• Journal of the Korean Society of Industry Convergence
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• v.22 no.6
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• pp.767-773
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• 2019

The thermal diffusion performance of the electronic device is a factor for evaluating the stability of the electronic device. Therefore, many of research have been conducted to improve the thermal characteristics of thermal interface materials, which are materials for thermal diffusion of electronic products. In this study, nano thermal grease was prepared by blending graphene, silver and copper nano powders into a thermal grease, a type of thermal interface materials, and the heat transfer rate was measured and compared for the purpose of investigating the improved thermal properties. As a result, the thermal properties were good in the order of graphene, silver and copper, which is thought to be due to the different thermal properties of the nano powder itself.

• Journal of Photoscience
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• v.9 no.2
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• pp.194-196
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• 2002

While ultraviolet radiation alters various cutaneous cell functions, little is known about photo-immunological and photobiological effects of infrared radiation (IR) on the skin except its local thermal effects. The fIrst part of this study demonstrated that single exposure of mouse skin to near IR (0.7 - 1.3 $\mu$m) reversibly suppressed the proliferating activity of the epidermis, the density of Langerhans cells, and the ability of skin to induce contact hypersensitivity reaction. The second part demonstrated that the rate of wound closure was significantly accelerated by repeated exposures in animal models. The production of transforming growth factor-$\beta$l and matrix metalloproteinase-2, which are responsible for the wound healing processes, was significantly upregulated by irradiation, as shown by enzyme immunoassay, zymography, and reverse transcription polymerase chain reaction. Thermal controls were negative. The results suggest that near-IR irradiation can modulate the epidermal proliferation and part of the skin immune system, and stimulate the wound healing processes, presumably by non-thermal effects.

• Journal of Ginseng Research
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• v.42 no.2
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• pp.225-228
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• 2018

Our results suggested that thermal stress can lead to activation of hippocampal cell damage and reduction of memory-associated molecules in HT22 cells. These findings also provide a part of molecular rationale for the role of ginsenoside Rg5 as a potent cognitive impairment preventive compound in blocking the initiation of hippocampal damage.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.20 no.10
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• pp.3408-3414
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• 1996

This paper investigated plane strain stress intensity factors caused by thermal impact on a center-crack strip. The crack was aligned perpendicularly to the strip boundary. The problem was analysed by determining the dislocation density function in the singular integral equations formulated by the dislocation theory. Under the abrupt temperature change along the edge, the center crack behaved as a mode I crack due to the symmetric geometry. The value of maximum stress intensity factor monotonically increased until the ratio of dimensionless crack length approached to about 0.3, followed by gradual decrease. As a result, a critical corresponding crack length was determined.

• Advances in nano research
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• v.8 no.4
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• pp.283-292
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• 2020

In the present research, differential quadrature (DQ) method has been utilized for investigating free vibrations of porous functionally graded (FG) micro/nano beams in thermal environments. The exact location of neutral axis in FG material has been assumed where the material properties are described via porosity-dependent power-law functions. A scale factor related to couple stresses has been employed for describing size effect. The formulation of scale-dependent beam has been presented based upon a refined beam theory needless of shear correction factors. The governing equations and the associated boundary conditions have been established via Hamilton's rule and then they are solved implementing DQ method. Several graphs are provided which emphasis on the role of porosity dispersion type, porosity volume, temperature variation, scale factor and FG material index on free vibrational behavior of small scale beams.

• Computational Structural Engineering
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• v.11 no.1
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• pp.153-160
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• 1998

A small break loss of coolant accident is postulated as a pressurized thermal shock accident in this study. From the temperature and pressure histories of coolant, distributions of the temperature and stress in a vessel wall are analytically calculated. The stress intensity factor and fracture toughness of the vessel wall are determined at the crack tip using the ASME code method and they are compared to check if cracking is expected to occur during the transient postulated. The maximum allowable reference nil-ductility transition temperatures are determined for various crack sizes and the results are discussed.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.16 no.6
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• pp.94-102
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• 2007

Applications of bonded dissimilar materials such as large scale integration (LSI) packages, ceramics/metal and resin/metal bonded joints, are very increasing in various industry fields. It is very important to analyze the thermal stress and stress singularity at interface edge in LSI. In order to investigate stress singularities on the bonded interface edges and delamination of die pad and resin in the IC package. In this paper, stress singularity factors(${\Gamma}_i$) and stress intensity factors($K_i$) considering thermal stress in the IC package were analyzed by using the 2-dimensional elastic boundary element method(BEM).

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.07b
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• pp.916-919
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• 2004

This paper studied about the (100) orientation of PZT thin films coated on the LNO electrode using a different thermal annealing. The thermal annealing method is divided into two things. The one is the method transferring heat to only the lower substrate and another is transferring heat to all directions. Orientation factor of PZT in the method of transferring heat to only the lower substrate was F=99% in the thermal annealing of the LNO. Orientation factor of PZT was F=67% in the method of transferring heat to all directions.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.12 no.1
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• pp.26-32
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• 2000

Design load calculations which depend on the thermal characteristics of the building structure such as the wall, roof, and fenestration provide the basic data for selecting an HVAC system and its equipment. Most of domestic multi-family houses include a high thermal storage layer like massive concrete structure and a floor heating structure. This study is to compare the results of the design heating load between steady state and unsteady state calculation in order to comprehend the thermal storage effect in multi-family houses. The design heating load under the steady state calculation is estimated from 5.4% to 7.8% larger than that under the unsteady state in the typical floor of a multi-family house model. The design heating load considered the safety factors like a orientation and location factor also is 21.4% to 26.5% larger than that by the unsteady state calculation. So, the safety factors for use of the practicing engineer are analyzed as the main factor of a heating plant oversizing.

• The Magazine of the Society of Air-Conditioning and Refrigerating Engineers of Korea
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• v.12 no.3
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• pp.189-197
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• 1983

In this study, the thermal environment of a certain building was investigated by using of concerned equipments and enquete sheets. The measured items were temperature, humidity, air flow and radiant heat, and thermal responses for the occupants were checked also, which are oriented to be used as basic data for environmental design. The results of this study are as followed. 1. The optimal room temperature was $24\~26.5^{\circ}C$ DBT in cooling season. 2. Under the condition from $50\%\;to\;70\%$ of relative humidity, the difference of relative humidity did not impact upon the feeling temperature. 3. In cooling season, the average clothing factor of occupants was 0.34 clo ; 0.49 clo for men and 0.25 clo for women. 4. The average working factor of occupants was $1.1\~1.3\;Met$ in that cooling season.