• Proceedings of the KIEE Conference
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• 2006.07e
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• pp.7-8
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• 2006

가공배전선로의 이도는 탄성계수와 선팽계수에 따라 온도 및 장력의 변화에 대하여 다른 변화를 나타낸다. 따라서 본 연구에서는 정확한 이도설계와 선로의 장기신뢰성 확보를 위해 배전선 주요 규격에 대하여 탄성계수와 선팽창계수를 실측하여 계산값과 측정값에 어떠한 차이가 있는지를 비교하였다. 시험결과 전선의 탄성계수와 선팽창계수는 제작공정상의 여러 요인들에 의하여 영향을 받는 것으로 나타났으며, 이도설계시 탄성계수와 선팽창계수는 배전선의 측정값을 적용하는 것이 바람직 한 것으로 나타났다.

• Journal of the Korean Ceramic Society
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• v.40 no.11
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• pp.1127-1131
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• 2003

Phosphate glasses known for low melting temperature glasses in electrical parts has been recently used in wide area with modification of thermal properties using alkali oxides. It is our purpose to find a correlation between thermal expansion coefficient, glass transition temperature and melting temperature through investigating thermal properties in P$_2$O$\sub$5/-SnO-ZnO-SiO$_2$/B$_2$O$_3$. As a result, the product of thermal expansion coefficient and the glass transition temperature in the glasses is found to be a constant value would be a unique value for knowing one of thermal properties.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.11a
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• pp.520-521
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• 2007

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.06a
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• pp.549-550
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• 2006

• Journal of Korea Foundry Society
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• v.42 no.4
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• pp.255-260
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• 2022

• Journal of the Korea institute for structural maintenance and inspection
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• v.11 no.5
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• pp.89-98
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• 2007

This study investigates the deformation behavior, related to debonding failure, of adhesion and repairing-strengthening materials of RC construction. A strain-stress curve shows that when the stress of specimens reached the highest and then fails, the strain value of cement mortar is $2.0{\times}10^{-3}$, while concrete was indicated at around $1.3{\times}10^{-3}$, epoxy resins are $0.8{\times}10^{-3}$, polymer mortar is $2.5{\times}10^{-3}$, steel plate is $2.5{\times}10^{-3}$, and carbon bar was $9.1{\times}10^{-3}$, respectively. For a thermal expansion coefficient with temperature variation, those basis materials, cement mortar and concrete, exhibited around $10{\mu}{\varepsilon}/{^{\circ}C}$, but adhesive materials, such as epoxy resins and polymer mortar, were $41{\sim}54{\mu}{\varepsilon}/{^{\circ}C}$ and $-0.5{\sim}0.7{\mu}{\varepsilon}/{^{\circ}C}$, respectively. In the case of steel plate is similar to basic materials but carbon fiber is indicates at $-1.7{\mu}{\varepsilon}/{^{\circ}C}$, which is the lowest value. Especially, between basic and adhesive materials, the thermal expansion coefficient was highly different. Although the coefficient depends on the type of epoxy resins, it is clear that the epoxy resins are susceptible to be debonded in nature, when the difference of environmental temperature varies more than $20{\sim}35{^{\circ}C}$.

• Korean Journal of Materials Research
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• v.11 no.4
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• pp.305-311
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• 2001

$PbO-B_2O_3-SiO_2-Al_2O_3$, system was investigated for optical, thermal and electrical properties of transparent dielectric. We also studied the reaction between transparent dielectric and transparent electrode(Indium Tin Oxide, ITO) during firing. For the evaluation of properties, dielectrics were prepared under the conditions fired at 520~58$0^{\circ}C$ with 12$\mu\textrm{m}$ thickness. In the reaction between dielectrics and electrode(ITO), In ions diffused into dielectric layer, while Sn ion diffusion was not observed. The coefficient of thermal expansion, the dielectric constant, the glass transition temperature and the transmittance of the dielectric were greatly dependent on PbO content. The increase of the coefficient of thermal expansion and the dielectric constant were monitored by increasing PbO, while the glass transition temperature and the transmittance were decreased. With the increased $Al_2O_3/B_2O_3$ ratio, the coefficient of thermal expansion and the transmittance were decreased, while the dielectric constant was increased. The glass transition temperature did not change significantly.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2011.04a
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• pp.119-122
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• 2011

분자동역학 전산모사를 통하여 에폭시에 다양한 반경의 구형 실리콘 카바이드를 삽입한 나노복합재를 모델링하고, 이들의 기계적 물성과 열적 물성 해석을 다양한 온도조건 하에서 수행하였다. 전산모사 결과 동일한 체적분율 하에서 나노복합재는 입자의 크기가 작아질수록 탄성계수와 전단계수가 상승하는 동시에 선팽창계수는 감소하는 입자의 크기효과를 보였다. 또한 온도 상승에 따른 기계적 물성의 하락이 잘 관찰되었다. 본 연구에서는 이러한 분자동역학 해석 결과를 바탕으로 다양한 온도조건 하에서의 입자의 크기효과를 고려한 멀티스케일 3상 모델을 제시하였다. 유리상 조건 범위에서 온도 변화에 따른 나노복합재 계면의 열응력텐서와 열변형률텐서의 정보를 통해 복합재 내에서 계면이 차지하는 부피비를 온도에 대한 함수로 고려하고, 이를 멀티스케일 모델에 반영함으로써 다양한 온도조건에 대한 나노복합재 열탄성 물성의 예측해를 제시하였다. 본 연구에서 제시한 모델에서 계산된 3상 복합재의 물성은 분자동역학 전산모사의 결과에서 나타나는 나노입자의 크기효과를 잘 반영하였다.

• Journal of Korea Foundry Society
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• v.17 no.1
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• pp.36-50
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• 1997

Invar-type austenitic cast irons are being used as low thermal expansive materials because of its good low thermal expansion characteristics and castability despite its low hardness. The effects of alloying elements such as Cr, Ti, V, and Mo on hardness and linear thermal expansion coefficient of the invar-type austenitic cast irons were investigated. A combined use of V and Mo addition was found to be the most effective for the improvement of hardness without causing an increase in the thermal expansion coefficient. With a combined addition of 4.6wt%V and 3.8wt%Mo, the hardness increased up to 180HB and the thermal expansion coefficient was kept at a relatively low value of $4.6{\times}10^{-6}/^{\circ}C$ in the temperature range from room to $250^{\circ}C$.

• Journal of Engineering Education Research
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• v.16 no.2
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• pp.24-30
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• 2013

This paper deals with the measurement theory and technique of linear expansion coefficient for solid material using Michelson interferometer. The Michelson interferometer produces interference fringes by splitting a beam of monochromatic light so that one beam strikes a fixed mirror and the other a movable mirror. When the reflected beams are brought back together, an interference pattern results. Precise distance measurements until a quarter of wave length can be made with the Michelson interferometer by moving the mirror and counting the interference fringes which move by a photo diode. This paper represents the application of Michelson interferometer for measuring infinitesimal length system and shows the measurement method of linear expansion coefficients for various materials like copper, aluminum and iron. the results are good agreement with theoretical value within margin of error for each materials.