• 한국진공학회:학술대회논문집
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• 한국진공학회 2011년도 제40회 동계학술대회 초록집
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• pp.50-50
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• 2011

The aluminum nitride films were prepared by RF magnetron sputtering using an AlN ceramic target. The crystallinity, grain size, Al-N bonding and thermal conductivity were investigated in dependence on the plasma power densities (4.93, 7.40, 9.87 W/$cm^2$) during sputtering. High thermal conductivity is important properties of A1N passivation layer for functioning properly in thermal inkjet printhead. The crytallinity, grain size, Al-N bonding formation and chemical composition were observed using X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), fourier transform infrared (FTIR) and X-ray photoelectron spectroscopy (XPS), respectively. The AlN thin film was changed from amorphous to crystalline as the power density was increased, and the largest grain size appeared at medium power density. The near stoichiometry Al-N bonding ratio was acquired at medium power density. So, we know that the AlN thin film had better thermal conductivity with crystalline phase and near stoichometry Al-N bonding ratio at 7.40 W/$cm^2$ power density.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2011년도 제40회 동계학술대회 초록집
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• pp.14-14
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• 2011

Graphene is known to possess excellent thermal properties, including high thermal conductivity, that make it a prime candidate material for heat management in ultra large scale integrated circuits. For device applications, the key parameters are the thermal expansion coefficient and the thermal conductivity. There has been no reliable experimental determination on the thermal expansion coefficient of graphene whereas the estimates of the thermal conductivity vary widely. In this work, we estimate the thermal expansion coefficient of graphene on silicon dioxide by measuring the temperature dependence of the Raman spectrum. The shift of the Raman peaks due to heating or cooling results from both the intrinsic temperature dependence of the Raman spectrum of graphene and the strain on the graphene film due to the thermal expansion mismatch with silicon dioxide. By carefully comparing the experimental data against theoretical calculations, it is possible to determine the thermal expansion coefficient. The thermal conductivity is measured by estimating the thermal profile of a graphene film suspended over a circular hole of the substrate.

• E2M - 전기 전자와 첨단 소재
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• 제10권7호
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• pp.713-718
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• 1997

Polyaniline free standing films cast from N-methyl-2-pyrrolidinone(NMP) solution, camphorsulfonic acid(HCSA), dodecylbenzensulfonic acid(HDBSA), inorganic matter(carbon black, graphite) and metal(silver) were prepared by processings. The properties of these films such as crystallinity, near-infrared absorption spectra and conductivity were investigated. The HCSA and HDBSA doped polyaniline films cast from m-cresol and chloroform solvents showed the metallic property and high crystallinity, respectively. The value of conductivity in the HCSA doped polyaniline film obtained 180 S/cm. We have obtained the value of conductivity 200 S/cm in the metal(silver) doped polyaniline film, which is higher than that of the HCSA doped polyaniline film. The metal(silver) doped polyaniline film shows good properties as a electromagnetic shielding material.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2001년도 추계학술대회 논문집
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• pp.451-454
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• 2001

The ionic conductivity of cubic solid solutions in the system Y$_2$O$_3$-ZrO$_2$ prepared by SHS was examined. Conductivity-temperature data obtained at 1000$^{\circ}C$ in atmosphere of low oxygen partial pressure (10$\^$-40/ atm) for Y$_2$O$_3$-ZrO$_2$ cubic solid solutions indicated that these materials could be reduced, the degree of reduction being related to the measuring electric field. At low impressed fields no reduction was observed. Thus, these conductivity data give a transference number for the oxygen ion in Y$_2$O$_3$-ZrO$_2$ cubic solid solutions greater than 0.99.

• Macromolecular Research
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• 제10권6호
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• pp.345-358
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• 2002

The electrical conductivity during vulcanization process was measured as a function of time for the system of TiC loaded styrene-butadiene rubber (SBR) composites. The phenomenon of negative and positive temperature coefficients of conductivity and its conduction mechanism were also studied for the SBR polymeric composites. The current-voltage characteristics of the polymeric composites were non-linear in high voltage and showed a switching effect. The effects of temperature on the thermal conductivity and effective dielectric constant were measured. The measured parameters were found to be dependent on TiC concentration. The electromagnetic wave shielding (EMS) of the SBR-TiC polymeric composite was also examined. The SBR filled with TiC could be expected to be promising novel smart polymeric composites for self-electrical heating, temperature sensor, time delay switching, and electro-magnetic wave shielding effectiveness.

• Nuclear Engineering and Technology
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• 제50권5호
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• pp.731-737
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• 2018

In this research paper, the thermal transport in thorium dioxide is investigated by using nonequilibrium molecular dynamics. The thermal conductivity of bulk thorium dioxide was measured to be 20.8 W/m-K, confirming reported values, and the phonon mean free path was estimated to be between 7 and 8.5 nm at 300 K. It was observed that the thermal conductivity of thorium dioxide shows a strong dependency on temperature; the highest thermal conductivity was estimated to be 77.3 W/m-K at 100 K, and the lowest thermal conductivity was estimated to be 4.3 W/m-K at 1200 K. In addition, by simulating thorium dioxide structures with different lengths at different temperatures, it was identified that short wavelength phonons dominate thermal transport in thorium dioxide at high temperatures, resulting in decreased intrinsic phonon mean free paths and minimal effect of boundary scattering while long wavelength phonons dominate the thermal transport in thorium dioxide at low temperatures.

• Bulletin of the Korean Chemical Society
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• 제6권1호
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• pp.11-15
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• 1985

Electrical conductivites of polycrystalline yttrium sesquioxides containing 1.6 and 3.2 mol % of holmium sesquioxdes have been measured from 650 to $1050^{\circ}C$ under oxygen partial pressures of $1{\times}10^{-5}$ to $2{\times}10^{-1}$ atm. Plots of log conductivity vs. 1/T at constant oxygen partial pressures are found to be linear away from the two inflection points. The low- and high-temperature dependences of conductivity show different defect structures of yttrium sesquioxide. The plots of log conductivity vs. log $PO_2$ are found to be linear at $PO_{2'}$s of $10^{-5}$ to $10^{-1} atm. The electrical conductivity dependences on $PO_2$ are found to be $1}5.3$ at $950-1050^{\circ}C$, $\frac{6}{1}$ at $800-950^{\circ}C$ and ($\frac{6.2}{1}$) - ($\frac{6.5}{1}$) at $650-800^{\circ}C$, respectively. The defect structures and conduction mechanisms have been suggested.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2021년도 봄 학술논문 발표대회
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• pp.127-128
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• 2021

Rigid urethane foam is widely applied because it is light and has superior insulation performance compared to insulation materials such as EPS or glass wool. However, it has the disadvantage of being vulnerable to fire. Therefore, in this study, before proceeding with the research to improve the fire resistance of the rigid polyurethane foam, we would like to investigate the change in density and thermal conductivity of the rigid polyurethane foam according to the change in the mixed weight of the main material and the curing agent. It was found that the density increased as the mixed weight increased. The thermal conductivity showed similar values overall. As for the density distribution, the central part was low and the outer part was high.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2023년도 봄 학술논문 발표대회
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• pp.45-46
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• 2023

CLC is used as a filling material for many buildings, and according to energy saving design standards, CLC also requires insulation performance. However, it shows lower insulation performance compared to organic insulation, so additional research is needed. Therefore, in this study, the insulation properties of CLC were analyzed by incorporating EPS beads with high insulation performance into CLC. In this experiment, EPS beads and blast furnace slag were replaced, and W/B was fixed at 33%. The EPS Bead mixing ratio was divided into 5 levels: 0, 0.5, 1.0, 1.5, 2.0 (%), and the experimental items were measured for apparent density and thermal conductivity. As a result of the experiment, the apparent density and thermal conductivity tended to decrease as the mixing ratio of EPS beads increased. It is judged that the density decreased due to the low density and the micropores inside, and the thermal conductivity also decreased.

• 폴리머
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• 제27권3호
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• pp.265-270
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• 2003

고분자 젤은 높은 이온 전도도를 가지는 대신에 나쁜 기계적 물성 때문에 많은 문제점을 가지고 있다. 다소 낮은 이온 전도도를 나타내면서 기계적, 열적, 화학적, 전기 화학적으로 우수한 특성을 가지는 근식 고체계와, 고분자 복합재료에 대한 많은 연구들이 진행 중에 있다. 본 연구는 PEO-LiClO$_4$(8:1)에 기초한 고체 고분자 전해질에 액체 상의 가소제가 아닌 고체 상으로 가소제의 역할을 하는 세라믹과 고무를 첨가시켜서 이온 전도도와 기계적 물성을 증가시키는 것에 대한 것이다. 이온 전도도는 세라믹 상과 고무상을 도입한 두 가지 경우 모두 ~$10^{-5}$ $cm^{-1}$ / 정도로 비슷하게 나타났는데, 이는 현재까지 연구되어진 것 중 최고의 값을 가지는 것과 비슷했다. 더 높은 이온 전도도를 얻기 위하여 다양한 분자량 (600~8000)을 가진 고분자를 혼합하였고, 염의 함량에 변화를 주었다. 염의 첨가와 첨가된 염의 함량에 따라 높은 결정성을 가지는 PEO가 무정형으로 바뀌는 것을 DSC 곡선을 통해 알 수 있었고, 다양한 함량의 LiClO$_4$를 첨가한 경우 고분자 유동성의 변화를 FT-IR을 통해 알 수 있었다.