset distance as in the case of Abbe error. Because most of thermal error compensation function is based on a good correlation between temperature change and thermal deformation, angular thermal deformation is often to be the most difficult hurdle for enhancing compensation accuracy. In this regard, this paper investigates the effect of thermal bending to total thermal error and gives how to deal with thermally induced bending effects in thermal error compensation.

• 한국의류학회지
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• 제8권1호
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• pp.1-11
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• 1984

An attempt was made to determine individual thermal resistances of 2-lining fabrics ad 4-outer fabrics for Korean-styled clothes, and 4-lining fabrics ad 5-outer fabrics for Western-styled clothes at $19^{\circ}C$ and $24^{\circ}C$. The thermal insulation effects for different lining fabrics in Korean and Western-styled clothes were deduced in determining heart rate, rectal temperature, mean skin temperature and microclimates of subjects. The subjects were dressed experimental clothing which were made of lining and outer fabrics in question, and seated in an environmental chamber during the experiment. 1. Thermal resistances of lining fabrics : For Korean-styled clothes. nylon sheer is larger than unzosa. For Western-styled clothes, rayon, acetate, nylon(taffeta) and kalkali in that order. 2. Thermal resistances of lining fabrics combined : with outer fabrics: For Korean-styled clothes. the measured value is larger than the one of simple aggregate value. But in the case of Western-styled clothes, the measured value is smaller than simple aggregate value. 3. The effects of lining on the thermal insulation of the whole clothing: In case when subjects wore unlimited number of underwear, no matter what lining fabrics were used in Korean and Western-styled clothes less thermal insulation effects were indicated. For the case, however, if subjects wore only limited underwear, there are significant differences of thermal insulation between experimental clothings.

• 한국세라믹학회지
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• 제55권6호
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• pp.608-617
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• 2018

The effects of the purity and monoclinic phase of feedstock powder on the thermal durability of thermal barrier coatings (TBC) were investigated through cyclic thermal exposure. Bond and top coats were deposited by high velocity oxygen fuel method using Ni-Co based feedstock powder and air plasma spray method using three kinds of yttria-stabilized zirconia with different purity and monoclinic phase content, respectively. Furnace cyclic thermal fatigue test was performed to investigate the thermal fatigue behavior and thermal durability of TBCs. TBCs with high purity powder showed better sintering resistance and less thickness in the thermally grown oxide layer. The thermal durability was found to strongly depend on the content of monoclinic phase and the porosity in the top coat; the best thermal fatigue behavior and thermal durability were in the TBC prepared with high purity powder without monoclinic phase.

• 한국의류학회지
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• 제23권8호
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• pp.1110-1118
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• 1999

This study was to examine the effects of garment types on thermal insulation using a thermal manikin. cotton polyester wool silk and rayon were selected as outer wears like a blouse a skirt slacks and one-piece for this study Acetate was chosen as a lining. Brief and upper innerwear with long sleeves(cotton) were also chosen as the innerwear. The results were as follows: 1. The thermal insulation of the garment of single layer was in proportion to the covering area of garment in all types of clothing. 2. On adding the innerwear or the lining or both the thermal insulation of the each garment of single layer were showed a different trends by garment types. The thermal manikin insulations of one-piece dress adding the innerwear was higher than those of blouse-skirt suits. The thermal insulation of one-piece dress adding the innerwear and lining was lower than those of blouse-skirt suits. 3. The increasing rates of thermal insulation of multi-layered garments had different value by garment types but garment made of rayon and silk were showed very high increasing rates of thermal insulation. 4. The increasing rates of the thermal insulation of one-piece dress added the lining the innerwear or both except polyester showed the highest value and then blouse-slacks suits' turn came ound Blouse-skirt suits had the lowest the increasing rates of thermal insualition value.

• 호남수학학술지
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• 제38권3호
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• pp.435-454
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• 2016

This paper investigates the effect of dual-phase-lags on a thermoviscoelastic orthotropic solid with a cylindrical cavity. The cylindrical cavity is subjected to a thermal shock varying heat and its material is taken to be of Kelvin-Voigt type. The phase-lag thermoelastic model, Lord and Shulman's model and the coupled thermoelasticity model are employed to study the thermomechanical coupling, thermal and mechanical relaxation (viscous) effects. Numerical solutions for temperature, displacement and thermal stresses are obtained by using the method of Laplace transforms. Numerical results are plotted to illustrate the effect phase-lags, viscoelasticity, and the variability thermal conductivity parameter on the studied fields. The variations of all field quantities in the context of dual-phase-lags and coupled thermoelasticity models follow similar trends while the Lord and Shulman's model may be different. The influence of viscosity parameter and variability of thermal conductivity is very pronounced on temperature and thermal stresses of the thermoviscoelastic solids.

• Nuclear Engineering and Technology
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• 제56권6호
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• pp.2099-2112
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• 2024

This study examined the effects of CRUD on reflood heat transfer behaviors of nuclear fuel rods during a loss-of-coolant-accident (LOCA) in a pressurized water reactor using a best-estimate thermal-hydraulic analysis code. Changes in thermal properties and boiling heat transfer characteristics of the CRUD layer were extensively reviewed, and a set of correction factors to reflect the changes was implemented into the code. A heat structure layer reflecting the effects of CRUDs on the properties was added to the outer surface of the fuel cladding. Numerical simulations were conducted to examine the effects of CRUDs on reflood cooling of overheated fuel rods for representative separate and integral effect tests, FLECHT-SEASET and LOFT. In LOFT analysis, the average cladding temperature was increased due to the low thermal conductivity of CRUD during steady-state operation; however, in both analyses, the peak cladding temperature decreased, and the quenching time was reduced. Obtained results revealed that when the porous CRUD layer is deposited on the fuel cladding, two opposite effects appear. Low thermal conductivity of the CRUD layer always increases fuel temperature during normal operation; however, its hydrophilic porous structures may contribute to accelerated reflood cooling of fuel rods during a LOCA.

• Tribology and Lubricants
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• 제11권3호
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• pp.31-39
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• 1995

Grease thermal elastohydrodynamic lubrication (TEHL) problems of line contacts are analyzed numerically. The effects of temperature and rheological paraineters on grease TEHL are investigated using the Herschel-Bulkley model as a theological model of greases. The pressure distribution, the shape of grease film, mean film temperature and surface temperature of solid wall in line contacts are obtained. It is found that thermal effects on the minimum film thickness become remarkable at high rolling speeds. The effect of yield stress of Herschel-Bulkley model on minimum film thickness is negligible, while the theological index and viscosity parameter have significant effects on minimum film thickness.

• Bulletin of the Korean Chemical Society
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• 제17권8호
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• pp.682-685
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• 1996

Photothermal properties depend on the characteristics of energy transfer processes in solution. In this study, a time-resolved single beam thermal lens experiment in various solvents is employed to investigate the energy coupling effects which govern the energy transfer processes. Interestingly, it is observed that the behaviour of the photothermal propagation in solution depends on the property of solution and the concentration of solute in a single beam thermal lens configuration. These characteristics lead us to consider the solute-solvent coupling effects as well as the solvent-solvent interactions.

• Journal of applied mathematics & informatics
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• 제32권5_6호
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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.